Electroweak corrections to squark--anti-squark pair production at the LHC
O(alpha) QED Corrections to Polarized Elastic $mu e$ and Deep Inelastic l N Scattering
a r X i v :h e p -p h /9711228v 1 4 N o v 1997hep-ph/9711228October 1997O (α)QED Corrections to Polarized Elastic µe and Deep Inelastic lN ScatteringDima Bardin a,b,c ,Johannes Bl¨u mlein a ,Penka Christova a,d ,and Lida Kalinovskaya a,caDESY–Zeuthen,Platanenallee 6,D–15735Zeuthen,GermanybINFN,Sezione di Torino,Torino,ItalycJINR,ul.Joliot-Curie 6,RU–141980Dubna,RussiadBishop Konstantin Preslavsky University of Shoumen,9700Shoumen,BulgariaAbstractTwo computer codes relevant for the description of deep inelastic scattering offpolarized targets are discussed.The code µe la deals with radiative corrections to elastic µe scattering,one method applied for muon beam polarimetry.The code HECTOR allows to calculate both the radiative corrections for unpolarized and polarized deep inelastic scattering,including higher order QED corrections.1IntroductionThe exact knowledge of QED,QCD,and electroweak (EW)radiative corrections (RC)to the deep inelastic scattering (DIS)processes is necessary for a precise determination of the nucleon structure functions.The present and forthcoming high statistics measurements of polarized structure functions in the SLAC experiments,by HERMES,and later by COMPASS require the knowledge of the RC to the DIS polarized cross-sections at the percent level.Several codes based on different approaches for the calculation of the RC to DIS experiments,mainly for non-polarized DIS,were developped and thoroughly compared in the past,cf.[1].Later on the radiative corrections for a vast amount of experimentally relevant sets of kinematic variables were calculated [2],including also semi-inclusive situations as the RC’s in the case of tagged photons [3].Furthermore the radiative corrections to elastic µ-e scattering,a process to monitor (polarized)muon beams,were calculated [4].The corresponding codes are :•HECTOR 1.00,(1994-1995)[5],by the Dubna-Zeuthen Group.It calculates QED,QCD and EW corrections for variety of measuremets for unpolarized DIS.•µe la 1.00,(March 1996)[4],calculates O (α)QED correction for polarized µe elastic scattering.•HECTOR1.11,(1996)extends HECTOR1.00including the radiative corrections for polarized DIS[6],and for DIS with tagged photons[3].The beta-version of the code is available from http://www.ifh.de/.2The Programµe laMuon beams may be monitored using the processes ofµdecay andµe scattering in case of atomic targets.Both processes were used by the SMC experiment.Similar techniques will be used by the COMPASS experiment.For the cross section measurement the radiative corrections to these processes have to be known at high precision.For this purpose a renewed calculation of the radiative corrections toσ(µe→µe)was performed[4].The differential cross-section of polarized elasticµe scattering in the Born approximation reads,cf.[7],dσBORNm e Eµ (Y−y)2(1−P e Pµ) ,(1)where y=yµ=1−E′µ/Eµ=E′e/Eµ=y e,Y=(1+mµ/2/Eµ)−1=y max,mµ,m e–muon and electron masses,Eµ,E′µ,E′e the energies of the incoming and outgoing muon,and outgoing electron respectively,in the laboratory frame.Pµand P e denote the longitudinal polarizations of muon beam and electron target.At Born level yµand y e agree.However,both quantities are different under inclusion of radiative corrections due to bremsstrahlung.The correction factors may be rather different depending on which variables(yµor y e)are used.In the SMC analysis the yµ-distribution was used to measure the electron spin-flip asymmetry A expµe.Since previous calculations,[8,9],referred to y e,and only ref.[9]took polarizations into account,a new calculation was performed,including the complete O(α)QED correction for the yµ-distribution,longitudinal polarizations for both leptons,theµ-mass effects,and neglecting m e wherever possible.Furthermore the present calculation allows for cuts on the electron re-coil energy(35GeV),the energy balance(40GeV),and angular cuts for both outgoing leptons (1mrad).The default values are given in parentheses.Up to order O(α3),14Feynman graphs contribute to the cross-section forµ-e scattering, which may be subdivided into12=2×6pieces,which are separately gauge invariantdσQEDdyµ.(2) One may express(2)also asdσQEDdyµ+P e Pµdσpol kk=1−Born cross-section,k=b;2−RC for the muonic current:vertex+bremsstrahlung,k=µµ;3−amm contribution from muonic current,k=amm;4−RC for the electronic current:vertex+bremsstrahlung,k=ee;5−µe interference:two-photon exchange+muon-electron bremsstrahlung interference,k=µe;6−vacuum polarization correction,runningα,k=vp.The FORTRAN code for the scattering cross section(2)µe la was used in a recent analysis of the SMC collaboration.The RC,δA yµ,to the asymmetry A QEDµeshown infigures1and2is defined asδA yµ=A QEDµedσunpol.(4)The results may be summarized as follows.The O(α)QED RC to polarized elasticµe scattering were calculated for thefirst time using the variable yµ.A rather general FORTRAN codeµe la for this process was created allowing for the inclusion of kinematic cuts.Since under the conditions of the SMC experiment the corrections turn out to be small our calculation justifies their neglection. 3Program HECTOR3.1Different approaches to RC for DISThe radiative corrections to deep inelastic scattering are treated using two basic approaches. One possibility consists in generating events on the basis of matrix elements including the RC’s. This approach is suited for detector simulations,but requests a very hughe number of events to obtain the corrections at a high precision.Alternatively,semi-analytic codes allow a fast and very precise evaluation,even including a series of basic cuts andflexible adjustment to specific phase space requirements,which may be caused by the way kinematic variables are experimentally measured,cf.[2,5].Recently,a third approach,the so-called deterministic approach,was followed,cf.[10].It treats the RC’s completely exclusively combining features of fast computing with the possibility to apply any cuts.Some elements of this approach were used inµe la and in the branch of HECTOR1.11,in which DIS with tagged photons is calculated.Concerning the theoretical treatment three approaches are in use to calculate the radiative corrections:1)the model-independent approach(MI);2)the leading-log approximation(LLA); and3)an approach based on the quark-parton model(QPM)in evaluating the radiative correc-tions to the scattering cross-section.In the model-independent approach the QED corrections are only evaluated for the leptonic tensor.Strictly it applies only for neutral current processes.The hadronic tensor can be dealt with in its most general form on the Lorentz-level.Both lepton-hadron corrections as well as pure hadronic corrections are neglected.This is justified in a series of cases in which these corrections turn out to be very small.The leading logarithmic approximation is one of the semi-analytic treatments in which the different collinear singularities of O((αln(Q2/m2l))n)are evaluated and other corrections are neglected.The QPM-approach deals with the full set of diagrams on the quark level.Within this method,any corrections(lepton-hadron interference, EW)can be included.However,it has limited precision too,now due to use of QPM-model itself. Details on the realization of these approaches within the code HECTOR are given in ref.[5,11].3.2O (α)QED Corrections for Polarized Deep Inelastic ScatteringTo introduce basic notation,we show the Born diagramr rr r j r r r r l ∓( k 1,m )l ∓( k 2,m )X ( p ′,M h )p ( p ,M )γ,Z ¨¨¨¨B ¨¨¨¨£¢ ¡£¢ ¡£¢ ¡£¢ ¡£¢ ¡£¢ ¡£¢ ¡£¢ ¡£¢ ¡£¢ ¡z r r r r r r r r r r r r r rr ¨¨¨¨B ¨¨¨¨r r r r j r r r r and the Born cross-section,which is presented as the product of the leptonic and hadronic tensordσBorn =2πα2p.k 1,x =Q 2q 2F 1(x,Q 2)+p µ p ν2p.qF 3(x,Q 2)+ie µνλσq λs σ(p.q )2G 2(x,Q 2)+p µ s ν+ s µ p νp.q1(p.q )2G 4(x,Q 2)+−g µν+q µq νp.qG 5(x,Q 2),(8)wherep µ=p µ−p.qq 2q µ,and s is the four vector of nucleon polarization,which is given by s =λp M (0, n )in the nucleonrest frame.The combined structure functions in eq.(8)F1,2(x,Q2)=Q2e Fγγ1,2(x,Q2)+2|Q e|(v l−p eλl a l)χ(Q2)FγZ1,2(x,Q2)+ v2l+a2l−2p eλl v l a l χ2(Q2)F ZZ1,2(x,Q2),F3(x,Q2)=2|Q e|(p e a l−λl v l)χ(Q2)FγZ3(x,Q2),+ 2p e v l a l−λl v2l+a2l χ2(Q2)F ZZ3(x,Q2),G1,2(x,Q2)=−Q2eλl gγγ1,2(x,Q2)+2|Q e|(p e a l−λl v l)χ(Q2)gγZ1,2(x,Q2),+ 2p e v l a l−λl v2l+a2l χ2(Q2)g ZZ1,2(x,Q2),G3,4,5(x,Q2)=2|Q e|(v l−p eλl a l)χ(Q2)gγZ3,4,5(x,Q2),+ v2l+a2l−2p eλl v l a l χ2(Q2)g ZZ3,4,5(x,Q2),(9) are expressed via the hadronic structure functions,the Z-boson-lepton couplings v l,a l,and the ratio of the propagators for the photon and Z-bosonχ(Q2)=Gµ2M2ZQ2+M2Z.(10)Furthermore we use the parameter p e for which p e=1for a scattered lepton and p e=−1for a scattered antilepton.The hadronic structure functions can be expressed in terms of parton densities accounting for the twist-2contributions only,see[12].Here,a series of relations between the different structure functions are used in leading order QCD.The DIS cross-section on the Born-leveld2σBorndxdy +d2σpol Borndxdy =2πα2S ,S U3(y,Q2)=x 1−(1−y)2 ,(13) and the polarized partdσpol BornQ4λp N f p S5i=1S p gi(x,y)G i(x,Q2).(14)Here,S p gi(x,y)are functions,similar to(13),and may be found in[6].Furthermore we used the abbrevationsf L=1, n L=λp N k 12πSy 1−y−M2xy2π1−yThe O(α)DIS cross-section readsd2σQED,1πδVRd2σBorndx l dy l=d2σunpolQED,1dx l dy l.(16)All partial cross-sections have a form similar to the Born cross-section and are expressed in terms of kinematic functions and combinations of structure functions.In the O(α)approximation the measured cross-section,σrad,is define asd2σraddx l dy l +d2σQED,1dx l dy l+d2σpol radd2σBorn−1.(18)The radiative corrections calculated for leptonic variables grow towards high y and smaller values of x.Thefigures compare the results obtained in LLA,accounting for initial(i)andfinal state (f)radiation,as well as the Compton contribution(c2)with the result of the complete calculation of the leptonic corrections.In most of the phase space the LLA correction provides an excellent description,except of extreme kinematic ranges.A comparison of the radiative corrections for polarized deep inelastic scattering between the codes HECTOR and POLRAD[17]was carried out.It had to be performed under simplified conditions due to the restrictions of POLRAD.Corresponding results may be found in[11,13,14].3.3ConclusionsFor the evaluation of the QED radiative corrections to deep inelastic scattering of polarized targets two codes HECTOR and POLRAD exist.The code HECTOR allows a completely general study of the radiative corrections in the model independent approach in O(α)for neutral current reac-tions including Z-boson exchange.Furthermore,the LLA corrections are available in1st and2nd order,including soft-photon resummation and for charged current reactions.POLRAD contains a branch which may be used for some semi-inclusive DIS processes.The initial state radia-tive corrections(to2nd order in LLA+soft photon exponentiation)to these(and many more processes)can be calculated in detail with the code HECTOR,if the corresponding user-supplied routine USRBRN is used together with this package.This applies both for neutral and charged current processes as well as a large variety of different measurements of kinematic variables. Aside the leptonic corrections,which were studied in detail already,further investigations may concern QED corrections to the hadronic tensor as well as the interference terms. References[1]Proceedings of the Workshop on Physics at HERA,1991Hamburg(DESY,Hamburg,1992),W.Buchm¨u ller and G.Ingelman(eds.).[2]J.Bl¨u mlein,Z.Phys.C65(1995)293.[3]D.Bardin,L.Kalinovskaya and T.Riemann,DESY96–213,Z.Phys.C in print.[4]D.Bardin and L.Kalinovskaya,µe la,version1.00,March1996.The source code is availablefrom http://www.ifh.de/~bardin.[5]A.Arbuzov,D.Bardin,J.Bl¨u mlein,L.Kalinovskaya and T.Riemann,Comput.Phys.Commun.94(1996)128,hep-ph/9510410[6]D.Bardin,J.Bl¨u mlein,P.Christova and L.Kalinovskaya,DESY96–189,hep-ph/9612435,Nucl.Phys.B in print.[7]SMC collaboration,D.Adams et al.,Phys.Lett.B396(1997)338;Phys.Rev.D56(1997)5330,and references therein.[8]A.I.Nikischov,Sov.J.Exp.Theor.Phys.Lett.9(1960)757;P.van Nieuwenhuizen,Nucl.Phys.B28(1971)429;D.Bardin and N.Shumeiko,Nucl.Phys.B127(1977)242.[9]T.V.Kukhto,N.M.Shumeiko and S.I.Timoshin,J.Phys.G13(1987)725.[10]G.Passarino,mun.97(1996)261.[11]D.Bardin,J.Bl¨u mlein,P.Christova,L.Kalinovskaya,and T.Riemann,Acta Phys.PolonicaB28(1997)511.[12]J.Bl¨u mlein and N.Kochelev,Phys.Lett.B381(1996)296;Nucl.Phys.B498(1997)285.[13]D.Bardin,J.Bl¨u mlein,P.Christova and L.Kalinovskaya,Preprint DESY96–198,hep-ph/9609399,in:Proceedings of the Workshop‘Future Physics at HERA’,G.Ingelman,A.De Roeck,R.Klanner(eds.),Vol.1,p.13;hep-ph/9609399.[14]D.Bardin,Contribution to the Proceedings of the International Conference on High EnergyPhysics,Warsaw,August1996.[15]M.Gl¨u ck,E.Reya,M.Stratmann and W.Vogelsang,Phys.Rev.D53(1996)4775.[16]S.Wandzura and F.Wilczek,Phys.Lett.B72(1977)195.[17]I.Akushevich,A.Il’ichev,N.Shumeiko,A.Soroko and A.Tolkachev,hep-ph/9706516.-20-18-16-14-12-10-8-6-4-200.10.20.30.40.50.60.70.80.91elaFigure 1:The QED radiative corrections to asymmetry without experimental cuts.-1-0.8-0.6-0.4-0.200.20.40.60.810.10.20.30.40.50.60.70.80.91elaFigure 2:The QED radiative corrections to asymmetry with experimental cuts.-50-40-30-20-100102030405000.10.20.30.40.50.60.70.80.91HectorFigure 3:A comparison of complete and LLA RC’s in the kinematic regime of HERMES for neutral current longitudinally polarized DIS in leptonic variables.The polarized parton densities [15]are used.The structure function g 2is calculated using the Wandzura–Wilczek relation.c 2stands for the Compton contribution,see [6]for details.-20-100102030405000.10.20.30.40.50.60.70.80.91HectorFigure 4:The same as in fig.3,but for energies in the range of the SMC-experiment.-20-10010203040500.10.20.30.40.50.60.70.80.91HectorFigure 5:The same as in fig.4for x =10−3.-200-150-100-5005010015020000.10.20.30.40.50.60.70.80.91HectorFigure 6:A comparison of complete and LLA RC’s at HERA collider kinematic regime for neutral current deep inelastic scattering offa longitudinally polarized target measuring the kinematic variables at the leptonic vertex.。
