Beijing time, December 18, according to foreign media reports, gamma rays are some kind of electromagnetic radiation, like radio waves, infrared radiation, ultraviolet radiation, X-rays and microwaves. Gamma rays can be used for cancer treatment, and gamma-ray eruptions are a major focus on astronomical research. Electromagnetic radiation can be transmitted in the form of waves or particles with different wavelengths and frequencies.
This sky panorama is a collection of data collected by NASA Fermi Gamma Space Telescope for two years, showing the universe's appearance under gamma rays.
Gamma ray storm concept map.
The wavelength coverage area is called the electromagnetic spectrum and is usually divided into seven parts. When wavelength decreases, energy and frequency increase. The seven sections are typically radio waves, microwaves, infrared light, visible light, ultraviolet light, x-rays and gamma rays.
Gamma rays are positioned higher in the electromagnetic spectrum than "soft x-rays", with frequencies exceeding 1018 Hz per second and wavelengths less than 100 picometers (1 picometer equivalent to 1 trillionth of a meter).
The positions of gamma rays and hard X rays in the electromagnetic spectrum overlap, making it difficult to distinguish between the two. Within the field of astrophysics, researchers will force a line to separate rays over a certain wavelength in x-rays and under a certain wavelength are gamma rays. Both gamma and x-ray are high energy radiation that can destroy biological tissue. But almost all gamma rays in the universe are blocked by the Earth's atmosphere.
Gamma ray discovery
Gamma rayen was first discovered in 1900 by the French chemist Paul Villard when studying radium radiation. A few years later, the chemist and physicist Ernest Rutherford proposed the "gamma ray" according to alpha and beam generated by the nuclear reaction. This name has been retained so far. .
Source and effect of gamma ray
Gamma rays are mainly produced by four nuclear reactions: nuclear fusion, nuclear fission, alpha death and gamma loss.
Nuclear fusion is the source of energy for the sun and other stars. The reaction is carried out in several steps. Under extremely high temperature and pressure, four protons or hydrogen nuclei are forced to polymerize in a helium core with two protons and two neutrons. The mass of the helium core is about 0.7% less than the mass of the original four protons. According to Einstein's mass equation E = mc ^ 2, this part of the mass difference is converted into energy and two thirds of the energy is gamma. The shape of the horse beam is released. (The remaining energy is released in the form of neutrinos, a very weakly interacting particle with almost zero mass). At the end of the star life, after the hydrogen fuel is exhausted, the elements produced by nuclear fusion will become heavier and heavier until the iron element. But the energy generated at each step will also decrease.
Another source of gamma rays is nuclear cleavage, which should be familiar to humans. Lawrence Berkeley National Laboratory defines nuclear cleavage as: a heavier atomic nucleus is split into approximately equal halves, which in turn becomes the core of the lighter element. This process involves the effects of other particles. When heavier nuclei like uranium and thorium are bombarded by other particles, they are divided into lighter substances such as sputum and sputum. The new particles produced by the bombardment will hit other heavy cores and form a chain reaction. Energy is also released during this process because the sum of the mass of particles produced by the fission is lower than the mass of the original heavy nuclei. This part of the mass is also transformed into energy, in the form of kinetic energy, neutrins and gamma rays of smaller nuclei.
Alfa decomposition and gamma loss can also produce gamma rays. Alfa degradation occurs when heavy nuclei emit a 氦 -4 nucleus, the number of atoms decreases and the atomic weight decreases by 4. This process leads to excessive energy in the nucleus, and excess energy is released as gamma rays. If there is too much energy in the core, gamma loss occurs, which emits gamma rays without altering the charge or mass composition at the core.
Gamma ray therapy
Gamma rays can destroy tumor cell DNA and, therefore, are sometimes used to treat malignant tumors. However, one must take care when using this therapy, as gamma rays also destroy the DNA of surrounding healthy tissue cells.
One way to maximize radiation exposure of cancer cells while minimizing radiation to healthy cells is to have multiple rays of gamma rays from different directions passing through a linear accelerator to a small area. How does CyberKnife and Gamma Knife Therapy work?
Gamma Knife Radiosurgery uses a special device to beat almost 200 radiation strokes on brain tumors or other targets. Each radiation beam has little effect on the brain tissue passing through it, but the radiation dose at the junction is high.
Gamma Ray and astronomy
Gamma ray bursts are one of the most interesting sources of gamma rays. This is an extremely high energy astronomical event ranging from a few milliseconds to a few minutes. Researchers first observed this phenomenon in the 1960s, and now they are observed approximately once a day.
NASA pointed out that gamma ray bursts are "the most energetic form of light." Its brightness is hundreds of times higher than that of a typical supernova, about one billion times that of the sun.
According to Robert Patterson, a professor of astronomy at Missouri State University, researchers once believed that gamma-ray bursts came from the end of the mini-black hole that was evaporated. But now scientists believe that gamma-ray bursts should stem from the collision of dense objects like neutron stars. There are also theories that gamma-ray bursts can also occur when super massive stars collapse and form black holes.
Regardless of its source, the gamma radiation break gives enough energy to illuminate a whole galaxy in seconds. However, because the atmosphere of the Earth can block most gamma rays, only observations with high altitude observations and track telescopes can observe their existence.