1896 Nian, A.-H. Becquerel discovered natural radioactivity, the first man to observe changes in the nuclear, nuclear physics as it normally would start. The next 40 years, mainly engaged in research and radiation radioactive decay law of nature, and to explore the use of the atomic nucleus as a ray; also created a series of detection methods and measuring instruments, some basic equipment such as various counters, ionization chambers, etc. are still in use. Detect, record-ray and determine its nature, it has always been a central part of the study of nuclear physics and nuclear technology application. Etc.
study demonstrated a radioactive decay into another element one element may decay by α or β decay, overthrow view immutable elements; further established the statistical decay law. Is a fundamental statistical properties of the microscopic world of physical movement, physical movement with the macroscopic world of classical mechanics and electromagnetism studied differ in principle. Decay energy emitted large rays, especially α-rays, to explore the atomic structure provides unprecedented weapons. In 1911, E Rutherford, etc. with α-rays bombarding various atoms, atomic structure established nuclear radiation deflected from the analysis and proposed a planetary model of atomic structure, lay the foundation for the atomic physics; It is also the first time the atomic nucleus the word soon find out the initial law of motion shell structure of the atom and the electron, the establishment and development of micro clarify the movement of the material world of quantum mechanics.
1919 Rutherford et al found that α-rays released by proton bombardment of a nitrogen nucleus, the first time an artificial nuclear reaction. After this method to cause a nuclear reaction with rays gradually become the main means of research nuclei. Significant results achieved initial preparation of artificial radionuclides discovery of the neutron in 1932 and 1934. Nucleus is composed of neutrons and protons. Discovery of the neutron not only provide the necessary precondition for the study of nuclear structure, but also because it is uncharged, not nuclear charge repulsion, easy access to the nucleus and the neutron induced nuclear reaction, has become an important means to study the atomic nucleus. In the 1930s, it also found that positrons and "meson" From observations of cosmic ray (later known as μ child), which is the first of its kind found in particle physics.
late 1920s, began to explore the principles of accelerated charged particles. Early 1930s, static electricity, lines, and other types of particle accelerators swing is now taking shape, achieve initial nuclear reaction in the high-pressure multiplier. Using the accelerator beam can get stronger, higher and more diverse energy ray beam, greatly expanding the study of nuclear reactions, the accelerator gradually become a research nucleus, the necessary equipment for the application of nuclear technology.
have been noted in the initial stage of its application to nuclear physics, nuclear radiation therapy in particular diseases such as tumor effect. This is an important reason it was valued by the community.
period of great development
1939 Nian, O. F. Hahn and Strassmann discovered nuclear fission in 1942, E. Fermi He established the first fission reactor, creating a human master nuclear energy in the new century. Access to nuclear energy is almost inexhaustible energy, in order to effectively use of nuclear energy, nuclear weapons, the need to address a series of complex scientific and technical issues, and nuclear physics and nuclear technology is the central link. Therefore, the rapid development of nuclear physics, become very intense competition in the field of science and technology. This phase lasts about 30 years, nuclear physics great period of development. In the meantime, the particle acceleration and detection technologies have great development: 1930s, protons accelerated to at most 1 × 106 electron volts (eV) magnitude; 1970s, has reached 4 × 1011eV, the divergence can be generated especially small, ultra-high degree of collimation or stream large variety of beam intensity. In the detection technology, the application of the semiconductor counter greatly improves the resolution of the measurement ray energy. The rapid development of nuclear electronics and computing technology, improve the ability to acquire and process experimental data fundamentally, but also greatly expands the range of theoretical calculations. All this effectively promoted the study of nuclear physics and nuclear technology application. Variation of the basic structure and the nucleus has a better understanding, the basic ascertain the nature of the interaction between various nuclear; and a longer lifetime of stable nuclide radionuclides ground state and excited states (with nuclear level) the nature of the accumulated experimental data systematically; and theoretical analysis, the nuclei of various models applicable, successfully explained the various nuclear phenomena and nuclear reactions. In addition, also carried out research on high energy heavy ion nuclear reactions and nuclear reactions.
nuclear reactions, synthetic transuranic of 17 atomic number greater than 92 and thousands of new radionuclide elements show only under certain conditions relatively stable material structural unit, is not eternal. Astrophysical studies have shown: nuclear reaction is a process of evolution of celestial bodies play a key role, nuclear energy is the main source of celestial bodies. Also learned that preliminary cosmogonic process is the formation of various atomic nuclei and the process of evolution, the birth of a new edge disciplines such as cosmic chemical. And nuclei by high energy ultra high energy beam interaction and found hundreds of short-lived particles, including various sub-weight, mesons, leptons particles and resonances. Emergence of a large family of particles, and the study of the physical world into a new stage, the establishment of particle physics. This is the new frontier research of the structure of matter, proving once again that inexhaustible substance. A variety of high-energy beam also provides knowledge of nuclear structure can not be achieved by other means.
depth study of nuclei found in addition to the electromagnetic long-range interactions between macroscopic objects within the nucleus range, other than gravitational interaction, there is strong short interactions and weak interaction. Parity violation in weak interactions discovery is a major breakthrough in the traditional physics of space-time. Research on these four basic laws of interaction and possible links has become particle physics and quantum mechanics an important issue, nuclear physics will make new contribution in this regard. Nuclear Physics also provides for the design of nuclear devices increasingly accurate data to improve the efficiency of the use of nuclear energy and economic indicators, prepare conditions for larger scale development of nuclear energy. The application of various isotopes artificially prepared throughout engineering, agriculture and health sectors. New technologies such as nuclear magnetic resonance, Mössbauer spectroscopy, etc., are rapidly applied. Extensive application of nuclear technology has become one of modern science and technology sign.