对电极涂覆AgNWs对聚3-(2-羟乙基)噻吩变色性能的影响
第41卷第2期2021 年4 月西 安 工 业 大 学 学 报JournalofXi 'anTechnologicalUniversityVol. 41 No. 2Apr2021DOI ： 10. 16185/j. jxatu. edu. cn. 2021. 02. 002http : //xb. xatu. edu. cn对电极涂覆AgNWs 对聚3-(2-羟乙基)噻吩变色性能的影响** 收稿日期:2020-08-16基金资助：陕西省自然科学基础研究计划项目(2019JM-225)。
第一作者简介：王 潇(1996-),女，西安工业大学硕士研究生。
通信作者简介：张文治(1980-)男，西安工业大学副教授，主要研究方向为光电功能材料与器件,E-mail :zhangwz @xatu. edu. cn 。
引文格式：王潇，张文治.对电极涂覆AgNWs 对聚3-(2-羟乙基)噻吩变色性能的影响西安工业大学学报,2021,41(2):132-139.WANG Xiao,ZHANG Wenzhi. Influence of Coating Silver Nanowires on Counter Electrode on the Electrochromic Proper ties of Poly(3-thiopheneethanol ) )J]. Journal of Xi an Technological University , 2021,41(2) : 132-139.王潇，张文治(西安工业大学材料与化工学院，西安710021)摘要：为提高聚噻吩类衍生物电致变色器件的响应速度和循环稳定性，采用电化学聚合法制备聚3-(2-^乙基)噻吩(P3TE )薄膜，同时将银纳米线(AgNWs )分散液滴涂到ITO 玻璃上制得AgNWs 导电薄膜，分别以ITO 玻璃上的P3TE 和AgNWs 薄膜为工作电极和对电极，与凝胶电解质一起组装成电致变色器件。
Electron-Positron colliders
a r X i v :h e p -e x /0111070v 1 22 N o v 2001ELECTRON-POSITRON-COLLIDERSR.-D.HEUERInstitut f¨u r Experimentalphysik,Universit¨a t Hamburg,Luruper Chaussee 149,22761Hamburg GermanyE-mail:rolf-dieter.heuer@desy.deAn electron-positron linear collider in the energy range between 500and 1000GeV is of crucial importance to precisely test the Standard Model and to explore the physics beyond it.The physics program is complementary to that of the Large Hadron Collider.Some of the main physics goals and the expected accuracies of the anticipated measurements at such a linear collider are discussed.A short review of the different collider designs presently under study is given including possible upgrade paths to the multi-TeV region.Finally a framework is presented within which the realisation of such a project could be achieved as a global international project.1IntroductionA coherent picture of matter and forces has emerged in the past decades through in-tensive theoretical and experimental studies.It is adequately described by the Standard Model of particle physics.In the last few years many aspects of the model have been stringently tested,some to the per-mille level,with e +e −,ep and p ¯p machines making com-plementary contributions,especially to the determination of the electroweak bining the results with neutrino scatter-ing data and low energy measurements,the experimental analysis is in excellent concor-dance with the electroweak part of the Stan-dard Model.Also the predictions of QCD have been thoroughly tested,examples being precise measurements of the strong coupling αs and probing the proton structure to the shortest possible distances.Despite these great successes there are many gaps in our understanding.The clearest one is the present lack of any direct evidence for the dynamics of electroweak symmetry breaking and the generation of the masses of gauge bosons and fermions.The Higgs mechanism which generates the masses of the fundamental particles in the Standard Model,has not been experimentally estab-lished though the indirect evidence from pre-cision measurements is very strong.Even ifsuccessfully completed,the Standard Model does not provide a comprehensive theory of matter.There is no explanation for the wide range of masses of the fermions,the grand unification between the two gauge theories,electroweak and QCD,is not realised and gravity is not incorporated at the quantum level.Several alternative scenarios have been de-veloped for the physics which may emerge beyond the Standard Model as energies are increased.The Supersymmetric extension of the Standard Model provides a stable bridge from the presently explored energy scales up to the grand unification scale.Alternatively,new strong interactions give rise to strong forces between W bosons at high energies.Quite general arguments suggest that such new phenomena must appear below a scale of approximately 3TeV.Extra space dimen-sions which alter the high energy behaviour in such a way that the energy scale of gravity is in the same order as the electroweak scale are another proposed alternative.There are two ways of exploring the new scales,through attaining the highest possible energy in a hadron collider and through high precision measurements at the energy fron-tier of lepton colliders.This article is based on the results ofmany workshops on physics and detector studies for linear colliders.Much more can be found in the respective publications1,2,3,4 and on the different Web sites5,6,7,8.Many people have contributed to these studies and the references to their work can be found in the documents quoted above.2Complementarity of Lepton and Hadron MachinesIt is easier to accelerate protons to very high energies than leptons,but the detailed colli-sion process cannot be well controlled or se-lected.Electron-positron colliders offer a well√defined initial state.The collision energying generation of colliders.The physics case for such a machine will depend on the results from the LHC and the linear collider in the sub-TeV range.3Selected Physics TopicsIn this chapter,some of the main physics top-ics to be studied at a linear collider will bediscussed.Emphasis is given to the study of the Higgs mechanism in the Standard Model,the measurements of properties of su-persymmetric particles,and precision tests of the electroweak theory.More details about these topics as well as information about the numerous topics not presented here can be found in the physics books published in the studies of the physicspotential offuture lin-ear colliders 1,2,3,4.3.1Standard Model Higgs BosonThe main task of a linear electron-positron collider will be to establish experimentally the Higgs mechanism as the mechanism for generating the masses of fundamental parti-cles:•The Higgs boson must be discovered.•The couplings of the Higgs boson to gauge bosons and to fermions must be proven to increase with their masses.•The Higgs potential which generates the non-zero field in the vacuum must be reconstructed by determining the Higgs self-coupling.•The quantum numbers (J P C =0++)must be confirmed.The main production mechanisms for Higgs bosons in e +e −collisions are Higgs-strahlung e +e −→HZ and WW-fusion e +e −→νe ¯νe H ,and the corresponding cross-sections as a function of M H are depicted in figure 2for three different centre of mass en-ergies.With an integrated luminosity of 500Figure 2.The Higgs-strahlung and WW fusion pro-duction cross-sections as a function of M H for differ-ent√sof about 800GeV;for 1000fb −1an accuracyof 6%can be expected.The Higgs boson quantum numbers can be determined through the rise of the cross sec-tion close to the production threshold and through the angular distributions of the H and Z bosons in the continuum.Recoil Mass [GeV ]N u m b e r o f E v e n t s / 1.5 G e VFigure 3.The µ+µ−recoil mass distribution in theprocess e +e −→HZ →µ+µ−for M H =120GeV,500fb −1at√2of the self potential of the Higgs field V =λ(φ2−14λH4.The trilinearHiggs coupling λHHH =6λv can be mea-sured directly in the double Higgs-strahlung process e +e −→HHZ →q ¯q b ¯bb ¯b .The fi-nal state contains six partons resulting in a rather complicated experimental signature with six jets,a challenging task calling for ex-cellent granularity of the tracking device and the calorimeter 9.Despite the low cross sec-tion of the order of 0.2fb for M H =120GeV at√s =500GeV with an integrated luminosity of 1ab −1as shown in figure 6.Measurements of Higgs boson properties and their anticipated accuracies are sum-marised in table 1.In summary,the Higgs mechanism can be established in an unambiguous way at a high luminosity electron-positron collider with a centre-of-mass energy up to around one TeV as the mechanism responsible for the sponta-neous symmetry breaking of the electroweak interactions.3.2Supersymmetric ParticlesSupersymmetry (SUSY)is considered the most attractive extension of the Standardg c /g c (SM)g b /g b (S M )0.80.850.90.9511.051.11.151.2Figure 5.Higgs coupling determination:The con-tours for g b vs.g c for a 120GeV Higgs boson normalised to their Standard Model expectations as measured with 500fb −1.Model,which cannot be the ultimate the-ory for many reasons.The most impor-tant feature of SUSY is that it can explain the hierarchy between the electroweak scale of ≈100GeV,responsible for the W and Z masses,and the Planck scale M P l ≃1019GeV.When embedded in a grand-unified the-ory,it makes a very precise prediction of the electroweak mixing angle sin 2θW in excellent concordance with the precision electroweak measurement.In the following,only the min-imal supersymmetric extension to the Stan-dard Model (MSSM)will be considered and measurements of the properties of the super-symmetric particles will be discussed.Stud-ies of the supersymmetric Higgs sector can be found elsewhere 1,2,3,4.In addition to the particles of the Stan-dard Model,the MSSM contains their su-persymmetric partners:sleptons ˜l ±,˜νl (l =e,µ,τ),squarks ˜q ,and gauginos ˜g ,˜χ±,˜χ0.In the MSSM the multiplicative quantum num-ber R-parity is conserved,R p =+1for par-10012014016018000.20.10.3M H [GeV ]SM Double Higgs-strahlung: e + e - → ZHH σ [fb ]√s = 800 GeV√s = 500 GeVFigure 6.The cross-section for doubleHiggs-strahlung in the Standard Model at√120GeVmass 0.05%spin yes CPyes6%g HZZ 1%g HW W 2%g Hbb 2%g Hcc 10%g Hττ5%g Htt 6%λHHH∼30%ticles and R p =−1for sparticles.Spar-ticles are therefore produced in pairs and they eventually decay into the lightest spar-ticle which has to be stable.As an example,smuons are produced and decay through theprocess e +e −→˜µ+˜µ−→µ+µ−χ01χ01with χ01as the lightest sparticle being stable and,therefore,escaping detection.The mass scale of sparticles is only vaguely known.In most scenarios some spar-ticles,in particular charginos and neutrali-nos,are expected to lie in the energy region accessible by the next generation of e +e −200400600800Figure 7.Examples of mass spectra in mSUGRA,GMSB and AMSB models.colliders alsosupported bythe recentmea-surement of (g −2)µ10.Examples of massspectra for three SUSY breaking mechanisms (mSUGRA,GMSB,AMSB)are given in fig-ure 7.The most fundamental problem of super-symmetric theories is how SUSY is broken and in which way this breaking is communi-cated to the particles.Several scenarios have been proposed in which the mass spectra are generally quite different as illustrated in fig-ure 7.High precision measurements of the particle properties are therefore expected to distinguish between some of these scenarios.The study and exploration of Supersymmetry will proceed in the following steps:•Reconstruction of the kinematically ac-cessible spectrum of sparticles and the measurement of their properties,masses and quantum numbers•Extraction of the basic low-energy pa-rameters such as mass parameters,cou-plings,and mixings•Analysis of the breaking mechanism and reconstruction of the underlying theory.While it is unlikely that the complete spectrum of sparticles will be accessible at acollider with√Figure 9.Cross section near threshold for the processe +e −→˜χ+1˜χ−1,10fb−1per point.approach,the measured electroweak scaleSUSY parameters are extrapolated to high energies using these RGE’s.Due to the high precision of the measured input variables,only possible at the linear collider,an accurate test can be performed at which energy scale certain parameters be-come equal.Most interesting,the assump-tion of grand unification of forces requires the gaugino mass parameters M 1,M 2,M 3to meet at the GUT scale (figure 10(left)).Different SUSY breaking mechanisms predict different unification patterns of the sfermion mass parameters at high energy.With the high accuracy of the linear collider measure-ments these models can be distinguished as shown in figure 10for the case of mSUGRA (middle)and GMSB (right).In summary,the high precision studies of supersymmetric particles and their properties can open a window to energy scales far above the scales reachable with future accelerators,possibly towards the Planck scale where grav-ity becomes important.3.3Precision MeasurementsThe primary goal of precision measurements of gauge boson properties is to establish the non-abelian nature of electroweak interac-tions.The gauge symmetries of the Stan-dard Model determine the form and the strength of the self-interactions of the elec-troweak bosons,the triple couplings W W γand W W Z and the quartic couplings.Devi-ations from the Standard Model expectations for these couplings could be expected in sev-eral scenarios,for example in models where there exists no light Higgs boson and where the W and Z bosons are generated dynam-ically and interact strongly at high scales.Also for the extrapolation of couplings to high scales to test theories of grand unifi-cation such high precision measurements are mandatory.For the study of the couplings between gauge bosons the best precision is reached at the highest possible centre of mass energies.These couplings are especially sen-sitive to models of strong electroweak sym-metry breaking.W bosons are produced either in pairs,e +e −→W +W −or singly,e +e −→W eνwith both processes being sensitive to the triple gauge couplings.In general the total errors estimated on the anomalous couplings are in the range of few ×10−4.Figure 11com-pares the precision obtainable for ∆κγand ∆λγat different machines.The measurements at a linear collider are sensitive to strong symmetry breaking be-yond Λof the order of 5TeV,to be com-pared with the electroweak symmetry break-ing scale ΛEW SB =4πv ≈3TeV.One of the most sensitive quantities to loop corrections from the Higgs boson is the effective weak mixing angle in Z boson de-cays.By operating the collider at ener-gies close to the Z -pole with high luminos-ity (GigaZ)to collect at least 109Z bosons in particular the accuracy of the measure-Figure 10.Extrapolation of SUSY parameters measured at the electroweak scale to high energies.10-410-310-2∆κγLEP TEV LHCTESLA TESLA 50080010-410-310-2∆λγLEP TEV LHCTESLA TESLA500800Figure parison of constraints on the anomalous couplings ∆κγand ∆λγat different machinesment of sin 2θleff can be improved by one or-der of magnitude wrt.the precision obtained today 11.With both electron and positronbeams longitudinally polarised,sin 2θleff can be determined most accurately by measur-ing the left-right asymmetry A LR =A e =2v e a e /(v 2e +a 2e )with v e (a e )being the vec-tor (axialvector)couplings of the Z boson tothe electron and v e /a e =1-4sin 2θleff for pure Z exchange.Particularly demanding is the precision of 2×10−4with which the po-larisation needs to be known to match the statistical accuracy.An error in the weakmixing angle of ∆sin 2θleff =0.000013can be expected.Together with an improved de-termination of the mass of the W boson toa precision of some 6MeV through a scan of the W W production threshold and with the measurements obtained at high energy run-ning of the collider this will allow many high precision tests of the Standard Model at the loop level.As an example,figure 12shows the variation of the fit χ2to the electroweak measurements as a function of M H for the present data and for the data expected at a linear collider.The mass of the Higgs bo-son can indirectly be constraint at a level of 5%.Comparing this prediction with the di-rect measurement of M H consistency tests of the Standard Model can be performed at the quantum level or to measure free parameters in extensions of the Standard Model.This is5101520101032000LCm hχ2Figure 12.