Atoms and Nuclei
原子物理原子核物理概论总结
原子物理原子核物理概论总结英文回答：Introduction:In the field of atomic and nuclear physics, we study the fundamental properties and behaviors of atoms and atomic nuclei. This branch of physics explores the structure, composition, and interactions of these microscopic particles. By understanding the principles of atomic and nuclear physics, we gain insights into the nature of matter and the forces that govern the universe.Atomic Physics:Atomic physics focuses on the study of atoms, which are the building blocks of matter. It investigates the behavior of electrons within atoms and the interactions between atoms and electromagnetic radiation. One of the key concepts in atomic physics is the energy levels ofelectrons in atoms. These energy levels are quantized, meaning that electrons can only occupy specific energy states. The study of atomic physics has led to the development of various technologies, such as lasers, atomic clocks, and atomic spectroscopy.Nuclear Physics:Nuclear physics, on the other hand, deals with the structure and behavior of atomic nuclei. It explores the properties of protons and neutrons, which are the constituents of atomic nuclei. Nuclear physics investigates nuclear reactions, such as nuclear fission and fusion, which release vast amounts of energy. It also examines the stability and decay of atomic nuclei, including radioactive decay. Nuclear physics has applications in fields such as energy production, medicine (e.g., nuclear medicine), and nuclear weapons.Connection between Atomic and Nuclear Physics:Atomic and nuclear physics are closely related fields,as they both study the fundamental particles that make up matter. Atomic physics provides a foundation for understanding the behavior of electrons, which play a crucial role in determining the properties of atoms. Nuclear physics, on the other hand, delves into the structure and properties of atomic nuclei, which are composed of protons and neutrons. The study of atomic and nuclear physics together allows us to comprehend the complex interactions between electrons and atomic nuclei, leading to a deeper understanding of matter and the universe.Conclusion:In conclusion, atomic and nuclear physics are essential branches of physics that explore the properties and interactions of atoms and atomic nuclei. Atomic physics focuses on the study of electrons and their behavior within atoms, while nuclear physics investigates the structure and behavior of atomic nuclei. These fields are interconnected, providing a comprehensive understanding of the fundamental particles that make up matter. The knowledge gained fromatomic and nuclear physics has led to numerous technological advancements and applications in various fields. By continuing to study and explore these areas, we can further unravel the mysteries of the universe.中文回答：介绍：原子物理和核物理是研究原子和原子核的基本性质和行为的领域。
核能课件ppt英文
Advantages and Disadvantages of Nuclear Energy
Advantages
Nuclear energy is a sustainable source of energy that can provide a stable and related supply of electricity It does not emit greenhouse gases or air pollutants during operation, making it environmentally friendly Nuclear energy can also be used to produce medical isotopes and for other industrial applications
History of Nuclear Energy
The discovery of nuclear energy Began in the early 20th century with the discovery of radioactivity by Antoine Henri Becquerel in 1896
Nuclear Power Courseware PowerPoint English
• Introduction • Nuclear Physics • Nuclear Reactors • Safety and Security of Nuclear
Reactors • Future of Nuclear Energy
01 Introduction
Definition of Nuclear Energy
应用地球化学元素丰度数据手册-原版
应用地球化学元素丰度数据手册迟清华鄢明才编著地质出版社·北京·1内容提要本书汇编了国内外不同研究者提出的火成岩、沉积岩、变质岩、土壤、水系沉积物、泛滥平原沉积物、浅海沉积物和大陆地壳的化学组成与元素丰度，同时列出了勘查地球化学和环境地球化学研究中常用的中国主要地球化学标准物质的标准值，所提供内容均为地球化学工作者所必须了解的各种重要地质介质的地球化学基础数据。
本书供从事地球化学、岩石学、勘查地球化学、生态环境与农业地球化学、地质样品分析测试、矿产勘查、基础地质等领域的研究者阅读，也可供地球科学其它领域的研究者使用。
图书在版编目（CIP）数据应用地球化学元素丰度数据手册/迟清华，鄢明才编著. －北京：地质出版社，2007.12ISBN 978－7－116－05536－0Ⅰ. 应… Ⅱ. ①迟…②鄢…Ⅲ. 地球化学丰度－化学元素－数据－手册Ⅳ. P595－62中国版本图书馆CIP数据核字（2007）第185917号责任编辑：王永奉陈军中责任校对：李玫出版发行：地质出版社社址邮编：北京市海淀区学院路31号，100083电话：（010）82324508（邮购部）网址：电子邮箱：zbs@传真：（010）82310759印刷：北京地大彩印厂开本：889mm×1194mm 1/16印张：10.25字数：260千字印数：1－3000册版次：2007年12月北京第1版•第1次印刷定价：28.00元书号：ISBN 978－7－116－05536－0（如对本书有建议或意见，敬请致电本社；如本社有印装问题，本社负责调换）2关于应用地球化学元素丰度数据手册（代序）地球化学元素丰度数据，即地壳五个圈内多种元素在各种介质、各种尺度内含量的统计数据。
它是应用地球化学研究解决资源与环境问题上重要的资料。
将这些数据资料汇编在一起将使研究人员节省不少查找文献的劳动与时间。
这本小册子就是按照这样的想法编汇的。
核药英语
Recall that isotopes are atoms with the same numbers of protons but different numbers of neutrons. Some isotopes are stable (e.g. 15N); but some are not stable and decay spontaneously - these are radioactive isotopes.The radioactive isotopes of most use in biological techniques decay with the conversion of the neutron to a proton and an electron which is emitted as a beta particle. Examples are: 14C -->14N + e-32P -->32S + e-35S -->35Cl + e-3H -->3He + e-Radioactive decay is a first-order process that is specified by a decay constant that is characteristic for each isotope. Basically, the decay constant is the fraction of radioactive atoms that decay in a small unit of time.Isotopes such as 32P have high decay constants; isotopes such as 14C and 3H have low decay constants.Another way to view the decay constant is the half-life which is the time required for half of the original number of atoms to decay. Isotopes with high decay constants have short half-lives; isotopes with low decay constants have long half-lives.In any compound not all of the molecules will contain the radioactive isotope. The specific activity is a measure of the amount of radioactivity per unit amount of substance. This is based on the number of disintegrations per minute (dpm) per unit amount where the amount can be expressed as grams or moles.A sample with a higher specific activity will have more disintegrations per minute - it will emit more beta particles and these can be counted or recorded on film. A sample with a lower specific activity will have fewer disintegrations per minute. Clearly, a sample with a higher specific activity will cause a stronger/darker impression on film than will a sample of low specific activity.If you are interested in more information on autoradiography and particularly how it applies to whole-body situations (e.g. PET) then you can explore the pages linked to the above.The specific activity of nucleic acid probes is an important parameter to control, since it determines the sensitivity of nucleic acid detection. Probe specific activity is not only dependent on the specific activity and amount of radiolabeled nucleotide incorporated into the probe, but also on the amount of probe available for hybridization. Therefore, when choosing a method for synthesis of high