Medical and radiation physics

Question

Show that the probability of a nucleon to exist in single state is small but cross section in this state is much more than in triplet state

Answer 1

Hi Mishal M.,

Sorry but your question is meaningless. A system can only exist in a singlet or triplet state if there are at least 2 entities to pair or unpair. A single nucleon doesn't have that. A nucleus with multiple baryons, yes (with multiple states possible); an atom with 2 valence shell electrons, yes. Even molecules, with molecular orbitals, are said to have singlet or triplet states; for molecules that's interesting since quantum rules forbid simply dropping from a triplet to a singlet state, hence triplet states tend to be long-lived even though of higher energy than the corresponding singlet ground state.

Even when not forbidden, low-energy transitions can be slow. As extreme examples, 209-Bi (bismuth-209) has an estimated half-life of 10^19 years (with alpha emission), and 128-Te has 10^24 years (with double beta-minus emission).

--Cheers, --Mr. d.