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 LG: Nuclear Structure VI |
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Chair: Andrea Mattera, Brookhaven National Laboratory Room: Hyatt Regency Hotel Celestin G |
Saturday, October 29, 2022 2:00PM - 2:12PM |
LG.00001: Coulomb excitation of 102Ru Paul E Garrett, M. Zielinska, A, Bergmaier, T.R. Rodríguez, D. Kalaydjieva, M. Siciliano, H. Hidaman, V. Bildstein, C. Burbadge, A. Diaz Varela, D. T Doherty, T. Faestermann, K. Hadynska-Klek, R. Hertenberger, N. Keeley, A. Laffoley, A.D. MacLean, M. Mahgoub, A. Radich, M. Rocchini, P. Spagnoletti, S. Triambak, M. Vandebrouck, K. Wrzosek-Lipska Coulomb excitation of 102Ru was performed with beams of 12C and 16O ions at the Maier-Leibnitz Laboratory, with the scattered particles momentum analyzed using a Q3D magnetic spectrograph. Both the elastic and inelastically scattered particles were detected, and the resolution achieved enabled the populations of the 21+, 22+/41+ doublet, 23+, 24+/31- doublet, and 32- states to be determined as a function of the scattering angle, which were compared with GOSIA calculations. The deduced B(E2;21+→01+) = 41.5±2.3 W.u. is in good agreement with the ENSDF value of 44.7±0.7 W.u., while the B(E2;22+→01+ ) = 1.75±0.11 W.u. is approximately 40% larger than the ENSDF value.The weakly populated 23+ state was observed for a single angle only, and a fit to its population results in B(E2; 23+→01+ ) = 0.053±0.011 W.u. Using the known γ-ray branching ratios, the B(E2; 23+→02+) value is calculated to be 18±4 W.u., substantially less than the B(E2; 21+→01+) value, suggesting that the deformation of the 02+ state is less than that of the ground state. The results are compared with beyond-mean-field calculations with the Gogny-D1S interaction using the symmetry-conserving configuration-mixing method, and placed in context of the systematics for Ru isotopes. |
Saturday, October 29, 2022 2:12PM - 2:24PM |
LG.00002: Decay Spectroscopy of 134Sb with the X-Array and SATURN at CARIBU Graeme Morgan, Scott T Marley, Patrick A Copp, Sudarsan Balakrishnan, Michael P Carpenter, Partha Chowdhury, Daryl J Hartley, Heshani Jayatissa, Kay Kolos, Filip G Kondev, Sergio Lopez-Carceres, A.J. Mitchell, Claus Muller-Gatermann, Soumen Nandi, Walter Reviol, Andrew Rogers, Dariusz Seweryniak, Rachel M Shaffer, Barbara S Wang, Sanjanee W Waniganeththi, Gemma L Wilson The ground-state decay of 134Sb is reported to be dominated by a 0-→0+ first-forbidden Gamow-Teller transition to the 134Te ground state (Iβ = 97.6%, Qβ = 8.515MeV). In 2013, a campaign of recoil-ion time-of-flight (RI-TOF) spectroscopy measurements of β-delayed neutron precursors with the Beta-decay Paul Trap (BPT) used the 134Sb ground state decay as a calibrant for the detector system. Unexpectedly, analysis of the data from the BPT study indicated that the ground-state feeding of 134Te is weaker than reported with ∽17% of the overall β-decay strength feeding higher-energy transitions. To search for these transitions, the Scintillator and Tape Using Radioactive Nuclei (SATURN) decay station and X-Array were used in a study of 134Sb decay using radioactive beams produced by the Californium Rare Isotope Breeder Upgrade (CARIBU) at Argonne National Laboratory (ANL). A description of the experiment and preliminary results will be presented. |
Saturday, October 29, 2022 2:24PM - 2:36PM |
LG.00003: Ongoing Development of Nuclear Data Web Services Benjamin Shu, Elizabeth McCutchan, Donnie Mason Past and present developments in nuclear physics research have generated a considerable quantity of valuable data. But while this data is publicly available, it still needs to be organized and distributed for anyone who wants to use it. The National Nuclear Data Center (NNDC) is updating its web services to make low energy nuclear physics data more accessible. The most visible of these updates is a redesign of the front page and several important websites for more convenient navigation. This involves adding new banners and menus to better direct visitors to the data they're most interested in. To support these changes, the development process for web applications has been streamlined to encourage standardization and re-use of code. This new process has also enabled updates to web-based tools for data retrieval and calculation. Lastly, the NNDC is also branching out into social media outreach and mobile app development. A Twitter account provides opportunities to engage with current users and attract new ones, while mobile apps can provide portable access to NNDC data. Through continued development on all of these projects, the NNDC intends to keep providing its services to meet future data needs. |