specific activity probes, one should take into account the ability of the enzymatic reaction to incorporate low concentrations of high specific activity radiolabeled nucleotides (e.g. 800 Ci/mmol, 10 mCi/ml vs. 6000 Ci/mmol, 10 mCi/ml) and what amount of radiolabeled nucleotide can be economically afforded perreaction. These factors should be balanced with the ability to degrade or separate the template used from the probe synthesized so that the template will not decrease the effective amount of probe available for hybridization. Below, four methods for generating labeled nucleic acids are evaluated for their ability to produce probes of high specific activity, taking into account these criteria.The specific activity of a labeled compound is a measure of the radioactivity per unit mass, and is commonly quoted in terms of µCi/mg, mCi/mg, Ci/mmol and Bq/mmol. When there is sufficient mass of a radiolabeled compound for a small sample to be accurately weighed and counted by liquid scintillation counting the specific activity is expressed as µCi/mg for example. The conversion from µCi/mg to mCi/mmol is simply carried out by multiplying by the molecular weight and dividing by 1000. When the specific activity is greater than 1Ci/mmol there is often insufficient material present to be weighed. In such cases the specific activity may be calculated by relating the radioactive concentration (determined by liquid scintillation counting) to the chemical concentration, and then converting the figure obtained to Ci/mmol (Bq/mmol). The chemical concentration is commonly determined by U.V. spectroscopy, or an appropriate colorimetric method (comparing color density of the unknown strength solution with that of a range of known strength).When the degree of labeling exceeds 10% at one or more positions, mass spectrometry can be used. This is very frequently the method of choice for carbon-14 and tritium-labeled compounds.Typical values of specific activities are: 1.85-2.22 GBq/mmol, 50-60 mCi/mmol for carbon-14 compounds 1.1-3.7 TBq/mmol, 30-100 Ci/mmol for tritium compounds ~ 74 TBq/mmol, ~ 2000 Ci/mmol for iodine-125 compounds ~ 111-222 TBq/mmol, ~3000-6000 Ci/mmol for phosphorus-32 compounds ~ 55.5-9.25 TBq/mmol, ~ 1500-2500 Ci/mmol for phosphorus-33 compounds ~ 37 TBq/mmol, ~ 1000 Ci/mmol for sulfur-35 compounds.Working safely with radioactive materialsThe safety requirements for any of the less toxic nuclides, for example carbon-14 and tritium, may be less complex and less restrictive than the Regulations or Codes of Practice appear to indicate. This does not mean that these materials may be treated casually.Compounds labeled with low energy beta-emitters may be handled safely in the small quantities found in most research and teaching laboratories with only modest precautions.These quantities represent no greater hazard than working with many other laboratory chemicals.It is important to follow the code of good laboratory practice in addition to specific precaution relating to the particular radionuclides used, for example when handling high energy beta-emitters, such as phosphorus-32 or gamma-labeled compounds.Although radiation protection can be a complex subject it is possible to simplify it to ten golden rules, which should always be observed.The three types of nuclear radioactive decay are alpha, beta and gamma emission. An alpha particle is a Helium 4 nucleus (two protons and two neutrons). It is produced by nuclear fission in which a massive nucleus breaks apart into two less-massive nuclei (one of them the alpha particle). This is a strong interaction process. A beta particle is an electron. It emerges from a weak decay process in which one of the neutrons inside an atom decays to produce a proton, the beta electron and an anti-electron-type neutrino. Some nuclei instead undergo beta plus decay, in which a proton decays to become a neutron plus a positron (anti-electron or beta-plus particle) and an electron-type neutrino.A gamma particle is a photon. It is produced as a step in a radioactive decay chain when a massive nucleus produced by fission relaxes from the excited state in which it first formed towards its lowest energy or ground-state configuration.Radioactive decay8-9-00Sections 30.1 - 30.6The nucleusWhen we looked at the atom from the point of view of quantum mechanics, we treated the nucleus as a positive point charge and focused on what the electrons were doing. In many cases, such as in chemical reactions, that's all that matters; in other cases, such as radioactivity, or for nuclear reactions, what happens in the nucleus is critical, and the electrons can be ignored.A nucleus consists of a bunch of protons and neutrons; these are known as nucleons. Each nucleus can be characterized by two numbers: A, the atomic mass number, which is the total number of nucleons; and Z, the atomic number, representing the number of protons. Any nucleus can be written in a form like this:where Al is the element (aluminum in this case), the 27 is the atomic mass number (the number of neutrons plus the number of protons), and the 13 is Z, the atomic number, the number of protons.How big is a nucleus? We know that atoms are a few angstroms, but most of the atom is empty space. The nucleus is much smaller than the atom, and is typically a few femtometers. The nucleus can be thought of as a bunch of balls (the protons and neutrons) packed into a sphere, with the radius of the sphere being approximately:The strong nuclear forceWhat holds the nucleus together? The nucleus is tiny, so the protons are all very close together. The gravitational force attracting them to each other is much smaller than the electric force repelling them, so there must be another force keeping them together. This other force is known as the strong nuclear force; it works only at small distances. The strong nuclear force is a very strong attractive force for protons and neutrons separated by a few femtometers, but is basically negligible for larger distances.The tug-of-war between the attractive force of the strong nuclear force and the repulsive electrostatic force between protons has interesting implications for the stability of a nucleus. Atoms with very low atomic numbers have about the same number of neutrons and protons; as Z gets larger, however, stable nuclei will have more neutrons than protons. Eventually, a point is reached beyond which there are no stable nuclei: the bismuth nucleus with 83 protons and 126 neutrons is the largest stable nucleus. Nuclei with more than 83 protons are all unstable, and will eventually break up into smaller pieces; this is known as radioactivity.Nuclear binding energy and the mass defectA neutron has a slightly larger mass than the proton. These