After the establishment of particle physics, in a 1960s nuclear physics and particle physics parted ways, study the structure of matter in nuclear physics is no longer the most cutting edge. This is a major mistake on the nature of human knowledge, but also a tragedy of modern physics. Nuclear is the cornerstone of microscopic material, in a sense, whether it is elementary particle theory or atomic theory should be built on the basis of Theoretical Nuclear Physics. Atomic nuclei only in a representation space outside the core (0.1 nm), and a special (e.g., the global environment) in phase, the nuclei in the outer nuclear more general spatial phase is present in the plasma state. The simplest core nucleus is hydrogen, also known as a proton, neutron referred another nucleus, is the most basic nucleus particles, other particles, such as physical mesons, leptons other nuclear reaction products are the best in the nuclear reaction the basic quantum number nuclear mass number a, which is a conserved quantity. Physics is suspected of putting the cart before, this is the nucleus of observational data quality and deep inelastic electron scattering (deep inelastic scattering) experimental data conclusions. We can look back on the history of atomic physics and nuclear physics, from 1913 to 1927, four of these theories about the hydrogen atom theory (Bohr theory, Sommerfeld theory, Schrodinger and Dirac theory) could have occurred Description spectrum of hydrogen atoms, and from 1932 after Heisenberg proposed nuclear structure, nearly eight decades, the theory has many nuclei appear, no single theory can explain radioactive nuclei such as the quality of static data and cores, Description of basic awareness of the atom was correct, and the understanding of atomic nuclei from the outset into the misunderstanding.
use of nuclear energy is also not as an urgent need to provide nuclear physics data the previous stage, the development of key equipment. Since the 1970s, nuclear physics entered a more mature depth development and wide application stage.
Nuclear Physics Today
At this stage, since the heavy ions accelerated technology development, are effective in accelerating the hydrogen to the uranium ions from all the elements, the energy per nucleon reaches 1 × 109eV, the expansion means changes in the nucleus, the heavy ion nuclear physics research have a comprehensive development. Strong beam of high-energy accelerator not only provides direct accelerated ion flow, but also provide services such as π mesons, Κ meson beam of secondary particles, on the other hand the means to expand research in nuclear 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 quality of the beam.
methods and nuclear physics experiments ray detection technology with new development. Microprocessors and improved data acquisition and processing system, a far-reaching impact. In the past, the process of nuclear simultaneous determination of several parameters is very difficult at present, once recorded dozens of parameters is very common. Some high energy heavy ions to nuclear reaction, thousands of detectors can work simultaneously, and a recording process thousands of parameters, for the measurement and identification of thousands of particles emitted. On the other hand, some special equipment nuclear technology with an automatic data processing system, the operation is simplified, generalized use.
The main goal of basic research in nuclear physics has two aspects: ① study the nature and role of particles by nucleation, especially the interaction between nucleons. Some important issues neutron electric dipole moment, and the quality of life proton neutrinos experimentally determined to be a low energy nuclear physics; knowledge important interaction between the particles of high energy nuclear physics can also be provided. Multi-core movement system ②. Nuclear multisystem motion form very rich systems, in the past mainly the ground state and excited states of the nature of some of the nuclear reaction mechanism for the high spin state, highly excited, great changes morphology and away from special movement patterns β stability line nuclides such as Research is just beginning, the experimental knowledge of the ground state and excited states are also inadequate, far less than the many-body wave function of the information provided. Study on the movement patterns of a main portion of the core will be the basis of nuclear physics research for a long period of time.
widespread application of nuclear technology is an important feature of this phase. Commonly used compact accelerator has been put into industrial production, thousands of accelerator operation in research institutions, universities, factories and hospitals, the use of cobalt-60 radioactive sources is more prevalent; on the other hand, almost no one not engaged in nuclear physics laboratory application of nuclear technology. The main application of nuclear technology in the following areas: ① nuclear energy development services to provide more accurate data to miniature nuclear batteries for large power plants and more efficient use of channels. ② isotope applications, which is the most widely used nuclear technology, including isotope tracers, isotopes and isotope pharmaceutical and other instruments. Application ③ ray irradiation, the use of the accelerator and the isotope radiation source for radiation processing, disinfection of food preservation, radiation breeding, medical and radiation detection. Application of the neutron beam ④, in addition to neutron diffraction analysis of the material structure, for the further irradiation, doping, logging, prospecting, and biological effects, such as cancer. ⑤ ion beam application, a large amount of the accelerator is to provide an ion beam design, is an important means of ion implantation in semiconductor physics and manufacturing a semiconductor device, the ion beam is non-destructive, fast, major trace analysis methods, in particular m proton beam to scan the surface of the analysis, the detection limit of the element content of up to 1 × 10-15 ~ 1 × 10-18 g, are difficult to compare with other methods.
In Nuclear physics was born, grow and consolidate the process, the study of the application of nuclear technology nuclear physics basis of broad support, which in turn is the former constantly open up new avenues. These two areas need to promote the development of nuclear physics and particle acceleration technology experimental techniques; and development of these two new technologies, but also effectively promoted the study of nuclear physics and basic applications. This mutual promotion and common development trend, will play an increasingly important role in the new phase of nuclear physics.
Another objective is to use particle physics, nuclear recoil technology for the benefit of mankind, if successfully developed compact accelerator, mankind will enter a new stage of society (communist system can be implemented, on-demand).