What Is Nuclear Physics?

Nuclear physics, also known as nuclear physics, is a branch of physics newly established in the 20th century. It studies the structure and changing laws of atomic nuclei; the generation, detection, and analysis techniques of ray beams; and physical issues related to nuclear energy and the application of nuclear technology. It is a discipline that has both profound theoretical and practical significance.

Nuclear physics, also known as nuclear physics, is a branch of physics newly established in the 20th century. It studies the structure and changing laws of atomic nuclei; the generation, detection, and analysis techniques of ray beams; and physical issues related to nuclear energy and the application of nuclear technology. It is a discipline that has both profound theoretical and practical significance.

History of Nuclear Physics

Early nuclear physics development

In 1896, Bekerel discovered natural radioactivity, the first nuclear change observed. This major discovery is often regarded as the beginning of nuclear physics. For more than 40 years since then, people have mainly engaged in the study of radioactive decay laws and ray properties, and have made preliminary discussions on atomic nuclei using radioactive rays. This is the initial stage of nuclear physics development. During this period, in order to detect various rays, identify their species and determine their energy, a series of detection methods and measuring instruments were initially created. Most detection principles and methods have been developed and applied in the future. Some basic equipment, such as counters and ionization chambers, are still in use today. Detecting, recording and determining the properties of radiation has always been a central link in nuclear physics research and the application of nuclear technology. Radioactive decay studies have proven that one element can become another element through decay, overturning the element's immutable view and establishing the statistical nature of the decay law. Statistics is an important feature of material movement in the micro world, and it differs in principle from classical mechanics and electromagnetic laws. Radioactive elements can emit high-energy rays, which provides an unprecedented weapon for exploring atoms and nuclei. In 1911, Rutherford and others used alpha rays to bombard various atoms and observe the deflection of alpha rays, thereby establishing the nuclear structure of the atom and proposing a planetary model of the atomic structure. This achievement laid the foundation for the study of atomic structure. The foundation. Soon after, people initially understood the atomic shell structure and the laws of electron movement, and established and developed quantum mechanics that describes the laws of matter movement in the microworld.
In 1919, Rutherford and others discovered that bombarding the nitrogen nucleus with alpha particles would release protons, which was the first artificial nuclear metathesis reaction. Since then, the method of bombarding the nucleus with rays to cause a nuclear reaction has gradually become the main means of studying the nucleus.

Major achievements in nuclear physics

In the early nuclear reaction research, the most important results were the discovery of neutrons in 1932 and the synthesis of artificial radionuclides in 1934. The nucleus is composed of neutrons and protons. The discovery of neutrons provides the necessary prerequisites for the study of nuclear structure. Neutrons are not charged and are not rejected by nuclear charges. They easily enter the nucleus and cause nuclear reactions. Therefore, neutron nuclear reaction has become an important means for studying atomic nuclei. In the 1930s, people also discovered positrons and mesons through the study of cosmic rays. These discoveries were the first of their kind in particle physics.
In the late 1920s, the principle of accelerating charged particles was already being explored. By the early 1930s, static electricity,
Nuclear physics
Linear and cyclotron accelerators have taken shape, and preliminary nuclear reaction experiments have been performed on high-pressure multipliers. Accelerators can be used to obtain stronger beams, higher energy and more types of ray beams, which greatly expands the research work on nuclear reactions. Since then, accelerators have gradually become necessary equipment for studying nuclear and applied technologies.
In the early stages of nuclear physics development, people noticed its possible applications, and soon discovered the therapeutic effect of radioactive rays on certain diseases. This was an important reason why it was valued by the society at that time. Until today, nuclear medicine is still an important area for the application of nuclear technology.

The great development period of nuclear physics

Around the 1940s, nuclear physics entered a stage of great development. In 1939, Hahn and Strathman discovered the phenomenon of nuclear fission; in 1942, Fermi established the first chain-type fission reactor, which was the beginning of mankind's grasp of nuclear energy.
In the 1930s, people could only accelerate protons to the order of one million electron volts. By the 1970s, people had been able to accelerate protons to 400 billion electron volts, and they could produce various energy divergences according to work needs Small, extremely high collimation or extremely strong beams.
Since the 1940s, particle detection technology has also developed a lot. The application of semiconductor detectors has greatly improved the resolution of measuring ray energy. The rapid development of nuclear electronics and computing technology has fundamentally improved the ability to acquire and process experimental data, while also greatly expanding the scope of theoretical calculations. All of this has opened up the scope of observable nuclear phenomena, improved the accuracy of observations and the ability of theoretical analysis, thereby greatly promoting the application of nuclear physics research and nuclear technology.
Through a large number of experimental and theoretical studies, people have a deeper understanding of the basic structure and changing laws of atomic nuclei. Basically clarified the various properties of the interaction between nucleons (collectively called protons and neutrons), and have accumulated systematic experiments on the properties of the stable and stable radionuclide or long-lived radionuclide in the ground and low-excitation states data. Through theoretical analysis, various applicable models have been established.
Through nuclear reactions, 17 kinds of transuranium elements with an atomic number greater than 92 and thousands of new radionuclides have been artificially synthesized. This kind of research further shows that elements are simply structural units of matter that are relatively stable under certain conditions, and are not immutable.
Astrophysics research shows that nuclear process is a key process in the evolution of celestial bodies, and nuclear energy is the main source of celestial energy. People also have a preliminary understanding of the formation and evolution of various nuclei during the evolution of celestial bodies. In the natural world, various elements have a process of development and change, all in eternal change.
Through the interaction of high-energy and ultra-high-energy ray beams and nuclei, people have discovered hundreds of short-lived particles, namely baryons, mesons, leptons, and particles of various resonance states. The discovery of a huge family of particles has pushed people's research into the physical world to a new stage and established a new discipline-particle physics, sometimes called high-energy physics. Various high-energy beams are also new weapons for studying nuclear nuclei, and they can provide some knowledge about nuclear structure that cannot be obtained by other methods.

