English name: nuclear physics, belonging tophysicsBranch.ResearchNucleusOfstructureandchangeThe technology of obtaining ray beam and using it for detection and analysis, as well as the technology of researchnuclear technologyApplication related physical problems.abbreviationnuclear physics。If the dispersion of light reveals the reason why the repulsive force is inversely proportional to the square of distance, then the superposition interference of light is also calledquantumEntanglement reveals the cause of the repulsive force of the charge and the nuclear force.
Chinese name
Nuclear physics
Foreign name
nuclear physics
First level discipline
physics
Secondary discipline
Particle Physics and Nuclear Physics
application area
National defense, nuclear energy and radioactive applications
In 1896, A. - HBecquerelDiscover natureradioactivity, the first nuclear change observed by human beings is generally regarded asNuclear physicsThe beginning of.Over the next 40 years, he mainly engaged in radioactivitydecayThe study of the law and the properties of radiation, and the preliminary study of atomic nuclei with radiation;It has also created a series of detection methods and measuring instruments, some basic equipment such as variousCounter、ionization chamberAnd so on.To detect, record and determine the properties of radiation has always been the focus of nuclear physics research andnuclear technologyA central link of application.wait[1]
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Alpha ray
The study of radioactive decay has proved that one element can change into another through alpha decay or beta decay, which has overturned the view that elements cannot be changed;It also establishedDecay lawStatistics of.Statistic is the micro worldMaterial movementA fundamental property ofelectromagnetismStudiedMacro worldThe movement of matter differs in principle.Decay emittingenergyLarge radiation, especiallyAlpha ray, to exploreatomic structureIt has provided unprecedented weapons.In 1911, E. Rutherford et al. bombarded various atoms with alpha rays, and established the atomicNuclear structure, and proposeatomic structureThe planet model of isAtomic physicsLay the foundation;It was also the first time that the term "atomic nucleus" was put forward, and soon we had a preliminary understanding of the shell structure of atoms and the electronicLaw of motion, established and developed the clarification of the micro worldMaterial movementRegularquantum mechanics。[2]
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In 1919,rutherfordUsed by others for discoveryAlpha rayWhen bombarding nitrogen nuclei, protons are released, and artificial nuclear reaction is realized for the first time.Later caused by radiationnuclear reactionThe method ofNucleusThe main means.The major achievement in the early stage was in 1932neutronThe discovery ofArtificial radionuclidePreparation of.The nucleus is composed ofneutronandprotonComposed of.neutronThe discovery ofchargeIt is not repelled by nuclear charge and is easy to enter the atomic nucleusNeutron nuclear reactionAnd become an important means of studying atomic nuclei.In the 1930's, people alsocosmic rayObservations ofpositronAnd“meson”(later calledMuon）These findings areParticle physicsIs the first of its kind.
In the late 1920s, we began to explore the accelerationcharged particlePrinciple of.In the early 1930s,static electricity, straight line and cyclotronParticle acceleratorIt has taken shape inhigh pressurePrimary nuclear reaction is realized on the multiplier.The accelerator can be used to obtain stronger beam currentenergyHigher and more kinds of ray beam, greatly expandednuclear reactionThe research ofacceleratorIt has gradually become the necessary equipment for studying atomic nuclei and applying nuclear technology.
staynuclear physicsWe have paid attention to its application at the initial stage ofNuclear rayTreat diseases such astumourRole of.This is an important reason why it was valued by the society at that time.
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Great development period
In 1939, O. Hahn and FStrassmanfindNuclear fissionIn 1942, E. Fermi established the first fissionreactorAnd ushered in a new century in which mankind has mastered nuclear energy.nuclear energyAlmost inexhaustible energy is used for effective utilizationNuclear energy, Developmentnuclear weapon, need to solve a series of very complex scientific and technological problems, andnuclear physicsandnuclear technologyIt is the central link.Therefore, nuclear physics has developed by leaps and bounds, becoming a highly competitive scientific and technological field.This stage lasts about 30 years, which is a period of great development of nuclear physics.in the meantime,particleThe acceleration and detection technology ofprotonAccelerate to 1 × 106Electron volt(eV);In the 1970s, it has reached 4 × 1011eV and can generate energydivergenceVarious beams with extremely small, high collimation or extremely strong current.In terms of detection technology, the application of semiconductor counters has greatly improved the detection of radiationenergyResolution of.Nuclear electronicsThe rapid development of and computing technology has fundamentally improved the ability to obtain and process experimental data, and greatly expanded the scope of theoretical calculation.All these have greatly promoted the research of nuclear physics and the application of nuclear technology.I also have a deeper understanding of the basic structure and change law of the atomic nucleus, and basically understandnucleonThe nature of the interaction between them;For stabilitynuclideAnd long-lived radionuclidesground stateAnd lowexcited state(withNuclear grade）Systematic experimental data have been accumulated by the nature of;Through theoretical analysis, various applicableNuclear model, successfully explained various nuclear phenomena andnuclear reaction。In addition, high-energy nuclear reactions andHeavy ion nuclear reactionResearch.
