Bulletin of the American Physical Society
2013 Fall Meeting of the APS Division of Nuclear Physics
Volume 58, Number 13
Wednesday–Saturday, October 23–26, 2013; Newport News, Virginia
Session NG: Nuclear Structure V |
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Chair: Steven Yates, University of Kentucky Room: Pearl Ballroom II |
Saturday, October 26, 2013 8:30AM - 8:42AM |
NG.00001: Precise $\beta^{-}$- and $\gamma$-ray emission probabilities in the decay of $^{67}$Cu Jun Chen, Filip Kondev, Irshad Ahmad, Michael Carpenter, David Ehst, John Greene, Vakhtang Makarashivili, Nick Smith, Shaofei Zhu The $^{67}$Cu radionuclide has a potential for wide applications in cancer therapy and SPECT imaging. However, important decay properties that impact those applications are determined from a single measurement that was carried out about 60 years ago and reported without any uncertainties [1]. We have performed new measurements using chemically-purified $^{67}$Cu sources, produced via the $^{68}$Zn($\gamma$,p) reaction [2], in conjunction with the $\gamma$-ray spectroscopy technique. Both single and $\beta\gamma$-coincidence experiments were carried out using LEPS ($\gamma$ rays) and PIPS ($\beta^{-}$ and CE) detectors. Absolute $\beta^{-}$ and $\gamma$-ray emission probabilities were determined and those were found to differ significantly compared to the previously adopted values. The details of those measurements will be presented and their impact on the application of $^{67}$Cu as a therapeutic radionuclide in cancer therapy, as well as on various production-reaction cross sections, will be discussed. \\[4pt] [1] H.T. Easterday, Phys. Rev. 91, 653 (1953).\\[0pt] [2] N.A. Smith, D.L. Bowers and D.A. Ehst, Appl. Radiat. Isot. 70, 2377 (2012). [Preview Abstract] |
Saturday, October 26, 2013 8:42AM - 8:54AM |
NG.00002: Dipole Resonances of $^{76}$Ge R.S. Ilieva, N. Cooper, V. Werner, G. Rusev, N. Pietralla, J.H. Kelly, W. Tornow, S.W. Yates, B.P. Crider, E. Peters Dipole resonances in $^{76}$Ge have been studied using the method of Nuclear Resonance Fluorescence (NRF). The experiment was performed using the Free Electron Laser facility at HI$\gamma$S/TUNL, which produced linearly polarised quasi-monoenergetic photons in the 4-9 MeV energy range. Photon strength, in particular dipole strength, is an important ingredient in nuclear reaction calculations, and recent interest in its study has been stimulated by observations of a pygmy dipole resonance near the neutron separation energy $S_n$ of certain nuclei. Furthermore, $^{76}$Ge is a candidate for $0\nu2\beta$-decay. The results are complimentary to a relevant experiment done at TU Darmstadt using Bremsstrahlung beams. Single-resonance parities and a preliminary estimate of the total photo-excitation cross section will be presented. [Preview Abstract] |
Saturday, October 26, 2013 8:54AM - 9:06AM |
NG.00003: Deformation and shape coexistence in $^{66,70}$Ni and $^{69,71}$Cu nuclei near N $=$ 40 W.B. Walters, J. Harker, C.J. Chiara, R.V.F. Janssens, M. Albers, M. Alcorta, P.F. Bertone, M.P. Carpenter, C.R. Hoffman, F.G. Kondev, T. Lauritsen, A.M. Rogers, D. Seweryniak, S. Zhu, R. Broda, B. Fornal, W. Krolas, J. Wrzesinski, N. Larson, S.N. Liddick, C. Prokop, S. Suchyta, H.M. David, D.T. Doherty New data will be presented for the levels of $^{66,70}$Ni and $^{69,71}$Cu that extend some of the previously indicated features of deformation and shape coexistence in this region. [R. Broda et al., Phys. Rev. C 86, 064312 (2012)] Excited states in these nuclei were populated through multinucleon-transfer reactions using $^{70}$Zn beams provided by the ATLAS facility at ANL. In particular, possible structure associated with the 0$_{3}^{+}$ level in $^{66}$Ni will be discussed. New levels will be presented in $^{69,71}$Cu that extend the 2-particle-1-hole structures to higher energy and spin. [C. J. Chiara et al., Phys. Rev. C 85, 024309 (2012)] Data will be presented that support the placement of a new level in $^{70}$Ni at 2912 keV with a spin and parity of (5-). [Preview Abstract] |
