Home / Store / Journals / Electronic Articles / Nuclear Science and Engineering / Volume 148 / Number 1 / Pages 43-49

Soo-Youl Oh, Jonghwa Chang, Luiz C. Leal

Nuclear Science and Engineering / Volume 148 / Number 1 / Pages 43-49

September 2004

Format:electronic copy (download)

We have derived formulas in a general form for suggesting the neutron orbital angular momentum quantum number l to each neutron resonance if it is not identified experimentally. By assuming the (2J + 1) law of level density, these general formulas are reduced to the formulas found in previous works. The suggestion of l is based on the probability that a resonance having a certain value of g_{n} is an l-wave resonance. The probability is calculated from the Bayes theorem on conditional probability. For each l, the probability density function (pdf) of g_{n} was derived from the ^{2} distribution proposed by Porter and Thomas. The pdf takes into account two possible channel spins that result in the same total spin for a given l larger than zero. Meanwhile, regardless of the resolution of measurement, we suggest adopting the level density as the prior probability in the Bayesian approach, as Gyulassy et al. did. As a sample problem, we presented the result of l-assignment for ^{109}Ag resonances. The SUGGEL code, in which the methodology is incorporated, correctly assigned l's for 67 among 70 resonances for which l's had been determined experimentally. The other test for ^{27}Al showed the applicability of the code as a preanalysis tool, even though such applicability is limited to a certain extent for light nuclides. The use of the code SUGGEL is expected to reduce the number of repeated runs of a fitting code such as SAMMY, thus reducing time and effort for the extraction of resonance parameters from measurements.

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