are often given in terms of an atomic mass unit, where one atomic mass unit (u) is defined as 1/12th of the mass of a carbon-12 atom.Something should probably strike you as being a bit odd here. The carbon-12 atom has a mass of 12.000 u, and yet it contains 12 objects (6 protons and 6 neutrons) that each have a mass greater than 1.000 u. The fact is that these six protons and six neutrons have a larger mass when they're separated than when they're bound together into a carbon-12 nucleus.This is true for all nuclei, that the mass of the nucleus is a little less than the mass of the individual neutrons and protons. This missing mass is known as the mass defect, and is essentially the equivalent mass of the binding energy.Einstein's famous equation relates energy and mass:If you convert some mass to energy, Einstein's equation tells you how much energy you get. In any nucleus there is some binding energy, the energy you would need to put in to split the nucleus into individual protons and neutrons. To find the binding energy, then, all you need to do is to add up the mass of the indiv idual protons and neutrons and subtract the mass of the nucleus:The binding energy is then:In a typical nucleus the binding energy is measured in MeV, considerably larger than the few eV associated with the binding energy of electrons in the atom. Nuclear reactions involve changes in the nuclear binding energy, which is why nuclear reactions give you much more energy than chemical reactions; those involve changes in electron binding energies.Radioactive decayMany nuclei are radioactive. This means they are unstable, and will eventually decay by emitting a particle, transforming the nucleus into another nucleus, or into a lower energy state. A chain of decays takes place until a stable nucleus is reached.During radioactive decay, principles of conservation apply. Some of these we've looked at already, but the last is a new one:∙conservation of energy∙conservation of momentum (linear and angular)∙conservation of charge∙conservation of nucleon numberConservation of nucleon number means that the total number of nucleons (neutrons + protons) must be the same before and after a decay.There are three common types of radioactive decay, alpha, beta, and gamma. The difference between them is the particle emitted by the nucleus during the decay process. Alpha decayIn alpha decay, the nucleus emits an alpha particle; an alpha particle is essentially a helium nucleus, so it's a group of two protons and two neutrons. A helium nucleus is very stable. An example of an alpha decay involves uranium-238:The process of transforming one element to another is known as transmutation.Alpha particles do not travel far in air before being absorbed; this makes them very safe for use in smoke detectors, a common household item.Beta decayA beta particle is often an electron, but can also be a positron, a positively-charged particle that is the anti-matter equivalent of the electron. If an electron is involved, the number of neutrons in the nucleus decreases by one and the number of protons increases by one. An example of such a process is:In terms of safety, beta particles are much more penetrating than alpha particles, but much less than gamma particles.Gamma decayThe third class of radioactive decay is gamma decay, in which the nucleus changes from a higher-level energy state to a lower level. Similar to the energy levels for electrons in the atom, the nucleus has energy levels. The concepts of shells, and more stable nuclei having filled shells, apply to the nucleus as well.When an electron changes levels, the energy involved is usually a few eV, so a visible or ultraviolet photon is emitted. In the nucleus, energy differences between levels are much larger, typically a few hundred keV, so the photon emitted is a gamma ray.Gamma rays are very penetrating; they can be most efficiently absorbed by a relatively thick layer of high-density material such as lead.The reason alpha decay occurs is because the nucleus has too many protons which cause excessive repulsion. In an attempt to reduce the repulsion, a Helium nucleus is emitted. The way it works is that the Helium nuclei are in constant collision with the walls of the nucleus and because of its energy and mass, there exists a nonzero probability of transmission. That is, an alpha particle (Helium nucleus) will tunnel out of the nucleus. Here is an example of alpha emission with americium-241:Beta decay occurs when the neutron to proton ratio is too great in the nucleus and causes instability. In basic beta decay, a neutron is turned into a proton and an electron. The electron is then emitted. Here's a diagram of beta decay with hydrogen-3:There is also positron emission when the neutron to proton ratio is too small. A proton turns into a neutron and a positron and the postiron is emitted. A positron is basically a positively charged electron. Here's a diagram of positron emission with carbon-11The final type of beta decay is known as electron capture and also occurs when the neutron to proton ratio in the nucleus is too small. The nucleus captures an electron which basically turns a proton into a neutron. Here's a diagram of electron capture with beryllium-7:Gamma decay occurs because the nucleus is at too high an energy. The nucleus falls down to a lower energy state and, in the process, emits a high energy photon known as a gamma particle. Here's a diagram of gamma decay with helium-3:Elements such as uranium, thorium, and plutonium are observed to emit particles and thereby undergo radioactive decay. By emitting particles, the original (or parent) element alters its composition to another element known as the daughter element. If the daughter element is also radioactive, then it will emit a particle and decay into yet another daughter element. The decay process continues until the final daughter product is no longer radioactive.The emitted particles are known as: alpha, beta, and gamma. Alpha particles have a positive charge, an atomic mass of 4, and are essentially a helium atom without any electrons. Beta particles have a negative charge, an atomic mass of 0, and are electrons. Gamma rays are high energy rays that are emitted by nearly all radioactive materials and have no mass or charge.Radioactive decay is an exponential process such that half of the parent element will decay to the daughter element in a set amount of time (known as the half-life). Each element has a unique half-life, but that half-life is constant in time and space. The equation that governs radioactive decay is:Extremely low-frequency radiation has very long wave lengths (on the order of a million meters or more) and frequencies in the range of 100 Hertz or cycles