Saturday, October 26, 2013 9:06AM - 9:18AM |
NG.00004: Shape coexistence in $^{68}$Ni S. Suchyta, S. Liddick, M. Bennet, N. Larson, C. Prokop, S. Quinn, A. Spyrou, A. Chemey, A. Simon, T. Otsuka, Y. Tsunoda, N. Shimizu, M. Honma, Y. Utsuno, V. Tripath, J. VonMoss $^{68}$Ni has been a focus of recent work aiming to understand the apparent rapid development of collectivity along neutron-rich $N=$40 nuclei, but despite many studies, is not entirely understood. The decay of the first excited 0$^{+}$ state in $^{68}$Ni was investigated at the NSCL. Ions of $^{68}$Co were implanted into a planar germanium double-sided strip detector (GeDSSD). The beta decay of $^{68}$Co populated the first excited 0$^{+}$ state in $^{68}$Ni and within hundreds of nanoseconds the decay of the first excited 0$^{+}$ state was measured in the GeDSSD. Both the energy of the first excited 0$^{+}$ state and the electric monopole transition strength from the first excited 0$^{+}$ state were precisely determined. Comparisons to Monte Carlo Shell Model calculations suggest shape coexistence between spherical ground and oblate first excited 0$^{+}$ states in $^{68}$Ni. The experimental results and theoretical interpretation will be presented. [Preview Abstract] |
Saturday, October 26, 2013 9:18AM - 9:30AM |
NG.00005: First study of neutron-transfer onto neutron-rich $^{80}$Ge S. Ahn, K.L. Jones, S.T. Pittman, G. Arbanas, D.W. Bardayan, K.Y. Chae, C.D. Nesaraja, S.D. Pain, M.S. Smith, A.S. Adekola, J.A. Cizewski, S. Hardy, M.E. Howard, B. Manning, P.D. O'Malley, W.A. Peters, I. Spassova, K.A. Chipps, J.C. Blackmon, M. Matos, B.C. Rasco, R.L. Kozub Sensitivity studies have shown that the individual neutron capture rates and the structure of exotic nuclei near neutron closed shells are particularly important for constraining models of rapid neutron capture nucleosynthesis. Currently, there is little experimental data for the relevant unstable nuclei such as $^{81}$Ge. The low-lying levels of the $N$ = 49 nucleus $^{81}$Ge have been studied by the first neutron transfer measurement on beams of exotic $^{80}$Ge nuclei at 310~MeV (3.875~MeV/u) in inverse kinematics at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. The excitation energies and the angular distributions of low-lying levels were measured, and neutron capture cross sections on $^{80}$Ge have been calculated in a direct-semidirect model. The experimental setup and the preliminary results will be presented. [Preview Abstract] |
Saturday, October 26, 2013 9:30AM - 9:42AM |
NG.00006: Beta-decay spectroscopy of neutron-rich 84-86Ga isotopes Farheen Naqvi, Zhengyu Xu, Volker Werner, Megumi Niikura, Shunji Nishimura The low lying excited states in 84-86Ge were studied via the beta-gamma spectroscopy of 84-86Ga nuclei. The study focused on the beta-delayed neutron emission probabilities and the beta-decay lifetimes, relevant for the astrophysical r process path in the region. The neutron-rich Ga isotopes were produced by in-flight fragmentation of 238U beam on a 9Be target. The experiment was performed at the Radioactive Ion Beam Facility (RIBF) at RIKEN, Japan. The BigRIPS spectrometer was utilized to identify and separate the reaction residues and the ions of interest were implanted in a segmented Si detector array called WASABI. Gamma rays emitted after the beta decay were identified by the EURICA array. Results of the ongoing analysis will be presented. [Preview Abstract] |