Saturday, October 29, 2022 2:36PM - 2:48PM |
LG.00004: β-decay spectroscopy of the light rare-earth nuclei 158Pm and 160Sm Sanjanee W Waniganeththi, Andrew Rogers, Filip G Kondev, Patrick A Copp, Daniel E Hoff, Sean P Byrne, Michael P Carpenter, Partha Chowdhury, Jason A Clark, EJ Gass, Daryl J Hartley, Torben Lauritsen, Sergio Lopez-Caceres, Scott T Marley, Alan J Mitchell, G. E Morgan, Chris Morse, Claus Mueller Gatermann, Walter Reviol, Guy Savard, Dariusz Seweryniak, Kartikeya Sharma, Marco Siciliano, Yiyi Zhu Probing the intrinsic and collective structure of nuclei in the light rare-earth region, provides important insight into the evolution of nuclear deformation and the properties of neutron-rich nuclei. This understanding is critical for exploring the formation of the rare-earth peak in the r-process abundance pattern, where new data can influence constraints on the astrophysical sites and conditions. The odd-odd nucleus 158Pm is a particularly interesting case as a predicted isomeric state has yet to be clearly established and its lifetime determined (T1/2 >16μs). Investigating such isomers is critical to determining their structure as well as to remove ambiguities that can arise in direct mass measurements. To investigate this region a β-decay experiment was performed at ANL which combined the HPGe detectors of X-Array with the SATURN tape system. Radioactive ions produced by the CARIBU facility were isobarically separated and delivered to the decay station and βγγ-coincidence measurements performed. Tape cycles were optimized for the decay of 158Pm and 160Sm. Preliminary results and a summary of ongoing analysis will be presented. |
Saturday, October 29, 2022 2:48PM - 3:00PM |
LG.00005: High-K Isomers in deformed neutron-rich A~190 nuclei via fragmentation reactions Kartikeya Sharma, Partha Chowdhury, Andrew Rogers, Oleg Tarasov, Kenny Haak, Daniel E Hoff, Peter C Bender, Thomas Baumann, Daniel Bazin, Jun Chen, Alfredo Estradé, Michael A Famiano, Dan C Foulds-Holt, Naoki Fukuda, Alexandra Gade, Tom Ginter, Richard W Gohier, Marc Hausmann, A. M 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, Mallory K Smith, Mark Spieker, Chandana Sumithrarachchi, Hiroshi Suzuki, Kailong Wang, Sanjanee W Waniganeththi, Dirk W Weisshaar, S. Zhu Deformed Hf-Ta-W nuclei in the 180 |
Saturday, October 29, 2022 3:00PM - 3:12PM |
LG.00006: Machine Learning and Particle Identification for Neutron-Unbound Studies at FRIB Andrew Wantz, Thomas Redpath, Belen Monteagudo Godoy, Paul L Gueye, Thomas Baumann Particle identification is a critical task when performing measurements involving rare isotope beams. Invariant mass spectroscopy for the study of neutron-unbound states, the focus of the MoNA Collaboration, requires that the fragments resulting from the decay of the unbound states be accurately identified. These measurements necessitate deconvolving the flight time and emittance parameters for ions deflected by the Sweeper magnet in order to identify the products of individual reaction channels. For the first time, machine learning approaches are being pursued to streamline this step of the analysis. The Toolkit for Multivariate Analysis (TMVA), which is included within the analysis tool ROOT, was used. Both experimental data and simulation produced with NPTool (a ROOT-and-GEANT4-based tool) were used for training and evaluating the performance of machine learning algorithms. Classification and regression algorithms were applied to test their particle identification capabilities. The primary methods used for training were the deep neural network and the multilayer perceptron. A comparison of various methods of particle identification will be presented. |
