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 LH: Nuclear Reactions: Heavy-Ions/Rare isotope Beams III |
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Chair: Alan McIntosh, Texas A&M University Room: Hyatt Regency Hotel Celestin H |
Saturday, October 29, 2022 2:00PM - 2:12PM |
LH.00001: Investigating High Spin States in 59Co and 59Ni Samuel O Ajayi, Vandana Tripathi, Samuel L Tabor, Caleb B Benetti, James M Allmond, Elizabeth Rubino, Rebeka Lubna, Yutaka Utsuno, Noritaka Shimizu A fusion evaporation reaction, 14C on 48Ti was carried out at the John Fox Laboratory, FSU to populate high spin states in 59Co and 59Ni. The evaporation channels, 2np and 3n from the compound nucleus, 62Ni lead to the 59Co and 59Ni being studied. In the shell model picture, 59Co has a ground state of 7/2- because of an unpaired valence proton in the 1f7/2 level while 59Ni has a ground state of 3/2- because of an unpaired neutron in the 2p3/2 level. The current experiment has established the presence of several positive states of high spin in both nuclei, arising from cross shell excitations from the fp shell to the g9/2 orbital. The level scheme of 59Co has been expanded to around 11MeV with spin 31/2+ assigned. The highest negative parity state experimentally determined is 27/2- at around 9.5MeV. For 59Ni, the highest state is still at 37/2+, though at lower energy than the previous study on 59Ni. This work has extended the negative states of 59Ni to 31/2- at around 15MeV. In the high spin states of both nuclei, we have configurations allowing for rotation bands because of excitations of particles into the g9/2 orbital and presence of holes in the f7/2 orbitals. Detailed results and comparison with shell-model calculations will be presented. |
Saturday, October 29, 2022 2:12PM - 2:24PM |
LH.00002: Experimental Investigation of Suppression Factors in Knockout and (p,2p) Reactions Axel Frotscher The knockout of nucleons from nuclei is a powerful tool to investigate nuclear structure. However, when comparing the cross sections of one-nucleon knockout reactions to theory, one finds a systematic overestimation, which can be corrected for using a reduction factor R. |
Saturday, October 29, 2022 2:24PM - 2:36PM |
LH.00003: A Study of the ½+ State of 9B with the Super-Enge Split-Pole Spectrograph (SE-SPS) and the Silicon Array for Branching Ratio Experiments (SABRE) Rachel M Shaffer, Scott T Marley, Catherine M Deibel, Balakrishnan Sudarsan, Khang H Pham, Keilah S Davis, William D Braverman, Zach Purcell, Erin C Good, Kevin T Macon, Ingo Wiedenhoever, Lagy T Baby, Gordon W McCann, Ken Hanselman, Eilens Lopez, Vignesh Sitaraman, Bryan Kelly, Ashton B Morelock, Alex C Conley, Chris Esparza, Ben Asher, Caleb Benetti, Eli Temanson, Jesus F Perello Izaguirre We used the single-particle transfer reaction 10B(3He,α) to investigate the low-lying structure of the light, neutron-deficient nucleus 9B. Previous studies of 9B report discrepant values for the energy and width of this isotope’s first-excited state, Experimental results for this state’s energy range between 0.7-1.8 MeV with widths between 0.3-1.5 MeV. We performed the 10B(3He,α) reaction at Florida State University with a 7.5-MeV 3He beam incident on an isotopically enriched 10B target. Alpha particles were momentum-analyzed by the Super-Enge Split-Pole Spectrograph (SE-SPS) and detected at the focal plane, while the decay particles of 9B were detected by the Silicon Array for Branching Ratio Experiments (SABRE) at backward laboratory angles. Preliminary results from this experiment will be presented. |
Saturday, October 29, 2022 2:36PM - 2:48PM |
LH.00004: Measurement of B(E2↑) for 36Ca Nicolas Dronchi In a pair of experiments, the B(E2; 0+g.s –>2+1) 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 p/g branching ratio required as a correction to this cross section because the 2+1 state of 36Ca is above the proton separation energy. The corrected B(E2) was measured to be 131(20) e2fm4 and the proton branching ratio was measured to be 0.087(8). These values differ from those used in calculations that were previously employed in x-ray burst simulations. The B(E2) and branching ratio are needed to calculate the partial decay widths needed for the 35K(p,γ)36Ca reaction rate, a reaction which escapes the 34Ar waiting point in the rp-process. The B(E2) is also used as a correction for collectivization in the method of mirror charge radii for determining L, the slope of the symmetry energy with denisty. |
Saturday, October 29, 2022 2:48PM - 3:00PM |
LH.00005: Kinematic Correction for Fast Gamma Ray Transitions using Clarion2 and Trinity Catur Wibisono, Samuel L Tabor, Vandana Tripathi, Soumik Bhattacharya, Caleb B Benetti, Samuel O Ajayi, Timothy Gray, James M Allmond Fast gamma ray transitions often appear to be broad and hard to see accurately without correcting the emitted gamma rays for Doppler shifting. With the help of charged particle detector array Trinity, the energies of light charged particles emitted from fusion evaporation can be deduced; hence the energies and the angles of the recoil nuclei can be determined from simple kinematics. In this talk, techniques to do Doppler correction of the gamma rays from the data taken using Clarion2-Trinity at Florida State University from the reaction O16+O18 at 30 MeV will be discussed. Furthermore, preliminary results from the proton and alpha decay channels will be reported. |