Saturday, October 26, 2013 9:42AM - 9:54AM |
NG.00007: Total Absorption Spectroscopy of N=51 85Se K.C. Goetz, K.P. Rykaczewski, R.K. Grzywacz, M. Karny, M. Woli\'nska-Cichocka, A. Fija{\l}kowska, C.J. Gross, B.C. Rasco, R. Goans, J. Johnson, D. Miller, C. Jost, M. Madurga, K. Miernik, S.V. Paulauskas, M. Al-Shudifat, E. Spejewski, D. Stracener, E. Zganjar An experimental campaign utilizing the Modular Total Absorption Spectrometer (MTAS) was conducted at the HRIBF facility in January of 2012. The campaign studied 22 isotopes, many of which were identified as high priority needs for nuclear energy applications in the Nichols et al. report [1]. The case of 85Se will be discussed. 85Se is a Z=34, N=51 nucleus, therefore its decay properties are determined by interplay between first forbidden decays of valence neutrons and Gamow-Teller decay. Preliminary analysis indicates a significant modification of the beta strength function when compared with high-resolution spectroscopy data [2]. The modification of the beta-strength function appears as a group of previously undetected levels around 5.5 MeV suggesting previously unobserved core excitations. \\[4pt] [1] A.L. Nichols ``Nuclear Data Requirements for Decay Heat Calculation'' Workshop 2002\\[0pt] [2] M. Zendel ``Decay of 85-88Se to levels in 85-88Br'' Nucl.Chem.Vol42, p1387-1395,1980. [Preview Abstract] |
Saturday, October 26, 2013 9:54AM - 10:06AM |
NG.00008: Nuclear level densities of 64,66Zn from neutron evaporation Anthony Paul Ramirez, Alexander Voinov, Steven Grimes, Carl Brune, Thomas Massey The neutron spectra from the reactions $^{63}$Cu(d,n)$^{64}$Zn and $^{65}$Cu(d,n)$^{66}$Zn have been measured at deuteron beam energies of 6 and 7.5 MeV. Level densities of the residual nuclei $^{64}$Zn and $^{66}$Zn were extracted and compared with different level density models: (1) Gilbert-Cameron model, (2) Backshifted Fermi gas model using the Egidy systematics, and (3) microscopic combinatorial level densities. We found that the Gilbert-Cameron model closely agrees with the experimental results. We have also studied the non-compound component of the reactions from the neutron angular distributions. The non-compound component has been shown to be dominant in forward angles and is more pronounced at high neutron emission energies. We have also observed a slight enhancement of the non-compound contribution as the incident deuteron energy is increased. [Preview Abstract] |
Saturday, October 26, 2013 10:06AM - 10:18AM |
NG.00009: A Compact Magnetic Cloaking Device for Future Collider Experiments Benjamin Coe, Klaus Dehmelt, Abhay Deshpande, Nils Feege Accelerator-based nuclear physics experiments need detectors capable of measuring momenta of charged particles in the very far forward direction from the interaction point. This requires a uniform magnetic field close to and perpendicular to the collider's beam pipe. If there were a magnetic field inside the beam pipe, however, it would displace and depolarize the (charged, polarized) colliding beams. It has been demonstrated, although on a small scale, that a magnetic cloaking device combining a superconducting layer and a ferromagnetic layer can maintain a uniform magnetic field outside while creating a field-free region within. We present the design of a device based on the idea, which meets the size and magnetic field shielding requirements for a detector for the Electron Ion Collider (EIC). We report on the progress towards building a functional prototype. [Preview Abstract] |
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