Saturday, October 29, 2022 3:12PM - 3:24PM |
LG.00007: Probing elemental chemistry with physics techniques: studying holmium chemistry through its nuclear physics properties Fatima H. Garcia, Jennifer L Pore, Jacklyn M Gates, John Gooding, Mallory McCarthy, Rodney Orford, Mark A Stoyer In recent years, the push to study the chemical and physical properties of the heaviest elements has been driven by their application in nuclear medicine, waste disposal and nuclear power. Their chemical behaviors have been a challenge to observe as they are primarily radioactive and are produced in minute quantities, making traditional benchwork nearly impossible. At the 88-inch cyclotron facility of Lawrence Berkeley National Laboratory, a novel gas-phase chemistry technique has been created, using the Berkeley Gas-Filled Separator and the FIONA mass analyzer experimental setup. This setup makes atom-at-a-time chemistry possible, where single radioactive ions are trapped and reacted with various gasses, allowing the formation of complexes. The resulting molecules are then identified by their mass, providing a laboratory for simple and clean chemistry. The technique can be benchmarked by comparison to traditional chemistry laboratory experiments on holmium while at the same time providing complementary information on this element. The use of this novel technique will be described and preliminary results on the chemistry of holmium will be presented. |
Saturday, October 29, 2022 3:24PM - 3:36PM |
LG.00008: Production of the New Isotope 255Db Jennifer L Pore It is challenging to produce neutron-deficient nuclei of super heavy elements due to low production cross sections. There have been previous claims of the observation of the light-dubnium isotope 255Db [1-3], however none of these have been confirmed or accepted by the community as an identification. An experiment was performed at the Lawrence Berkeley National Laboratory’s 88-inch cyclotron facility in an attempt to produce both the previously observed isotope 256Db and the new isotope 255Db. The fusion evaporation reaction 206Pb(51V, 1-2n)255-256Db was chosen for the production of these dubnium isotopes, which took place upstream of the Berkeley Gas-filled Separator (BGS). The BGS then served to separate the dubnium isotopes from any unreacted beam material of reaction by-products. The decay properties of the dubnium isotopes could then be observed with a double-sided silicon-strip detector that was installed at the BGS focal plane. Preliminary results from this measurement will be presented. |
Saturday, October 29, 2022 3:36PM - 3:48PM |
LG.00009: Shell-model calculations for two-neutron transfer near the N=20 island of inversion Alan H Wuosmaa, Juliette K Stecenko We have performed shell-model calculations of two-neutron amplitudes (TNA) relevant for the two-neutron transfer reactions 28Mg(t,p)30Mg and 30Mg(t,p)32Mg. The neutron-rich isotopes of Mg are central to the understanding of intruder configurations responsible for the “Island of Inversion” at N=20. Of particular interest are 0+ states populated in (t,p) reactions as shown by early studies more than 10 years ago [1]. With coming radioactive-beam facilities, new experiments are planned for similar studies. We use shell-model calculations with two interactions, SDPF-MU and SDPF-M, to illustrate how different nuclear structure leads to different predictions for observables in the 2n transfer reactions 28,30Mg(t,p)30,32Mg. Reaction strengths were obtained using calculated Two Neutron Amplitudes (TNA) as input to Distorted-Wave Born Approximation cross-section calculations. The shell-model calculations were performed using the code “KSHELL” [2] and ran on the High-Performance Computing Facility at the University of Connecticut. The results of the calculations and the implications for future studies of two-neutron transfer in the Mg region will be discussed. |
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