per second or less. Radio frequencies have wave lengths of between 1 and 100 meters and frequencies in the range of 1 million to 100 million Hertz. Microwaves that we use to heat food have wavelengths that are about 1 hundredth of a meter long and have frequencies of about 2.5 billion Hertz.Higher frequency ultraviolet radiation begins to have enough energy to break chemical bonds. X-ray and gamma ray radiation, which are at the upper end of magnetic radiation have very high frequency --in the range of 100 billion billion Hertz--and very short wavelengths--1 million millionth of a meter. Radiation in this range has extremely high energy. It has enough energy to strip off electrons or, in the case of very high-energy radiation, break up the nucleus of atoms.Non-ionizing radiation ranges from extremely low frequency radiation, shown on the far left through the audible, microwave, and v isible portions of the spectrum into the ultraviolet range.Radiation having a wide range of energies form the electromagnetic spectrum, which is illustrated below. The spectrum has two major div isions: Ionizing & Non-Ionizing RadiationRadiation that has enough energy to move atoms in a molecule around or cause them to vibrate, but not enough to remove electrons, is referred to as "non-ionizing radiation." Examples of this kind of radiation are sound waves, visible light, and microwaves. We take advantage of the properties of non-ionizing radiation for common tasks:l microwave radiation-- telecommunications and heating foodl infrared radiation --infrared lamps to keep food warm in restaurantsl radio waves-- broadcastingRadiation that falls w ithin the “ionizing radiation" range has enough energy to remove tightly bound electrons from atoms, thus creating ions. This is the type of radiation thatpeople usually think of as 'radiation.' We take advantage of its properties to generate electric power, to kill cancer cells, and in many manufacturing processes.Ionization is the process in which a charged portion of a molecule (usually an electron) is given enough energy to break away from the atom. This process results in the formation of two charged particles or ions: the molecule with a net positive charge, and the free electron with a negative charge.Each ionization releases approximately 33 electron volts (eV) of energy. Material surrounding the atom absorbs the energy. Compared to other ty pes of radiation that may be absorbed, ionizing radiation deposits a large amount of energy into a small area. In fact, the 33 eV from one ionization is more than enough energy to disrupt the chemical bond between two carbon atoms. All ionizing radiation is capable, directly or indirectly, of removing electrons from most molecules.There are three main kinds of ionizing radiation:l alpha particles, which include two protons and two neutrons;l beta particles, which are essentially electrons; andl gamma rays and x-rays, which are pure energy (photons).Liquid Scintillation Counters are instruments commonly used to detect radioisotopes that emit low energy β-particles. A sample with an unknown amount of a radioisotope is placed into an organic or aqueous solution. This solution, commonly called the “counting cocktail” causes the radioisotope to emit small flashes of light.These flashes are detected and converted to amplified electrical pulses by a photomultiplier tube.Liquid scintillation counters can distinguish between different isotopes and different energy types emitted by an isotope.In general, Liquid Scintillation Counters carry out the following functions:1.Sense light flashes from the radioisotope and converts this energy to voltages thatare proportional to the intensity of the light flash.2.Sort through these voltages and put them into energy ranges.3.Count the number of voltages in each energy categoryLiquid scintillation counters can be used to detect radioisotopes in any liquid sample.This includes blood, urine, cytosol, or any other homogenous liquid.This method can be useful in the biological sciences as well as more traditional chemistry. The following list includes some of the ways Liquid Scintillation Counters can be used:∙§ For safety inspections. Liquid scintillation counters are extremely sensitive, and can detect radioactivity below the detection limits of traditional GeigerCounters.∙§ To track radioisotopes as they are digested in an animal or cell culture.This quantitatively determines the extent by which a specific nutrient/molecule ismetabolized.∙§ Quantifying genetic material (DNA and RNA) with radioactive nucleotides More generally, any experiment involving radioactivity can use a liquid scintillation counter in some way.RadiationNaturally occurring elements have several different isotopes. While most of these isotopes are stable, a few may be unstable. This instability is a result of the imbalance of protons and neutrons in the nucleus of the atom. The atom attempts to compensate for this imbalance by rearranging the protons and neutrons, ejecting kinetic energy from the nucleus of the atom. As a result, the atom emits secondary particles and/or electromagnetic rays/photons during a process called radioactive decay. Any isotope capable of undergoing radioactive decay is considered radioactive.Types of RadiationThere are four basic types of radiation emitted during decay. These types can be emitted alone or in combination with one another. Radiation interacts with atoms and molecules in its surrounding environment, releasing their kinetic energy along the way. This is why the more intense radioisotopes require special handling.β-ParticlesLiquid Scintillation Counters are designed to detect isotopes that emit low levels ofβ-particles, which is basically an electron that carries a single electricalcharge. Depending on the type of isotope, radioisotopes can emit either a positive or negative charge.∙§ A positron (+β) results when the neutron:proton ratio is too low.The result is a nucleus of the same mass, but with one less atomic number.∙§ An electron (-β) occurs when the neutron:proton ratio is toohigh. Consequently, a neutron transforms into a proton and an electron. Thiselectron is ejected from the nucleus, and the number of protons in the nucleusincreases by one.β-Emitters are small particles with a low charge, so they only pose a potential hazard if they enter the body somehow. Some examples of β-emitters that can be detected by liquid scintillation counters are 3H, 14C, 32P, 33P, 35S, 45Ca, and 125I.*Detection by the Liquid Scintillation CounterCommercial liquid scintillation counters contain the following components:1. 1. Sample Chamber: The sample vial is placed in a chamber that is completelyclosed off to outside light so that flashes of light from the sample can be detected.1. 