TY - JOUR

T1 - Fixed spin and parity nuclear level density for restricted shell model configurations

AU - Horoi, Mihai

AU - Ghita, Monica

AU - Zelevinsky, Vladimir

N1 - Funding Information:
The authors acknowledge support from the NSF, under Grant No. PHY-0244453.

PY - 2004/4

Y1 - 2004/4

N2 - In a recent paper [M. Horoi, J. Kaiser, and V. Zelevinsky, Phys. Rev. C 67, 054309 (2003)] proposed a method of calculating J-, T-, and parity-dependent shell model nuclear level densities using centroids and widths for configurations with fixed spin, isospin and parity quantum numbers, and the energies of the yrast states calculated with the exponential convergence method [M. Horoi, A. Volya, and V. Zelevinsky, Phys. Rev. Lett. 82, 2064 (1999); M. Horoi, B. A. Brown, and V. Zelevinsky, Phys. Rev. C 65, 027303 (2002); 67, 034303 (2003)]. When used in many major shell model spaces the results are affected by contributions of the spurious center-of-mass states. Attempts to eliminate these contributions would require knowledge of fixed-J centroids and widths for restricted shell model configurations, such as the Nℏω excitations. We derive explicit expressions for matrix elements that can be used to calculate the fixed-J configuration widths and use them to reduce the contribution of the spurious center-of-mass states to the nuclear level density for excitation energies <20 MeV. This approach could be also applied to other many-fermion systems, such as atomic clusters.

AB - In a recent paper [M. Horoi, J. Kaiser, and V. Zelevinsky, Phys. Rev. C 67, 054309 (2003)] proposed a method of calculating J-, T-, and parity-dependent shell model nuclear level densities using centroids and widths for configurations with fixed spin, isospin and parity quantum numbers, and the energies of the yrast states calculated with the exponential convergence method [M. Horoi, A. Volya, and V. Zelevinsky, Phys. Rev. Lett. 82, 2064 (1999); M. Horoi, B. A. Brown, and V. Zelevinsky, Phys. Rev. C 65, 027303 (2002); 67, 034303 (2003)]. When used in many major shell model spaces the results are affected by contributions of the spurious center-of-mass states. Attempts to eliminate these contributions would require knowledge of fixed-J centroids and widths for restricted shell model configurations, such as the Nℏω excitations. We derive explicit expressions for matrix elements that can be used to calculate the fixed-J configuration widths and use them to reduce the contribution of the spurious center-of-mass states to the nuclear level density for excitation energies <20 MeV. This approach could be also applied to other many-fermion systems, such as atomic clusters.

UR - http://www.scopus.com/inward/record.url?scp=3042680450&partnerID=8YFLogxK

U2 - 10.1103/PhysRevC.69.041307

DO - 10.1103/PhysRevC.69.041307

M3 - Article

AN - SCOPUS:3042680450

SN - 0556-2813

VL - 69

SP - 041307-1-041307-4

JO - Physical Review C - Nuclear Physics

JF - Physical Review C - Nuclear Physics

IS - 4

M1 - 041307

ER -