Answer to Question #210490 in Atomic and Nuclear Physics for asad

Question

Write down the apparatus used to investigate attenuation of radiations with absorption of beta particles. 

Answer 1

All nuclei heavier than lead (and many isotopes of lighter nuclei) have a finite probability of decaying spontaneously into another nucleus plus one or more lighter particles. One of the decay products may be an alpha-particle (two protons and two neutrons--the stable nucleus of a helium atom). Alternatively, a nucleus with more neutrons than it can maintain in stability may decay by emission of an electron from the nucleus (beta-decay) which corresponds to the conversion of a neutron to a proton. These electrons may emerge with a kinetic energy of up to several MeV.

After alpha or beta decay, the residual nucleus may be left in an excited state. In this case, a transition to a state of lower energy of the same nucleus will occur almost immediately with the emission of a photon (gamma ray). The spectrum of photons emitted from the various excited states of a nucleus will have discrete frequencies ν, corresponding to transitions ∆E = hν, between discrete energy levels of the nucleus. The gamma ray spectrum from an excited nucleus is thus analogous to the line spectrum of visible radiation from an atom due to excited electrons, with the notable difference that the MeV energy changes of the nucleus are approximately 106 times as large as energy changes in transitions between atomic states (where ∆Eatomic ≈ several eV).

Attention cofficient

$I=I_0e^{-\mu t}$

Where $I_0$ initial intensity

$I$ final intensity

$\mu=$ attunation cofficient

t=thikness of foil (Al)

Negative sign represent intensity decrease with respect thickness

In early experiments on beta-decay, it was observed that each decay was not a simple one in which an electron and the recoil nucleus came off with equal and opposite momentum. The electrons, in fact, were emitted with a continuous spectrum of energies .

It was subsequently suggested by Pauli and Fermi that in each decay, another particle of zero mass and charge, called the neutrino, was emitted. Experimental verification of the neutrino has been obtained by observation of its rare interaction with matter.

End point energy of beta particle:-

Maximum energy of beta particle corresponding number of electron