# Nuclear spin and parity

I understand that the spin and parity of the nucleus is determined by looking at hte unpaired nucleon (is that the correct way of saying it?). But what if we were looking at nulceus where 2 or more nucleons were excited from the ground state?? What would the spin and parity of the nucleus be, then??

What if we had a lithium-7 (Z=3) nucleus, say where the a proton from $1s_{1/2}$was excited (by some means) to the $2s_{1/2}$ state. Now we have 2 unpaired protons, one in the $1p_{3/2}$ state and the $2s_{1/2}$

what would the spin and the parity of this nucleus be??

Do we still look at the unpaired nucleon in teh outermost shell only??
In this case, then the spin would be $(1/2)^+$, since the j value of the outermost nucleon in 1/2 and l=0.

(Spin and parity is given by $i^{\pi}$
where i=j
and $\pi = (-1)^l$)

## Answers and Replies

Old stuff, but lets give an answer: All unpaired nucleons contribute to spin and parity, that is ALL three protons. Smallest possible spin is 1/2 and highest 5/2. Parity is evidently negative (1s and 2s protons contribute nothing, the p proton contributes negative).