2. Light Detector System: This usually consists of a photomultiplier tube (PMT)that senses the light flashes, converts them to voltage, and amplifies them.1. 3. Amplification System: To intensify the detection.1. 4. Analyzing System: To determine the pulse intensity/height.1. 5. Scalar System: This counts the electrical impulses over a certain timeinterval.Many elements have both:stable isotopes (non-radioactive, eg 12C),andunstable isotopes (radioactive, eg 14C).Different numbers of neutrons in nucleus.Electronic configurationthe same as that of non-radioactive isotope of same element, so chemical properties are the same.Hence use in chemistry and biology ofRADIOACTIVE TRACERSSubstitute radioactive for stable isotope, undergoes exactly same reactions but can be detected and measured as required by radiation monitoring device.Detection and Measurement of RadioactivityGeiger-Muller counterRadiation causes ionization of gas in tube---> current flow.Portable, useful for monitoring of spillages.Scintillation CountersPreferred for most quantitative work:Radiation from radio-isotope ---> excitation of electrons in a SCINTILLANT or FLUOR ---> emission of LUMINESCENCE, measure with photodetector.Solid scintillation counter(gamma counter)g-rays emerge from sample tube - impinge on external scintillant crystal (NaI/T1I) --> emits light pulses to photomultiplier.Liquid scintillation counter(beta counter)b-particles often too weak to use external fluor.Sample mixed in solution with "scintillation cocktail". Captures b-emission at source ---> photons. May be 2-stage process involving primary and secondary fluors.Units of RadioactivityFundamental (and SI) unit is the Becquerel (Bq) which is the number ofDISINTEGRATIONS PER SECOND (dps), ie. the number of nuclei that break down per second.For historical reasons, radioactiv ity often measured in Curie (Ci) units.1Ci = 3.7 x 1010 BqBecause of the magnitudes, common derived units are :the microCurie (mCi) the megaBecquerel (MBq)Measuring device reads counts per minute (cpm). In a scintillation counter each "count" = pulse of light from fluor activated by radiation.Counting efficiency < 100%, because of:∙radiation escaping without activating fluor ∙fluors undergoing quenching ∙ hn from fluors not reaching photodetectorBq = cpm 60 x 100counting efficiency (%)Specific RadioactivityThis is radioactivity per gramor per mole of compoundIsotopically labelled compounds usually diluted with an excess of unlabelled compound (carrier ) in order to:∙use biologically relevant concentrations without excessive radiation hazard ∙ avoid excessive loss of isotope by adsorption etc .labelled speciescarrierIsotope dilution analysis depends on principle of adding labelled species of knownspecific activity then measuring specific activ ity of a recovered sample, hence calculate amount of unlabelled species in sample.Decay Kinetics: Half-LifeDisintegrations of radioactive nuclei in sample are in proportion to number present (1st order kinetics), so isotope decays exponentially. (Holme & Peck Ch 5).Half-life (t0.5)= Time for no. of radioactive nuclei to decay by halfImportant factor in planning experiments with isotopes.....Long t0.5 (eg 14C, 5570 years):∙no complications due to loss of isotope over duration of experiment, but∙significant hazard if ingested (long-term exposure)Shorter t0.5 (eg 32P, 14.2 days)∙plan purchase so delivery only when ready to use∙allow for decay during experiment (especially if measuring, eg metabolic elimination)Biochemical Aplications of IsotopesRadioimmunoassayThe original form of competitive-binding immunoassay. Labelled (usually 125I) and unlabelled antigen (Ag) compete for limited antibody (Ab).Solid scintillation counting (SSC) is an attractive alternative to conventional liquid scintillation counting. With this method, a sample is deposited directly onto a solid scintillating material, dried, and counted in a scintillation counter. Small volumes of nonvolatile, radioactively labeled samples in a volatile solvent can be quantitated. Samples from enzyme inhibition, cytotoxicity, immunoassay, receptor binding, and various metabolic studies can be counted with solid scintillators.Solid scintillators have several advantages over liquid scintillators. They are not volatile, toxic, or flammable, and hence are safer to use. Waste disposal costs are reduced since the sample is dried onto the solid scintillating material and may be disposed of as solid waste. In some cases it is possible to recover dried samples for further processing, because they are not destroyed during the counting counting process. For small volume, valuable samples, this can be the counting method of choice.Although solid scintillation counting offers many advantages over conventional liquid scintillation counting (LSC), there has been no convenient way to utilize this technology for the variety of assays performed in the microplate format. Until recently, samples to be。
原子核的基本性质
原子核的半径
r r0 A
• 原子核密度的量级：
1
3
• 原子核半径参数r0：1.1(1.2)fm（核电荷分 布）， 1.4~1.5fm（核力作用） 1014 g/cm3
讨论和提问
Werner Heisenberg
• born Dec. 5, 1901, Wurzburg, Ger. died Feb. 1, 1976, Munich • German physicist and philosopher who discovered a way to formulate quantum mechanics in terms of matrices (1925). For that discovery, he was awarded the Nobel Prize for Physics for 1932. • In 1927 he published his indeterminacy, or uncertainty, principle, upon which he built his philosophy and for which he is best known.
中子(neutron)
• 电荷、质量 • 存在方式 • 发现: 9Be(α,n)12C
• 用途 • 稳定性
James Chadwick
• born Oct. 20, 1891, Manchester, Eng. died July 24, 1974, Cambridge, Cambridgeshire
Proton
• The discovery of the proton dates to the earliest investigations of atomic structure. • While studying streams of ionized gaseous atoms and molecules from which electrons had been stripped, Wilhelm Wien (1898) and J.J. Thomson (1910) identified a positive particle equal in mass to the hydrogen atom. • Ernest Rutherford showed (1919) that nitrogen under alpha-particle bombardment ejects what appear to be hydrogen nuclei. • By 1920 he had accepted the hydrogen nucleus as an elementary particle, naming it proton.
全英化学资料 atoms1
The Spacious Atom
Microcosms of our solar system, atoms are dominantly empty space:
electron orbits
If an oxygen atom had a total radius of 100 km, the nucleus would be a ~1 m diameter sphere in the middle.
Each atom can be described by its atomic weight (or mass), which is the sum of the protons and neutrons.
lithium: atomic number = 3 3 protons 4 neutrons atomic weight = 3 + 4 = 7
BUT... although each element has a
defined number of protons, the number of neutrons is not fixed. Atoms with the same atomic number but variable numbers of neutrons are called isotopes.
