The Source and History of Gamma Rays

Gamma rays, also known as gamma rays or gamma particle flows, are a type of electromagnetic wave with the shortest wavelength, highest frequency, and highest energy in the electromagnetic spectrum. Its wavelength is generally less than 0.01 nanometers, with a frequency of up to 1019 hertz and an energy of up to 106 electron volts. It has extremely strong penetration and destructive power. This article will delve into the sources and historical development of gamma rays.



The Discovery and Naming of Gamma Rays

The discovery of gamma rays can be traced back to physics and chemical research in the late 19th and early 20th centuries. One of the earliest researchers was French chemist Paul Villard. In 1900, while studying the radiation of radium, he discovered this new type of radiation. A few years later, another famous physicist and chemist, Ernest Rutherford, named this newly discovered ray "Gamma Ray" based on the alpha and beta rays produced by nuclear reactions, a name that has been used to this day.

The source of gamma rays

Gamma rays mainly come from four nuclear reactions: fusion, fission, alpha decay, and gamma decay.

nuclear fusion

Nuclear fusion is the main source of energy for the Sun and other stars. In extremely high temperature and pressure environments, hydrogen nuclei (protons) are forced to polymerize into helium nuclei, releasing enormous energy during this process. According to Einstein's mass energy equation E=mc ^ 2, a slight decrease in mass in fusion reactions will be converted into enormous energy, of which about two-thirds of the energy is released in the form of gamma rays. This process not only occurs inside the star, but can also be simulated in a nuclear fusion reactor in the laboratory.



Nuclear fission

Nuclear fission is another important source of gamma rays. A heavier atomic nucleus splits into two or more smaller nuclei, releasing energy and particles. Lawrence Berkeley National Laboratory defines nuclear fission as a process that involves collisions with other particles. Part of the energy released in fission reactions is converted into gamma rays, while also producing particles such as neutrinos. Nuclear fission is not only the working principle of nuclear power plants, but also the foundation of atomic bomb explosions.

Alpha decay and gamma decay

Alpha decay is the process in which a heavy atomic nucleus releases a helium-4 nucleus, resulting in a decrease of 2 atoms and a decrease of 4 atoms in weight. During this process, there is excess energy in the atomic nucleus, which is released in the form of gamma rays. Gamma decay occurs when there is too much energy in the nucleus, reducing energy by emitting gamma rays without altering the charge or mass composition of the nucleus.

Gamma ray sources in the universe

In addition to nuclear reactions, gamma rays in the universe also originate from some extreme celestial phenomena, such as supernova explosions, black holes devouring matter, neutron star collisions, and gamma ray bursts.

Supernova explosion

Supernova explosions are the final events in a star's life cycle. When a star runs out of nuclear fuel, its core collapses and triggers an explosion, releasing enormous amounts of energy and matter. This process generates a large amount of gamma rays, which becomes an important clue for astronomers to study the evolution of stars and the distribution of matter in the universe.

Black holes devour matter

Black holes are celestial bodies with extremely strong gravitational pull in the universe, and no matter or light can escape their gravitational range. But there is an accretion disk around the black hole, composed of matter attracted by the black hole. These substances are accelerated to near the speed of light and undergo intense friction and collisions before being engulfed by black holes, producing high temperatures and high-energy radiation, including gamma rays. By observing these gamma rays, scientists can understand the properties and activity of black holes.

Neutron star collision

Neutron stars are extreme celestial bodies in the late stage of stellar evolution, with extremely high density and strong magnetic fields. When the neutron stars collide with each other, they release enormous energy and particles, including gamma rays. This collision event not only generates strong gamma ray bursts, but may also form new celestial bodies, such as black holes or pulsars.

Gamma ray burst

Gamma ray bursts are one of the most powerful astronomical phenomena known to date, with brightness reaching several hundred times that of typical supernovae and approximately one trillion times that of the Sun. Scientists first observed this phenomenon in the 1960s and found that its duration ranged from a few milliseconds to a few minutes. There are various theories about the origin of gamma ray bursts, including supernova explosions, binary neutron star mergers, and so on. These events release enormous energy in a very short amount of time, producing gamma rays that are enough to illuminate the entire galaxy. However, due to the obstruction of the Earth's atmosphere, only high-altitude observation balloons and orbital telescopes can observe their existence.