Atomic synthesis
Through nuclear reaction, 17 kinds ofTransuranic elementAnd thousands of new onesRadionuclide, indicating that the element is only a relatively stable unit of material structure under certain conditions, and is not eternal.Astrophysical research proves that nuclear reactions areCelestial evolutionThe process that plays a key role in,nuclear energyIs a celestial bodyenergyThe main source of.It is also preliminarily understood that the evolution process of celestial bodies is the formation and evolution process of various atomic nuclei, and new frontier disciplines such asCosmochemistry。Hundreds of short-livedparticle, including various baryonsmeson, leptons andResonance stateParticles.The emergence of a huge particle family has brought the study of the material world to a new stage and established particle physics.This is a new frontier in the study of material structure, which once again proves the inexhaustibility of matter.Various high-energy ray beams also provide nuclear structure knowledge that cannot be obtained by other methods.
Interaction
ByNucleusIn addition to the long-range electromagnetic and gravitational interactions between macroscopic objects, there are also short-range strong and weak interactions in the nuclear range.stayWeak actionThe discovery of nonconservation of lower parity is a major breakthrough in the traditional view of time and space in physics.Study the fourBasic interactionThe laws and possible connections of the nuclear physics have become an important topic in particle physics and quantum mechanics. Nuclear physics will also make new contributions in this regard.Nuclear physics is alsonuclear energyThe design of the device provides increasingly accurate data, improves the efficiency and economic indicators of nuclear energy utilization, and prepares conditions for large-scale nuclear energy development.The application of artificially prepared isotopes has spread to all departments of science, industry, agriculture and medicine.New nuclear technologies such asnuclear magnetic resonance、Mossbauer spectroscopyAnd so on.The wide application of nuclear technology has become one of the symbols of scientific and technological modernization.
Particle physics
After the establishment of particle physics, in the 1960s, nuclear physics and particle physics went their separate ways, and nuclear physics is no longer at the forefront of material structure research.This is human rightnatureA major mistake in understanding is also a tragedy of modern physics.The nucleus ismicrocosmicThe cornerstone of matter, in a sense, whetherElementary particleTheory or atomic theory should be based on nuclear theory.Atoms are just nuclei in outer space (0.1nanometer）It is also a special phase (such as the earth environment). The more common phase of the atomic nucleus in the outer space isPlasma state。The simplest nucleus is the hydrogen nucleus, also known asproton, anothernucleonbe calledneutronNucleon is the most basic particle, and other physical particles such asmeson、LeptonThey are the products of nuclear reactions, and are the most basic in nuclear reactionsQuantum numberIs the mass number A of the nucleus, which is a conserved quantity.Physics has the suspicion of putting the cart before the horse. This is a conclusion drawn from the observation data of atomic nucleus mass and the experimental data of deep inelastic scattering of electrons.We can review the history of atomic physics and nuclear physics. From 1913 to 1927, there were four theories about hydrogen atom（Bohr theorySommerfeld's theory, Schrodinger's theory anddirac theory ）These theories can explain the spectrum of hydrogen atom, andheisenberg After the nuclear structure was proposed in 1932, there have been many nuclear theories in the past 80 years, none of which can explain the mass of the atomic nucleus, etcStatic dataNuclearradioactivityThis shows that people's understanding of the atom is basically correct, while the understanding of the atomic nucleus has entered a misunderstanding from the beginning.
