Spectral distribution calculations of the level density ofMg24

Abstract

A recent paper compared moment method and Lanczos method calculations of the level density of 2~The present work extends this comparison to include a new type of Lanczos expansion. This expansion procedure shares the advantage of the traditional Lanczos method of a positive definite level density, but unlike the latter, may be used in an essentially infinite basis. Calculations utilizing dsdf and ppdsd bases have been compared with experimental values for the level density, parity ratio and spin cutoff parameters to determine the appropriateness of the input parameters and the model, while calculations in a dsd basis are compared with exact calculated results to test the accuracy of representation provided by the expansion technique.

Similarity renormalization group and many-body effects in multiparticle systems

“…The theory also provides the means to calculate important average contributions, nuclear level densities, degree of symmetry 044003-2 violation, as well as various measures. The SDT approach has been successfully applied to studies of energy spectra and reactions for p-, sd, and fp-shell nuclei [18][19][20][21][22][23], as well as for understanding dominant features and differences among sd-shell realistic effective interactions [24,25]. Recent applications include explorations on quantum chaos, nuclear structure, and parity/time-reversal violation (for example, see [13,[26][27][28][29][30]).…”

Mass-number and excitation-energy dependence of the spin cutoff parameter

“…Other techniques have also been used to calculate the spin cutoff parameter. Authors have used [5,[15][16][17][18][19][20] techniques which use the full two-body interaction to calculate both level densities and spin cutoff parameters. These have been concentrated in a mass region below A=65 but at least one paper presents calculations near A=160 [20].…”

Gaussian polynomial method for spin-dependent level density and new formula for spin distribution

“…We show that the spin-dependent level density can be presented, to a good approximation, in a factorized form (24) as a product of the total level density and a spin distribution function. The total level density in the GPM factorized form is well approximated by the Bethe formula while for the spin distribution function we propose a new phenomenological form (25) deduced from the GPM calculated spin distributions.…”

“…3 and 4 provide a hint that GPM results can be approximately described for all spins by an algebraic formula factorized similarly as the Bethe formula: (24) where P r (E) has the same form as Bethe formula for total level density (6), while the spin-distribution function fal'M (E, J) has a new form…”

“…We stress a structural difference between the new factorized form (24) and the extended thermodynamic form (18). Namely, the extended thermodynamic form (18) can be approximately factorized in the low-spin limit only, while the new formula (24) is factorized for all spins.…”