Bulletin of the American Physical Society
APS April Meeting 2022
Volume 67, Number 6
Saturday–Tuesday, April 9–12, 2022; New York
Session K13: Nuclear Structure IRecordings Available
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Sponsoring Units: DNP Chair: Shelly Lesher, University of Wisconsin - La Crosse Room: Empire |
Sunday, April 10, 2022 1:30PM - 1:42PM |
K13.00001: A Reexamination of the Isoscalar Giant Monopole Resonance In Well Studied Nuclei Using 6Li Joseph M Arroyo, Umesh Garg The incompressibility of infinite nuclear matter (IINM) is a parameter in the nuclear equation of state that holds relevance in both small and large scale systems of nucleons. The standard method of studying this parameter is through the use of the isoscalar giant monopole resonance (ISGMR) in finite nuclei. The standard method of studying this parameter is through probing the ISGMR in finite nuclei using α-particles. This work explores 6Li as a probe and its use in studying the ISGMR in 58Ni, 90Zr, 116Sn, and 208Pb. Inelastic and elastic data for these nuclei was collected at the Research Center for Nuclear Physics in Osaka University. Extracted strength distributions for these aforementioned nuclei will be compared to data utilizing α-particles to gauge the efficacy of 6Li as a probe for potential future experiments. |
Sunday, April 10, 2022 1:42PM - 1:54PM |
K13.00002: Angular distributions of high spin states produced via 27Al(α,d)29Si Caleb B Benetti, Samuel L Tabor, Catur Wibisono, Gordon W McCann, Kenneth G Hanselman, Ingo L Wiedenhoever, Lagy T Baby, Mark Spieker, Vandana Tripathi The investigation of nuclear structure in the mass 16-60 region has provided rich experimental data to test microscopic theory. Previously our group has used the tools and techniques of multi-gamma spectroscopy to chart out the high-spin yrast states in this mass region. It has been shown1 that (α,d) reactions also have a preference for high spin states since the proton and neutron from the deuteron can both occupy the same state of maximal J. I will present work using the FSU Super Engie Split Pole Spectrograph (SE-SPS). Angular distributions for states produced via 27Al(α,d)29Si will be shown for high spin states for the first time. Comparison of these states will be made with the FSU shell model2 interaction. |
Sunday, April 10, 2022 1:54PM - 2:06PM |
K13.00003: Imaging nuclear structure in high-energy heavy-ion collisions Jiangyong Jia The hydrodynamic modeling of the quark-gluon plasma (QGP) permits us today not only to perform quantitative extractions of the transport properties of the QGP, but also to strongly constrain its initial condition. A growing body of experimental evidence shows that the QGP initial condition is strongly impacted by the shape and radial structure of the colliding nuclei. We discuss the exciting prospect of using precision flow measurements as a tool to image the structure of atomic nuclei, and show how such measurements probe the quadrupole, octupole, and triaxial deformations of the colliding ions, as well as their neutron skin. Motivated by recent groundbreaking measurements from RHIC and LHC, we discuss in particular the case of collisions of isobaric nuclei, which provide the cleanest access route to the collective structure of the colliding ions. We discuss the implications of obtaining an information about the structure of nuclei from high-energy collisions that is fully complementary to that obtained in low-energy experiments, and argue that a scan of stable isobars at high-energy colliders may open a new exciting direction of research in nuclear physics. |
Sunday, April 10, 2022 2:06PM - 2:18PM |
