Nuclear-level densities around Z = 50 from neutron evaporation spectra in (p, n) reactions

Journal Article · Wed Mar 15 00:00:00 EST 2006 · Physics of Atomic Nuclei

DOI:https://doi.org/10.1134/S106377880603001X· OSTI ID:21076107

Zhuravlev, B V; Lychagin, A A; Titarenko, N N ^[1]

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1. Institute for Physics and Power Engineering (Russian Federation)

Neutron excitation functions, spectra, and angular distributions in the (p, n) reactions on the isotopes {sup 116}Sn, {sup 118}Sn, {sup 122}Sn, and {sup 124}Sn were measured in the proton-energy range 7-11 MeV. The measurements were performed by the time-of-flight method with the aid of a fast-neutron spectrometer at the EGP-15 pulsed tandem accelerator of the Institute of Physics and Power Engineering (Obninsk). A high resolution (about 0.6 ns/m) and a high stability of the time-of-flight spectrometer made it possible to identify reliably low-lying levels along with the continuous section of the neutron spectra. The data obtained in this way were analyzed on the basis of the statistical equilibrium and preequilibrium models of nuclear reactions. The respective calculations were performed with the aid of the precise Hauser-Feshbach formalism of statistical theory. The nuclear-level densities in the isotopes {sup 116}Sb, {sup 118}Sb, {sup 122}Sb, and {sup 124}Sb were determined, along with their energy dependences and model parameters. In the excitation-energy range 0-2 MeV, the energy dependence of the nuclear-level densities exhibits a structure that is associated with the shell inhomogeneities of the spectrum of single-particle states near filled shells. The isotopic dependence of the nuclear-level density is discovered and explained. It is also shown that the data obtained here for the nuclear-level density differ markedly from the predictions of model systematics of nuclear-level densities.

• OSTI ID: 21076107
• Journal Information: Physics of Atomic Nuclei, Vol. 69, Issue 3; Other Information: DOI: 10.1134/S106377880603001X; Copyright (c) 2006 Nauka/Interperiodica; Article Copyright (c) 2006 Pleiades Publishing, Inc; Country of input: International Atomic Energy Agency (IAEA); ISSN 1063-7788
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ANGULAR DISTRIBUTION
ANTIMONY 116
ANTIMONY 118
ANTIMONY 122
ANTIMONY 124
ENERGY-LEVEL DENSITY
EXCITATION FUNCTIONS
FAST NEUTRONS
MEV RANGE
NEUTRON SPECTRA
NUCLEAR REACTIONS
PROTON-NEUTRON INTERACTIONS
PROTONS
TANDEM ELECTROSTATIC ACCELERATORS
TIME-OF-FLIGHT METHOD
TIME-OF-FLIGHT SPECTROMETERS
TIN 116
TIN 118
TIN 122
TIN 124