Bulletin of the American Physical Society
Fall 2022 Meeting of the APS Division of Nuclear Physics
Volume 67, Number 17
Thursday–Sunday, October 27–30, 2022; Time Zone: Central Daylight Time, USA; New Orleans, Louisiana
Session JK: Mini-Symposium: Nuclear Pademonium: How Total Absorption Spectrometry Informs Outstanding Issues in Nuclear Physics I |
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Chair: Artemis Spyrou, Michigan State University Room: Hyatt Regency Hotel Imperial 5AB |
Saturday, October 29, 2022 8:30AM - 9:06AM |
JK.00001: The Physics Impacts of Total Absorption Spectroscopy Invited Speaker: Bertis C Rasco Total Absorption Spectroscopy (TAS) is a unique nuclear physics technique. But what is it? The total absorption in TAS refers to near 100% detector efficiency, with an emphasis on near 100% γ-ray detection. This very high γ-ray efficiency also leads to the detection of other particles emitted in β decay, such as βs and neutrons. TAS detector designs over the last 50 years have evolved from 2 face to face 5"x5" NaI detectors to modern TAS detectors that have from several hundred kilograms up to one ton of NaI. There are several groups in the USA and Europe that operate modern TAS detectors. |
Saturday, October 29, 2022 9:06AM - 9:18AM |
JK.00002: Incorporating TAGS data in the ENDF/B decay data sub-library Alejandro A Sonzogni, Andrea Mattera, Elizabeth McCutchan TAGS data from experiments performed by physicists from INL, Valencia, Nantes, Jyvaskyla and MSU have been steadily incorporated in the ENDF/B decay data sub-library, resulting in a far better description of decay heat as well as reactor antineutrino spectra and yields. A careful study of the recent Daya Bay measurement of the antineutrino spectrum for energies in the 8-11 MeV range will be presented, since this measurement provides a unique opportunity to pinpoint the handful of fission products that can contribute at such high energies, which could be the goal of future TAGS experiments. |
Saturday, October 29, 2022 9:18AM - 9:30AM |
JK.00003: The journey of Modular Total Absorption Spectrometer from ORNL via ANL to FRIB. Thomas T King The ORNL’s Modular Total Absorption Spectrometer (MTAS) was born in 2009 following the American Recovery and Reinvestment Act funding, with the goals to improve our knowledge on the decay heat and anti-neutrino emission from nuclear reactors while also informing the nuclear structure of fission products. MTAS is the largest and most efficient total absorption spectrometer in the world with about 1 ton of active NaI(Tl). MTAS has a unique 19-module hexagonal construction, now upgraded to 24 segments. MTAS is shielded with 6 tons of lead against background gamma radiation as a mix of lead plates and SWX foam. |
Saturday, October 29, 2022 9:30AM - 9:42AM |
JK.00004: Total Absorption Spectroscopy of Ground and Isomeric States in 70Cu Eleanor Ronning, Andrea L Richard, Sean Liddick, Artemis Spyrou, Ryan Ringle, Isaac T Yandow, Aaron Chester, Katherine L Childers, Paul A Deyoung, Jordan Owens-Fryar, Alec S Hamaker, Caley Harris, Rebecca Lewis, Kasey R Lund, Stephanie M Lyons, Alicia R Palmisano, Daniel Puentes, Rachel Sandler, Chandana Sumithrarachchi, Mathis Wiedeking, Yongchi Xiao One of the underlying assumptions in astrophysical reaction rate calculations is the generalized Brink-Axel (gBA) hypothesis, which states that the γ-ray strength function (γSF) is independent of the initial excitation energy and spin of nuclear states in the compound nucleus. While the initial excitation energy independence of the gBA has been previously studied, the spin-independence remains untested. Here, we test the spin-independence of the gBA by investigating the β-decay of 70Cu, which offers a unique opportunity to study the γSF over different spin ranges at similar excitation energies in the daughter nucleus. 70Cu has three β-decaying spin-parity states (6− ground state, and two isomeric states: 3−, and 1+). In an experiment performed at the National Superconducting Cyclotron Laboratory 70Cu was produced, isolated by the Low-Energy Beam and Ion Trap (LEBIT), and then delivered to the Summing NaI (SuN) Total Absorption Spectrometer. Preliminary results from total absorption spectroscopy following the β-decay of each of the three β-decaying spin-parity states will be presented. The data will be used in future β-Oslo analysis to obtain γSF and nuclear level densities and test the spin-independence of the gBA hypothesis. |
Saturday, October 29, 2022 9:42AM - 9:54AM |