∆χ2as a function of the Higgs boson mass for the electroweak precision data today (2000)and after GigaZ running (LC).of particular importance if M H >200GeV in contradiction to the current electroweak mea-surements.In summary,there is strong evidence for new phenomena at the TeV energy scale.Only the precision exploration at the linear collider will allow,together with the results obtained at the Large Hadron Collider,the understanding of the underlying physics and will open a new window beyond the centre-of-mass energies reachable.Whatever sce-nario is realized in nature,the linear collider will add crucial information beyond the LHC.There is global consensus in the high energy physics community that the next accelera-tor based project needs to be an electron-positron linear collider with a centre-of-mass energy of at least 500GeV.4Electron-Positron Linear CollidersThe feasibility of a linear collider has been successfully demonstrated by the operationof the SLAC Linear Collider,SLC.How-ever,aiming at centre-of-mass energies at the TeV scale with luminosities of the order of 1034cm −2s −1requires at least two orders of magnitude higher beam power and two orders of magnitude smaller beam sizes at the inter-action point.Over the past decade,several groups worldwide have been pursuing differ-ent linear collider designs for the centre-of-mass energy range up to around one TeV as well as for the multi-TeV range.Excel-lent progress has been achieved at various test facilities worldwide in international col-laborations on crucial aspects of the collider designs.At the Accelerator Test Facility at KEK 12,emittances within a factor two of the damping ring design have been achieved.At the Final Focus Test Beam at SLAC 13de-magnification of the beams has been proven;the measured spot sizes are well in agreement with the theoretically expected values.The commissioning and operation of the TESLA Test Facility at DESY 14has demonstrated the feasibility of the TESLA technology.In the following,a short review of the different approaches is given.4.1TeV rangeThree design studies are presently pursued:JLC 15,NLC 16and TESLA 17,centred around KEK,SLAC and DESY,respectively.Details about the design,the status of de-velopment and the individual test facilities can be found in the above quoted references as well as in the status reports presented at LCWS200018,19,20.A comprehensive sum-mary of the present status can be found in the Snowmass Accelerator R&D Report 21,here only a short discussion of the main features and differences of the three approaches will be given with emphasis on luminosity and en-ergy reach.One key parameter for performing the physics program at a collider is the centre-of-mass energy achievable.The energy reachof a collider with a given linac length and a certain cavityfilling factor is determined by the gradient achievable with the cavity tech-nology chosen.For normalconducting cavi-ties the maximum achievable gradient scales roughly proportional to the RF frequency used,for superconducting Niobium cavities, the fundamental limit today is around55 MV/m.The second key parameter for the physicsprogram is the luminosity L,given byL=n b N2e f rep(σ∗x+σ∗y)2.Choos-ing aflat beam size(σ∗x≫σ∗y)at the inter-action point,δE becomes independent of the vertical beam size and the luminosity can be increased by reducingσ∗y as much as possi-ble.Sinceσ∗y∝sn b N e f rep=ηP AC is obtained from themains power P AC with an efficiency η.Equation(1)can then be rewritten asL∝ηP AC s ǫy(2)High luminosity therefore requires high ef-ficiencyηand high beam quality with low emittanceǫy and low emittance dilution ∆ǫ/ǫ∝f6RF,which is largely determined by the RF frequency f RF of the chosen technol-ogy.The fundamental difference between the three designs is the choice of technology for the accelerating structures.The design of NLC is based on normalconducting cavities using f RF of11.4GHz(X-band),for JLC two options,X-band or C-band(5.7GHz)are pursued.The TESLA concept,developed by the TESLA collaboration,is using supercon-ducting cavities(1.3GHz).As an example for a linear collider facility,figure13shows the schematic layout of TESLA.Figure13.Schematic layout of TESLATable2compares some key parameters for the different technologies at√Figure 14.Evolution of superconducting cavity per-formance.The average gradient achieved with TESLA 9-cell cavities produced in industry (first test,no additional processing)is shown as dots.with N b bunches,the time ∆T b between bunches within a train which allows head on crossing of the bunches for TESLA but requires a crossing angle for the other de-signs.The design luminosity L ,beam power P beam and the required mains power P AC il-lustrate that for a given mains power the su-perconducting technology delivers higher lu-minosity.On the other hand the lower gradi-ent G acc requires a longer linac for the samecentre-of-massenergy reach.As can be seen from table 2the X-band machines call for a beam loaded (unloaded)gradient of some 50(70)MV/m for√s =500GeV,a gradient which is mean-while routinely achieved for cavities fabri-cated in industry as illustrated in figure 14.Table 2also contains the presently planned length of the facilities 17,16,22,23.AnFigure 15.Excitation curves of three electropolished single-cell cavities.Gradients well above 35MV/m are reached.upgrade in energy up to around one TeV seems possible for all designs.In the NLC case,more cavities would be installed within the existing tunnel,in the JLC case,the tunnel length would have to be increased to house more cavities.In the TESLA case,a gradient of around 35MV/m is neededto reach√Table parison of some crucial parameters at 500GeV for the different technologies under study,see text for details.NLCJLC-C51502820190337 1.4head on angle 20.7σ∗x/y [nm ]245/2.7318/4.3δE [%]4.73.93.42.64P beam [MW ]13.212.6P AC (linacs )[MW ]13222023.550.23316s of 3TeV,usinghigh frequency (30GHz)normalcon-ducting structures operating at very high ac-celerating fields (150MV/m).The present design calls for bunch separations of .67ns,a vertical spotsize of 1nm and beamstrahlung δE of 30%.For this promising concept a new test facility is under construction at CERN which should allow tests with full gradient starting in 2005.5RealisationThe new generation of high energy colliders most likely exceeds the resources of a coun-try or even a region.There is general consen-sus that the realisation has to be done in an international,interregional framework.One such framework,the so called Global Accel-erator Network (GAN),has been proposed to ICFA in March 2000.A short discussion of the principle considerations will be presented here,more details can be found in ref.25.The GAN is a global collaboration of lab-oratories and institutes in order to design,construct,commission,operate and main-tain a large accelerator facility.The model is based on the experience of large experi-mental collaborations,particularly in particle physics.Some key elements are listed below:•it is not an international permanent in-stitution,but an international project of limited duration;•the facility would be the common prop-erty of the participating countries;•there are well defined roles and obliga-tions of all partners;•partners contribute through components or subsystems;•design,construction and testing of com-ponents is done in participating institu-tions;•maintenance and running of the accel-erator would be done to a large extent from the participating institutions.The GAN would make best use of world-wide competence,ideas and resources,create a visible presence of activities in all partici-pating countries and would,hopefully,make the site selection less controversial.study general considerations of implementing a GAN and to study the technical considera-tions and influence on the design and cost of the accelerator.The reports of these working groups can be found on the web26.Their overall conclusion is that a GAN can be a fea-sible way to build and operate a new global accelerator,although many details still need to be clarified.6SummaryThere is global consensus about the next ac-celerator based project in particle physics.It has to be an electron-positron linear collider with an initial energy reach of some500GeV with the potential of an upgrade in centre-of-mass energy.The physics case is excellent, only a few highlights could be presented here. There is also global consensus that concur-rent operation with LHC is needed and fruit-ful.Therefore,a timely realisation is manda-tory.The technical realisation of a linear col-lider is now feasible,several technologies are either ripe or will be ripe soon.A fast consen-sus in the community about the technology is as a global project with the highest possible luminosity and a clear upgrade potential be-yond500GeV.AcknowledgmentsThe author would like to express his grati-tude to all people who have contributed to the studies of future electron-positron linear colliders from the machine design to physics and detector studies.Special thanks go to the organisers and their team for a very well or-ganised,inspiring conference as well as for the competent technical help in preparing this presentation.References1.J.A.Aguilar-Saavedra et al,TESLATechnical Design Report,Part III,Physics at an e+e−Linear Collider,DESY2001-011,ECFA2001-209,hep-ph/0106315.2.T.Abe et al,Linear Collider Physics Re-source Book for Snowmass2001,BNL-52627,CLNS01/1729,FERMILAB-Pub-01/058-E,LBNL-47813,SLAC-R-570,UCRL-ID-143810-DR,LC-REV-2001-074-US,hep-ex/0106055-583.K.Abe et al,Particle Physics Exper-iments at JLC,KEK-Report2001-11, hep-ph/0109166.4.Proceedings of LCWS,Physics and Ex-periments with Future Linear Colliders, eds A.Para,H.E.Fisk,(AIP Conf.Proc.,Vol578,2001).5.Worldwide Study of the Physics and De-tectors for Future e+e−Colliders/lc/6.ACFA Joint Linear Collider Physics andDetector Working Grouphttp://acfahep.kek.jp/7.2nd Joint ECFA/DESY Studyon Physics and Detectors for a Linear Electron-Positron Colliderhttp://www.desy.de/conferences/ecfa-desy-lc98.html8.A Study of the Physics and Detectors forFuture Linear e+e−Colliders:American Activities/lc/ameri-ca.html9.G.Alexander et al,TESLA TechnicalDesign Report,Part IV,A Detector for TESLA,DESY2001-011,ECFA2001-209.10.H.N.Brown et al.[Muon g-2Collabo-ration],Phys.Rev.Lett.86(2001)222711.J.Drees,these proceedings12.E.Hinode et al,eds.,KEK Internal95-4,1995,eds J.Urakawa and M.Yoshioka, Proceedings of the SLAC/KEK Linear Collider Workshop on Damping Ring, KEK92-6,199213.The FFTB Collaboration:BINP(Novosibirsk/Protvino),DESY, FNAL,KEK,LAL(Orsay),MPI Mu-nich,Rochester,and SLAC14.Proposal for a TESLA Test Facility,DESY TESLA-93-01,199215.KEK-Report97-1,1997.16.Zeroth Order Design Report for theNext Linear Collider,SLAC Report474,1996.2001Report on the Next Linear Collider,Fermilab-Conf-01-075-E,LBNL-47935,SLAC-R-571,UCRL-ID-14407717.J.Andruszkow et al,TESLA TechnicalDesign Report,Part II,The Accelerator, DESY2001-011,ECFA2001-20918.O.Napoly,TESLA Linear Collider:Sta-tus Report,in ref419.T.O.Raubenheimer,Progress in theNext Linear Collider Design,in ref4 20.Y.H.Chin et al Status of JLC Accelera-tor Development,in ref421.A.Chao et al,2001Snowmass Accelera-tor R&D Report,http://www.hep.anl.gov/pvs/dpb/Snowmass.pdf22.Y.H.Chin,private communication23.H.Matsumoto,T.Shintake,private com-munication24.I.Wilson,A Multi-TeV Compact e+e−Linear Collider,in ref425.F.Richard et al,TESLA Technical De-sign Report,Part I,Executive Summary, DESY2001-011,ECFA2001-209,hep-ph/0106314.26./directorate/icfa/icfa reports.html。
反铁电TEM 研究
