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 LE: Nuclear Astrophysics VI |
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Chair: Ashton Morelock, Florida State University Room: Hyatt Regency Hotel Celestin C |
Saturday, October 29, 2022 2:00PM - 2:12PM |
LE.00001: Using transfer reaction $^{28}$Si($^6$Li,t)$^{31}$S(p)$^{30}$P to study resonances near proton-threshold in $^{31}$S Sudarsan Balakrishnan, Kevin T Macon, Jeffery C Blackmon, Catherine M Deibel, William D Braverman, Keilah S Davis, Erin C Good, David He, Sergio Lopez-Caceres, Khang H Pham, Zachary M Purcell, Rachel M Shaffer, Gordon W McCann, Kenneth G Hanselman, Lagy T Baby, Ingo L Wiedenhover, Samuel Ajayi, Benjamin W Asher, Caleb Bennetti, Alex C Conley, Juan C Esparza, Bryan Kelly, Ashton B Morelock, Jesus F Perello, Gary C Ragsdale, Eilens Lopez Saavedra, Eli Temanson, Catur Wibisono Properties of states near the proton threshold in $^{31}$S are important towards determining the $^{30}$P(p,$\gamma$) reaction rate, which is a key nucleosynthesis reaction occurring in ONe nova explosions. Variations in this reaction rate strongly influence the final abundances of several isotopes including $^{30}$Si, $^{31}$P, $^{32}$S, $^{35}$Cl and $^{36}$Ar. An improved constraint on this rate will have implications for the use of observed Si-Ca abundances in ONe novae to constrain their temperature, and help shed light on the degree of mixing between the accreted hydrogenic matter and the nova surface. At present, proton branching ratios are known for states up to 600 keV above the proton threshold – with information on states within the Gamow window still lacking. We used the transfer reaction $^{28}$Si($^6$Li,t) to study $^{31}$S states in this region using the FSU Super-Enge Split-Pole Spectrograph (SE-SPS). Decay protons from these states were detected in coincidence with the tritons reaction products using the Silicon Array For Branching Ratio Experiments (SABRE). Preliminary results and astrophysical implications of this study will be discussed. |
Saturday, October 29, 2022 2:12PM - 2:24PM |
LE.00002: New Tools for Explosive Nucleosynthesis Studies at the Notre Dame Nuclear Science Lab (NSL) Dan W Bardayan, Scott R Carmichael, Patrick O'Malley, Tan Ahn, Chevelle Boomershine, Sydney Coil, Manoel Couder, Daniel Robertson, Anna Simon, Edward Stech, Samuel Thomas, William von Seeger Explosive nucleosynthesis occurs in a number of astrophysical environments including novae, supernovae, and X-ray bursts. Reactions on unstable nuclei critically determine the properties of these astrophysical explosions but are difficult to measure directly owing to the relatively low intensities of these at current-generation radioactive beam facilities. At the NSL, new equipment is being developed and installed in order to indirectly determine these astrophysical reaction rates on unstable nuclei. The Solenoid Spectrometer for Nuclear Astrophysics and Decays (SSNAPD) will utilize the first solenoid of TriSol (see the talk by P. O'Malley) to measure decay branching ratios as low as 10-5 originating from exotic nuclei. Second, an Enge Split-Pole Spectrometer has been transferred from Oak Ridge and is being installed at the NSL. These projects, their status, and plans will be discussed. |
Saturday, October 29, 2022 2:24PM - 2:36PM |
