Investigating the Site of the Weak Rapid Neutron Capture Process

Project Overview

The origin of the chemical elements heavier than iron and nickel in the galaxy is still an open question in nuclear astrophysics. One nucleosynthesis mechanism, the series of nuclear reactions which makes the elements, that is known to contribute is called the ‘weak rapid neutron capture process' (or ‘weak r-process') which occurs in core-collapse supernova. In the weak r-process successively heavier elements are made through a series of (α,n) reactions, where the nucleus of an atom captures an alpha particle (or He-4 nucleus) before emitting a neutron, thereby increasing the proton number by 2 and the neutron number by 1. Theoretical predictions for weak r-process nucleosynthesis are hindered by poor knowledge of (α,n) nuclear reaction rates on unstable nuclei and imprecise constraints on the astrophysical conditions due to lack of astronomical data. This project aims to test the weak r-process hypothesis through an improvement of the required nuclear data, measurement of meteoritic samples as a source of observational data, and the comparison between the calculated yields and the meteoritic samples. This is the first comprehensive study of the weak r-process which integrates nuclear physics, cosmochemistry, and computational astrophysics.

Mission Impact

This research increases the portfolio of cosmochemical research as well as that of the Space Science Institute at Lawrence Livermore National Laboratory. The nuclear physics techniques tested in the project will have applications in measuring similar nuclear physics reaction cross-sections that are of interest to NNSA's stockpile stewardship mission. This highly interdisciplinary project is a potential seed for a larger nuclear astrophysics program at Livermore and brings together the expertise in the Nuclear and Particle Physics, Nuclear Data, and Chemical and Isotopic Signatures groups.

Publications, Presentations, and Patents

Ong, Wei Jia. 2018. "Nuclear Reactions in Neutron Stars." Invited talk, American Physical Society Division of Nuclear Physics Meeting, October 23 2018. IM #1040291.

Ong, Wei Jia. 2019. "Nuclear Astrophysics with MUSIC (Multi-Sampling Ionization Chamber)." Contributed talk, Low Energy Community Meeting, August 8 2019. IM #976147.

Ong, Wei Jia. 2020. "Presolar Grains and Supernova Nucleosynthesis." Invited seminar, The Ohio State University Nuclear Physics, January 22 2020. IM #1005911.

Ong, Wei Jia. 2020. "Investigating Explosive Nucleosynthesis with Stellar Debris." Invited seminar, Argonne National Laboratory Physics Division, February 3 2020. IM #1040293.

Ong, Wei Jia. 2020. "Production and Impact of Urca Nuclides in X-ray Bursting Systems." Invited talk, American Physical Society Division of Nuclear Physics Meeting, October 30 2020. IM #1025537.

Ong, Wei Jia. 2020. "Accreting Neutron Stars and Nuclear Physics Challenges." Invited plenary talk, JINA Horizons Meeting, Dec 1 2020. IM #1040636.

Ong, Wei Jia. 2021. "Galactic Forensics: Utilizing Stella Debris to Investigate Explosive Nucleosynthesis." Invited seminar, Oak Ridge National Laboratory Physics Division, February 25 2021. IM #1031155.

Ong, Wei Jia. 2021. "The Search for Weak r-process Signatures in Stardust." Invited talk, Workshop on (a,n) reactions for Astrophysics, July 15 2021. IM #1038051.

Ong, Wei Jia. 2021. "Clues to the Origin of the p-nuclei." Invited plenary talk, Low Energy Community Meeting, August 11 2021. IM #1039939.

Ong, Wei Jia, Brown, Ed, Browne, Justin, Ahn, Sunghyoon, Childers, Katie, Crider, Ben, Dombos, Alexander et al. 2020. "Beta decay of 61V and its Role in Cooling Accreted Neutron Star Crusts," Physical Review Letters 125, 262701. https://doi.org/10.1103/PhysRevLett.125.262701. IM #985839.

Wolf, Clemens, Langer, Christoph, Montes, Fernando, Pereira, Jorge, Ong, Wei Jia, Poxon-Pearson, Teri, Ahn Sunghyoon et al. 2019. "Constraining the Neutron Star Compactness: Extraction of the 23Al(p,gamma) Reaction Rate for the rp process," Physical Review Letters 122, 232701. https://doi.org/10.1103/PhysRevLett.122.232701. IM# 1040575.

Ong, Wei Jia, Valverde, Adrian, Brodeur, Maxime, Bollen, Georg, Eibach, Martin, Gulyuz, Kerim, Hamaker, Alex et al. 2018. "Mass measurement of 51Fe for the determination of the 51Fe(p,gamma)52Co reaction rate," Physical Review C 8, 065803. https://doi.org/10.1103/PhysRevC.98.065803. IM# 1040576.