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Title: Experimental (n,{gamma}) cross sections of the p-process nuclei {sup 74}Se and {sup 84}Sr

Abstract

The nucleosynthesis of elements beyond iron is dominated by the s and r processes. However, a small amount of stable isotopes on the proton-rich side cannot be made by neutron capture and are thought to be produced by photodisintegration reactions on existing seed nuclei in the so-called ''p process.'' So far most of the p-process reactions are not yet accessible by experimental techniques and have to be inferred from statistical Hauser-Feshbach model calculations. The parametrization of these models has to be constrained by measurements on stable proton-rich nuclei. A series of (n,{gamma}) activation measurements, related by detailed balance to the respective photodisintegrations, were carried out at the Karlsruhe Van de Graaff accelerator using the {sup 7}Li(p,n){sup 7}Be source for simulating a Maxwellian neutron distribution of kT = 25 keV. First results for the experimental (n,{gamma}) cross sections of the light p nuclei {sup 74}Se and {sup 84}Sr are reported. These experimental values were used for an extrapolation to the Maxwellian averaged cross section at 30 keV, <{sigma}>{sub 30}, yielding 271 {+-} 15 mb for {sup 74}Se, and 300 {+-} 17 mb for the total capture cross section of {sup 84}Sr. The partial cross section to the isomer in {sup 85}Srmore » was found to be 190 {+-} 10 mb.« less

Authors:
; ; ; ;  [1];  [2]
  1. Institut fuer Kernphysik, Forschungszentrum Karlsruhe, Postfach 3640, D-76021 Karlsruhe (Germany)
  2. (Switzerland)
Publication Date:
OSTI Identifier:
20771232
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. C, Nuclear Physics; Journal Volume: 73; Journal Issue: 1; Other Information: DOI: 10.1103/PhysRevC.73.015803; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; BERYLLIUM 7; CAPTURE; CROSS SECTIONS; DISTRIBUTION; HAUSER-FESHBACH THEORY; KEV RANGE; LITHIUM 7 TARGET; NEUTRON REACTIONS; NEUTRONS; NUCLEOSYNTHESIS; PHOTONUCLEAR REACTIONS; PROTON REACTIONS; R PROCESS; SELENIUM 74; STRONTIUM 84; STRONTIUM 85

Citation Formats

Dillmann, I., Heil, M., Kaeppeler, F., Rauscher, T., Thielemann, F.-K., and Departement Physik und Astronomie, Universitaet Basel, Klingelbergstrasse 82, CH-4056 Basel. Experimental (n,{gamma}) cross sections of the p-process nuclei {sup 74}Se and {sup 84}Sr. United States: N. p., 2006. Web. doi:10.1103/PhysRevC.73.015803.
Dillmann, I., Heil, M., Kaeppeler, F., Rauscher, T., Thielemann, F.-K., & Departement Physik und Astronomie, Universitaet Basel, Klingelbergstrasse 82, CH-4056 Basel. Experimental (n,{gamma}) cross sections of the p-process nuclei {sup 74}Se and {sup 84}Sr. United States. doi:10.1103/PhysRevC.73.015803.
Dillmann, I., Heil, M., Kaeppeler, F., Rauscher, T., Thielemann, F.-K., and Departement Physik und Astronomie, Universitaet Basel, Klingelbergstrasse 82, CH-4056 Basel. Sun . "Experimental (n,{gamma}) cross sections of the p-process nuclei {sup 74}Se and {sup 84}Sr". United States. doi:10.1103/PhysRevC.73.015803.
@article{osti_20771232,
title = {Experimental (n,{gamma}) cross sections of the p-process nuclei {sup 74}Se and {sup 84}Sr},
author = {Dillmann, I. and Heil, M. and Kaeppeler, F. and Rauscher, T. and Thielemann, F.-K. and Departement Physik und Astronomie, Universitaet Basel, Klingelbergstrasse 82, CH-4056 Basel},
abstractNote = {The nucleosynthesis of elements beyond iron is dominated by the s and r processes. However, a small amount of stable isotopes on the proton-rich side cannot be made by neutron capture and are thought to be produced by photodisintegration reactions on existing seed nuclei in the so-called ''p process.'' So far most of the p-process reactions are not yet accessible by experimental techniques and have to be inferred from statistical Hauser-Feshbach model calculations. The parametrization of these models has to be constrained by measurements on stable proton-rich nuclei. A series of (n,{gamma}) activation measurements, related by detailed balance to the respective photodisintegrations, were carried out at the Karlsruhe Van de Graaff accelerator using the {sup 7}Li(p,n){sup 7}Be source for simulating a Maxwellian neutron distribution of kT = 25 keV. First results for the experimental (n,{gamma}) cross sections of the light p nuclei {sup 74}Se and {sup 84}Sr are reported. These experimental values were used for an extrapolation to the Maxwellian averaged cross section at 30 keV, <{sigma}>{sub 30}, yielding 271 {+-} 15 mb for {sup 74}Se, and 300 {+-} 17 mb for the total capture cross section of {sup 84}Sr. The partial cross section to the isomer in {sup 85}Sr was found to be 190 {+-} 10 mb.},
doi = {10.1103/PhysRevC.73.015803},
journal = {Physical Review. C, Nuclear Physics},
number = 1,
volume = 73,
place = {United States},
year = {Sun Jan 15 00:00:00 EST 2006},
month = {Sun Jan 15 00:00:00 EST 2006}
}