A major breakthrough in nuclear physics

In the past, through the study of macroscopic objects, people know that there are two long-range interactions between electromagnetic interactions and gravitational interactions (gravitational interactions) between materials; through in-depth study of atomic nuclei, it is found that there are two short-range interactions between materials Interactions, that is, strong interactions and weak interactions. The discovery of parity non-conservation under weak action is a major breakthrough in the traditional space-time view of physics. It has become an important subject of particle physics to study the laws of these four interactions and the possible connections between them, and to explore the possible Jin interactions. There is no doubt that nuclear physics research will also make new and important contributions in this regard.
The development of nuclear physics has continuously provided increasingly accurate data for the design of nuclear energy devices, thereby improving the efficiency and economic indicators of nuclear energy utilization, and preparing the conditions for larger-scale nuclear energy utilization. The use of artificially prepared various isotopes has been applied in various departments of science, technology, agriculture and medicine. New nuclear techniques, such as nuclear magnetic resonance, Mössbauer spectroscopy, channel effects and blocking effects of crystals, and perturbation angle correlation techniques have been rapidly applied. The widespread application of nuclear technology has become one of the hallmarks of modern science and technology.

Nuclear Physics Improvement and Improvement

In the 1970s, as particle physics gradually became an independent discipline, nuclear physics was no longer at the forefront of studying the structure of matter. The use of nuclear energy is not as urgent as in the past, and nuclear physics has entered a new and more mature stage of in-depth development and widespread application.
At this stage, new progress has been made in particle acceleration technology. Due to the development of heavy ion acceleration technology, people have been able to effectively accelerate the ions of all elements from hydrogen to uranium, and their energy can reach one billion electron volts per nucleus. This greatly expands the means for people to change the atomic nucleus and enables the comprehensive development of heavy ion nuclear physics research.
With the development of high-energy physics, people have been able to build strong beam high-energy accelerators. This type of accelerator can provide not only directly accelerated ion current, but also secondary particle beams. These high-energy particle flows have on the other hand expanded the means of studying atomic nuclei, making high-energy nuclear physics a dynamic research area.
From the basic research of nuclear physics, the main goals are in two aspects: one is to study the properties and interactions of particles through nuclear phenomena, especially the interactions between nuclei; Obviously, the study of nuclear motion patterns will occupy a major part of the basic research of nuclear physics for a long period of time.

Nuclear Physics Application

The reason why nuclear physics research is valued by people and receives strong support from society is closely related to its wide and important application value. Few nuclear physics laboratories are not engaged in applied research in nuclear technology. Some equipment is even mainly engaged in the application of nuclear technology.

Nuclear physical isotope tracer

The application of nuclear technology mainly serves the development of nuclear energy, such as providing more accurate nuclear data and exploring ways to use nuclear energy more effectively. In addition, the application of isotopes is the most widely used field of nuclear technology. Isotope tracing has been used in various scientific and technological fields; isotope medicaments are used in the diagnosis or treatment of certain diseases; isotope meters are used in various industrial sectors as production line monitoring or quality control devices.
Accelerators and isotope radiation sources have been used in industrial radiation processing, food preservation and medical disinfection, radiation breeding, radiation inspection, and radiation medicine. In order to study the interaction between radiation and matter and irradiation technology, technical disciplines such as radiation physics, radiation chemistry and radiation technology have been established.
Because the neutron beam is in the material structure, solid physics. Widely used in polymer physics and other fields, people have established special high-neutron flux reactors to provide strong neutron beams. Neutron beams are also used in irradiation, analysis, logging and prospecting. Biological effects of neutrons are an important research direction, and fast neutrons have achieved certain effects in treating cancer.

Application of nuclear physical ion beam

It is a nuclear technology sector that is receiving increasing attention. A large number of small accelerators are designed to provide ion beams. Ion implantation technology is an important method for studying semiconductor physics and preparing semiconductor devices. Ion beams have been widely used in research in materials science and solid state physics. Ion beams are also an important means for non-destructive, fast, and trace analysis, especially proton microbeams, which can be used to scan and analyze surfaces. Its accuracy is difficult to compare with other methods.
Throughout the entire process of the birth, growth, and consolidation of nuclear physics, through the application of nuclear technology, nuclear physics and other disciplines as well as production, medical, military, and other parts have established extensive relations and obtained strong support; Open new ways for the application of nuclear technology. The need for basic nuclear research and the application of nuclear technology has promoted the development of particle acceleration technology and nuclear physics experimental technology; and the new development of these two technologies has strongly promoted the basic and applied research of nuclear physics.

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