In situ transmission electron microscopy study of the electric field-induced transformation of incommensurate modulations in a Sn-modified lead zirconate titanate ceramicH. He and X. TanCitation: Appl. Phys. Lett. 85, 3187 (2004); doi: 10.1063/1.1805179View online: /10.1063/1.1805179View Table of Contents: /resource/1/APPLAB/v85/i15Published by the American Institute of Physics.Related ArticlesComplete set of elastic, dielectric, and piezoelectric constants of [011]C poled rhombohedral Pb(In0.5Nb0.5)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3:Mn single crystalsJ. Appl. Phys. 113, 074106 (2013)Compressible spherical dipolar glass model of relaxor ferroelectricsJ. Appl. Phys. 112, 114122 (2012)Tunable self-biased magnetoelectric response in homogenous laminatesAppl. Phys. Lett. 101, 232905 (2012)Self-assembled NaNbO3-Nb2O5 (ferroelectric-semiconductor) heterostructures grown on LaAlO3 substrates Appl. Phys. Lett. 101, 132902 (2012)Pressure and electric field effects on piezoelectric responses of KNbO3J. Appl. Phys. 112, 064106 (2012)Additional information on Appl. Phys. Lett.Journal Homepage: /Journal Information: /about/about_the_journalTop downloads: /features/most_downloadedInformation for Authors: /authorsIn situ transmission electron microscopy study of the electric field-induced transformation of incommensurate modulations in a Sn-modified lead zirconate titanate ceramicH.He and X.Tan a )Department of Materials Science and Engineering,Iowa State University,Ames,Iowa 50011(Received 7May 2004;accepted 11August 2004)Electric field-induced transformation of incommensurate modulations in a Sn-modified lead zirconate titanate ceramic was investigated with an electric field in situ transmission electron microscopy technique.It is found that the spacing between the ͑1/x ͕͒110͖satellite spots and the fundamental reflections do not change with external electric field,indicating that the modulation wavelength stays constant under applied field.The intensity of these satellites starts to decrease when the field level reaches a critical value.Further increase in the field strength eventually leadsto the complete disappearance of the satellite reflections.In addition,the 12͕111͖-type superlattice reflections showed no response to electrical stimuli.©2004American Institute of Physics .[DOI:10.1063/1.1805179]Incommensurate modulations have been observed experimentally with transmission election microscopy (TEM )in many perovskite ferroelectric ceramics,such as PbZrO 3,1Pb ͑Zr 1−x Ti x ͒O 3,2,3Sn-modified Pb ͑Zr 1−x Ti x ͒O 3(PZST ),4–7La-modified Pb ͑Zr 1−x Ti x ͒O 3(PLZT ),8–10Pb ͑Co 1/2W 1/2͒O 3,11,12and Pb ͑Sc 1/2Ta 1/2͒O 3.12,13They are characterized by the satellite reflections in electron diffrac-tion patterns and the regular fringes in image contrast.The modulation wave vector represented by the satellites is along the normal direction of those fringes,and the distance of the satellites to the fundamental reflections in reciprocal space corresponds to the spacing of the fringes in real space.The wave vector is parallel to the ͗110͘direction in most cases and the wavelength lies in the range of 5ϳ20a ,where a is the lattice parameter for the parent paraelectric structure.8Transformation of the intermediate incommensurate phase to other phases can be triggered by external stimuli,such as chemical composition and temperature.6–10Sn-or Ti-content in the PZST system and La content in the PLZT system were utilized before as controlling variables for the phase transformation.8–10In the PZST system,it has been shown that decrease in Sn content or increase in Ti content leads to the incommensurate antiferroelectric-to-ferroelectric phase transformation.In the PLZT system,the modulation wavelength was observed to increase with Ti molar fraction.8Utilizing temperature as the controlled variable in the study of such transformations allows in situ TEM studies,where the evolution of the satellite reflections can be directly observed.6,7The hot-stage in situ TEM observations revealed that the modulation wavelength increases continuously with increasing temperature.Based on these studies,Viehland et al.8suggested that the competing ferroelectric and antiferro-electric ordering in these perovskites are responsible for the presence of incommensurate modulations.However,unam-biguous evidence has yet to be found.In this letter,we report the study of the incommensurate phase transformation trig-gered by controlled electric fields.The evolution of the sat-ellite spots driven by external electrical stimuli is recorded.A hybrid coprecipitation method similar to that used by Yang and Payne 14was followed to prepare the ceramic powder with a chemical formula Pb 0.99Nb 0.02͓͑Zr 0.55Sn 0.45͒0.94Ti 0.06͔0.98O 3(abbreviated as PZST 45/6/2).Pressed cylinders,15mm in diameter by 20mm thick,were formed by cold-isostatic pressing at 350MPa.The preformed pellets were then hot pressed in an Al 2O 3die at 1150°C for 2h in air.Thin slices from the hot-pressed piece were annealed at 1300°C for 2h in an atmosphere containing excess PbO.The annealed slices were then ground,polished,and electroded.Dielectric character-ization was performed with an LCR meter (HP-4284A,Hewlett-Packard )at frequency of 1kHz in conjunction with an environmental chamber.A heating rate of 3°C/min was used during measurement.Electric field-induced polariza-tions were recorded with a standardized ferroelectric test sys-tem (RT-66A,Radiant technologies ).TEM specimens were prepared from ultrasonically cut 3-mm-diam disks.The thickness of these disks was reduced to ϳ150m by grinding and polishing.The center portion was further thinned to ϳ10m by dimpling.The dimpled specimens were then annealed at 300°C for 30min to mini-mize residual stresses.An argon ion mill was used for further thinning until final perforation occurred in the center.Gold electrodes with spacing of 250µm were evaporated to the TEM specimens,and platinum wires were used to connect the electrodes to the electrical contacts on the TEM specimen holder.Figure 1shows the schematic diagram of the TEM specimen configuration.Details of the electric field in situ TEM technique can be found elsewhere.15–18TEM studies were carried out on a Phillips CM-30microscope operating at 300kV .Temperature dependence of the dielectric permittivity of PZST 45/6/2is shown in Fig.2.The dielectric constant peaks with a value of 920at the temperature of 167°C.Electric field-induced polarization measurement showed double hysteresis loops (Fig.3),indicating an electric field-induced antiferroelectric-to-ferroelectric phase transforma-tion at room temperature.These results are consistent with previous observations from other researchers.5–7In order to determine the field level needed for the in situa )Electronic mail:xtan@APPLIED PHYSICS LETTERS VOLUME 85,NUMBER 1511OCTOBER 20040003-6951/2004/85(15)/3187/3/$22.00©2004American Institute of Physics3187TEM study and to assess the sample geometry effect on the field-induced antiferroelectric-to-ferroelectric phase transfor-mation,a dimpled and annealed 3-mm-diam disk specimen was tested for the hysteresis measurement and the result is also plotted in pared to the conventional circular plate sample with electric field applied along the thickness direction,the TEM-specimen-like disk shows a more gradual phase transformation with much broader loops.Furthermore,the backward switch from the induced ferroelectric phase to the antiferroelectric phase is sluggish,and a nonzero remnant polarization is detected.In situ TEM studies were carried out on a disk specimen with a central perforation.Actual electric field in the speci-men is disturbed (intensified in some areas while diluted in others )by the presence of the perforation.Electron transpar-ent areas that are subjected to intensified electric fields in the specimen were located in the TEM and one grain within this area was focused for the successive detailed in situ study.For an ideal circular perforation,the intensification ratio is 2.19The local electric field strength in this grain was thus esti-mated by doubling the nominal field strength.The evolution of the satellite spots in a ͗112͘-zone axis selected area diffraction pattern under static electric fields is shown in Fig.4.Initially,this grain displays one set of in-commensurate modulations.In the electron diffraction pat-tern,one set of the ͑1/x ͕͒110͖satellite spots is evident,as shown in Fig.4(a ).No detectable changes to these satellite spots were observed with applied static electric field up to 40kV/cm.At the field level of 48kV/cm,these satellites become weaker in their intensity [Fig.4(b )].This field level lies in the close vicinity of the E F (the critical field to trigger the antiferroelectric-to-ferroelectric transformation )mea-sured from the bulk sample.However,careful measurement indicates that the modulation wavelength does not change with increasing field strength.When the field strength reached 56kV/cm,most satellite spots disappeared.As shown in Fig.4(c ),only very weak satellites can be barely seen surrounding the three strong fundamental reflections in the left of this micrograph.The field strength was then re-duced to 40kV/cm.The satellites reappeared,with the strongest ones sitting in the upper-left corner of Fig.4(d ).When the field level was raised again to 56kV/cm [Fig.4(e )],all the satellite spots completely disappeared,indicat-ing the complete transformation to the ferroelectric phase.After the electric field was completely removed,no satellite spots were observed to reappear,as shown in Fig.4(f ).The observation confirms the sluggish nature of the backward ferroelectric-to-antiferroelectric transformation that has been noticed by other researchers in a similar composition.20It has been suggested that in PZT-based ferroelectric per-ovskites,the presence of incommensurate modulations in the antiferroelectric phase is a result of the competition between the ferroelectric and antiferroelectric ordering.8The continu-ous increase in the modulation wavelength with increasing temperature is interpreted that there exists a ferroelectric phase within a narrow temperature range just below the paraelectric transition temperature.When temperature is raised close to this temperature range the ferroelectric order-ing is enhanced.The modulation wavelength is thus in-creased.However,our observations on the electric field-induced transformation of the incommensurate modulation show a different scenario.The intensity of the satellite reflec-tions,rather than the modulation wavelength,changes with the applied electric field strength.The wavelength stays con-stant at a value of 2.3nm.Since external electric field is known to enhance the ferroelectric ordering,we suggest that the electric field-induced antiferroelectric (incommensurate )-to-ferroelectric transformation proceeds as following.When the applied electric field reaches E F ,the phase transformation is initiated in some areas of the grain.The transformation is an abrupt one and no intermediate changes in the modulation wavelength takes place.With increasing electric field strength,the fraction of the transformed area increases and the intensity of the satellite diffraction peaks getsweaker.FIG.2.Temperature dependence of dielectric constant at 1kHz in the PZST 45/6/2ceramic.FIG.3.Electric field-induced polarization measurement at 4Hz in a bulk circular plate sample and an unperforated TEMspecimen.FIG.1.Schematic diagram of specimens for the electric field in situ TEM study.Obviously,a mechanism involving the nucleation of ferro-electric phase and the motion of the phase boundary controls the transformation process.Further studies will be focused on these issues.In addition to the ͑1/x ͕͒110͖satellite spots,12͕111͖-type superlattice reflections were also present in the ͗112͘-axis diffraction pattern,as labeled in Fig.4(e ).The structural ori-gin for these superlattice reflections is still under debate.2,5–7,9,21However,the present in situ TEM study pro-vides valuable insight into the physics mechanism for the presence of these superlattice reflections.It is clear in Fig.4that the intensity of the 12͕111͖spots does not change with the applied electric field,implying a mechanism that is quite rigid to external disturbance.This seems to favor the oxygen octohedra tilting model.21To summarize,in situ TEM technique was applied to the study of the electric field-induced antiferroelectric-to-ferroelectric phase transformation in a PZT-based ceramic.Upon application of external electric fields,the wavelength of the incommensurate modulation in the antiferroelectric phase showed no change but the intensity of the satellite reflections decreased when the field exceeds a critical value.This critical strength matches closely to the E F measured in the bulk sample.This work was supported by the Process Science Initia-tive (PSI )program at Ames Laboratory,U.S.DOE (GrantNo.10-501-115612).The authors are grateful to Dr.David Cann for the access to the dielectric characterization instru-ment in his group at Iowa State University.1Z.Xu,X.Dai,D.Viehland,and D.A.Payne,J.Am.Ceram.Soc.78,2220(1995).2J.Ricote,D.L.Corker,R.W.Whatmore,S.A.Impey,A.M.Glazer,J.Dec,and K.Roleder,J.Phys.:Condens.Matter 10,1767(1998).3S.Watanabe and Y .Koyama,Phys.Rev.B 66,134102(2002).4J.S.Speck,M.De Graef,A.P.Wilkinson,A.K.Cheetham,and D.R.Clarke,J.Appl.Phys.73,7261(1993).5D.Viehland,D.Forst,Z.Xu,and J.Li,J.Am.Ceram.Soc.78,2101(1995).6Z.Xu,D.Viehland,P.Yang,and D.A.Payne,J.Appl.Phys.74,3406(1993).7Z.Xu,D.Viehland,and D.A.Payne,J.Mater.Res.10,453(1995).8D.Viehland,X.Dai,J.Li,and Z.Xu,J.Appl.Phys.84,458(1998).9J.Knudsen,D.I.Woodward,and I.Reaney,J.Mater.Res.18,262(2003).10Z.Xu,X.Dai,and D.Viehland,Phys.Rev.B 51,6261(1995).11S.Watanabe and Y .Koyama,Phys.Rev.B 65,064108(2002).12C.A.Randall,S.A.Markgraf,A.S.Bhalla,and K.Baba-Kishi,Phys.Rev.B 40,413(1989).13K.Z.Baba-Kishi and D.J.Barber,J.Appl.Crystallogr.23,43(1990).14P.Yang and D.A.Payne,J.Appl.Phys.71,1361(1992).15Z.Xu,X.Tan,P.Han,and J.K.Shang,Appl.Phys.Lett.76,3732(2000).16X.Tan,Z.Xu,J.K.Shang,and P.Han,Appl.Phys.Lett.77,1529(2000).17X.Tan,Z.Xu,and J.K.Shang,Mater.Sci.Eng.,A 314,157(2001).18X.Tan,and J.K.Shang,Philos.Mag.A 82,1463(2002).19R.M.McMeeking,ZAMP 40,615(1989).20W.Chan,H.Chen,and E.V .Colla,Appl.Phys.Lett.82,2314(2003).21D.Viehland,Z.Xu,and D.A.Payne,J.Appl.Phys.74,7454(1993).FIG.4.Evolution of the ͗112͘selected area diffraction pattern under applied electric fields in PZST 45/6/2.(a )Original state,(b )48,(c )56,(d )40,and (e )56kV/cm,and (f )field removed.。
Water-Splitting Electrocatalysis in Acid Conditions Using RuthenateIridate Pyrochlores-s
Figure
S1:
Refined
powder
XRD
patternsfor来自(a)(Na0.33Ce0.67)2(Ir)2O7
(b)
(Na0.33Ce0.67)2(Ir0.5Ru0.5)2O7 and (c) (Na0.33Ce0.67)2(Ru)2O7. In (a) * and # indicate small amounts of IrO2 and CeO2 impurity, respectively.
