Engineering topics

Vassh, Nicole

Publications and source records attributed to Vassh, Nicole.

3 records

DOE OSTI2024

Thallium-208: A Beacon of In Situ Neutron Capture Nucleosynthesis

Here, we demonstrate that the well-known 2.6 MeV gamma-ray emission line from thallium-208 could serve as a real-time indicator of astrophysical heavy element production, with both rapid (r) and intermediate (i) neutron capture processes capable of its synthesis. We consider the r process in a Galactic neutron star merger and show Tl-208 to be detectable from ~12 hours to ~ten days, and again ~1–20 years postevent. Detection of Tl-208 represents the only identified prospect for a direct signal of lead production (implying gold synthesis), arguing for the importance of future MeV telescope missions which aim to detect Galactic events but may also be able to reach some nearby galaxies in the Local Group.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2023

5-10 Years Cross-cutting Priorities on the Topic of Nuclear Data Covariances and Uncertainty Quantification for Users

The goal of this meeting was to draft a whitepaper on prioritized nuclear data covariance and uncertainty quantification needs impacting users for the next 5 to 10 years. These needs are described herein in an actionable context (i.e., a high-level plan is given to address them), and are feasible for the community to tackle the need (i.e., high-level idea of funding is provided). It should be noted that each of these proposed projects are ideal for training new nuclear data evaluators who are also integrated into application needs.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2022

Solar data uncertainty impacts on MCMC methods for r-process nucleosynthesis

In recent work, we developed a Markov Chain Monte Carlo (MCMC) procedure to predict the ground state masses capable of forming the observed Solar r-process rare-earth abundance peak. By applying this method to nucleosynthesis calculations which make use of distinct astrophysical conditions and comparing our results to the latest precision mass measurements, we are able to shed light on the conditions/masses capable of producing a rare-earth peak which matches Solar data. Here we examine how our mass predictions change when using a few different sets of r-process Solar abundance residuals that have been reported in the literature. We explore how the differing error estimates of these Solar evaluations propagate through the Markov Chain Monte Carlo to our mass predictions. We find that Solar data which reports the rare-earth peak to have its highest abundance at mass number A = 162 can require distinctly different mass predictions from data with the peak centered at A = 164. Nevertheless, we find that two important general conclusions from past work, regarding the inconsistency of ‘cold’ astrophysical outflows with current mass measurements and the need for local stability at N = 104 in ‘hot’ scenarios, remain robust in the face of differing Solar data evaluations. Additionally, we show that the masses our procedure finds capable of producing a peak at A < 164 are not in line with the latest precision mass measurements.

79 ASTRONOMY AND ASTROPHYSICS↗