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Title: Nuclear Structure Properties of Astrophysical Importance for 19Ne above the Proton Threshold Energy

Abstract

Knowledge of the 18F(p,a)15O and 18F(p,g)19Ne astrophysical reaction rates are important to understand -ray emission from nova explosions and heavy-element production in x-ray bursts. The rates for these reactions have been uncertain, in part due to a lack of a comprehensive examination of the available structure information in the compound nucleus 19Ne. We have examined the latest experimental measurements with radioactive and stable beams, collected all the structure information in the nucleus 19Ne and its mirror 19F, and made estimates of unmeasured 19Ne nuclear-level parameters. These parameters will be useful for future reaction rate calculations.

Authors:
 [1];  [1];  [1];  [1];  [2];  [3];  [1]
  1. ORNL
  2. China Institute of Atomic Energy
  3. Tennessee Technological University
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Holifield Radioactive Ion Beam Facility
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
931877
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review C; Journal Volume: 75; Journal Issue: 5
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 73 NUCLEAR PHYSICS AND RADIATION PHYSICS; EXPLOSIONS; MIRRORS; NUCLEAR STRUCTURE; PRODUCTION; PROTONS; REACTION KINETICS; THRESHOLD ENERGY; NEON 19

Citation Formats

Nesaraja, Caroline D, Shu, Nengchuan, Bardayan, Daniel W, Blackmon, Jeff C, Chen, Y. S., Kozub, R. L., and Smith, Michael Scott. Nuclear Structure Properties of Astrophysical Importance for 19Ne above the Proton Threshold Energy. United States: N. p., 2007. Web. doi:10.1103/PhysRevC.75.055809.
Nesaraja, Caroline D, Shu, Nengchuan, Bardayan, Daniel W, Blackmon, Jeff C, Chen, Y. S., Kozub, R. L., & Smith, Michael Scott. Nuclear Structure Properties of Astrophysical Importance for 19Ne above the Proton Threshold Energy. United States. doi:10.1103/PhysRevC.75.055809.
Nesaraja, Caroline D, Shu, Nengchuan, Bardayan, Daniel W, Blackmon, Jeff C, Chen, Y. S., Kozub, R. L., and Smith, Michael Scott. Mon . "Nuclear Structure Properties of Astrophysical Importance for 19Ne above the Proton Threshold Energy". United States. doi:10.1103/PhysRevC.75.055809.
@article{osti_931877,
title = {Nuclear Structure Properties of Astrophysical Importance for 19Ne above the Proton Threshold Energy},
author = {Nesaraja, Caroline D and Shu, Nengchuan and Bardayan, Daniel W and Blackmon, Jeff C and Chen, Y. S. and Kozub, R. L. and Smith, Michael Scott},
abstractNote = {Knowledge of the 18F(p,a)15O and 18F(p,g)19Ne astrophysical reaction rates are important to understand -ray emission from nova explosions and heavy-element production in x-ray bursts. The rates for these reactions have been uncertain, in part due to a lack of a comprehensive examination of the available structure information in the compound nucleus 19Ne. We have examined the latest experimental measurements with radioactive and stable beams, collected all the structure information in the nucleus 19Ne and its mirror 19F, and made estimates of unmeasured 19Ne nuclear-level parameters. These parameters will be useful for future reaction rate calculations.},
doi = {10.1103/PhysRevC.75.055809},
journal = {Physical Review C},
number = 5,
volume = 75,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • Knowledge of the {sup 18}F(p,{alpha}){sup 15}O and {sup 18}F(p,{gamma}){sup 19}Ne astrophysical reaction rates are important to understand {gamma}-ray emission from nova explosions and heavy-element production in x-ray bursts. The rates for these reactions have been uncertain, in part due to a lack of a comprehensive examination of the available structure information in the compound nucleus {sup 19}Ne. We have examined the latest experimental measurements with radioactive and stable beams, collected all the structure information in the nucleus {sup 19}Ne and its mirror {sup 19}F, and made estimates of unmeasured {sup 19}Ne nuclear-level parameters. These parameters will be useful for futuremore » reaction rate calculations.« less
  • The {sup 15}O({alpha},{gamma}){sup 19}Ne reaction plays a role in the ignition of type I x-ray bursts on accreting neutron stars. The lifetimes of states in {sup 19}Ne above the {sup 15}O+{alpha} threshold of 3.53 MeV are important inputs to calculations of the astrophysical reaction rate. These levels in {sup 19}Ne were populated in the {sup 3}He({sup 20}Ne,{alpha}){sup 19}Ne reaction at a {sup 20}Ne beam energy of 34 MeV. The lifetimes of six states above the threshold were measured with the Doppler-shift attenuation method. The present measurements agree with previous determinations of the lifetimes of these states and in some casesmore » are considerably more precise.« less
  • Breakout from the extended HotCNO cycle may occur through the reaction sequence {sup 18}F(p,{gamma}){sup 19}Ne(p,{gamma}){sup 20}Na. At astrophysically interesting temperatures and densities the extent of breakout is determined by competition between {sup 18}F(p,{gamma}){sup 19}Ne and {sup 18}F(p,{alpha}){sup 15}O through resonances in the compound nucleus, {sup 19}Ne. The current knowledge of the partial gamma widths of the important resonances in these reactions comes from their mirror states in {sup 19}F. Though the mirror identifications for most of these resonances have been studied through the {sup 16}O({sup 6}Li,{sup 3}He){sup 19}F and {sup 16}O({sup 6}Li,t){sup 19}Ne reactions, they are not well known. Tomore » further investigate these mirror identifications the authors populated the relevant states by the direct reactions {sup 20}Ne(d,{sup 3}He){sup 19}F and {sup 20}Ne(d,t){sup 19}Ne at a beam energy of 30 MeV. Cross sections were measured between 12.5{degrees} and 40{degrees} in the lab, and a high resolution measurement was made at 20{degrees}. Resulting mirror identifications and astrophysical implications will be discussed.« less
  • A 180DE double-focusing magnetic spectrometer was used to investigate the nuclear energy levels of F/sup 19/, F/sup 21/, Ne/sup 22/ >s, and Ne/sup 24/ by analysis of protons and alpha particles produced by (t,p) and (t, alpha ) reactions with natural neon and with Ne/sup 22/ gas targets. Between excitation energies of 2.8 and 6.5 Mev, new levels in Fla were found at 5.102, 5.539, 5.628, 5.937, and 6.l69 Mev. Previously reported levels at 3.29, 4.48, and 4.95 Mev were not observed. Up to an excitation energy of 4.3 Mev in F/sup 21/, new levels were seen at 3.451, 3.509,more » 3.635, at 0.285, 1.104, 1.743, and 2.047 Mev were confirmed. The mass M of F/sup 21/ was determined to be 21.006624 plus or minus 0.000011 amu (O/sup 16/ standard); (M-A) = 6.168 plus or minus 0.010 Mev. In Ne/sup 22/ 38 excited states were observed up te an excitation of 9.4 Mev. Levels at 1.277, 3.343, and 4.473 Mev were confirmed, while a reported level at 4.9 Mev was not observed. Energy levels in Ne/sup 24/, up to an excitation energy of 6.4 Mev, were found at Mev. The mass of Ne/sup 24/ was determined to be 24.001238 plus or minus Standard deviations in the values for the excitation energies vary from 0.015 to 0.025 Mev. Some representative cross sections are reported. (auth)« less