LE.00003: Neutron-upscattering enhancement of the triple-alpha process Jack E Bishop, Cody E Parker, Grigory V Rogachev, Sunghoon Ahn, Evgeniy Koshchiy, Kristyn H Brandenburg, Carl R Brune, Robert J Charity, Joseph Derkin, Nicolas Dronchi, Gulakhshan M Hamad, Yenuel Jones-Alberty, Tzany Kokalova, Thomas N Massey, Zachary P Meisel, Viktoria Ohstrom, Som N Paneru, Emanuel Pollacco, Mansi Saxena, Nisha Singh, Robin Smith, Lee G Sobotka, Douglas B Soltesz, Shiv K Subedi, Alexander Voinov, Justin N Warren, Carl Wheldon The neutron inelastic scattering of carbon-12, populating the Hoyle state, is a reaction of interest for the triple-alpha process. The inverse process (neutron upscattering) can enhance the Hoyle state’s decay rate to the bound states of 12C, effectively increasing the overall triple-alpha reaction rate. The cross section of this reaction is impossible to measure experimentally but has been determined here at astrophysically-relevant energies using detailed balance. Using a highly-collimated monoenergetic beam, we measured neutrons incident on the Texas Active Target Time Projection Chamber (TexAT TPC) filled with CO2 gas, measuring the 3α-particles (arising from the decay of the Hoyle state following inelastic scattering) and a cross section was extracted. The results of this recently-published work will be discussed. |
Saturday, October 29, 2022 2:36PM - 2:48PM |
LE.00004: Active Target Measurement of the 25,26Mg(α,n)28,29Si Total Cross Section Drew Blankstein, Dan W Bardayan, Jacob Allen, Thomas L Bailey, Chevelle Boomershine, Daniel P Burdette, Lauren K Callahan, Scott R Carmichael, Adam M Clark, Alexander C Dombos, Orlando J Olivas-Gomez, Samuel L Henderson, Kevin Lee, Luis A Morales, Austin D Nelson, Patrick O'Malley, Graham L O'Donnell, John Wilkinson, Sydney D Coil The observation of gamma rays from the decay of 26Al provides direct evidence of ongoing nucleosynthesis in the galaxy. While the observed distribution of 26Al points to massive stars as the main production site, the underlying nuclear processes are uncertain. Two reactions contributing to the uncertainty of 26Al production are the 25Mg(α,n)28Si and 26Mg(α,n)29Si reactions. While previous measurements have been made, discrepant data has led to uncertainties in these reaction rates for explosive and shell C/Ne burning in massive stars. To resolve these uncertainties, a measurement of the 25,26Mg(α,n)28.29Si total cross-section was performed with a new Active Target Detector at The University of Notre Dame’s Nuclear Science Lab. The results of these measurements will be discussed. |
Saturday, October 29, 2022 2:48PM - 3:00PM |
LE.00005: First direct measurement of the 34Ar(α,p)37K reaction cross section for x-ray burst nucleosynthesis Kelly A Chipps, Justin Browne As the final step in the αp process, the 34Ar(α,p)37K reaction has a considerable impact on the observable light curves of x-ray bursts and the isotopic abundance pattern of the ashes left behind on the neutron star crust. For many of the αp process cases for which some experimental constraint exists, statistical model predictions are found to differ substantially; in the case of 34Ar(α,p), reaction rates derived from indirect techniques disagree with Hauser Feshbach calculations by nearly three orders of magnitude. We report the first direct measurement of the 34Ar(α,p)37K reaction cross section, utilizing the Jet Experiments in Nuclear Structure and Astrophysics (JENSA) gas jet target. JENSA is unique in providing a windowless, pure, and highly-localized target of helium for high-resolution spectroscopic studies of (α,p) reactions on proton-rich nuclei. The JENSA target was coupled to the superORRUBA and SIDAR silicon detector arrays and ANASEN position-sensitive ionization chamber and instrumented with a mixed digital/analog DAQ. Experimentally-derived cross sections for the (α,xp), (α,p0), and (α,2p) reactions are compared to HF predictions using TALYS. The impact of the direct measurement on various x-ray burst observational signatures will be discussed. |
Saturday, October 29, 2022 3:00PM - 3:12PM |