3
TGA/DSC (using a Mettler-Toledo TGA/DSC1 instrument) were recorded under a flow of air with a 10 °C min-1 heating rate. All show 5 % surface water/hydroxide mass loss to 600 ° C. The Ircontaining materials additionally show mass loss at >900 °C which corresponds to reduction to Ir metal; this generally increases with increasing Ir content in the series of materials (athough the mass loss is not always complete at 1000 °C.
4
Polarisation curves were obtained by logarithmically spaced galvanostatic steps with electrochemical impedance spectroscopy at each step. The EIS curves were fitted using a resistor, inductor, and Cole-element in series as the equivalent circuit using ZView. Exhaust gas was fed to a Spectra mass spectrometer and continuously monitored throughout the entire test protocol for oxygen evolution and carbon corrosion products from competing side reactions. Electrochemical work at Diamond Light Source used a Hg/Hg2SO4 (MMS) reference electrode in 0.5M H2SO4 which was calibrated against a hydrogen reference electrode off site at 0.68V vs RHE such that 1.00 V vs MMS signal was equivalent to 1.68 V vs RHE. Table S2 shows the mass activity and onset for oxygen evolution data collected during voltammetry. Also included in the table are the fit parameters found for data collected at 10 mA cm2 during polarisation. The parameters indicate DC resistance, R0, charge transfer resistance, Rct, capacitive time constant, τ, and phase, α.
Weak Interactions of Light Flavours
LSM = LH (φ) + LG (W, Z, G) + Higgs Gauge ¯ / ψ+ ψiD
ψ=fermions ψ,ψ′ =fermions
The Standard Model Lagrangian has four parts: ¯ ′ gψψ′ ψφψ Yukawa
QCD and QED conserve C,P,T separately. Local Field theory by itself implies CPT. The fermion and Higgs2 part of the SM-lagrangian conserves CP and T as well. The only part that violates CP and as a consequence also T is the Yukawa part. The Higgs part is responsible for two parameters, the gauge part for three and the HiggsFermion part contains in principle 27 complex parameters, neglecting Yukawa couplings to neutrinos. Luckily most of the 54 real parameters in the Yukawa sector are unobservable. After diagonalizing the lepton sector there only the three charged lepton masses remain. The quark sector can be similarly diagonalized leading to 6 quark masses, but some parts remain in the difference between weak interaction eigenstates and mass-eigenstates. The latter is conventionally put in the couplings of the charged W -boson, which is given by Vud Vus Vub dα g α − uα cα t γ µ (1 − γ5 ) Vcd Vcs Vcb sα − √ Wµ 2 2 V V V b
hep-phyymmnnn Brown-HET-990 Minimal Ansatz for the Neutrino Mass Matrix Consistent with Atm
Kyungsik Kang
Department of Physics, Brown University Providence, Rhode Island 02912, USA
1
The minimal standard model (MSM) has been highly successful in describing interactions among elementary particles from low energy up to 100 GeV. The only possible exception may be various types of neutrino oscillation experiments. There have been positive indications from large scale experiments for solar and atmospheric neutrinos that a certain amount of mixing between neutrino species may be present 1]. The recent report from the LSND experiment at the laboratory scale provides us with another hint of such a possible neutrino mixing 2]. Since neutrinos in the MSM are exactly massless, there can be no mixing among them, and it is impossible to accomodate such neutrino mixing data in the framework of the MSM. This situation is rather encouraging, since it is at present the only place where we can grasp a hint of new physics beyond the MSM. In view of this, it is quite interesting to consider what type of neutrino mass matrix can t all the data from the various types of neutrino oscillation experiments. It is our purpose to present such a mass matrix in this work. Most analyses on the neutrino oscillation assume two neutrinos oscillating with one mass di erence parameter, m2. However, the LSND experiment and the atmospheric and solar neutrino data hint at least two mass di erence parameters, requiring oscillations among at least three neutrinos. For oscillations with three neutrinos, we have two mass di erences and three real angles. In order to simplify the analysis, a certain ansatz for the mass matrix is required. In this vein, we rst brie y discuss the maximal mixing scenario for the neutrino sector. We then present our ansatz for the neutrino mass matrix as well as the numerical analyses to t the atmospheric, the LSND, and the solar neutrino data from GALLEX and SAGE. Finally, we suggest a possible Z4 symmetry model that can give the neutrino mass matrix of our ansatz. In this work, we consider only oscillations among three neutrinos, ! . One of the popular ansatz for the neutrino mass matrix is the maximal mixing one (equivalent to a cyclic permutation symmetry among three generations) 3] :
Synthesis_of_zinc_oxide_nanotetrapods_by_a_novel_fast_microemulsion-based_hydrothermal_method
Synthesis of zinc oxide nanotetrapods by a novel fast microemulsion-based hydrothermal methodJunying Jiang,Yanfen Li,Shengwei Tan,Zaiyin Huang ⁎College of Chemistry and Ecological Engineering,Guangxi University for Nationalities,Nanning 530006,PR Chinaa b s t r a c ta r t i c l e i n f o Article history:Received 25April 2010Accepted 8July 2010Available online 14July 2010Keywords:ZnO nanotetrapodsMicroemulsion-mediated hydrothermal Electrochemical analysisZnO nanotetrapods have been successfully synthesized via a novel microemulsion-mediated hydrothermal route at 120°C for 12h.X-ray power diffraction (XRD),field-emission scanning electron microscopy (FESEM),transmission electron microscopy (TEM),selected-area electron diffraction analysis (SAED),and electrochemical analysis (EA)were employed to study the structural features and electrochemical behavior of the products.It was found that these tetrapod ZnO nanostructures had a single crystal hexagonal wurtzite structure with lattice constants of a =0.3249nm and c =0.5205nm.And they exhibited a clearly electrocatalytic response,showing potential applications for sensor constructions.©2010Elsevier B.V.All rights reserved.1.IntroductionZnO is an attractive semiconductor material with a wide direct band gap (3.37eV at room temperature),large exciton binding energy (60meV),and high refractive index (N 2).It has attracted intensive research for its unique properties and versatile applications in transparent electronics,ultraviolet light emitters,piezoelectric devices,chemical sensors,spin electrics and so on [1,2].As we all know,the ability to control particle morphology is an important object in the synthesis of nanocrystals,as size and shape can signi ficantly in fluence various properties [3–5].Therefore,the target-oriented preparation of ZnO has become a big issue.Many techniques involving chemical vapor deposition,aqueous solution precipitation,microwave irradiation,thermal evaporation technique,hydrothermal synthesis,microemulsion method,gel –sol process,and electrodeposition have been used to prepare ZnO nanostructures.And lots of morphologies,such as nanobelts,nanowires,nanoneedles,nanotubes,nanosheets,and nanotetrapods have been obtained [6–18].Among them,nanote-tropod is a common morphology for ZnO and it has been extensively studied.Several methods have been developed to synthesize ZnO nanote-tropods,such as thermal evaporation methods [19–21],chemical vapor deposition [22–24],aqueous solution route and rapid thermal annealing technique [25],and so on.However,the most reported synthesis techniques are complicated,time and energy consuming.In particular,when organo-metallic precursors are used,complex procedures,high temperatures and sophisticated equipment to control the growth process are involved.For the further use of ZnOnanotetropods,a simple and inexpensive process with gentle conditions is required.Here,we present a novel fast microemulsion-based hydrothermal method to prepare ZnO nanotetrapods,which overcomes the shortcomings of previous preparation methods.Also,their electrochemical behavior was investigated by EA.2.ExperimentalZn(Ac)2·2H2O,NaOH,n-octanol,TritonX-100and cyclohexane were from Xilong Chemical Reagent Factory,which were of analytical grade and used without further puri fication.Poly (vinyl alcohol)(PVA MW 89,000–98,000)was bought from Sigma-Aldrich.Hemoglobin (Hb)from bovine blood was obtained from Fluka.In a typical procedure,firstly,one reverse microemulsion solution was prepared by adding 0.66mL 0.1M Zn(Ac)2aqueous solution into TritonX-100/cyclohexane/n-octanol system (according to the mass ratio TritonX-100/cyclohexane/n-octanol =3/8/2),which was stirred for 10min at room temperature until the microemulsion became transparent.Secondly,0.66mL 0.6M NaOH aqueous solution was added dropwise into the as-prepared reverse microemulsion solution and was kept stirred for another 20min.Then the mixed solutions were transferred to a 25mL Te flon-lined stainless-steel autoclave and kept at 120°C for 12h.After being cooled to room temperature naturally,white products were harvested by centrifugation and washed several times with acetone,deionized water and absolute ethanol,and then dried in vacuum at room temperature.The as-prepared products were characterized by X-ray diffraction (XRD,Philips PW1710with Cu K αradiation,λ=1.5406Å),field-emission scanning electron microscopy (FESEM,JEOL JSM-6700F),transmission electron microscopy (TEM,JEOL JEM-2010,200KV)andMaterials Letters 64(2010)2191–2193⁎Corresponding author.Tel.:+867713262120;fax:+867713261718.E-mail address:hzy210@ (Z.Huang).0167-577X/$–see front matter ©2010Elsevier B.V.All rights reserved.doi:10.1016/j.matlet.2010.07.026Contents lists available at ScienceDirectMaterials Lettersj o u r na l ho m e p a g e :w w w.e l s ev i e r.c o m /l o c a t e /m a t l e telectrochemical analysis(CHI660A and CHI440A electrochemical workstation,Shanghai Chenhua Instrument Co.,China).3.Results and discussionPowder XRD pattern of the as-prepared products is shown in Fig.1a.All of the diffraction peaks can be indexed to hexagonal wurtzite structural ZnO,and match well with standard hexagonal ZnO (a=3.249Å,c=5.205Å,JCPDS Card No.005-0664).The sharp and narrow diffraction peaks reveal that the synthesized nanotetrapods are highly crystallized[26].No impurity peaks were detected, indicating the formation of pure products.A typical FESEM image of the ZnO nanotetrapods is shown in Fig.1b, from which it can be seen that the as-prepared ZnO nanostructures were mainly tetrapods with leg length between200and300nm.To obtain further information about the nanostructure of these ZnO nanotetra-pods,TEM,HRTEM,and SAED analysis were performed.Fig.1c and d shows two typical TEM images of ZnO nanotetrapods,which have a typical leg length of~250nm.Fig.2a is the TEM image of the core of ZnO nanotetrapod corresponding to Fig.1d.Fig.1f,g and Fig.2b present the corresponding SAED patterns.The presence of the sharp diffraction spots rather than an amorphous ring is suggestive of the predicted formation of single crystalline ZnO.And these SAED patterns can be indexed to pure ZnO crystals of a hexagonal wurtzite structure.The HRTEM images(Fig.1e,Fig.2c and d)further indicate that the observed ZnO nanotetrapods are single crystalline with no defects of dislocations. The lattice fringes reveal that the single crystalline ZnO nanotetrapods possess interplanar spacing of about0.53nm,corresponding to the (002)plane of hexagonal ZnO.This clearly indicates that the ZnO nanoleg preferred growth along the[001]direction(c-axis).The HRTEM and SAED results also indicate that all four legs of the nanotetrapods grow along the[001]direction.Tetrapod-like ZnO with200–300nm length legs were prepared by a microemulsion-mediated hydrothermal process,which was due to the preferential growth of ZnO crystal growth along the[001] direction.Based on surface energy minimization,ZnO crystallites form zinc hydroxyl nucleate together because of excess saturation. Each of them individually grows along the c-axis into rod-like crystal, and then tetrapod-like architectures arefinally formed.A possible growth mechanism for the formation of nano-ZnO via a microemul-sion-mediated hydrothermal process was reported in the literature [27].The formation mechanism of ZnO nanoparticles was proposed based on the restriction effect of microemulsions in the crystal growth process.It is possible that many internal or external factors determined thefinal morphologies of nanocrystals during the process of nucleation and growth.The clear formation mechanism is not clear yet,we believe that the restricting effect of the microemulsion,the surfactant and cosurfactant molecules play critical roles in the morphology control.The details need further research.To investigate the electrochemical characteristics of ZnO nanote-trapods,we prepared a hydrogen peroxide(H2O2)sensor by doping ZnO nanotetrapods to the hybrid materials PVA/TiO2.Fig.3shows a typical cyclic voltammograms of the different modified electrodes in the absence of H2O2.It was found that the reduction peak current of Hb-PVA/TiO2/ZnO nanotetrapods/GC electrode(b)increased obvi-ously comparing with that of Hb-PVA/TiO2/GC electrode(a), indicating that the as-prepared ZnO nanotetrapods accelerate electrontransfer.Fig.1.(a,b)Power XRD pattern and typical FESEM image of the as-synthesized ZnO nanotetrapods,respectively,(c)TEM image of a single ZnO nanotetrapod,and the corresponding SAED pattern of the core(f),(d)TEM image of a single ZnO nanotetrapod,(e)HRTEM image from the outlined area in(d),and the corresponding SAED pattern(g).2192J.Jiang et al./Materials Letters64(2010)2191–21934.ConclusionIn summary,ZnO nanotetrapods have been successfully synthe-sized via a simple microemulsion-mediated hydrothermal route.The as-prepared products are high phase-purity with hexagonal wurtzite in crystal structure.Clearly EA at room temperature suggests that these materials may have good potential applications for sensor constructions.Further studies on the growth mechanism and characterization experiments are underway.AcknowledgementsThis work is financially supported by the National Natural Science Foundation of China (No.20963001);and theGuangxi Natural Science Foundation of China (No.0575030and No.0832078).References[1]Wang ZL.Chinese Sci Bull 2009;54:4021–34.[2]Wang ZL.Mater Sci Eng R 2009;64:33–71.[3]Ischenko V,Polarz S,Grote D,Stavarache V,Fink K.Adv Funct Mater 2005;15:1945–54.[4]Gao PX,Ding Y,Wang ZL.Nano Lett 2003;3:1315–20.[5]Zhang N,Yi R,Shi RR,Gao GH,Chen G,Liu XH.Mater Lett 2009;63:496–9.[6]Zhang YG,Lu F,Wang ZY,Zhang LD.J Phys Chem C 2007;111:4519–23.[7]Fu YS,Du XW,Kulinich SA,Qiu JS,Qin WJ,Li R,et al.J Am Chem Soc 2007;129:16029–33.[8]Seungho C,Seung HJ,Kun HL.J Phys Chem C 2008;112:12769–76.[9]Zhang J,Yang YD,Xu BL,Jiang FH,Li JP.J Cryst Growth 2005;280:509–15.[10]Deng Y,Wang GS,Li N,Guo L.J Lumin 2009;129:55–8.[11]Niederberger M.Acc Chem Res 2007;40:793–800.[12]Xu LF,Guo Y,Liao Q,Zhang JP,Xu DS.J Phys Chem B 2005;109:13519–22.[13]Pan ZW,Dai ZR,Wang ZL.Science 2001;291:1947–9.[14]Huang MH,Mao S,Feick H,Yan HQ,Wu YY,Kind H,et al.Science 2001;292:1897–9.[15]Zhang ZX,Yuan HJ,Zhou JJ,Liu DF,Luo SD,Miao YM,et al.J Phys Chem B 2006;110:8566–9.[16]Gao PX,Ding Y,Mai WJ,Hughes WL,Lao CS,Wang ZL.Science 2005;309:1700–4.[17]Yan HQ,He RR,Pham J,Yang PD.Adv Mater 2003;15:402–5.[18]Dai Y,Zhang Y,Wang ZL.Solid State Commun 2003;126:629–33.[19]Al-Azri K,Nor RM,Amin YM,Al-Ruqeishi MS.Appl Surf Sci 2010;256:5957–60.[20]Liu F,Zhang HR,Li JQ,Gao HJ.Nanotechnology 2004;15:949–52.[21]Wei J,Yang C,Man BY,Liu M.Physica B 2010;405:1976–9.[22]Ahmad M,Pan CF,Zhao J,Iqbal J,Zhu J.Mater Chem Phys 2010;120:319–22.[23]Zhang ZX,Sun LF,Zhao YC,Liu Z.Nano Lett 2008;8:652–5.[24]Yan BH,He RR,Pham J,Yang PD.Adv Mater 2003;15:402–5.[25]Lupan O,Chow L,Chai GY,Roldan B.Mater Sci Eng B 2007;145:57–66.[26]Marques APA,Picon FC,Melo DMA,Pizani PS,Leite ER,Varela JA,et al.J Fluoresc2008;18:51–9.[27]Li XC,He GH,Xiao GK,Liu HJ,Wang M.J Colloid Interface Sci 2009;333:465–73.Fig.2.TEM images of the core of ZnO nanotetrapod corresponding to Fig.1d (a),junction of three legs (c),and junction between two legs (d),respectively.(b)The SAED pattern of the tetrapod in(a).Fig.3.The cyclic voltammograms of different modi fied electrodes:(a)Hb-PVA/TiO2/GC electrode and (b)Hb-PVA/TiO2/ZnO nanotetrapods/GC electrode in the absence of H2O2in 0.12M pH 6.2PBS.2193J.Jiang et al./Materials Letters 64(2010)2191–2193。
锰的溶解。LiMn2O4中Mn3...
