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 JH: Nuclear Reactions: Heavy-Ions/Rare isotope Beams I |
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Chair: Wei Jia Ong, Lawrence Livermore Natl Lab Room: Hyatt Regency Hotel Celestin H |
Saturday, October 29, 2022 8:30AM - 8:42AM |
JH.00001: New Isotopes in Neutron Rich Hf-Lu Region via Fragmentation of 198Pt Kenny Haak, Oleg Tarasov, Partha Chowdhury, Andrew Rogers, Kartikeya Sharma, Thomas Baumann, Daniel Bazin, P.C. Bender, Jun Chen, Alfredo Estrade, Michael A Famiano, Dan C Foulds-Holt, Naoki Fukuda, Alexandra Gade, Tom Ginter, Richard W Gohier, Marc Hausmann, Daniel E Hoff, Ava Hill, Levi Klankowski, Elaine Kwan, Jing Li, Sean Liddick, Brenden R Longfellow, Stephanie M Lyons, Chris Morse, Mauricio Portillo, Daniel M Rhodes, Andrea L Richard, S. Samaranayake, Bradley M Sherrill, Mallory K Smith, Mark Spieker, Chandana Sumithrarachchi, Hiroshi Suzuki, Kailong Wang, Sanjanee W Waniganeththi, Dirk W Weisshaar, S. Zhu The properties of neutron rich heavy isotopes are fundamentally important to various aspects of nuclear physics including the r-process in astrophysics, N=126 shell closure, and heavy ion fragmentation reactions. Despite the interest, this region is largely unexplored; only a few N=126 isotopes of elements lighter than lead have been produced and identified. In order to establish a footing in this region and eventually reach out toward the location of the r-process pathway and beyond, an experiment was performed at NSCL to study production of neutron rich isotopes in the Hf-Os region. |
Saturday, October 29, 2022 8:42AM - 8:54AM |
JH.00002: Experimental impact of inverse kinematics and preliminary results from the (d,pγ) reaction measurement with 95Mo beams and GODDESS Heather I Garland, Jolie A Cizewski, Steven D Pain, Andrew Ratkiewicz, Harrison E Sims, Gwenaelle Seymour, Alexandre A Lepailleur Roughly half of the elements heavier than iron are synthesized through the rapid neutron-capture process (the r process). Unfortunately, the isotopes that lie along the r-process path are too short lived to create a viable target. However, techniques for constraining neutron capture through indirect measurements are being developed and benchmarked. One such technique is the Surrogate Reaction Method (SRM) which has been validated for the (d,pγ) reaction as a surrogate for (n,γ) in normal kinematics. A measurement to benchmark the SRM in inverse kinematics and prepare for studies with rare isotope beams (RIBs) was conducted at the ATLAS facility at Argonne National Laboratory. An 8 MeV/u 95Mo beam was impinged upon C2D4 targets and the (d,pγ) reaction was measured with GODDESS (Gammasphere ORRUBA: Dual Detectors for Experimental Structure Studies). The techniques needed to transition from normal to inverse kinematics measurements using RIBs will be discussed. In preparation for an SRM analysis, preliminary results for the (d,p) proton angular distributions and deduced 96Mo level scheme will be presented. |
Saturday, October 29, 2022 8:54AM - 9:06AM |
JH.00003: Exploration of Excited Stated in Alpha Conjugate Reaction Systems Bryan M Harvey, Andy Hannaman, Kris Hagel, Alan B McIntosh, Sherry J Yennello In the past few years, there has been some experimental efforts to explore the possibility of high-spin nuclei being stabalized by a toroidal configuration in high excitation energy states, particularly in 28Si. This possibility has theoretical backing, particularly in alpha conjugate nuclei within the mass range 24 <= A <= 40. A recent experiment with 36Ar and 20Ne + C at 35 MeV/u has been performed using the FAUST detector array to continue to probe these potential excited states over a wider mass range. The FAUST array was chosen for these studies for it's sub-millimeter position resolution allowing for very precise reconstructions of excitation functions. The data from this experiment will be presented along with preliminary findings of any potential excited states. |
