Alpha/beta-Discrimination
From mn/safe/nukwik
Revision as of 17:05, 19 June 2012 by Hansvl@uio.no (talk | contribs) (Created page with "In modern LSC equipment it is possible to discriminate between the - and -emissions. The resolution of the -peaks is relatively poor due to the small number of excitatio...")
In modern LSC equipment it is possible to discriminate between the - and -emissions. The resolution of the -peaks is relatively poor due to the small number of excitations produced but the background associated with the -emissions is very small.
The ability to discriminate between - and -particles lies in the small difference in pulse shapes. The following steps explain the difference in pulse profile.
- The initial interaction of the -particle is much stronger than the -particle due to a) the double charge, and b) the low velocity. The -range is much less than -range so that the ionisations produce a very high-density track. Compared with the -particle, the -particle produces fewer excitations (~ 0.4%). Since it is the excitations which contribute to the pulse, equal energies of and give an -pulse height approximately 10% of the -pulse height. It is the greater density of ions and electrons which will produce the difference in pulse profile.
- Due to the density of ions, the probability of recombination of an ion and electron is greater for than .
- Recombination may produce a ground state molecule or an excited molecule.
- Quantum mechanics postulates the number of states (orientations) is given by 2s + 1, where s = spin. Spin of singlet (S) = 0, spin of triplet (T) = 1. Hence, for a singlet, the number of states = 1 whereas for a triplet, the number of states = 3.