The application and hazards of gamma rays

Gamma rays are widely used in multiple fields due to their unique properties, but they also bring potential hazards.

Medical applications

Gamma rays have strong penetration and destructive power, which can destroy the DNA of tumor cells, thereby inhibiting their growth and spread. Therefore, gamma rays are widely used in tumor treatment, especially in radiation therapy. By precisely controlling the dose and range of gamma rays, doctors can effectively kill tumor cells while reducing damage to normal tissues.
Industrial gamma rays have a wide range of applications in the industrial field, and their unique penetrability and high energy make them key tools for non-destructive testing, material modification, radiation processing, and other aspects. The following are the main aspects of gamma rays in industrial applications:
1. Non destructive testing
Definition and application:
Non destructive testing refers to a technique that uses principles and techniques such as radiation, ultrasound, infrared, and electromagnetic to determine the internal defects, geometric characteristics, and physical properties of materials and products without damaging the tested object. Gamma rays are widely used for internal defect detection in welding, castings, pipelines, and other products due to their strong penetrability, which can penetrate thicker metal and non-metallic materials.
Specific examples:
Welding inspection: Gamma rays can detect defects such as incomplete fusion, incomplete penetration, slag inclusion, and porosity in welded joints, ensuring welding quality.
Casting inspection: By conducting gamma ray radiography on castings, defects such as shrinkage, porosity, and cracks inside the castings can be detected, improving the quality of the castings.
Pipeline inspection: In industries such as petroleum and chemical, gamma rays are used to detect defects such as corrosion and cracks in pipelines, ensuring their safe operation.
2. Radiation processing
Definition and application:
Radiation processing is a processing technique that utilizes the interaction between ionizing radiation (including gamma rays) and substances to produce physical, chemical, or biological effects, thereby achieving modification, disinfection, sterilization, solidification, and other purposes.



Specific examples:

Food preservation: Gamma rays have a bactericidal effect, which can kill harmful microorganisms such as bacteria, molds, and parasites in food, thereby extending the shelf life of food. For example, using gamma rays generated by cobalt-60 to irradiate food can effectively prevent food spoilage and spoilage.

Medical device disinfection: Gamma rays can also be used for the disinfection and sterilization of medical devices. By irradiation treatment, bacteria, viruses, and other microorganisms on medical devices can be completely killed, ensuring the hygiene and safety of medical devices.

Polymer material modification: Gamma ray irradiation can change the molecular structure and properties of polymer materials, such as improving their strength, hardness, wear resistance, etc. This modification method does not require the addition of chemical reagents and has advantages such as environmental protection and high efficiency.

3. Liquid level measurement

Gamma rays are also commonly used for liquid level measurement in industry. The principle is to use the attenuation characteristics of gamma rays penetrating fluids to measure liquid levels. The specific method is to emit gamma rays from the source through the fluid in the container, gradually being absorbed and attenuated by the fluid. The detector placed on the other side of the container measures the intensity of gamma rays penetrating the container, and determines the liquid level by calculating the amount of radiation emitted and detected. This method is suitable for measuring the liquid level of liquids such as water and oil, and has the advantages of a large measurement range and high accuracy.

4. Art restoration and preservation

Although gamma rays have relatively few direct applications in art restoration, their high-energy properties can be used for non-destructive testing or special processing of artworks in some cases. For example, through gamma ray spectroscopy analysis, the chemical composition and internal structure of artworks can be understood, providing important references for restoration work. Meanwhile, gamma rays can also be used for radiation disinfection of artworks, killing potential microorganisms and protecting their long-term preservation.

In summary, gamma rays have broad application prospects and important practical value in the industrial field. With the continuous progress of technology and the expansion of applications, gamma rays will play an important role in more fields.