Saturday, October 29, 2022 9:06AM - 9:18AM |
JH.00004: Extraction of Gamow-Teller Strength via the (d,2He) Reaction in Inverse Kinematics Zarif M Rahman, Zarif M Rahman, Simon Giraud, Remco G Zegers, Juan C Zamora, Daniel Bazin, Miles DeNudt, Yassid Ayyad, Shumpei Noji, Saul Beceiro-Novo, Cavan Maher, Jaclyn M Schmitt, Felix Ndayisabye, Wolfgang Mittig, Jorge Pereira, Jie Chen, Marco Cortesi, Zach M Serikow, Jason Surbrook, Lijie Sun, Nathan Watwood, Tyler Wheeler Electron-capture (EC) rates play a decisive role in core-collapse and thermonuclear supernovae, the crust of accreting neutron stars in binary systems, and the final core evolution of intermediate mass stars. Charge-exchange reactions (CERs) at intermediate energies (~100 MeV) are crucial in extracting information for neutron-rich nuclei as the EC Q-values are positive for such nuclei. The differential cross-sections in CERs at zero momentum transfer are proportional to the Gamow-Teller strength, B(GT), from which the EC rates can be calculated. In a first of a kind experiment, the S800 spectrometer at National Superconducting Cyclotron Laboratory (NSCL) along with Active-Target Time Projection Chamber (AT-TPC) setup was used to run an experiment with (d,2He) probe in inverse kinematics to study unstable nuclei. Data from the experiment for the 13N(d,2He)13C reaction is being analyzed to extract the differential cross-section for ground and excited states which will be utilized in measuring the B(GT). |
Saturday, October 29, 2022 9:18AM - 9:30AM |
JH.00005: Nuclear Data Gone Awry: Error in the IAEA Beam Monitor Reference Cross Section, natNi(d,x)61Cu, Discovered while Measuring a Discrepant 40Ar(d,p)41Ar Reaction. Darren L Bleuel, Scott G Anderson, Lee A Bernstein, Josh A Brown, Joseph A Caggiano, Bethany L Goldblum, Joseph M Gordon, James M Hall, Keegan P Harrig, Micah S Johnson, Thibault A Laplace, Roark A Marsh, Mairaid E Montague, Jonathan T Morrell, Andrew Ratkiewicz, Brian Rusnak, Ray Souza, Carol A Velsko, Andrew S Voyles To investigate the use of argon as a deuteron beam stopping material, the 40Ar(d,p)41Ar cross section was measured at average deuteron energies of 3.6 MeV, 5.5 MeV, and 7.0 MeV using an activation method with nickel degraders. The natNi(d,x)61Cu reaction has historically been one of only a few IAEA-recommended deuteron beam monitor reactions. A discrepancy was observed between the accepted and measured values of the intensity ratio of the two strongest gamma rays following 61Cu β decay. This has significant impact to published cross sections measured in ratio to that beam monitor cross section. To determine the error's magnitude, over a hundred measurements of the 283 keV to 656 keV gamma-ray emission ratio were collected from seven experiments and a variety of detectors and geometries. A weighted average indicates an error in the value listed in the Nuclear Data Sheets of 11%. Following this correction, the 40Ar(d,p)41Ar cross section was determined from activation to be ~40% higher than a previous measurement and an order of magnitude higher than TENDL, further demonstrating the need for multiple, independent measurements of often-accepted nuclear data. |
Saturday, October 29, 2022 9:30AM - 9:42AM |
JH.00006: Results on the Production of the Astrophysically-Relevant 41Ca and the Medically-Relevant 43,44Sc from the Reaction of 3He on natCa Austin D Nelson, Adam M Clark, Lauren K Callahan, Philippe A Collon, Thomas L Bailey 41Ca (t1/2=9.94 x 104 yrs) is an important stellar radionuclide as its production in the Early Solar System from various irradiation scenarios can help determine the viability of models of early stellar processes. A novel reaction technique has been under development and recently tested at the NSL at the University of Notre Dame. This technique utilizes an “in-cathode” reaction method, where natural CaF2 material is packed into an ion source sample holder (cathode) and then irradiated and subsequently measured using