JK.00005: Measurements of 92Mo(p,γ)93Tc and 94Mo(p,γ)95Tc cross sections Rebeka Kelmar, Anna Simon, Jane O'Reilly, Alexander C Dombos, August Gula, Jes Koros, Khachatur Manukyan, Miriam Matney, John P McDonaugh, Orlando Gomez, Daniel Robertson, Edward Stech When modeling the γ-process a consistent underproduction of the lighter p-nuclei molybdenum and ruthenium has been observed. Past measurements of the 92Mo(p,γ)93Tc cross section showed the possibility of irregularities within the Gamow window, which deviate from the smooth cross sections predicted by Hauser-Feschbach based models. Since deviations from a smooth energy dependence of the cross section within the Gamow window could have a strong effect on the reaction rates, a detailed scan of the cross section for both the 92Mo(p,γ)93Tc and the 94Mo(p,γ)95Tc reactions was performed at the University of Notre Dame’s Nuclear Science Laboratory using the High EfficienCy TOtal absorption spectrometeR (HECTOR) and the 5U 5 MV single-ended accelerator over the energy range Ep = 1.4–4.4 MeV. The data was analyzed using the γ-summing technique. For the energy range where the sum-peak overlaps with possible contaminants, we developed a new method to separate those from true energy-sum events originating from the Mo targets. Here, this new method, preliminary cross section results, and network calculations performed using the new reactions rates will also be shown. |
Saturday, October 29, 2022 9:54AM - 10:06AM |
JK.00006: Using TAS Analysis to Contrain I(?) values for 51Fe and 60Ga Gerard J Owens-Fryar, Stephanie M Lyons, Andrea L Richard, Zachary P Meisel, Artemis Spyrou, Hannah C. C Berg, Kristyn H Brandenburg, Aaron Chester, Katie Childers, Paul A Deyoung, Erin C Good, Caley Harris, Alicia Palmisano, Mansi Saxena, Shiv K Subedi, Artemis Tsantiri Accreting neutron stars provide insight into the behavior of ultra dense, cold matter where quantum effects are present. Hydrogen and helium build up on the surface, until the rise in temperature and density reach thermonuclear runaway, which can result in a Type I X-ray burst (XRB). The nuclear burning that occurs is called the rapid proton capture (rp-) process. Abundance outputs of astrophysical models of XRBs depend on many nuclear reaction rates. 59Cu(p,γ) is an important reaction to ascertain if the rp-process stays in the Ni-Cu cycle or if the process moves to a higher atomic mass. The reaction rate has a strong effect on the light curves of XRBs; therefore, it needs to be constrained to improve comparisons between models and observations. These reaction rates cannot be measured directly, they are determined using experimental inputs for Hauser-Feshbach calculations. These inputs will be constrained using the β-Oslo technique; a method that has proven useful on neutron rich nuclei. To benchmark this method for ?+ decays, total absorption spectroscopy was used to study the β+ decay of 51Fe and 60Ga. TAS measurements were used to extract I(?) values for both nuclei. In this presentation, the first results of the TAS analysis will be discussed. |
Saturday, October 29, 2022 10:06AM - 10:18AM |
JK.00007: Beta-decay of 33Mg using Total Absorption Spectroscopy Rahul Jain, Hendrik Schatz, Wei Jia Ong, Kirby Hermansen, Nabin Rijal, Hannah C Berg, Paul A Deyoung, Eric Flynn, Caley M Harris, Sean Liddick, Stephanie M Lyons, Sara Miskovich, Fernando Montes, Timilehin H Ogunbeku, Alicia Palmisano, Andrea L Richard, Mackenzie Smith, Mallory K Smith, Artemis Spyrou Low mass X-ray binaries that transiently accrete matter onto their neutron stars are excellent laboratories for studying dense matter physics. These systems alternate between outburst and quiescence phases and monitoring the surface temperatures of neutron stars in quiescence reveals a great deal of information about their structure and composition. But infering these properties requires a complete understanding of different nuclear reactions that heat or cool the crust. Urca cooling is a source of neutrino cooling in the crust that strongly depends on the ground-state to ground-state beta decay transition strengths. The 33Mg - 33Al transition is predicted to be the strongest Urca cooling agent for crusts composed of X-ray burst ashes. This relies partly on the strong ground state branch measured in high-resolution beta-delayed gamma-spectroscopy of 33Mg. However, recent measurements of a negative parity ground state in 33Mg makes this a first forbidden decay and the strong transition strength is questioned in the literature, citing Pandemonium effect as a possible reason. We try to resolve this anomaly using Total Absorption Spectroscopy that is mostly free of this Pandemonium effect. I will present preliminary results from the beta-decay of 33Mg experiment performed at NSCL. |
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