关键词：锂离子电池；大容量；软包装材料；关键工艺；电化学性能
II
硕士学论文
Abstract
With the advent of the energy crisis and the environmental crisis, the whole world has an urgent need for renewable clean energy, as well as the electric vehicles industry. Lithium ion battery currently has got international attention as the new clean energy, which has high operating voltage, high specific energy, light weight, long cycle life, no memory effect, low self-discharge and pollution-free, etc. and has already been applied to all aspects of people's lives, especially widely used in digital products and electric vehicles. However, lithium ion battery also has some disadvantages, such as: low capacity and poor consistent performance, which will seriously affect the application of lithium battery, therefore, preparation of high capacity and good consistent performance of lithium ion battery will be a new challenge of the lithium ion battery industry.
physical metallurgy4
Lecture 4
Transmission Electron Microscope (TEM)
The transmission electron microscope (TEM) is, in many respects, analogous to an optical microscope. The source is electron gun instead of a light filament. The lenses are magnetic, being composed normally of a current-carrying coil surrounded by a soft iron case. The lenses are energized by direct current. The detail in the image is formed by the diffraction of electrons from the crystallographic planes of the object being investigated.
Transmission Electron Microscope (TEM)
The interaction between electron and the atoms in specimen can occur either elastically or inelastically.
Transmission Electron Microscan find that wavelength is equal 4x10-12 m what is equal 4x10-3 nm This is about two orders of magnitude smaller than the average length used in X-ray diffraction studies of metallic crystals.
电化学脱合金的英文
电化学脱合金的英文Electrochemical Dealloying: Principles, Applications, and Challenges.Introduction.Electrochemical dealloying is a process that involves the selective removal of one or more constituent metalsfrom a multicomponent metallic alloy by electrochemical means. This process, often referred to as "dealuminization" in the context of aluminum-based alloys, has found widespread applications in materials science, nanotechnology, and energy conversion and storage systems. The primary advantage of electrochemical dealloying lies in its ability to create nanostructured materials with unique physical and chemical properties, such as high surface area, porosity, and conductivity.Principles of Electrochemical Dealloying.The electrochemical dealloying process occurs when an alloy is immersed in an electrolyte solution and apotential is applied between the alloy and a counter-electrode. The applied potential drives the electrochemical reactions at the alloy surface, resulting in thedissolution of one or more constituent metals. The dissolution rate of each metal depends on its electrochemical properties, such as the redox potential and electrochemical activity in the given electrolyte.During the dealloying process, the alloy is typically the anode, and the counter-electrode is the cathode. The anode is connected to the positive terminal of the power source, while the cathode is connected to the negative terminal. When the potential is applied, the alloy begins to dissolve, and the dissolved metal ions migrate towards the cathode. At the cathode, the metal ions are reduced and deposited on the surface, forming a new metal layer.The rate of metal dissolution during electrochemical dealloying is controlled by several factors, including the electrolyte composition, applied potential, temperature,and alloy composition. By optimizing these parameters, researchers can precisely control the morphology, porosity, and composition of the resulting nanostructured materials.Applications of Electrochemical Dealloying.Electrochemical dealloying has found numerous applications in materials science and engineering. Some of the key applications are discussed below:1. Nanoporous Metals: Electrochemical dealloying is widely used to create nanoporous metals with high surface area and porosity. These materials exhibit unique physical and chemical properties that are beneficial in various applications, such as catalysis, sensors, and energy storage.2. Battery Materials: Nanoporous metals produced by electrochemical dealloying have been explored as anode materials for lithium-ion batteries. The high porosity and surface area of these materials enhance the lithium storage capacity and improve the battery's performance.3. Fuel Cells: Electrochemical dealloying has also been used to create nanostructured catalysts for fuel cells. These catalysts exhibit enhanced activity and durability, which are crucial for efficient fuel cell operation.4. Biomedical Applications: Nanoporous metals produced by electrochemical dealloying have potential applicationsin biomedicine, such as drug delivery, tissue engineering, and implant materials. The porous structure of these materials allows for controlled drug release and improved cell adhesion and growth.Challenges and Future Directions.Despite the significant progress made inelectrochemical dealloying, several challenges remain to be addressed. One of the primary challenges is the control of the dealloying process at the nanoscale, as it is crucialfor achieving the desired material properties. Additionally, the development of new electrolytes and optimization of dealloying parameters are ongoing research efforts.Future research in electrochemical dealloying could focus on exploring new alloy systems, optimizing the dealloying process for specific applications, and understanding the fundamental mechanisms underlying metal dissolution and nanostructure formation. Furthermore, the integration of electrochemical dealloying with other nanotechnology approaches, such as lithography and templating, could lead to the development of even more advanced materials with tailored properties.Conclusion.Electrochemical dealloying is a powerful technique for creating nanostructured materials with unique physical and chemical properties. Its applications span multiple fields, including materials science, energy conversion and storage, and biomedicine. While significant progress has been madein this field, there are still numerous challenges and opportunities for further research and development. With the advancement of nanotechnology and materials science, electrochemical dealloying holds promise for enabling thecreation of next-generation materials with improved performance and functionality.。
欧洲药典7.5版
INDEX
To aid users the index includes a reference to the supplement in which the latest version of a text can be found. For example : Amikacin sulfate...............................................7.5-4579 means the monograph Amikacin sulfate can be found on page 4579 of Supplement 7.5. Note that where no reference to a supplement is made, the text can be found in the principal volume.
English index ........................................................................ 4707
Latin index ................................................................................. 4739
EUROPEAN PHARMACOPபைடு நூலகம்EIA 7.5
Index
Numerics 1. General notices ................................................................... 7.5-4453 2.1.1. Droppers...................
一种对基于SG测试系统的反辐射导引头校正数据的处理方法
电子信息对抗技术Electronic Information Warfare Technology2021,36(2)㊀㊀中图分类号:TN974㊀㊀㊀㊀㊀㊀㊀文献标志码:A㊀㊀㊀㊀㊀㊀㊀文章编号:1674-2230(2021)02-0074-05收稿日期:2020-07-07;修回日期:2020-07-31作者简介:秦万治(1983-),男,硕士,高级工程师㊂一种对基于SG 测试系统的反辐射导引头校正数据的处理方法秦万治(电子信息控制重点实验室,成都610036)摘要:随着反辐射制导精度的提升,天线罩在探测过程中引入的幅相调制特性变得不可忽视,需通过头罩匹配进行补偿㊂为提升匹配效率,采用了SATIMO 公司的SG 系统完成快速测试,但通常情况下其原始数据不满足导引头使用,需做进一步转换㊂提出一种基于三方转换的坐标变换和插值处理的数据转换方法,可以非常方便地将SG 系统下测试得到的幅相数据,转化到任意形式的目标坐标系下㊂关键词:头罩匹配;幅相数据;三方转换;SG 系统DOI :10.3969/j.issn.1674-2230.2021.02.017A Process Method of Calibration Data Used by Anti -RadarSeeker Got by SG Testing SystemQIN Wanzhi(Science and Technology on Electronic Information Control Laboratory,Chengdu 610036,China)Abstract :As the guidance precision of anti -radar is higher,modulation of signal amplification and phase caused by random in radio direction finding could not be accepted as the past.These bad effects could be reduced with pre -calibration.A near field test system SG which pro-duced by SATIMO Co.is used to get an acceptable time in processing.The original data could not be used directly by anti -radar guider because of the coordinate not matching.A calibration data translation method based on tri -coordinate matching and interposition which can give a sim-ple way to covert the original data gotten by SG system into any target coordinate is studied.Key words :pre -calibration;amplification and phase data;tri -coordinate translate;SG system1㊀引言反辐射攻击[1-2]实现对敌雷达系统的硬摧毁能力,是电子战体系的重要组成部分㊂反辐射导引头对空间雷达信号进行侦收㊁识别,并通过电磁信号幅相特性实现对辐射源的测向,形成制导信号,引导反辐射武器完成整个打击过程,其测向性能决定了反辐射武器的攻击精度㊂随着反辐射制导精度的提高,天线罩在信号探测过程中引入的幅相调制变得不可忽略,需通过头罩匹配进行补偿[3-4]㊂工程上通常采用在微波暗室利用转台和辐射源对带罩状态下的导引头进行全角度㊁全频段测试来完成头罩匹配,但随着导引头带宽㊁探测视场㊁测试精度的逐步提升,匹配过程效率不足成为制约其工程应用的一个关键问题㊂导致头罩匹配效率低下的主要原因是转台运行效率不足,每转动一个角度,都需要经历 加速-匀速-减速-达位判定及停止 过程,当转台载荷较大,测试角度网格较密(角度步进小㊁数量多)时,运行效率显著47电子信息对抗技术㊃第36卷2021年3月第2期秦万治一种对基于SG 测试系统的反辐射导引头校正数据的处理方法降低㊂图1㊀基于二维转台的测试环境及转台速度曲线示意图理论上可以通过构建远场目标辐射阵列,将转台转动变为电信号空间移动来提升效率,但存在设备量大,建设及维护成本昂贵的问题㊂通常这样的阵列测试环境多用于半实物仿真制导控制验证,用于头罩匹配费效比过高㊂图2㊀基于远场阵列的测试环境示意图由于头罩匹配过程本质上是一个带罩条件下的天线测试过程,可直接借用专业的天线测试系统,如法国SATIMO 公司的SG 近场测试系统[5],该系统采用一维电扫的近场测试方式,建设空间小,在测试效率和设备费用上取得了较好的平衡㊂图3㊀SG 近场测试系统[5]虽然该系统能够自动完成电磁信号从近场到远场的数据转换,但数据坐标系为该测试系统定义的球坐标系,实际使用中需进一步转换到导引头制导所需的目标坐标系㊂目标坐标系通常由飞行控制系统指定,形式各不相同,本文仅以其中一种为特例进行阐释㊂本文涉及的SG 