C = carbon P = phosphorus K = potassium Ti = titanium Mn = manganese
Atomic Weight: It’s all in the Nucleus
Since electrons weigh virtually nothing, the mass of an atom is concentrated in its nucleus.
翻译(排序版)核专业英语~nuclear energy
A字开头A complete understanding of the microscopic structure of matter (物质微观结构) and the exact nature of the forces acting(作用力的准确性质) is yet to (有待于) be realized. However, excellent models have been developed to predict behavior to an adequate degree of accuracy for most practical purposes. These models are descriptive (描述的) or mathematical often based on analogy (类推) with large-scale process, on experimental data (实验数据), or on advanced theory.对物质的微观结构和作用力的准确性质的完全认识仍有待于实现。
然而，为了实际的用途，能足够精确地预知物质在微观世界行为的模型已经被研究出来。
这些模型是描述性的或数学的，基于对大尺度过程的类推、实验数据或先进的理论。
A nucleus can get rid of excess internal energy by the emission of a gamma ray, but in analternate process called internal conversion, the energy is imparted directly to one of the atomic electrons, ejecting it from the atom. In an inverse process called K-capture, the nucleus spontaneously absorbs one of its own orbital electrons. Each of these processes is followed by the production of X-rays as the inner shell vacancy is filled.一个原子核能够通过发射g 射线而除去过剩的内能，但在称为内转换的另一个交换过程中，能量直接传给原子中一个电子，使这一电子从原子中被逐出。
Nuclear fusion (核聚变)
壹
贰
Introduction
Fusion and fission Conditions Confinement principles
叁
肆 伍 陆
Important reactions
Applications
Introduction
Nuclear fusion is the process by which two
Fusion and fission
The binding energy per nucleon generally increases with increasing size, up to the elements iron and nickel, and then decreases for heavier nuclei. Eventually, very heavy nuclei (all with more than 208 nucleons) are not stable. The four most tightly bound nuclei, in decreasing order of binding energy per nucleon, are 62Ni, 58Fe, 56Fe, and 60Ni. 56Fe is the most common one.
Applications
Hydrogen bombs
They rely on fusion reactions between deuterium and tritium. The basic principle would be: • An implosion assembly type of fission bomb is exploded. This is the primary stage. If a small amount of deuterium/tritium gas is placed inside the primary's core, it will be compressed during the explosion and a nuclear fusion reaction will occur; the released neutrons from this fusion reaction will induce further fission in the plutonium-239 or uranium-235 used in the primary stage. • Energy released in the primary stage is transferred to the secondary stage. This energy compresses the fusion fuel and sparkplug; the compressed sparkplug becomes critical and undergoes a fission chain reaction, further heating the compressed fusion fuel to a high enough temperature to induce fusion, and also supplying neutrons that react with lithium to create tritium for fusion. • The fusion fuel of the secondary stage may be surrounded by depleted uranium or natural uranium, whose U-238 is not fissile and cannot sustain a chain reaction, but which is fissionable when bombarded by the high-energy neutrons released by fusion in the secondary stage.
键长是指成键原子的核间距离
键长是指成键原子的核间距离(中英文版)英文文档：The bond length refers to the distance between the nuclei of the atoms involved in a chemical bond.It is a crucial parameter in determining the strength and nature of the bond.The bond length is influenced by several factors, including the atomic radii of the participating atoms and the repulsion between their electron clouds.In a covalent bond, atoms share electrons, and the bond length is the average distance between the nuclei of the bonded atoms.It can vary widely depending on the elements involved.For example, the bond length in a hydrogen molecule (H-H) is shorter than that in a carbon dioxide molecule (C-O).The bond length is an essential concept in chemistry and is used in various calculations and predictions, such as determining the structure of molecules, predicting bond energies, and understanding the properties of materials.中文文档：键长是指成键原子的核间距离。
海马的结构及功能
• （ 3 ） 杏 仁 被 盖 束 amygdalo-tegmental tract：终止于下丘脑外侧区，黑质、蓝斑等。
• （ 4 ） 杏 仁 皮 质 投 射 amygdalo-cortical projection：投射至眶额回、颞上、中、下回。
• 根据细胞形态,不同皮质区发育旳差别以 及 多 种 纤 维 通 路 旳 不 同 ， Lorente do No{1934}把海马又提成CA1、CA2、CA3、 CA4 四 个 扇 形 区 。 CA4 位 于 齿 状 回 门 内,CA3区内有最大旳锥体细胞,CA3区由 大锥体细胞构成, CA1区是邻近下托旳部 分,由小锥体细胞构成,CA2区是移行区， 由大和小锥体细胞构成。
核等。外侧隔核接受大量从海马经穹窿来旳传
入纤维。
• 1.传入纤维
•
〈1〉发自海马旳纤维经穹隆止于外侧隔
核。
•
〈2〉发自杏仁体旳纤维经斜角带或终纹
止于隔核。
• 〈3〉发自中脑网状构造,黑质、蓝斑、中 缝核与下丘脑核旳纤维终止于内侧隔核。
• 〈4〉前穿质发纤维经内侧嗅纹至隔。
• （5）额叶新皮质和扣带回发纤维至隔。
• 3.海马构造旳纤维联络
•
〈1〉传入
•
①丰富旳传入来自内嗅区。
•
②扣带回发纤维经扣带束直接终止
于海马和或经内嗅区中继后发纤维维(胆碱能纤维)经穹
窿、海马伞,终止于海马和齿状回。
•
• ④一侧海马发纤维经同侧海马伞、穹窿 脚,经过海马连合至对侧穹窿脚与海马伞, 终止于对侧海马和齿状回。
核能专业英语
第一课词汇：•Concept概念, conception概念, conceive构想、理解•Isotope同位素, isomer同质异能素•element, atom, nucleus, nucleon–element, elements,–molecule, molecules, molecular–atom, atoms, atomic,–nucleus['nju:kliəs，'nu:kliəs]原子核 , nuclei, nuclear,–nucleon['nju:kliɔn]核子, nucleons, nucleonic核子的–particle, particles,•fissile易裂变的, fissionable可以发生裂变的•fertile可裂变的，fertile materials增殖材料•fission, fusion, decay•inner, innermost / outer, outermost•chain reaction•fragment碎片Expression：•times– A is ten times B.•varies inversely as•E equals m times c squared. E = mc2•the n-th power of a: an•result in / result from•is accompanied by / correspond to•The discovery of fission was made in Germany in 1938 by Hahn......•Be composed of 由…组成•Binding energy 结合能•Discrete excited states 不连续的激发态•Electromagnetic radiation 电磁辐射•Ev：electron-volt•Conservation of mass/energy 质量/能量守恒练习：•电子带负电，质子带正电。
1 Atoms, Molecules, Ions and Periodic Table-short
Fortunately, we can use a variety of experimental techniques to probe the atom to gain a clearer understanding of what it is like. In this chapter we will examine the basic structure of the atom and briefly discuss the formation of molecules and ions, thereby providing a foundation for exploring chemistry more deeply in later chapters.
