Question

the helium isotope 6He undergoes beta-minus decay. show the nucleons of the parent and daughter nuclei on the shell-model-level diagrams.

Answer 1

Helium 6 has 2 protons and 4 neutrons.

When it undergoes beta-minus decay,a neutron gets converted into proton. So the neutron number decreases by 1(i.e.3) and proton number increasrs by 1(i.e.3) .

The nuclear shell model level diagram of the parent nucleus looks like this:

The shell model level diagram for the daughter nucleus looks like this:

As shown in the figures above, the proton produced after beta-minus decay enters the 1P_3/2 energy level because the 1S level has an occupancy of 2 and is completely filled.