Bulletin of the American Physical Society
6th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Sunday–Friday, November 26–December 1 2023; Hawaii, the Big Island
Session 4WQA: Recent Highlights and Future Opportunities for In-beam Gamma-ray Spectroscopy in North America and Japan IInvited Workshop
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Chair: Pieter Doornenbal Room: Hilton Waikoloa Village Kona 2-3 |
Monday, November 27, 2023 2:00PM - 2:30PM |
4WQA.00001: In-beam gamma-ray spectroscopy of heavy actinides at the JAEA Tandem accelerator Invited Speaker: Riccardo Orlandi The existence of long-lived super heavy elements depends upon whether stability against fission can be sufficiently enhanced by shell effects. The largest effects are expected near the so-called Island of Stability (IoS), where the next spherical shell gaps are believed to occur. According to various models, the most likely locations for the next spherical shell closures are proton number Z=114, 120 or 126 and neutron number N=184. In the path to the IoS, small energy gaps also arise among the single-particle orbtals of deformed isotopes near (Z,N) = (100,152) and (108,162). These gaps, usually referred to as deformed shell gaps, significantly enhanced the stability of isotopes in their proximity, and extend our reach towards the IoS. Furthermore, some valence proton and neutron orbitals in neutron-rich actinides near N=152 correspond to substates, lowered by deformation, of orbits associated with the IoS. Extending our knowledge of the properties of actinides near these deformed shell gaps, and in particular a more precise mapping of the single-particle orbitals, can provide important benchmarks for theoretical models and permit more reliable extrapolations to the superheavy element region. Neutron-rich actinides, however, are still rather poorly known due to the difficulties connected with their production and identification. At the JAEA Tandem accelerator laboratory in Tokai, Japan, we developed a new setup that permits the in-beam gamma-ray spectroscopy of heavy actinides in experiments using rare radioactive actinide targets. With our setup, we investigated the structure of heavy actinides such as 248Cf (Z=98, N=150), 249Cf(Z=98, N=151), 254Es(Z=99, N=155) and 252Fm(Z=100,N=152). The nuclei of interest were either Coulomb excited (249Cf, 254Es), or produced using multi-nucleon transfer reactions of a 18O beam impinging onto a 249Cf actinide target ( 248Cf, 252Fm). A brief overview of some recent results will be presented. |
Monday, November 27, 2023 2:30PM - 3:00PM |
4WQA.00002: Physics of CLARION2-TRINITY at Florida State University Invited Speaker: James M Allmond CLARION2-TRINITY is a new Compton-suppressed HPGe and charged-particle array that is currently deployed at the John D. Fox Laboratory of Florida State University, which hosts a 9-MV FN Tandem and superconducting LINAC. The TRINITY charged-particle array contains 64 Cerium-doped Gadolinium Aluminum Gallium Garnet (GAGG:Ce) crystals configured into five rings spanning 7–54 degrees, and two annular silicon detectors that can shadow or extend the angular coverage to backward angles. The CLARION2 array supports 16 Compton-suppressed HPGe Clover detectors (≈ 4% efficiency at 1 MeV) configured into four rings (eight HPGe crystal rings) using a non-Archimedean geometry that suppresses coincident 511-keV gamma rays. The device also consists of a downstream zero-degree detector for beam-composition and stopping-power measurements. The entire array is instrumented with waveform digitizers and optimized for trigger-less operation. While the array was designed for absolute cross-section measurements with inverse kinematic reactions, e.g., single-step Coulomb excitation and sub-barrier transfer, it also has demonstrated utility in fusion-evaporation and beta-decay measurements. |
Monday, November 27, 2023 3:00PM - 3:30PM |
4WQA.00003: In-beam Gamma-ray Spectroscopy at the RIBF: Recent Results and Future Perspectives Invited Speaker: Martha L Cortes Radioactive isotopes are produced at the RIBF by the fragmentation of a stable beam in a thick target. The beam cocktail produced by these reactions is selected and identified using the BigRIPS fragment separator. Secondary beams with energies between 100 - 250 MeV/u impinge in a secondary target, surrounded by a gamma-ray detection system. While the reaction products are detected with the ZeroDegree or SAMURAI spectrometers, the emitted gamma-rays are usually detected with the NaI(Tl) based DALI2 array. Recently a HPGe array was also used around the secondary target. In the presentation the experimental setups used at the RIBF for in-beam gamma ray spectroscopy will be shown, an overview of the results achieved using DALI2 combined with the MINOS liquid hydrogen target (SEASTAR project) will be presented, followed by a report on the use of Ge detectors at the RIBF (HiCARI project). Finally recent results and future perspectives, specially around the 100Sn region, will be discussed. |
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