Mod-01 Lec-26 Beta decay

[Music]

[Music] okay so we discussed alpha decay the key points I can summarize once again all nuclei with mass number Capital a greater than certain value somewhere around say 150 or so they are energetically they can Decay through this Alpha dek thing because that uh product nuclei the daughter nucleus and alpha particle rest mass energy of that

is lower than the rest mass energy of the parent once this capital A is more than 1550 or so so energetically it is favorable but then uh there are many stable nuclei or very nearly stable nuclei Beyond 150 and we saw that the key feature is that alpha particle forms inside this bigger

nucleus of course that preformation probability is also there not that all Heavy nuclei all already have alpha particle all the theory developed by GMA assumed something like that the preformation is also something which will depend on the nucleus but it's a an overall lowering of this total probability of Decay as far as the

variations are concerned it doesn't have much effect and this alpha particle when it tries to come out of the nucleus it encounters the kulum potential barrier so that's the key feature that's a central feature this alpha particle when tries to come out it Encounters this uh kulum

barrier the barrier height is around say 25 M or so and the energy of the alpha particle which one can uh uptain experimentally once it comes out that energy is somewhere around say 4 to 9 M we that is the Q value and this is that barrier and this barrier tunneling probability which is a purely Quantum