系统测试坐标系及飞控系统目标坐标系如图4所示㊂(a)SG系统测试坐标系(b)飞控系统目标坐标系图4㊀两种坐标系定义SG 系统测试坐标系中,目标点S ,定义OS 与x 轴的空间夹角XOS 为离轴角θ,S 在zoy 平面上投影线和Z 轴夹角ZOS 0为旋转角φ,则其参数方程为:x =R cos(θ)y =R sin(θ)sin (φ)z =R sin(θ)cos (φ)ìîíïïï(1)飞控系统目标坐标系中,目标点S ,定义其在xoy 平面上的投影线与X 轴夹角X 0S 0为俯仰角el ,定义目标矢量OS 和其在xoy 平面上的投影线0S 0线的空间角SOS 0为方位角az ,则其参数方程如为:x =R cos(az )cos(el )y =R cos az ()sin el ()z =R sin(az )ìîíïïï(2)2 数据转换方法㊀㊀由前文可知,为便于导引头使用,需将由SG 测试系统得到的幅相数据由球面坐标系转换到飞控系统指定的目标坐标系下㊂57秦万治一种对基于SG 测试系统的反辐射导引头校正数据的处理方法投稿邮箱:dzxxdkjs@2.1㊀基于角度逆变的直接转化由SG 系统可以得到三维空间中,辐射源与导引头在各相对角度条件下的信号幅相特性数据,该数据基于球面坐标系排列,需将其重新排列并转换到飞控系统指定的目标坐标系下㊂由于球坐标系下的整数角度格点和目标坐标系下的整数格点并不对应,而导引头使用时往往要求以整数格点为参考,还需对其进行插值处理㊂综上,整个转换过程分为两个主要步骤,首先完成坐标系的转化,然后再通过插值得到指定角度格点下的幅相数据㊂坐标转化既可以将SG 系统的[phi ,theta ]转化到飞控系统指定的[az ,el ],也可以将目标[az ,el ]逆向转化到[phi ,theta ]坐标系下,不失一般性,本文选用将[az ,el ]转换到[phi ,theta ]后再插值的方式,处理流程如图5所示㊂对于同一个空间点S ,联立两种坐标系下的参数方程,可以解出目标角度[az ,el ]变换到SG 球坐标角度[φ,θ]的转化公式[φ,θ]=F (az ,el )如下:cos θ=cos(az )cos(el )cos φ=sin(az )/sin(θ){(3)由飞控系统指定的参考目标角度tgtAng =[Az ,El ]导出其在SG 球坐标系下的对应角度rAng =F (tgtAng )=[φᶄ,θᶄ],以及由SG 系统实测幅相数据AmPh ,测试时目标信号角度sigAng =[φ,θ],通过插值运算可以很容易得到与参考目标角度相对应的幅相数据AmPhᶄ㊂AmPhᶄ=interp (sigAng ,AmPh ,rAng )(4)使用一段实测数据对以上方法进行验证,SG 系统原始数据角度范围为φɪ0,π[],θɪ[-π,π],将其转换到目标角度az ɪ[-π/6,π/6]及el ɪ[-π/6,π/6]范围内㊂图5㊀基于角度逆变的幅相数据转换流程插值采用MATLAB 提供的标准2维插值函数interp 2(),插值模式选用默认Linear 模式,在复数域对幅相进行联合插值,两个极化转换前后的幅相数据如图6所示㊂(a)SG测试系统得到的幅相数据图像(b)转化后幅相数据图6㊀幅相数据转换效果67电子信息对抗技术·第36卷2021年3月第2期秦万治一种对基于SG 测试系统的反辐射导引头校正数据的处理方法㊀㊀以上处理方法虽然非常直观,但在角度逆变过程中需要进行反三角运算,同时由于反三角函数的值域限制,需要在球面空间中分8个象限对运算结果进行调整,调整过程非常细致,且与两个系统的坐标系详细定义强相关㊂与此同时,还不排除存在由目标角度坐标系定义的参数方程与SG 系统参数方程联立后是一个超越方程,无法求得解析解的情况㊂4 基于三方坐标的间接转换㊀㊀无论是测试系统的球面坐标,还是飞行控制系统的目标坐标定义,都必定以两个正交运动为基准,对 目标-导引头 相对角度关系进行描述,只是选择的正交基有所不同,前文将飞控指定的目标坐标系角度[az ,el ]逆变到SG 系统球面坐标系的本质是使两者的坐标系基准相匹配㊂既然如此,将两者同时向第三种坐标基准定义转换,再完成数据插值,也能达到相同的效果㊂定义第三方坐标系如图7所示㊂图7㊀第三方坐标系定义目标点S ,定义其在xoz 平面内投影与x 轴夹角XOS 1为az 角,在xoy 平面内投影与x 轴夹角XOS 2为el 角,则:tg az ()=z /x tg el ()=y /x{(5)由式(5)可见,无论是SG 系统还是飞行控制系统,基于其参数方程,都可以很容易求得其对应于第三方坐标系下的变换角度,从而避免了联立方程组求解的过程㊂基于该方法的幅相数据处理流程如图8所示㊂图8㊀基于三方转换的幅相数据转换流程以上过程虽然避免了参数方程组的联立求解,但还是需要求解一次反正切函数㊂由插值处理过程可知,若原始参考坐标和最终插值坐标做同步变换,得到的插值结果不变,即:ZI =interp2(X ,Y ,Z ,XI ,YI )=interp2(T (X ),T (Y ),Z ,T (XI ),T (YI ))其中[X ,Y ,Z ]是已有数据样本的x ,y ,z 值,[XI ,YI ]是拟进行插值处理的[x ,y ]坐标值,ZI 是插值得到的z 坐标值,T ()是某种特定变换㊂图9㊀一维插值处理过程示意因此,进一步将第三方坐标系重定义为 角度的正切值 ,即 az 和el 的正切值 [tg Az ,tg El ],则可直接以两组参数方程各自在az 向和el 向的正切值,即[z x ,yx]为基准进行插值处理,进一步减少了反三角函数的解算过程㊂三方插值数据处理过程如下:1)由SG 系统测试得到复幅相数据AmPh (φ,θ)及与之对应的角度组合[φ,θ]2)由测试系统坐标系参数方程得到与之对应的第三方坐标[X ,Y ]=[z x ,yx ](φ,θ)77秦万治一种对基于SG 测试系统的反辐射导引头校正数据的处理方法投稿邮箱:dzxxdkjs@3)由飞控机指定的目标坐标系参数方程得到其对应的三方坐标[XI ,YI ]=[z x ,y x ](az ,el )4)利用MATLAB 提供的interp2()插值函数,在复数域进行幅相联合插值,得到与[az ,el ]对应的幅相数据AmPh (az ,el )=interp2(X ,Y ,AmPh (φ,θ),XI ,YI )经试验表明,由以上方式完成数据转换的效果与之前得到的结果一致,两种方式得到的转换幅相图像相同,转换结果可参看图6(b)㊂5㊀结束语㊀㊀通过SG 测试系统可以快速完成头罩匹配过程,但需将测试数据转到飞控系统指定的坐标空间,利用 三方转换 ,将SG 系统和飞行控制系统各自的数据坐标转化到一个虚拟的第三方坐标空间中进行插值处理,可避免对两种坐标系参数方程的联立求解,也可避免反三角函数求解过程中因值域限制导致的角度调整,能够非常便捷地实现由SG 系统实测幅相数据到任意指定坐标系数据的转换㊂参考文献:[1]㊀张立军.反辐射武器与反辐射攻击初探[J].中国航空武器试验训练靶场,2004(1):22-26.[2]㊀杨卫丽.国外反辐射导弹及其制导技术发展[J].战术导弹技术,2015(2):12-16.[3]㊀阮颖铮.天线罩对阵列天线方向图的影响[J].电子科技大学学报,1997,26(3):240-243.[4]㊀赖世明.天线罩对阵列DOA 估计性能影响及校正方法研究[D].哈尔滨:哈尔滨工业大学,2008.[5]㊀CHOUMANE A.Creation of An Isotropic Multi -PathPropagation Channel Using SATIMO SG24System [C]//Proceedings of the 5th European Conference onAntennas and Propagation (EUCAP ),2011:1644-1645.(上接第63页)法调度时间有一定的改善㊂但更加重要的是优化方法对阻断率的提升,从82%提升到96%,阻断率提升较为显著,说明了优化方法的有效性㊂6㊀结束语㊀㊀本文研究了便携式WiFi 管控设备设计与实现,在此基础上,提出了基于多维特征的非法WiFi 评估方法,最后对原始资源调度方案进行了优化,提出了基于调度表的多目标探测与阻断资源协调调度方法㊂本文提出的研究方法,对非法WiFi 的管控技术提供了一个新的可行的研究方案,可解决当前WiFi 管控的目标威胁评估及高效阻断的难题,具有较高工程应用价值㊂参考文献:[1]㊀YANG X Y,BANDELA C,YI P Y.Vulnerabilities andSecurity Enhancements for the IEEE 802.11WLANs[C]//GLOBECOM 2005 IEEE Global Telecommu-nications Conference,St.Louis,USA:IEEE,2005:1655-1659.[2]㊀杨新,付毓生.IEEE802.11无线局域网安全漏洞研究[J].信息安全与通信保密,2005.7(1):296-299.[3]㊀Statista Research Department.Global public Wi -Fihotspots 2016-2022[EB /OL].[2020-2-19].ht-tps:// /statistics /677108/global -public -wi -fi -hotspots /.[4]㊀黄院平.公共WiFi 安全检测技术研究与实现[D].上海:上海交通大学,2017:13-16.[5]㊀LIUP F,YANG P L,et al.Real -Time Identification ofRogue WiFi Connections Using Environment -Inde-pendent Physical Features [C ]//IEEE INFOCOM2019 IEEE Conference on Computer Communica-tions,Paris,France:IEEE,2019:190-198.[6]㊀陈伟,顾杨,李晨阳,等.无线钓鱼接入点攻击与检测技术研究综述[J].武汉大学学报(理学版),2014,60(2):13-23.[7]㊀SRILASAK S,WONGTHAVARAWAT K.An PhonphoemIntegrated Wireless Rogue Access Point Detection andCounterattack System [C]//2008International Confer-ence on Information Security and Assurance(ISA 2008),Taipei,China:IEEE,2008:326-331.87。
26457528_BDD阳极电活化硫酸盐降解除草剂阿特拉津的研究
BDD 阳极电活化硫酸盐降解除草剂阿特拉津的研究孙智宇,张峰,杨帆,崔建国(太原理工大学环境科学与工程学院,山西太原030024)[摘要]用掺硼金刚石(BDD )电极对硫酸盐进行阳极活化,结果发现,在循环阳极电极模式下,BDD 阳极电活化硫酸盐去除阿特拉津(ATZ )的速率较直接电解去除ATZ 的速率高出约14倍。
当电流密度为30mA/cm 2、Na 2SO 4电解质浓度为0.1mol/L 时,电活化硫酸盐产生的SO 4·-对ATZ 降解的相对贡献率可达90%以上。
[关键词]硫酸盐;掺硼金刚石;电活化;阿特拉津[中图分类号]X703[文献标识码]A[文章编号]1005-829X (2021)04-0062-04Degradation herbicide atrazine by BDD anode electro ⁃active sulfateSun Zhiyu ,Zhang Feng ,Yang Fan ,Cui Jianguo(College of Environmental Science and Engineering ,Taiyuan University of Technology ,Taiyuan 030024,China )Abstract :Boron ⁃doped diamond (BDD )electrode was used for anode activation of sulfate.The results showed that in the cycle anode electrode mode ,the rate of atrazine (ATZ )degradation by electro ⁃activated sulfate was about 14times higher than the rate of ATZ degradation by direct electrolysis.When the current density was 30mA/cm 2and theNa 2SO 4electrolyte concentration was 0.1mol/L ,the SO 4·-produced by electro ⁃activated sulfate could contribute morethan 90%to the degradation of ATZ.Key words :sulfate ;bcoron ⁃doped diamond ;electrical activation ;atrazine[基金项目]国家自然科学基金青年基金(51408397);山西省自然科学基金(201801D121275)阿特拉津(ATZ )是一种人工合成的除草剂,半衰期较长(41~231d ),进入环境中难以降解,对动植物和人类可产生不同程度的危害。
司法鉴定标准扫描电镜x射线能谱仪
司法鉴定标准扫描电镜x射线能谱仪英文回答：Scanning Electron Microscope X-ray Spectrometer for Forensic Science Standard.Introduction.Scanning electron microscopy (SEM) is a powerful analytical technique used in various scientific fields, including forensic science. When coupled with an X-ray energy dispersive spectrometer (EDS), SEM provides valuable information about the elemental composition of materials. This combination, known as scanning electron microscope X-ray spectrometers (SEM-EDS), plays a crucial role in forensic investigations.Forensic Applications.SEM-EDS has numerous forensic applications, such as:Identification and characterization of trace evidence: SEM-EDS can analyze and identify microscopic particles, such as gunshot residue, fibers, glass fragments, and paint chips. By determining the elemental composition, forensic scientists can link suspects, victims, and crime scenes.Analysis of firearms and ammunition: SEM-EDS can examine tool marks, striations, and other microscopic features on firearms and ammunition. It aids in identifying the type of firearm used in a crime and matching bullets to specific weapons.Drug analysis: SEM-EDS can detect and characterize drug residues, helping forensic scientists determine the type and quantity of drugs present.Analysis of counterfeit goods: SEM-EDS can identify and compare the elemental composition of materials used in counterfeit products, such as banknotes, artwork, and electronics.Forensic archaeology: SEM-EDS assists in the examination of archaeological artifacts, providing insights into their composition, manufacturing techniques, and potential provenance.Standards.To ensure the accuracy, reliability, and consistency of SEM-EDS results in forensic investigations, it is crucial to follow established standards. These standards encompass various aspects, including:Sample preparation: Proper sample preparation techniques are essential to minimize contamination and ensure representative results.Instrumentation calibration: SEM-EDS equipment must be calibrated regularly using certified reference materials to ensure accurate elemental quantification.Data acquisition and analysis: Standardized protocols for data acquisition and analysis should be employed tominimize operator bias and ensure the reliability of results.Reporting: Forensic reports should adhere to established guidelines, clearly presenting the findings and any limitations of the analysis.Conclusion.Scanning electron microscope X-ray spectrometers are indispensable tools in forensic science, providinginvaluable information about the elemental composition of materials. By following established standards, forensic scientists can utilize SEM-EDS to effectively analyze trace evidence, firearms and ammunition, drugs, counterfeit goods, and archaeological artifacts. The adherence to these standards ensures the accuracy, reliability, andconsistency of SEM-EDS results, contributing to robust and defensible forensic conclusions.中文回答：司法鉴定标准扫描电镜 X 射线能谱仪。
7. Strehl Ratio
The spherical wave coherence diameter determines the system resolution. The angular resolution looking up is λ/rosL, and that looking down is λ/ros0. For distant sources rosL ≈ r0, which allows ro to be used in resolution calculations looking towards space. For HV-21 turbulence r0 is about 5 cm at 0.5 μm. For a system looking down from 100 km above the earth the coherence diameter is 2.2 m at this wavelength, which is a factor of 44 times the resolution looking up. This is why the resolution of an imaging system looking down toward the earth is much greater than that of an imaging system on the ground looking at an object in space.
