Universität zu Köln

Netterdon, L., Mayer, J., Scholz, P. and Zilges, A. (2015). Total and partial cross sections of the Sn-112(alpha,gamma)Te-116 reaction measured via in-beam gamma-ray spectroscopy. Phys. Rev. C, 91 (3). COLLEGE PK: AMER PHYSICAL SOC. ISSN 1089-490X

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Abstract

Background: The nucleosynthesis of the neutron-deficient p nuclei remains an open question in nuclear astrophysics. Beside uncertainties on the astrophysical side, the nuclear-physics input parameters entering Hauser-Feshbach calculations for the nucleosynthesis of the p nuclei must be put on a firm basis. Purpose: An extended database of experimental data is needed to address uncertainties of the nuclear-physics input parameters for Hauser-Feshbach calculations. Especially alpha + nucleus optical model potentials at low energies are not well known. The in-beam technique with an array of high-purity germanium (HPGe) detectors was successfully applied to the measurement of absolute cross sections of an (alpha,gamma) reaction on a heavy nucleus at sub-Coulomb energies. Method: The total and partial cross-section values were measured by means of in-beam gamma-ray spectroscopy. For this purpose, the absolute reaction yield was measured using the HPGe detector array HORUS at the FN tandem accelerator at the University of Cologne. Total and partial cross sections were measured at four different alpha-particle energies from E-alpha = 10.5 MeV to E-alpha = 12 MeV. Results: The measured total cross-section values are in excellent agreement with previous results obtained with the activation technique, which proves the validity of the applied method. With the present measurement, the discrepancy between two older data sets is removed. The experimental data was compared to Hauser-Feshbach calculations using the nuclear reaction code TALYS. With a modification of the semi-microscopic alpha + nucleus optical model potential OMP 3, the measured cross-section values are reproduced well. Moreover, partial cross sections could be measured for the first time for an (alpha,gamma) reaction. Conclusions: A modified version of the semimicroscopic alpha + nucleus optical model potential OMP3, as well as modified proton and gamma widths, are needed in order to obtain a good agreement between experimental data and theory. It is found that a model using a local modification of the nuclear-physics input parameters simultaneously reproduces total cross sections of the Sn-112(alpha,gamma) and Sn-112(alpha,p) reactions. The measurement of partial cross sections turns out to be very important in this case in order to apply the correct gamma-ray strength function in the Hauser-Feshbach calculations. The model also reproduces cross-section values of alpha-induced reactions on Cd-106, as well as of (alpha,n) reactions on Sn-115,Sn-116, hinting at a more global character of the obtained nuclear-physics input.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Netterdon, L. UNSPECIFIED UNSPECIFIED UNSPECIFIED Mayer, J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Scholz, P. UNSPECIFIED UNSPECIFIED UNSPECIFIED Zilges, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-404893
DOI:	10.1103/PhysRevC.91.035801
Journal or Publication Title:	Phys. Rev. C
Volume:	91
Number:	3
Date:	2015
Publisher:	AMER PHYSICAL SOC
Place of Publication:	COLLEGE PK
ISSN:	1089-490X
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language P-PROCESS; NUCLEAR-PHYSICS; R-PROCESS; NUCLEOSYNTHESIS; MODEL; ASTROPHYSICS; STRENGTH; ENERGY Multiple languages Physics, Nuclear Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/40489