The use of nuclear energy is not as urgent as in the previous stage to provide data and develop nuclear physicsKey equipment。Since the 1970s, nuclear physics has entered a more mature stage of in-depth development and wide application.
Today's Nuclear Physics
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At the present stage, due to the development of heavy ion acceleration technology, the ions of all elements from hydrogen to uranium can be effectively accelerated, with the energy reaching 1 × 109eV per nucleon, expanding the means of reforming atomic nucleiHeavy ion nuclear physicsResearch has developed in an all-round way.Medium and high energy accelerators with high beam current not only provide directly accelerated ion current, but also providePionOn the other hand, the secondary particle beams, such as,,,,,,,,,, expand the means of studying atomic nuclei, and accelerate the development of high-energy nuclear physics.Superconducting accelerator will greatly reduce the size of the accelerator, reduce the cost and operating costs, and improve the beam quality.
New developments have also taken place in nuclear physics experimental methods and ray detection techniques.Microprocessor andData acquisitionWith the improvement of the processing system, the impact is far-reaching.In the past, it was difficult to measure several parameters simultaneously in the nuclear process. At present, it is common to record dozens of parameters at a time.For some high-energy heavy ion nuclear reactions, thousands of detectors can work at the same time, recording and processing thousands of parameters at a time, so that thousands of releasedparticleDetermine and identify.On the other hand, some special nuclear technology equipment is equipped with automaticdata processing system, simplify the operation and promote the use.
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The main objectives of basic research in nuclear physics are twofold: ① to study the properties and interactions of particles, especially the interactions between nucleons, through nuclear phenomena.Some important issues such asneutronOfElectric dipole moment, neutrino mass andprotonThe lifetime, etc. should be measured through low energy nuclear physics experiments;The important knowledge of the interaction between particles can also be provided by intermediate and high energy nuclear physics. ②The study of nuclear multi system motion.Nuclear multi system is a system with rich movement patterns, which was mainly studied in the pastground stateAnd lowexcited stateAnd some nuclear reaction mechanismsspinState, highly excited state, greatly changed state and far awayBeta stability lineThe research of nuclides and other special motion forms has just begun, and the experimental knowledge of ground state and low excited state is also insufficient, which is far less than the information provided by multibody wave functions.The study of nuclear motion morphology will become the main part of the basic research of nuclear physics for a long time.
The extensive application of nuclear technology is an important feature of this stage.Commonly used small accelerators have been put into industrial production. Thousands of accelerators are operating in research institutes, universities, factories and hospitalsRadioactive SourceIs more common;On the other hand, almost no nuclear physics laboratory is not engaged in the applied research of nuclear technology.The application of nuclear technology mainly includes the following aspects: ① providing services for the development of nuclear energy, providing more accurate data and more effective utilization ways for large nuclear power plants to micro nuclear batteries. ②isotopeThis is the most widely used nuclear technology, includingIsotope tracer、Isotope meterAnd isotope reagents, etc. ③Application of X-ray irradiation, using accelerator andisotopeRadiation source, radiation processing, food disinfection and preservation, radiation breeding, flaw detection and radiation medicine. ④neutronApplication of bundles, except utilizationNeutron diffractionIn addition to analyzing the material structure, it is also used for irradiation, dopinglogging, exploration and biological effects, such as cancer treatment. ⑤For the application of ion beam, a large number of accelerators are designed to provide ion beam,Ion implantation technologyIt is an important means to study semiconductor physics and prepare semiconductor devices. Ion beam is nondestructive, fastTrace analysisIn particularprotonMicron beam scanning analysis of the surface shows that the detection limit of element content can reach 1 × 10-15 ～ 1 × 10-18g, which is incomparable to other methods.
In the process of the birth, growth and consolidation of nuclear physics, the application of nuclear technology has made the basic research of nuclear physics widely supported, and the latter has constantly opened up new ways for the former.These two needs have promoted the development of particle acceleration technology and nuclear physics experiment technology;The new development of these two technologies has greatly promoted the research on the basis and application of nuclear physics.This trend of mutual promotion and common development will play an increasingly important role in the new stage of nuclear physics.
Another goal of nuclear physics is to useParticle recoilTechnology benefits mankind, if successfully developed smallacceleratorHuman beings will enter a new social stage (which can be implementedcommunismSystem,On demand distribution）。
