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Title: Neutron-capture rates for explosive nucleosynthesis: the case of 68Ni(n, γ) 69Ni

Abstract

Neutron-capture reactions play an important role in heavy element nucleosynthesis, since they are the driving force for the two processes that create the vast majority of the heavy elements. When a neutron capture occurs on a short-lived nucleus, it is extremely challenging to study the reaction directly and therefore the use of indirect techniques is essential. The present work reports on such an indirect measurement that provides strong constraints on the 68Ni(n,g) 69Ni reaction rate.The commonly used reaction libraries JINA-REACLIB and BRUSLIB are in relatively good agreement with the experimental rate. The impact of the new rate on weak r-process calculations is discussed.

Authors:
 [1];  [2];  [3];  [4];  [5];  [1];  [2];  [6];  [7];  [2];  [8];  [7];  [7];  [9];  [8];  [1];  [2];  [2];  [10]
  1. Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab.; Michigan State Univ., East Lansing, MI (United States). Dept. of Physics and Astronomy; Michigan State Univ., East Lansing, MI (United States). Joint Inst. for Nuclear Astrophysics
  2. Univ. of Oslo (Norway). Dept. of Physics
  3. Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab.; Michigan State Univ., East Lansing, MI (United States). Joint Inst. for Nuclear Astrophysics; Michigan State Univ., East Lansing, MI (United States). Dept. of Chemistry
  4. Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab.; Michigan State Univ., East Lansing, MI (United States). Joint Inst. for Nuclear Astrophysics
  5. Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab.
  6. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  7. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  8. Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab.; Michigan State Univ., East Lansing, MI (United States). Dept. of Chemistry
  9. Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab.; Michigan State Univ., East Lansing, MI (United States). Joint Inst. for Nuclear Astrophysics; Central Michigan Univ., Mount Pleasant, MI (United States). Dept. of Physics
  10. Univ. of Notre Dame, IN (United States). Dept. of Physics
Publication Date:
Research Org.:
Michigan State Univ., East Lansing, MI (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1360889
Alternate Identifier(s):
OSTI ID: 1378525
Report Number(s):
LLNL-JRNL-705342
Journal ID: ISSN 0954-3899
Grant/Contract Number:
NA0003221; NA0000979; NA0002132; AC52-07NA27344; AC52-06NA25396; PHY 1102511; PHY 1430152; PHY 1350234
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Physics. G, Nuclear and Particle Physics
Additional Journal Information:
Journal Volume: 44; Journal Issue: 4; Journal ID: ISSN 0954-3899
Publisher:
IOP Publishing
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS

Citation Formats

Spyrou, Artemis, Larsen, Ann-Cecilie, Liddick, Sean N., Naqvi, Farheen, Crider, Benjamin, Dombos, Alexander C., Guttormsen, Magne, Bleuel, Darren, Couture, Aaron, Campo, Lucia Crespo, Lewis, Rebecca, Mosby, Shea, Mumpower, Matthew, Perdikakis, George, Prokop, Christopher J., Quinn, Stephen J., Renstrom, Theresa, Siem, Sunniva, and Surman, Rebecca. Neutron-capture rates for explosive nucleosynthesis: the case of 68Ni(n, γ)69Ni. United States: N. p., 2017. Web. doi:10.1088/1361-6471/aa5ae7.
Spyrou, Artemis, Larsen, Ann-Cecilie, Liddick, Sean N., Naqvi, Farheen, Crider, Benjamin, Dombos, Alexander C., Guttormsen, Magne, Bleuel, Darren, Couture, Aaron, Campo, Lucia Crespo, Lewis, Rebecca, Mosby, Shea, Mumpower, Matthew, Perdikakis, George, Prokop, Christopher J., Quinn, Stephen J., Renstrom, Theresa, Siem, Sunniva, & Surman, Rebecca. Neutron-capture rates for explosive nucleosynthesis: the case of 68Ni(n, γ)69Ni. United States. doi:10.1088/1361-6471/aa5ae7.
Spyrou, Artemis, Larsen, Ann-Cecilie, Liddick, Sean N., Naqvi, Farheen, Crider, Benjamin, Dombos, Alexander C., Guttormsen, Magne, Bleuel, Darren, Couture, Aaron, Campo, Lucia Crespo, Lewis, Rebecca, Mosby, Shea, Mumpower, Matthew, Perdikakis, George, Prokop, Christopher J., Quinn, Stephen J., Renstrom, Theresa, Siem, Sunniva, and Surman, Rebecca. Wed . "Neutron-capture rates for explosive nucleosynthesis: the case of 68Ni(n, γ)69Ni". United States. doi:10.1088/1361-6471/aa5ae7. https://www.osti.gov/servlets/purl/1360889.
@article{osti_1360889,
title = {Neutron-capture rates for explosive nucleosynthesis: the case of 68Ni(n, γ)69Ni},
author = {Spyrou, Artemis and Larsen, Ann-Cecilie and Liddick, Sean N. and Naqvi, Farheen and Crider, Benjamin and Dombos, Alexander C. and Guttormsen, Magne and Bleuel, Darren and Couture, Aaron and Campo, Lucia Crespo and Lewis, Rebecca and Mosby, Shea and Mumpower, Matthew and Perdikakis, George and Prokop, Christopher J. and Quinn, Stephen J. and Renstrom, Theresa and Siem, Sunniva and Surman, Rebecca},
abstractNote = {Neutron-capture reactions play an important role in heavy element nucleosynthesis, since they are the driving force for the two processes that create the vast majority of the heavy elements. When a neutron capture occurs on a short-lived nucleus, it is extremely challenging to study the reaction directly and therefore the use of indirect techniques is essential. The present work reports on such an indirect measurement that provides strong constraints on the 68Ni(n,g)69Ni reaction rate.The commonly used reaction libraries JINA-REACLIB and BRUSLIB are in relatively good agreement with the experimental rate. The impact of the new rate on weak r-process calculations is discussed.},
doi = {10.1088/1361-6471/aa5ae7},
journal = {Journal of Physics. G, Nuclear and Particle Physics},
number = 4,
volume = 44,
place = {United States},
year = {Wed Feb 22 00:00:00 EST 2017},
month = {Wed Feb 22 00:00:00 EST 2017}
}

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  • Neutron-capture reactions play an important role in heavy element nucleosynthesis, since they are the driving force for the two processes that create the vast majority of the heavy elements. When a neutron capture occurs on a short-lived nucleus, it is extremely challenging to study the reaction directly and therefore the use of indirect techniques is essential. The present work reports on such an indirect measurement that provides strong constraints on the 68Ni(n, γ) 69Ni reaction rate. This is done by populating the compound nucleus 69Ni via the β decay of 69Co and measuring the γ-ray deexcitation of excited states inmore » 69Ni. The β-Oslo method was used to extract the γ-ray strength function and the nuclear level density. In addition the half-life of 69Co was extracted and found to be in agreement with previous literature values. Before the present results, the 68Ni(n, γ) 69Ni reaction was unconstrained and the purely theoretical reaction rate was highly uncertain. The new uncertainty on the reaction rate based on the present experiment (variation between upper and lower limit) is approximately a factor of 3. The commonly used reaction libraries JINA-REACLIB and BRUSLIB are in relatively good agreement with the experimental rate. The impact of the new rate on weak r-process calculations is discussed.« less
  • We have measured the {sup 147}Sm(n,{alpha}) cross section from 3 eV to 500 keV. These data were used to test nuclear statistical models which must be relied on to calculate the rates for as yet unmeasurable reactions occurring in explosive nucleosynthesis scenarios. It was found that our data are in reasonably good agreement with the reaction rate predicted by an older model but that the rates predicted by two very recent models are roughly a factor of 3 different from the data (in opposite directions). A detailed analysis indicates the strong dependence on the employed optical {alpha} potentials. These results,more » together with counting rate estimates for future experiments indicate that (n,{alpha}) measurements will be useful for improving reaction rate predictions across the global range of masses needed for explosive nucleosynthesis calculations.« less
  • New neutron capture cross sections of {sup 58,60}Ni were measured in the energy range from 100 eV to 600 keV using the Oak Ridge Electron Linear Accelerator. The combination of these new neutron capture data with previous transmission data allowed a resonance analysis up to 900 keV using R-matrix theory. The theoretically determined direct capture cross sections were included in the analyses. From these resonance parameters and the direct capture contribution, new (n,{gamma}) astrophysical reaction rates were determined over the entire energy range needed by the latest stellar models describing the so-called weak s process.