Self-consistent calculations of the strength function and radiative neutron capture cross section for stable and unstable tin isotopes

Journal Article · Wed Jun 15 00:00:00 EDT 2011 · Physical Review. C, Nuclear Physics

DOI:https://doi.org/10.1103/PHYSREVC.83.064316· OSTI ID:21502776

Avdeenkov, A; Goriely, S; Kamerdzhiev, S; Krewald, S ^[1]

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1. National Institute for Theoretical Physics (NITheP), Stellenbosch 7600 (South Africa) and Institute of Theoretical Physics, University of Stellenbosch, Stellenbosch 7600 (South Africa) and Skobeltsyn Institute of Nuclear Physics, Moscow State University, Leninskie gory, Moscow, RU-119991 (Russian Federation)

The E1 strength function for 15 stable and unstable Sn even-even isotopes from A=100 to A=176 are calculated using a self-consistent microscopic theory which, in addition to the standard (quasiparticle) random-phase approximation [(Q)RPA] approach, takes into account phonon coupling and the single-particle continuum (by means of the discretization procedure) with a cutoff of 100 MeV. Our analysis shows two distinct regions for which the integral characteristics of both the giant and pygmy resonances behave rather differently. For neutron-rich nuclei, starting from {sup 132}Sn, we obtain a giant E1 resonance which significantly deviates from the widely used systematics extrapolated from experimental data in the {beta}-stability valley. We show that the inclusion of phonon coupling is necessary for a proper description of the low-energy pygmy resonances and the corresponding transition densities for A<132 nuclei, while in the A>132 region the influence of phonon coupling is significantly smaller. The radiative neutron capture cross sections leading to the stable {sup 124}Sn and unstable {sup 132}Sn and {sup 150}Sn nuclei are calculated with both the (Q)RPA and the beyond-(Q)RPA strength functions and shown to be sensitive to both the predicted low-lying strength and the phonon-coupling contribution. The comparison with the widely used phenomenological generalized Lorentzian approach shows considerable differences both for the strength function and the radiative neutron capture cross section. In particular, for the neutron-rich {sup 150}Sn, the reaction cross section is found to be increased by a factor greater than 20. We conclude that the present approach may provide a complete and coherent description of the {gamma}-ray-strength function for astrophysics applications. In particular, such calculations are highly recommended for a reliable estimate of the electromagnetic properties of exotic nuclei.

• OSTI ID: 21502776
• Journal Information: Physical Review. C, Nuclear Physics, Vol. 83, Issue 6; Other Information: DOI: 10.1103/PhysRevC.83.064316; (c) 2011 American Institute of Physics; ISSN 0556-2813
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
CAPTURE
COMPARATIVE EVALUATIONS
COMPUTERIZED SIMULATION
COUPLING
CROSS SECTIONS
EVEN-EVEN NUCLEI
GAMMA RADIATION
INCLUSIONS
MEV RANGE 10-100
NEUTRON REACTIONS
NEUTRON-RICH ISOTOPES
NEUTRONS
PHONONS
RANDOM PHASE APPROXIMATION
RESONANCE
STABILITY
STRENGTH FUNCTIONS
TIN 124
TIN 132
TIN ISOTOPES
APPROXIMATIONS
BARYON REACTIONS
BARYONS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CALCULATION METHODS
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
ENERGY RANGE
EVALUATION
FERMIONS
FUNCTIONS
HADRON REACTIONS
HADRONS
INTERMEDIATE MASS NUCLEI
IONIZING RADIATIONS
ISOTOPES
MEV RANGE
NUCLEAR REACTIONS
NUCLEI
NUCLEON REACTIONS
NUCLEONS
QUASI PARTICLES
RADIATIONS
RADIOISOTOPES
SECONDS LIVING RADIOISOTOPES
SIMULATION
STABLE ISOTOPES