6
1 The Modern View of Atomic Structuf Rutherford, physicists have learned much about the detailed composition of atomic nuclei. In the course of these discoveries, the list of particles that make up nuclei has grown long and continues to increase. As chemists, we can take a very simple view of the atom because only three subatomic particles—the proton, neutron, and electron—have a bearing on chemical behavior.
3
科技英语 形核功
科技英语 形核功Nuclear fusion refers to the process of releasing energy by combining the nuclei of atoms. This scientific achievement has been a hot topic in the field of technology and energy for several decades. Fusion power has the potential to be a game-changer in the energy industry, as it offers a sustainable and virtually unlimited source of clean energy. The basic principle behind nuclear fusion is to replicate the same process that powers the sun. In the sun's core, hydrogen nuclei collide with such high energy that they combine and form helium, releasing an enormous amount of energy in the process. Scientists have been attempting to recreate this process on Earth to harness its energy potential.One of the main challenges in achieving nuclear fusion is creating and maintaining the extreme conditions required for the fusion reaction to occur. At extremely high temperatures, around 100 million degrees Celsius, hydrogen isotopes, such as deuterium and tritium, are heated to the point where they form a plasma state. This plasma is then confined and isolated from the surrounding environment using high magnetic fields.There are two main approaches to achieving controlled fusion reactions: magnetic confinement fusion (MCF) and inertial confinement fusion (ICF). MCF involves using magnetic fields to contain and manipulate the plasma, while ICF involves compressing small pellets of fusion fuel with powerful lasers. Both approaches aim to create an environment where the fuel ions can overcome their natural repulsion due to their positive electric charge and come close enough for the strong force to bind them together, releasing energy.Currently, the most well-known and advanced fusion experiment is the International Thermonuclear Experimental Reactor (ITER) in France. ITER is a collaborative project involving 35 countries that aims to demonstrate the feasibility of fusion power. It uses the MCF approach and is designed to produce 500 megawatts of fusion power for short bursts, equivalent to the power generated by a medium-sized coal-fired power plant. ITER is expected to be completed by 2025 and will serve as a stepping stone towards the development of commercial fusion power plants.The advantages of nuclear fusion are numerous. Firstly, fusion power does not produce greenhouse gas emissions or radioactive waste, making it an environmentally friendly andsustainable energy source. Secondly, fusion fuel, such as deuterium, is abundant and can be extracted from seawater, ensuring a virtually limitless supply. Additionally, fusion power plants would be inherently safe, as the fusion reaction can be easily controlled and any disruptions would cause the reaction to stop automatically.However, the road to practical fusion power is still filled with challenges and obstacles. The biggest challenge is achieving a net energy gain, meaning that the energy produced by the fusion reaction exceeds the energy input required to sustain it. To achieve this, scientists must find a way to sustain the plasma at high enough temperatures and for long enough periods of time. They must also develop advanced materials that can withstand the extreme conditions inside a fusion reactor.Despite these challenges, the potential benefits of nuclear fusion make it a promising avenue of research. If successful, fusion power could revolutionize the energy industry, providing a clean and sustainable alternative to fossil fuels. It has the potential to drastically reduce our dependence on nonrenewable energy sources and mitigate the harmful effects of climate change.In conclusion, nuclear fusion is a promising technology with the potential to solve many of the world's energy and environmental challenges. While significant progress has been made, there is still much work to be done before fusion power becomes a commercially viable option. However, with continued scientific research and international collaboration, practical fusion power may be within our reach in the near future.。
Atomic Structure 原子结构
It is the smaller of the two numbers shown in most periodic tables.
-10-
-4-
Mass and electrical charge
There are two properties of protons, neutrons and electrons that are especially important:
mass
electrical charge.
particle proton neutron electron
The atomic number (proton
What are the atomic (proton) numbers of these elements?
number)
sodium
11
iron
26
tin
50
fluorine
9
-11-
What is mass number?
Electrons have a mass of almost zero, which means that the mass of each atom results almost entirely from the number of protons and neutrons in the nucleus.
Atomic Structure
1 of 19
© Boardworks Ltd 2011
What are atoms?