Accelerator Mass Spectrometry without the need for any chemical processing. Multiple irradiations at various energies were performed using a 3He beam to measure the reaction natCa(3He,x)41Ca. In order to help quantify the amount of beam hitting the Cu cathode, all samples were placed in a gamma counting station after irradiation. The gamma spectra revealed noticeably distinct lines from 43Sc and 44Sc, encouraging an impromptu investigation into the production yields of these isotopes due to their significance as nuclear medical isotopes. This will be the first ever known result of thick target yields of the reactions natCa(3He,x)43,44Sc. Results on the production of 41Ca, 43Sc and 44Sc will all be presented. |
Saturday, October 29, 2022 9:42AM - 9:54AM |
JH.00007: Benchmarking the cross section for inelastic neutron scattering from 193Ir Athena M Marenco, Gencho Y Rusev, Evelyn M Bond, Todd A Bredeweg, Stefania Dede, Jenna Garcia, Matthew E Gooden, Walter A Moody, Sean W Finch, FNU Krishichayan, Werner Tornow, Anthony Paul D Ramirez, Jack A Silano, Anton P Tonchev Neutron activation measurements of the 193Ir(n,n')193mIr reaction were performed at the Triangle Universities Nuclear Laboratory to resolve a longstanding discrepency between integral and differential measurements. Samples of natural iridium and enriched 193Ir were irradiated with monoenergetic neutron beams with energies of 4.6 and 6.0 MeV. The de-excitation of the metastable state at 80.2 keV in 193mIr was determined by means of measuring X rays following electron conversion. Special attention was paid in the data analysis to the X-ray attenuation in the samples. Results from our activation measurements will be reported. |
Saturday, October 29, 2022 9:54AM - 10:06AM |
JH.00008: Differential cross-section measurements of the 18O(g,n) + 18O(g,nn) reactions at 23.7 and 32.0 MeV Collin R Malone, Calvin R Howell, Forrest Q Friesen, Ronald C Malone, Werner Tornow Photoneutron reactions on 18O offer an opportunity to examine the neutron-neutron interaction and may be used as a surrogate reaction for planning a 3H photodisintegration experiment at the TUNL. The relatively large 18O(g,nn) reaction cross section allows measurements of differential cross-section data for neutron-neutron coincidences at various opening angles between neutrons similar to the 3H(g,nn) reaction without handling a radioactive gas target. Cross sections for the sequential emission of neutrons in the 18O(g,nn) reaction are measured. The sequential decay is the dominant portion of the cross section. Simultaneous neutron emission is highly suppressed due to Isospin. |
Saturday, October 29, 2022 10:06AM - 10:18AM |
JH.00009: Measuring the Isoscalar Giant Monopole Resonance in 70Ni with the S800 Spectrometer Tan Ahn, Jaspreet Randhawa, Joseph Arroyo, Yassid Ayyad, Daniel Bazin, Saul Beceiro-Novo, Jie Chen, Umesh Garg, Simon Giraud, Samuel L Henderson, Wolfgang Mittig, Felix Ndayisabye, Shumpei Noji, Jorge Pereira, Zach M Serikow, Jason Surbrook, Juan C Zamora, Remco G Zegers The evolution of the giant monopole resonance as a function of isospin is important for constraining the nuclear equation-of-state, which has implications for understanding the nature of bulk nuclear matter and the size of neutron stars. In order to track this evolution in the medium-mass region, we have performed a measurement to measure the isoscalar giant monopole resonance (ISGMR) in 70Ni using inelastic alpha scattering. The helium target was provided by the Active-Target Time Projection Chamber which was coupled with the S800 spectrometer at the National Superconducting Cyclotron Laboratory. The use of the S800 allowed us to tag Ni isotope recoils of interest after the excitation of the ISGMR, greatly reducing the background from elastic scattering. The effectiveness and the challenges of this method will be presented as well as future efforts to measure the ISGMR in heavier nuclei. |
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