K13.00004: Gamma-ray spectroscopy for analysis of the decay of La-140 for nuclear forensics applications Noah Cabanas, Elizabeth A McCutchan 140La is an important isotope in nuclear forensics, used primarily as a chronometer for nuclear events. The decay of 140La, however, was last studied more than 30 years ago using a simple detector system. Utilizing the advancements in the instrumentation available to measure radioactive decay, we can obtain considerable improvement on the decay of 140La. 140La was produced through neutron irradiation of natural La (99.99% 139La) in the UMass Lowell research reactor. The Argonne National Laboratory where it was assayed with the Gammasphere array, consisting of up to 110 active high-purity Compton Suppressed germanium detectors in a spherical arrangement, can provide high-statistics measurements of low intensity gamma-rays. The analysis was carried out using a γ-γ coincidence matrix as well as a singles spectrum. Utilizing both allowed for us to determine a precise intensity on strong transitions and to better confirm weak transitions. An angular correlation analysis was also conducted using the coincidence matrix. In this talk, I will present a new decay scheme for 140La and discuss the improvements on prior measurements. |
Sunday, April 10, 2022 2:18PM - 2:30PM |
K13.00005: Measurement of B(E2↑) for 36Ca Nicolas Dronchi, Robert J Charity, Lee G Sobotka, Walter Reviol, Alexandra Gade, Dirk W Weisshaar, Alex Brown, Stephen Gillespie, Kyle W Brown In a pair of experiments, the B(E2; 2+1→0+g.s.) was measured for 36Ca. The first experiment measured a cross section for the Coulomb excitation of a 36Ca beam where only gamma decays were detected. The second experiment measured the branching ratio required as a correction to this cross section because the 2+1 state of 36Ca is above the proton separation energy. The measured B(E2) value significantly differs from that previously employed in an astrophysical calculation. This B(E2) is useful in x-ray burst simulations where 34Ar sits at a waiting point which is sensitive to the 35K(p,γ)36Ca reaction rate. |
Sunday, April 10, 2022 2:30PM - 2:42PM |
K13.00006: ENSDF Database Modernization with Python API Edwin Gomez, Adam Hayes, Elizabeth A McCutchan, Andrea Mattera, Shu Shu, Donnie Mason, Alejandro A Sonzogni, Carlos Soto, Sean McCorkle, Chris Morse, Shinjae Yoo, Filip G Kondev, Caleb Mattoon, Shaofei Zhu The Evaluated Nuclear Structure Data File (ENSDF) is a database that contains the level and decay properties for over 3,300 nuclides. ENSDF is accessible to anyone through the National Nuclear Data Center’s (NNDC) website. It is a highly used database with over 4.5 million data retrievals in 2019. However, its 80-column ASCII format makes it difficult to update and use. As such, the NNDC is working on a project that will update ENSDF to an object-oriented database. The database includes indexes, or “views,” that can be used to sort and filter data very efficiently. For example, a search through all ~200,000 gamma rays in the database requires only one line of code and takes ~100 ms. Researchers will be able to use the object-oriented Python3 API under development to retrieve data via the web, search, sort, and develop their own code projects. The API will also have built-in plotting functions for visualizing ENSDF data. |
Sunday, April 10, 2022 2:42PM - 2:54PM |
K13.00007: Nuclear excitation by electron capture in excited ions Simone Gargiulo, Ivan Madan, Fabrizio Carbone Since its recent observation in the 93Mo isomer depletion, nuclear excitation by electron capture (NEEC) is the object of a live debate: the large measured excitation probability Pexc differs by nine orders of magnitude from the state-of-the-art theoretical predictions. A new study slightly increased this theoretical limit, accounting for the momentum distribution of the target electrons. Authors showed that the depletion probability increases by several orders of magnitude in case of the L-shell. However, these L-channels do not contribute significantly to the Pexc. So far, the evaluation of the NEEC cross section has been carried out widely using the assumption that the ion is in its electronic ground state prior to the capture (GSA), prohibiting the capture in the innermost-shells as soon as the atomic orbitals fill up. For 73Ge this means that NEEC into K-shell cannot occur: the energy released through a K-capture exceeds the nuclear transition energy. By lifting this restriction and considering NEEC in excited ions, we show for 73Ge that many more capture channels emerge. These excited electronic configurations make K-capture now possible, through new channels with resonance strengths larger than any other channel obtained under GSA. |
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