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Title: Astrophysically Important 31S States Studied with the 32S(p,d) 31S Reaction

Abstract

In nova outbursts on ONe White Dwarfs, the 30P(p,g)31S reaction plays a crucial role in the synthesis of heavier nuclear species, from Si to Ca. However, this important rate is very uncertain as a result of the lack of spectroscopic information on most of the levels above proton threshold in 31S. To reduce these uncertainties, we have measured differential cross sections for the 32S(p,d)31S reaction and determined excitation energies for states in 31S. A total of 26 states in 31S were observed, including 17 above the proton threshold. Five new states were observed. Spins and parities were determined or constrained for 15 of the observed levels through a distorted wave Born approximation (DWBA) analysis of the angular distributions, of which 6 were made for the first time. We have evaluated 44 levels using existing data in combination with this measurement to calculate a new 30P(p,g)31S reaction rate. We confirmed the spin-parity assignment of 1/2+ for the state at 6263 keV which dominates the 30P(p,g)31S reaction rate at lower temperatures in novae, while the state at 6544 keV dominates at temperatures above 0.2 GK. Our results indicate that the 30P(p,g)31S rate is reduced by up to a factor of 10 atmore » nova temperatures compared to previous estimates.« less

Authors:
 [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1]
  1. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Holifield Radioactive Ion Beam Facility
Sponsoring Org.:
USDOE Laboratory Directed Research and Development (LDRD) Program; USDOE Office of Science (SC)
OSTI Identifier:
931776
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review C; Journal Volume: 76; Journal Issue: 1
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ANGULAR DISTRIBUTION; DIFFERENTIAL CROSS SECTIONS; REACTION KINETICS; SULFUR ISOTOPES; ASTROPHYSICS; NOVAE

Citation Formats

Ma, Zhanwen, Bardayan, Daniel W, Blackmon, Jeff C, Fitzgerald, Ryan, Guidry, Mike W, Grzywacz-Jones, Kate L, Hix, William Raphael, KOZUB, RAYMOND L, Livesay, Jake, Smith, Michael Scott, Thomas, Jeffrey S, and Visser, Dale William. Astrophysically Important 31S States Studied with the 32S(p,d)31S Reaction. United States: N. p., 2007. Web. doi:10.1103/PhysRevC.76.015803.
Ma, Zhanwen, Bardayan, Daniel W, Blackmon, Jeff C, Fitzgerald, Ryan, Guidry, Mike W, Grzywacz-Jones, Kate L, Hix, William Raphael, KOZUB, RAYMOND L, Livesay, Jake, Smith, Michael Scott, Thomas, Jeffrey S, & Visser, Dale William. Astrophysically Important 31S States Studied with the 32S(p,d)31S Reaction. United States. doi:10.1103/PhysRevC.76.015803.
Ma, Zhanwen, Bardayan, Daniel W, Blackmon, Jeff C, Fitzgerald, Ryan, Guidry, Mike W, Grzywacz-Jones, Kate L, Hix, William Raphael, KOZUB, RAYMOND L, Livesay, Jake, Smith, Michael Scott, Thomas, Jeffrey S, and Visser, Dale William. Mon . "Astrophysically Important 31S States Studied with the 32S(p,d)31S Reaction". United States. doi:10.1103/PhysRevC.76.015803.
@article{osti_931776,
title = {Astrophysically Important 31S States Studied with the 32S(p,d)31S Reaction},
author = {Ma, Zhanwen and Bardayan, Daniel W and Blackmon, Jeff C and Fitzgerald, Ryan and Guidry, Mike W and Grzywacz-Jones, Kate L and Hix, William Raphael and KOZUB, RAYMOND L and Livesay, Jake and Smith, Michael Scott and Thomas, Jeffrey S and Visser, Dale William},
abstractNote = {In nova outbursts on ONe White Dwarfs, the 30P(p,g)31S reaction plays a crucial role in the synthesis of heavier nuclear species, from Si to Ca. However, this important rate is very uncertain as a result of the lack of spectroscopic information on most of the levels above proton threshold in 31S. To reduce these uncertainties, we have measured differential cross sections for the 32S(p,d)31S reaction and determined excitation energies for states in 31S. A total of 26 states in 31S were observed, including 17 above the proton threshold. Five new states were observed. Spins and parities were determined or constrained for 15 of the observed levels through a distorted wave Born approximation (DWBA) analysis of the angular distributions, of which 6 were made for the first time. We have evaluated 44 levels using existing data in combination with this measurement to calculate a new 30P(p,g)31S reaction rate. We confirmed the spin-parity assignment of 1/2+ for the state at 6263 keV which dominates the 30P(p,g)31S reaction rate at lower temperatures in novae, while the state at 6544 keV dominates at temperatures above 0.2 GK. Our results indicate that the 30P(p,g)31S rate is reduced by up to a factor of 10 at nova temperatures compared to previous estimates.},
doi = {10.1103/PhysRevC.76.015803},
journal = {Physical Review C},
number = 1,
volume = 76,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}