LE.00006: Limits on the direct capture component of the 23Na(p, γ)24Mg reaction Richard J deBoer, A. Boeltzig, A. Best, A. Di Leva, Joachim Goerres, Gy. Gyurky, G. Imbriani, M. Junker, Khachatur Manukyan, Daniel M Odell, Edward Stech, Michael C F Wiescher The 23Na(p,γ)24Mg reaction plays an important role in the nucleosynthesis of elements in the hot bottom |
Saturday, October 29, 2022 3:12PM - 3:24PM |
LE.00007: Direct Measurement of the 26Al(a,p) Reaction Cross-Section Jason D Forson, Steven D Pain, Kelly A Chipps, Kate L Jones, Tony Ahn, Dan W Bardayan, Jolie A Cizewski, Heather I Garland, Rajesh Ghimire, Uwe Greife, Jerome Mathew Kovoor, Raymond L Kozub, Fernando Montes, Wei Jia Ong, Andrew Ratkiewicz, Nabin Rijal, Hendrik Schatz, Harrison E Sims, Rebecca Toomey, Louis Wagner, Shiva Agarwal, Chevelle Boomershine, Scott R Carmichael, Michael A Famiano, Ruchi Garg, Kevin I Hahn, Ana Henriques, Kirby Hermansen, Hwang Jongwon, Toby King, Alain Lapierre, Yuan Liu, Patrick O'Malley, Caleb A Marshall, Samuel Nash, Alicia Palmisano, Rahul Jain, E. Rubino, Kiana Setoodehnia, Chandana Sumithrarachchi, Antonio Villari The 26Al(a,p) reaction impacts final abundances in lower-temperature X-ray burst models. We have performed a direct thin-target measurement of this reaction at several energies approaching the Gamow window, by impinging a batch-mode beam of 10^6 26Al ions/s from the ReA3 accelerator on the JENSA gas-jet target. Ejectiles were detected using the ORRUBA silicon detector array and recoils were detected using the GODDESS position-sensitive fast ionization chamber. This approach enables determination of partial and total reaction cross sections, providing stringent constraints on Hauser-Feshbach predictions. An overview of the experiment and some preliminary results will be presented. Work supported in part by the US Department of Energy (Office of Science and National Nuclear Security Administration) and the National Science Foundation. |
Saturday, October 29, 2022 3:24PM - 3:36PM |
LE.00008: Commissioning of the SECAR recoil separator Ruchi Garg, Georg P Berg, Jeff C Blackmon, Kelly A Chipps, Manoel Couder, Catherine M Deibel, Nikolaos Dimitrakopoulos, Uwe Greife, Ashley A Hood, Rahul Jain, Caleb A Marshall, Zachary P Meisel, Sara Ayoub Miskovich, Fernando Montes, Georgios Perdikakis, Thomas J Ruland, Hendrik Schatz, Kiana Setoodehnia, Michael S Smith, Pelagia Tsintari, Louis Wagner Stellar explosions such as novae, supernovae, and X-ray bursts involve thermonuclear reactions on rare isotopes. Interpretation of observations such as the light curves, elemental abundances, or γ-rays from nuclear decay as well as predictions of nucleosynthesis are notably impacted by large uncertainties in the nuclear reaction rates. Many of these reactions either have no experimental data available or have only been constrained indirectly. |
Saturday, October 29, 2022 3:36PM - 3:48PM |
LE.00009: Mirror studies in the sd-shell using the (d,p) reaction Steven D Pain The odd-odd self-conjugate sd-shell nuclei - 18F, 22Na, 26Al, 30P, 34Cl and 38K - all play important roles in nucleosynthesis in massive stars and novae. Their self-conjugate nature makes them especially well suited for indirect studies via mirror symmetry, where proton-capture cross sections can be deduced from neutron-transfer reactions. These nuclides have been the targets of a series of experiments, using ORRUBA and GODDESS, at HRIBF, ATLAS and NSCL/FRIB. An overview of these measurements will be presented, with an emphasis on recent results and experimental campaigns, and a look toward the first experiments in the FRIB era. |
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