Saturday, October 29, 2022 3:00PM - 3:12PM |
LH.00006: New Angular Correlation Measurements of Continuum-Coupled Particle-Unbound Superradiant Nuclear States Kenneth G Hanselman, Ingo L Wiedenhoever, Lagy T Baby, Kevin T Macon, Alexander S Volya, Juan C Esparza, Gordon W McCann, Vignesh Sitaraman, Eli S Temanson There is now a community-wide push in nuclear physics away from isotopic stability toward the nucleon driplines and the continuum beyond. As modern accelerator facilities grant access to nuclei near the driplines, it becomes necessary to study the effect of the continuum on nuclear excitations. New angular correlations of the 12C(3He,dp)12C reaction have been measured using the SE-SPS (Super-Enge Split-Pole Spectrograph) at FSU and a new silicon barrel array. Coupled asymmetric decay patterns from both the sharp low-lying doublet and the broad high-lying superradiant state of 13N have been observed and analyzed in the coupled-channels-fed grand density matrix formalism (CC-GDM). It will be shown that the CC-GDM method works well to study the structure of sharp, long-lived unbound states, but requires more complex hypotheses to describe the unexpected decay patterns of states with strong continuum coupling and short lifetimes. |
Saturday, October 29, 2022 3:12PM - 3:24PM |
LH.00007: High-spin spectroscopy of 64Cu Antonella Saracino, Akaa D Ayangeakaa, Nirupama Sensharma, Robert V Janssens, Q. B Chen, Michael P Carpenter, Partha Chowdhury, Alexandra Gade, C. R Hoffmann, Filip G Kondev, Torben Lauritsen, Elizabeth McCutchan, Andrew Rogers, Dariusz Seweryniak
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Saturday, October 29, 2022 3:24PM - 3:36PM |
LH.00008: Elastic and inelastic Compton scattering from deuterium at HIγS Danula Godagama, Michael A Kovash The electromagnetic scalar polarizabilities (α, β) are fundamental structure constants of the nucleon, and precise experimental measurements of these are vital for a complete understanding of the nucleon’s internal structure. The scalar polarizabilities can be accessed via Compton scattering reactions, where the forward-angle scattering cross sections are more sensitive to α+β, while the backward-angle cross sections are more sensitive to α-β. Since the value of α+β is alternately given in a model-independent manner by the well-known Baldin sum rule, backward-angle cross sections are sufficient to obtain the individual polarizability values. A series of Compton scattering experiments is underway at the High Intensity Gamma-Ray Source (HIγS) at Triangle Universities Nuclear Laboratory, with the goal of extracting the electromagnetic scalar polarizabilities of the neutron (αn, βn). Two experiments were performed using a liquid deuterium target at incident photon energies of 61 and 81 MeV. Backward-angle scattering cross sections were measured using two large-volume high-resolution NaI detectors (DIANA and BUNI). The combined effect of the quasi-monoenergetic beam at HIγS and the excellent energy resolution of these detectors was adequate to resolve the inelastic contribution at two backward angles (115o, 150o). Preliminary elastic and inelastic cross section data at both 61 and 81 MeV will be presented. |
Saturday, October 29, 2022 3:36PM - 3:48PM |
LH.00009: Study of 11Be excited states via the 10Be(d,p) reaction in SOLARIS with the AT-TPC Michael Serikow, Daniel Bazin, Nabin Rijal, Jie Chen, Wolfgang Mittig, Saul Beceiro-Novo, Yassid Ayyad, Clementine A Santamaria The commissioning of using transfer reactions in inverse kinematics in SOLARIS with the Active Target Time Projection Chamber (AT-TPC) was successfully completed in the summer of 2021 at the NSCL. The goal of this experiment was to establish the possibility to perform transfer reactions at low beam intensities (typically 1-2 kHz) using the high luminosity provided by the AT-TPC. A beam of 10Be was accelerated to about 9 MeV/u in the ReA6 linac and delivered to the AT-TPC placed in a 3 Tesla magnetic field provided by the SOLARIS solenoid. The AT-TPC was filled with pure deuterium gas at 600 Torr pressure. Although multiple reaction channels were simultaneously detected, we focus on the 10Be(d,p) channel that populates bound and unbound states in 11Be, with a particular interest towards a 3.41 MeV state for which the parity is still an open question. We present the preliminary analysis for the 10Be(d,p) channel and its Q-value spectrum as well as angular distributions for various populated final states. With the ability to perform transfer reaction measurements by the AT-TPC demonstrated, many exciting prospects exist to study utilizing the rare isotope reaccelerated beams at FRIB, which just recently began its DOE mission. |
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