Fuctional Structure of Mammography Machine:
Bremsstrahlung (Bremsstrahlung), electron capture (Bremsstrahlung) and internal conversion (Bremsstrahlung) are three ways to produce X-rays. Bremsstrahlung is the mechanism by which an X-ray machine produces x-rays.
1. Electron capture: Beta decay consists of three modes: beta - decay, beta + decay and electron capture (EC). The decay of electron capture (EC) can be expressed as that the parent nucleus captures an exo-orbital electron, which converts a proton into a neutron and emits a neutrino, so the charge number of the child nucleus becomes Z-1 while the mass number remains unchanged. In general, electrons in the K shell are more likely to be captured by the nucleus, because the K shell is closest to the nucleus and has the highest probability of being captured, but the probability of being captured in the L shell also exists. After the nucleus captures electrons, there will be an electron vacancy in the K or L layer of the daughter nucleus atom. When an outer electron fills the vacancy, one of the following two situations may occur: Either the excess energy is released in the form of a signature X-ray, or the excess energy is given to another electron in another layer, which gains energy and leaves the atom as an Auger electron. Emission of x-rays or Auger electrons is a sign of K capture.
2. Internal transformation: Nuclei can reach an excited state by some means (such as beta decay). Nuclei in an excited state can transition to a lower excited state or ground state by emitting gamma rays. This phenomenon is called gamma decay or gamma transition. There is no essential difference between the photon emitted by nuclear level transition and that of atomic level transition. The difference is that the photon energy emitted by atomic level transition is only eV~keV, while the photon energy emitted by nuclear level transition is MeV. Without considering the recoil of the nucleus, the photon energy Eg can be expressed as Eg= es-ex. Sometimes the transition from an excited state to a lower energy state does not release photons, but gives energy directly to the electrons outside the nucleus, causing them to break away from the atom. This phenomenon is called internal conversion (IC), and the electrons that break away from the atom are called internal conversion electrons. The nuclei in the excited state can return to the ground state either by emitting γ photons or by producing internally converted electrons. The process completely depends on the energy level properties of the nuclei. The sum of the kinetic energy of the internally converted electron and the ionization energy of the shell electron should be the energy difference between the two energy levels of the nucleus. That's equal to the energy of the gamma photon emitted by the transition between the two atomic energy levels. The study of internal conversion is an important means to obtain the knowledge of nuclear energy level. Of course, it can also produce characteristic X-rays of atoms by means of internal conversion.