能量的来源
能量的来源能量的来源概说生命的物理和化学特性必须始于太阳--确切地说，是太阳的核心，而非地球。
能量来自太阳的核心。
在那个地点，太阳不停地以光和热的形式向空间倾泻出能量。
数十亿计的氢原子核在太阳的核心碰撞同时聚变生成氦。
在此过程中一部分原本储存于原子核中的能量被开释出来.太阳所产生的光和热需要每秒将六亿吨氢转化为氦。
如此的转化在太阳中差不多连续几十亿年了。
核能在太阳的核心被开释为高能的伽马射线。
这是一种电磁射线，就象光波和无线电波一样，只是波长要短得多。
这种伽玛射线被太阳内的原子所吸取，然后重新开释为波长稍长一些的光波。
这新的射线再次被吸取，而后开释。
在能量由太阳内部一层层渗透出来的过程中，它通过了光谱中x射线部分，最后变成了光。
在现在期，能量到达我们所称的太阳表层，同时离散到空间而不再被太阳原子所吸取。
只有专门小一部分太阳的光和热由此方向开释出来，同时未被阻挡，穿越星空，来到地球。
a summary of the physical and chemical nature of life must begin, not on the earth, but in the sun; in fact, at the sun`s very center. it is here that is to be found the source of the energy that the sun constantly pours out into space as light and heat. this energy is liberated at the center of the sun as billions upon billions of nuclei of hydrogen atoms collide with each other and fuse together to form nuclei of helium, and in doing so, release some of the energy that is stored in the nuclei of atoms.the output of light and heat of the sun requires that some 600 million tons of hydrogen be converted into helium in the sun every second. this the sun has been doing for several thousands of millions of years. the nuclear energy is released at the sun`s center as high-energy gamma radiation, a form of electromagnetic radiation like light and radio waves, only of very much shorter wavelength. this gamma radiation is absorbed by atoms inside the sun to be reemitted at slightly longer wavelengths. this radiation, in its turn is absorbed and reemitted. as the energy filters through the layers of the solar interior, it passes through the x-ray part of the spectrum eventually becoming light. at this stage, it has reached what we call the solar surface, and can escape into space without being absorbed further by solar atoms.a very small fraction of the sun`s light and heat is emitted in such directions that after passing unhindered through interplanetary space, it hits the earth.。
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E(1 amu) = 931.494 MeV
The Atomic Mass Unit
NUMBER DENSITY, N. Number of atom per cubic centimeter.
N
M
Na
EXAMPLE: Uranium with mass density of 19 g/cm3, has the number density of
Energy Levels of the Hydrogen Atom
Ionization Continuum 0 eV N=4 N=3
N=2 Balmer Series visible
-13.6 eV Lyman Series (ultraviolet)
N=1
Bohr’s Atomic Model
• Bohr postulates the first semi-classical model
– Angular momentum of electron is quantized:
• mvr = nħ
– Then energy and orbital radii are also quantized (derive radius on the board)
+ + -
-
+ -
The Rutherford Atomic Model - 1911
• 1900: Alpha, beta and gamma rays were discovered • 1909 Rutherford bombarded thin gold foils with alpha particles (Po(214-84)):
h E2 E1
Bohr’s Atomic Model
The normal condition of the atom, or ground state, is the state with n=1. The atom is in it’s lowest possible energy state and it’s most stable condition.
Conversion of Energy and Matter
• Proton rest mass
1.672 621 6×10-27 kg or 938.272 MeV 1.007 276 amu
• Neutron rest mass
1.674 927 2×10-27 kg or 939.565 MeV 1.008 664 amu
• c =3×108 m/s
• Matter can be converted into ENERGY, and ENERGY can be converted into MATTER • Conversion of 1 kg of matter into energy releases:
E =mc2 =(1 kg)(3×108 m/s)2= 9×1016 J
• rn = 0.529 n2/Z (Å) • En = -13.6 Z2/n2 (eV)
Bohr’s Atomic Model
The orbital electrons can revolve around the nucleus only in certain fixed radii, called stationary states such that the angular momentum of electrons must be integral multiplies of h/2π:
AVOGADRO’S Number, Nav = 6.022142x1023 atoms/mole
The Atomic Mass Unit
Is defined to be 1/12 the mass of a neutral ground-state atom of 12C
Avogadro’s number (Nav) = 6.022142x1023 molecules/mole
• Electron rest mass
9.109 381 9 ×10-31 kg or 0.511 MeV
Conversion of Energy and Matter
• In “burning” of 1 kg of uranium, 0.87 g of matter is converted into energy:
A crude approximation of the hydrogen atom is a MARBLE (the nucleus) in the center of a FOOTBALL STATIUM and PINHEAD (the electron) orbiting over the benches.
ELEMENTS • There are more than 120 chemical ELEMENTS (92 elements present in nature).
ATOMIC NUMBER, Z. All atoms of a given element have the same number of protons (electrons), which is called the atomic number. MASS NUMBER, A. The total number of nucleons (protons and neutrons) inside the nucleus is called the atomic mass number.
Atoms and Nuclei
Professor Jasmina Vujic
Lecture 1 Nuclear Engineering 162 Department of Nuclear Engineering University of California, Berkeley
ATOMS AND NUCLEI
mvr = n(h/2π)
where n is the principal quantum number h is Plank’s constant
A photon is emitted only when an electron falls from one orbit to another orbit of lower energy. The energy of photon is equal to the difference between the energy levels on the electron in the two orbits:
– Large angle deflection seen in 1/8000 alpha particles suggests the existence of a very small and massive nucleus – Proposed the planetary model
• We now know:
Models of Atom
• Thomson’s “plum pudding” model • Rutherford’s model - the first planetary model • Bohr’s model • Pauli’s exclusion principle (1925)
Thomson: The Plum Pudding Model
EU=(0.87)×(9×1016 J)=7.8×1013 J
• Combustion of 1 kg of gasoline releases:
Eg=5×107 J
• The energy yield from one kilogram of uranium is more than a MILLION times that from fossil fuel.
Excitation of the Atom
When a sufficient amount of energy is transferred to the atom, causing an electron to “jump” from the lower to higher energy levels, the atom is said to be “excited”.
ATOMS – “Greek: indivisible” – the smallest parts of matter that retain their physical and chemical properties
INSIDE THE ATOM
The center consists of a heavy NUCLEUS with a POSITIVE electric charge, which is surrounded by a swarm of much lighter particles, the NEGATIVELY charged ELECTRONS.
1 gram mole (12C) = 12.0000 g/mole
The mass of one (12C) atom
(12.0000 g/mole)/ Nav = 1.9926x10-23 g
1 amu = 1.9926x10-23 g/12
1 amu = 1.660538x10-24 g
The energy equivalent of 1 amu :
1 1
n Au
hydrogen gold uranium
197 79 238 92
U
ISOTOPES
• The nuclei with the same number of protons and different number of neutrons are called ISOTOPES. They pertain to the same element, they have the same chemical properties, but different physical properties (different mass numbers)