Mod-01 Lec-27 Beta decay Contd..

Beta decay we were discussing and I was in the middle of describing what is called Fermi theory of Beta Decay. You know in beta decay we have A nucleus with z protons and neutrons total mass number A decays to say Y z plus 1 A when a neutron is converted into a proton and then electron

and then this is beta minus decay. And when this beta minus decays are studied the kinetic energy of this electron, which is the experimentally accessible quantity that has got a distribution does the biggest mysteries. It something of this sort I will show you on the screen, a schematic drawing of this side is energy in M e V’s and this side

is the number of electrons detected and that energy. This kind of continuous distribution and this distribution ends somewhere, here which happens to be the q value of that we obtain from this equation. Similarly, for beta plus decay the equation is this goes to z minus 1, because a proton decays into neutron. And then you have this positron thing this neutrino thing beta plus, and here the spectrums

is slightly different looks like this, I will just show you on the screen, how these things look like again a schematic diagram only not taken from mark any measure result, but look at the screen. This is your beta minus spectrum, the axis on the horizontal site is the energy in mega electron volts. This is kinetic energy of the electron as measured in the detector in

the experiment. And then this side is the number of electrons, and that this is beta minus the electrons, which are coming throw this beta decay, their energy is distributed schematically in this fashion. Then if you look at the beta plus decays the typical energy distribution will be something like this. This is the kind of it is also a continuous distribution, but you can see the shapes are