BETA PARTICLE
Beta particle also called beta ray or beta radiation is a high-energy, high-speed
electron or positron emitted during beta decay. There are three forms of beta
decay beta negative, beta positive and electron capture.
Negatively charged beta particle identical to electron.
Positively charged beta particle identical to positron.
In beta decay unstable atomic nuclei spontaneously dissipate excess energy and
undergo a change of one unit of positive charge without any change in mass
number. Beta decay was named by Ernest Rutherford [1899], He called the less
penetrating rays alpha and more penetrating rays beta. More beta particles
ejected at speed approaching that of light.
Beta negative decay [electron emission decay]
All atoms consist of nucleus containing neutrons and protons, surrounded by
negative orbital electrons, these orbital electrons are not involved in the electron
emission associated with beta decay.
Negative beta emission occurs when the ratio of neutrons to protons in the
nucleus is too high. Excess neutron transforms in to electron, antineutrino and a
proton, that remains in the product nucleus.
Negative beta decay results in daughter nucleus, the proton number which is one
more than its parents, but the mass number remains same.
Eg: H-3 decays to He -3
Beta positive decay [positron emission]
Proton in the parent nucleus decays in to a neutron that remains in the daughter
nucleus, and the nucleus emit neutrino and a positron.
Beta positive decay produces a daughter nucleus, atomic number of daughter
nucleus one less then parent nucleus and mass number remains same.
Positron emission first discovered by Irene and Frederic Joliot – curie in 1934.