7.1 Strehl Ratio for Propagation Through Turbulence
The problem of determining the on-axis intensity of a plane wave propagating through atmospheric turbulence was analyzed by Fried (1966), and the resultant integral was evaluated numerically. Here a compact analytic expression for the Strehl ratio is obtained. A second form expressible as an infinite series is also obtained. This second solution is more convenient, since a few series terms give an accurate answer for small levels of turbulence. An asymptotic series is obtained that is applicable when turbulence is more severe. It is shown that the first two terms of the series give an accurate result in the regime in which most astronomical telescopes operate.
透射电镜故障管理方案
透射电镜故障管理方案英文回答：Transmitted electron microscopy (TEM) is an essential tool in materials science and nanotechnology research. However, like any complex instrument, TEMs can experience various malfunctions that can hinder their performance. To effectively manage TEM faults, a comprehensive plan should be in place. In this article, we will outline a fault management plan for TEMs.1. Regular Maintenance and Inspection:Regular maintenance and inspection are crucial for preventing and detecting potential faults in TEMs. This includes cleaning the system, checking for loose connections, and ensuring proper alignment of components. It is recommended to follow the manufacturer's guidelines for maintenance and inspection intervals.定期维护和检查：定期维护和检查对于预防和检测透射电镜中的潜在故障至关重要。
这包括清洁系统、检查松动的连接，并确保组件的正确对准。
建议按照制造商的维护和检查间隔进行操作。
维克拉莫尔单晶晶体管电流传感器产品说明书
4N E x t G E N E R a t i O NB U S B A R m O d u L E!VSPL/ENG/SC/106-Rev00Dimensions in mmsales @ THIS DATASHEET IS APPLICABLE FOR: elDora VSP.60.aaa.03 (aaa=250-270)CautiON: READ SAFETY AND INSTALLATION MANUAL BEFORE USING THE PRODUCT.Specifications included in this datasheet are subject to change without notice. Electrical data without guarantee. Please confirm your exact requirement with the company representative while placing your order.Performance WarrantyIV CurvesDS-60-P-4BB-E-R0135,3992956.44-7.5 × 7.5 / 2DRAIN HOLEJUNCTION BOX LABEL1000+–2–4⦰GROUNDINGHOLE8-6.5 × 1016-8 × 3.5VENT HOLEINSTALLINGHOLESIDE VIEWBACK VIEWSECTIONAL VIEW OF AL-PROFILE35.325.411.4164013608601000 W/m 2700 W/m 2400 W/m 2200 W/m 2100 W/m 2987654321C u r r e n t (A )VoltAge (V)0 5 10 15 20 25 30 35 40100%90%80%70%60%1 YEAR27 YEARS1 year: 97.5%27 years: 80.1%Electrical Data 1 All data refers to STC (AM 1.5, 1000 W/m 2, 25 °C)Peak Power P max (Wp)250252.5255257.5260262.5265267.5270maximum Voltage V mpp (V)30.4930.5430.6230.7330.8430.8930.9230.9831.03maximum current I mpp (a)8.208.278.338.388.438.508.578.648.704open circuit Voltage V oc (V)37.4437.5137.5937.7737.9537.9038.1238.238.28Short circuit current I sc (a)8.758.808.848.888.938.989.039.099.15module efficiency (%)15.3715.5215.6715.8315.9816.1416.2916.4416.601) STC: 1000 W/m 2 irradiance, 25°C cell temperature, AM 1.5g spectrum according to EN 60904-3.Average relative efficiency reduction of 5% at 200 W/m 2 according to EN 60904-1.Electrical Parameters at NOCT 2Power (W)185.62187.25188.88191.65192.79193.49194.69196.02197.77V @P max (V)27.6527.6927.7227.7727.8227.8627.9027.9528.01I @P max (a) 6.72 6.77 6.82 6.87 6.93 6.96 6.987.027.06V oc (V)35.1635.2535.3535.3635.3635.4235.4835.5335.59I sc (a)7.067.117.167.207.247.317.377.437.492) NOCT irradiance 800 W/m 2, ambient temperature 20°C, wind speed 1 m/secTemperature Coefficients (Tc) permissible operating conditionsTc of open circuit Voltage (β)-0.31%/°CTc of Short circuit current (α)0.058%/°C Tc of Power (γ)-0.41%/°C maximum System Voltage 1000 V nocT45°C ± 2°C Temperature range-40°C to + 85°CMechanical Datalength × Width × Height 1640 × mm × 992 mm × 36 mm Weight 18 kgJunction Box IP67, 3 bypass diodescable & connectors 1000 mm length cables,SOLARLOK PV4 connectors (MC4 compatible)application class Class A (Safety class II)Superstrate High transmission low iron tempered glass, AR coated cells60 polycrystalline solar cells, 4 bus bars cell encapsulant EVA (Ethylene Vinyl Acetate)Back Sheet Composite filmframeAnodized aluminium frame with twin wall profile mechanical load Test 5400 Pa maximum Series fuse rating15 AWarranty and CertificationsProduct Warranty**10 yearsPerformance Warranty**Linear power warranty for 27 years with 2.5% for 1st year degradation and 0.67% from year 2 to year 27approvals and certificatesIEC 61215 Ed2*, IEC 61730*, IEC 61701*, IEC 62716*, CE*, MCS*, PV Cycle, IEC 62804*, CEC (Australia)*Packaging InformationQuantity /Pallet28Pallets/container (40'Hc)28Quantity/container (40'Hc)784* All (*) certifications under progress.** Refer to Vikram Solar’s warranty document for terms and conditions.TECHNICAL DATAELDORA PRIME SERIES。
循环伏安法英文
循环伏安法英文Cyclic Voltammetry: A Comprehensive OverviewIntroduction:Cyclic Voltammetry (CV) is an electrochemical technique widely used to investigate the redox properties of electroactive species in a solution. It provides valuable information about the thermodynamics, kinetics, and mechanisms of redox reactions, making it an essential tool in various fields such as analytical chemistry, electrochemistry, and materials science. This article aims to provide a comprehensive overview of Cyclic Voltammetry, discussing its principles, experimental setup, data interpretation, and applications.Principles of Cyclic Voltammetry:Cyclic Voltammetry involves the application of a triangular potential waveform to an electrochemical cell, typically consisting of a working electrode, a reference electrode, and a counter electrode. The potential is swept linearly between a negative and positive potential limit (known as the scan range) at a constant scan rate. The resulting current response is recorded as a function of applied potential.Experimental Setup:A typical experimental setup for Cyclic Voltammetry includes a potentiostat, which controls the potential at the working electrode, and an electrochemical cell equipped with the necessary electrodes. The working electrode is typically made of a conductive material such as glassy carbon, platinum, or gold. The reference electrode provides a stable reference potential against which the potential at the working electrode is measured. The counter electrode completes the electrical circuit and allows the flow of current. The electrochemical cell also contains a supporting electrolyte, which enhances the conductivity of the solution.Data Interpretation:The resulting current-potential plot obtained from Cyclic Voltammetry is called a voltammogram. It consists of two curves - a forward sweep and a reverse sweep. The peak currents observed in the voltammogram correspond to the redox processes occurring at the working electrode. The peak potential (Ep) indicates the potential at which the redox reaction occurs. The peak current (Ip) is proportional to the concentration of the electroactive species and the scan rate. The shape and position of the peaks can provide information about the nature of the redox reaction, including the number of electrons involved, the reversibility of the reaction, and any subsequent chemical reactions.Applications of Cyclic Voltammetry:Cyclic Voltammetry finds applications in various fields:1. Electrochemical Sensors: It is used to determine the concentration of analytes in solution, making it suitable for sensing applications in environmental monitoring, food analysis, and clinical diagnostics.2. Energy Storage and Conversion: Cyclic Voltammetry helps characterize the electrochemical behavior of batteries, supercapacitors, and fuel cells, aiding in the design and optimization of energy storage and conversion devices.3. Corrosion Studies: It allows the investigation of corrosion processes by determining the corrosion potential and rate of materials exposed to corrosive environments.4. Determination of Mechanisms: Cyclic Voltammetry elucidates the reaction mechanisms of electroactive compounds, providing insights into their redox behavior and electron transfer processes.5. Material Characterization: It assists in the study of materials such as catalysts, nanomaterials, and thin films by analyzing their electrochemical properties.Conclusion:Cyclic Voltammetry is a powerful technique for exploring the redox properties of electroactive species. Its ability to provide quantitative information about thethermodynamics, kinetics, and mechanisms of redox reactions makes it an indispensable tool in various scientific disciplines. By understanding the principles, experimental setup, data interpretation, and applications of Cyclic Voltammetry, researchers and scientists can effectively harness its potential for their specific research interests and practical needs.。
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
Summary. — We present the complete NLO electroweak contribution to the production of diagonal squark–anti-squark pairs in proton–proton collisions. We discuss their effects for the production of squarks different from top squarks, in the SPS1a′ scenario.
2.1. Tree level EW contributions. – Tree-level EW contributions to the process (1), are of O(αsα) and O(α2). The interference of the tree-level electroweak and tree-level QCD diagrams give rise to terms of order O(αsα), while O(α2) terms are obtained squaring the aforementioned tree-level EW graphs. On top, we have also the photon-induced partonic process γg → Q˜aQ˜a∗, which contributes at O(αsα) owing to the non-zero photon density in the proton.
(1)
P P → Q˜a Q˜a∗ X (Q˜ = t˜) ,
NLO EW corrections can reach the same size as the tree-level EW contributions of O(αsα) and O(α2) [5].
1
2
W. HOLLIK ETC.
2. – EW contributions
Diagrams and corresponding amplitudes for the EW contributions to the process (1) are generated using FeynArts, FormCalc and LoopTools [6]. IR and Collinear singularities are regularized within mass regularization.
Real Corrections. In order to obtain IR and collinear finite results we need to include the processes of real photon emission. In the case of qq¯ annihilation real gluon emission of O(α2sα) has to be considered as well. The photon momentum integration and isolation of divergences has been performed using two different methods: phase space slicing and dipole subtraction. They give results in good numerical agreement. IR singularities drop out in the sum of virtual and real corrections. Collinear singularities do not and have to be absorbed into the definition of parton distribution functions (PDF) Results
For illustration of the EW effects, we study the production of the two up-squark u˜R and u˜L focusing on the SPS1a′ point of the MSSM parameter space, as suggested by the SPA convention [9]. A more comprehensive analysis can be found in ref. [5]. Fig. 1 contains the transverse momentum distribution of the squarks. The contribution from the gluon fusion channel is always positive and dominates at lower values of pT , wheras the qq annihilation channel part is negative and renders the EW contribution negative in the limit of large pT . The contribution of the gγ channel is independent on the squark chirality, determined only by the electric charge of the produced squarks. The EW effects are more pronounced for left-handed chirality yielding more than 30% negative contributions for large pT . In the u˜L case the LO EW contribution are positive for low pT , originating from the PDF-enhanced parton process dd¯ → u˜Lu˜L∗ through t-channel chargino exchange. This positive part is practically compensated by the NLO O(α2sα) contributions in the qq¯ annihilation channels.
arXiv:0807.4124v1 [hep-ph] 25 Jul 2008
MPP-2008-53
Electroweak corrections to squark–anti-squark pair production at the LHC
W. Hollik(1), E. Mirabella(1) (1) Max-Planck-Institut fu¨r Physik (Werner Heisenberg Institut) F¨ohringer Ring 6, D-80805
1. – Introduction
TeV-scale supersymmetry (SUSY) will be accessible to direct experimental studies at the LHC through the production of SUSY particles. In particular, colored particles will be copiously produced, and the hadronic production of squark–anti-squark pairs is expected to play an important role for SUSY hunting. The first prediction of the cross section for the process P P → Q˜a Q˜a∗ was done at lowest order O(α2s) in supersymmetric QCD [1]. The dominant NLO corrections, of O(α3s), were calculated more than ten years later [2]. There are also partonic processes of electroweak origin, like diagonal and non-diagonal squark pair production form qq¯ annihilation [3], contributing at O(αsα) and O(α2) at the tree-level. In particular the interference between the tree-level QCD and electroweak amplitudes at O(αsα) for Q˜ = t˜ can become sizable. NLO electroweak (EW) contributions were found to be significant in the case of topsquark pair production, with effects up to 20% [4]. In the case of the production of diagonal squark–anti-squark pair different from the top-squark
2.2. NLO EW contributions. – NLO EW corrections arise from two different channels, gluon fusion and quark–anti-quark annihilation channels.
Virtual Corrections. Virtual corrections arise from the interference of the tree-level diagrams with the one-loop EW graphs. In the case of qq¯ annihilation channels, there is also the interference between tree-level EW diagrams and QCD graphs. The renormalization of the squark, of the quarks, and of the gluino masses and wavefunctions has been performed in the on-shell scheme [7, 8] while the strong coupling is renormalized in the MS scheme. Massive particles (top, squarks, and gluino) have been decoupled subtracting their contribution at zero momentum transfer. Dimensional regularization spoils SUSY at higher order; we restore it by adding a finite counterterm for the renormalization of the q˜g˜q¯ Yukawa coupling.