Beta particle emission range

In contrast to alpha emission, beta emission is characterized by production of particles with a continuous spectrum of energies ranging from nearly zero to some maximum that is characteristic of each decay process. The jS particle is not nearly as effective as the alpha particle in producing ion pairs in matte r because of its small mass (about /7(XK) that of an alpha particle), At the same time, its penetrating power is substantially greater than that of the alpha particle. Beta-particle energies are frequently related to the thickness of an absorber, ordinarily aluminum, required to stop the particle. 

In order to match the light emission of scintillation materials with the spectral sensitivity of PMT, nanoparticles and inorganic nanocrystals with the emission in the range of 350-450 nm were synthesized, characterized, and applied to radiation detection. Results from the detection of beta particles, alpha particles, and neutron radiation are presented here. 

Scintillation detection has been used since the earliest days of radioactivity and is still today employed to measure the whole range of radioactive emissions — alpha-and beta-particles, gamma-rays, neutrons and the more exotic leptons and mesons. In this chapter, I will restrict myself exclusively to scintillation as apphed to gamma-ray measurements. 

A nucleus with an unstable ratio of neutrons to protons may decay through the emission of a high-speed electron defined as beta particle and results in a net change of one unit of atomic number. Beta particles are negatively charged, and the beta particles emitted by a specific radionuclide ranges in energy from near zero up to a maximum value, which is characteristic of the particular transformation. 

The third force is the "weak nuclear" or "Fermi"4 force (1934), which stabilizes many radioactive particles and the free neutron it explains "beta decay" and positron emission (e.g., the free neutron decays within a half-life of 13 minutes into a proton, an electron, and an electron antineutrino). The weak force has a very narrow range. 

After Abelson returned to Washington, McMillan pressed on. Unstable neptunium decayed by beta emission with a 2.3-day half-life he suspected it decayed to element 94. By analogy with uranium, which emits alpha particles naturally, element 94 should also be a natural alpha emitter. McMillan therefore looked for alphas with ranges different from the uranium alphas coming off his mixed luranium-neptunium samples. By autumn he had identified them. He tried some chemical separations, finding that the alpha-activity did not belong to an isotope of protactinium, uranium or neptunium. He was that close. 

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