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arXiv · 1304.7746

Testing the spin-cutoff parameterization with shell-model calculations

William M. Spinella·Calvin W. Johnson
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Abstract

The nuclear level density, an important input to Hauser-Feshbach calculations, depends not only on excitation energy but also on angular momentum J. The J-dependence of the level density at fixed excitation energy E_x is usually parameterized via the spin-cutoff factor sigma. We carefully test the statistical accuracy of this parameterization for a large number of spectra computed using semi-realistic interactions in the interacting shell model, with a nonlinear least-squares fit of sigma and finding the error bar in sigma. The spin-cutoff parameterization works well as long as there are enough states to be statistical. In turn, the spin-cutoff factor can be related to the average value of J^2 at a fixed excitation energy, and we briefly investigate extracting from a thermal calculation such as one might do via Monte Carlo.

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William M. Spinella, Calvin W. Johnson. 2014-07-08. Testing the spin-cutoff parameterization with shell-model calculations. https://doi.org/10.1103/physrevc.90.014315

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