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Title: β-delayed γ decay of 20Mg and the Ne 19 ( p , γ ) 20 Na breakout reaction in Type I X-ray bursts

Abstract

Certain astrophysical environments such as thermonuclear outbursts on accreting neutron stars (Type-I X-ray bursts) are hot enough to allow for breakout from the Hot CNO hydrogen burning cycles to the rapid proton capture (rp) process. An important breakout reaction sequence is 15O(α,γ) 19Ne(p,γ) 20Na and the 19Ne(p,γ) 20Na reaction rate is expected to be dominated by a single resonance at 457 keV above the proton threshold in 20Na. The resonance strength and, hence, reaction rate depends strongly on whether this 20Na state at an excitation energy of 2647 keV has spin and parity of 1 + or 3 +. Previous 20Mg (J π = 0 ++ decay experiments have relied almost entirely on searches for β-delayed proton emission from this resonance in 20Na to limit the log ft value and, hence, J π. However there is a non-negligible γ-ray branch expected that must also be limited experimentally to determine the log ft value and constrain . We have measured the β-delayed γ decay of 20Mg to complement previous β-delayed proton decay work and provide the first complete limit based on all energetically allowed decay channels through the 2647 keV state. Our limit confirms that a 1 + assignment formore » this state is highly unlikely.« less

Authors:
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Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1437815
Alternate Identifier(s):
OSTI ID: 1495977
Grant/Contract Number:  
SC0016052; AC05-00OR22725; NA0003221; NA0000979
Resource Type:
Journal Article: Published Article
Journal Name:
Physics Letters B
Additional Journal Information:
Journal Name: Physics Letters B Journal Volume: 778 Journal Issue: C; Journal ID: ISSN 0370-2693
Publisher:
Elsevier
Country of Publication:
Netherlands
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS

Citation Formats

Glassman, B. E., Pérez-Loureiro, D., Wrede, C., Allen, J., Bardayan, D. W., Bennett, M. B., Brown, B. A., Chipps, K. A., Febbraro, M., Friedman, M., Fry, C., Hall, M. R., Hall, O., Liddick, S. N., O'Malley, P., Ong, W. J., Pain, S. D., Prokop, C., Schwartz, S. B., Shidling, P., Sims, H., Thompson, P., and Zhang, H. β-delayed γ decay of 20Mg and the Ne 19 ( p , γ ) 20 Na breakout reaction in Type I X-ray bursts. Netherlands: N. p., 2018. Web. doi:10.1016/j.physletb.2018.01.041.
Glassman, B. E., Pérez-Loureiro, D., Wrede, C., Allen, J., Bardayan, D. W., Bennett, M. B., Brown, B. A., Chipps, K. A., Febbraro, M., Friedman, M., Fry, C., Hall, M. R., Hall, O., Liddick, S. N., O'Malley, P., Ong, W. J., Pain, S. D., Prokop, C., Schwartz, S. B., Shidling, P., Sims, H., Thompson, P., & Zhang, H. β-delayed γ decay of 20Mg and the Ne 19 ( p , γ ) 20 Na breakout reaction in Type I X-ray bursts. Netherlands. https://doi.org/10.1016/j.physletb.2018.01.041
Glassman, B. E., Pérez-Loureiro, D., Wrede, C., Allen, J., Bardayan, D. W., Bennett, M. B., Brown, B. A., Chipps, K. A., Febbraro, M., Friedman, M., Fry, C., Hall, M. R., Hall, O., Liddick, S. N., O'Malley, P., Ong, W. J., Pain, S. D., Prokop, C., Schwartz, S. B., Shidling, P., Sims, H., Thompson, P., and Zhang, H. Thu . "β-delayed γ decay of 20Mg and the Ne 19 ( p , γ ) 20 Na breakout reaction in Type I X-ray bursts". Netherlands. https://doi.org/10.1016/j.physletb.2018.01.041.
@article{osti_1437815,
title = {β-delayed γ decay of 20Mg and the Ne 19 ( p , γ ) 20 Na breakout reaction in Type I X-ray bursts},
author = {Glassman, B. E. and Pérez-Loureiro, D. and Wrede, C. and Allen, J. and Bardayan, D. W. and Bennett, M. B. and Brown, B. A. and Chipps, K. A. and Febbraro, M. and Friedman, M. and Fry, C. and Hall, M. R. and Hall, O. and Liddick, S. N. and O'Malley, P. and Ong, W. J. and Pain, S. D. and Prokop, C. and Schwartz, S. B. and Shidling, P. and Sims, H. and Thompson, P. and Zhang, H.},
abstractNote = {Certain astrophysical environments such as thermonuclear outbursts on accreting neutron stars (Type-I X-ray bursts) are hot enough to allow for breakout from the Hot CNO hydrogen burning cycles to the rapid proton capture (rp) process. An important breakout reaction sequence is 15O(α,γ)19Ne(p,γ)20Na and the 19Ne(p,γ)20Na reaction rate is expected to be dominated by a single resonance at 457 keV above the proton threshold in 20Na. The resonance strength and, hence, reaction rate depends strongly on whether this 20Na state at an excitation energy of 2647 keV has spin and parity of 1+ or 3+. Previous 20Mg (Jπ = 0+)β+ decay experiments have relied almost entirely on searches for β-delayed proton emission from this resonance in 20Na to limit the log ft value and, hence, Jπ. However there is a non-negligible γ-ray branch expected that must also be limited experimentally to determine the log ft value and constrain . We have measured the β-delayed γ decay of 20Mg to complement previous β-delayed proton decay work and provide the first complete limit based on all energetically allowed decay channels through the 2647 keV state. Our limit confirms that a 1+ assignment for this state is highly unlikely.},
doi = {10.1016/j.physletb.2018.01.041},
url = {https://www.osti.gov/biblio/1437815}, journal = {Physics Letters B},
issn = {0370-2693},
number = C,
volume = 778,
place = {Netherlands},
year = {2018},
month = {3}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at https://doi.org/10.1016/j.physletb.2018.01.041

Citation Metrics:
Cited by: 3 works
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Figures / Tables:

Figure 1 Figure 1: Relevant low-lying states in 19Ne and 20Na labeled with J π and energy in keV. Energies below the proton threshold in 20Na as well as J π are adopted from Seweryniak et al. [21] and energies above the proton threshold are from Wallace et al. [22].

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