Bulletin of the American Physical Society
2016 Fall Meeting of the APS Division of Nuclear Physics
Volume 61, Number 13
Thursday–Sunday, October 13–16, 2016; Vancouver, BC, Canada
Session NC: Nuclear Astro IV |
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Chair: Alan Chen, McMaster University Room: Junior Ballroom B |
Sunday, October 16, 2016 8:30AM - 8:42AM |
NC.00001: ABSTRACT WITHDRAWN |
Sunday, October 16, 2016 8:42AM - 8:54AM |
NC.00002: ABSTRACT WITHDRAWN |
Sunday, October 16, 2016 8:54AM - 9:06AM |
NC.00003: ABSTRACT WITHDRAWN |
Sunday, October 16, 2016 9:06AM - 9:18AM |
NC.00004: Role of Nucleon Strangeness in Core-Collapse Supernova Explosions Timothy Hobbs, Mary Alberg, Gerald Miller The ongoing quest to simulate explosions of core-collapse supernovae (CCSNe) in hydrodynamical calculations has placed an enormous premium upon the nuclear and hadronic processes integral to the system's evolution ({\it i.e.,} the {\it microphysics}). In this context, modifications to the neutrino-nucleon elastic cross section have been identified as potentially key to ensuring that stalled bounce shocks are sufficiently re-energized to produce the desired explosion. An important source of such corrections can be found in a negative value for the nucleon's strange helicity content $\Delta s$, which leads to the enhancement and suppression of the $\nu - p$ and $\nu -n$ total cross sections, respectively. In this talk, however, I summarize the results of a recent analysis which led to a comparatively small magnitude for the strange helicity ($\Delta s \ge -0.1$) --- a fact which renders nucleon strangeness an unlikely candidate for the decisive missing ingredient necessary in simulations for CCSN explosions. [Preview Abstract] |
Sunday, October 16, 2016 9:18AM - 9:30AM |
NC.00005: Heavy Photon Search Run and Results Update Holly Szumila-Vance The Heavy Photon Search (HPS) experiment at Jefferson Lab is searching for a hypothetical massive particle called the heavy photon which could mediate a dark electromagnetic-type force. If heavy photons kinetically mix with Standard Model photons, they may be radiated by electrons scattering from a heavy nucleus and then decay to $e^+$ $e^-$ pairs. HPS is uniquely suited to search for heavy photons that either decay at the target or a measurable distance after. The experiment utilizes a silicon vertex tracker for momentum and vertex reconstruction, together with an electromagnetic calorimeter for measuring particle energies and triggering events. The HPS experiment took its first data during the spring of 2015 using a 1 GeV electron beam incident on a tungsten target and completed a second run in the spring of 2016 at a beam energy of 2.3 GeV. This talk will describe detector and run details, along with preliminary results if they are available. [Preview Abstract] |
Sunday, October 16, 2016 9:30AM - 9:42AM |
NC.00006: Beta-delayed neutron spectroscopy using ion traps Barbara Wang, A. Czeszumska, K. Siegl, S. Caldwell, A. Aprahamian, M. Burkey, J. Clark, A. Levand, S. Marley, G. Morgan, E. Norman, A. Nystrom, R. Orford, S. Padgett, A. Perez Galvan, G. Savard, N. Scielzo, K. Sharma, S. Strauss Trapped radioactive ions suspended in vacuum allow for a new way to perform beta-delayed neutron spectroscopy. Decay branching ratios and energy spectra of the emitted neutrons are inferred from a measurement of the nuclear recoil, thereby circumventing the many limitations associated with direct neutron detection. Beta-delayed neutron measurements were carried out for \textsuperscript{137-138,140}I, \textsuperscript{134-136}Sb, and \textsuperscript{144-145}Cs at the Californium Rare Isotope Breeder Upgrade (CARIBU) facility at Argonne National Laboratory. The data collected are needed in many fields of basic and applied science such as nuclear energy, nuclear astrophysics, and stockpile stewardship. Results for the isotopes \textsuperscript{135-136}Sb and \textsuperscript{140}I will be presented. Supported by NSF under PHY-1419765, U.S. DOE under NEUP 13-5485, DE-AC02-06CH11357 (ANL), DE-AC52-07NA27344 (LLNL), and DE-NA0000979 (NNSA). [Preview Abstract] |
Sunday, October 16, 2016 9:42AM - 9:54AM |
NC.00007: Alpha Cluster States in $^{16}$O Bryce Frentz, Armen Gyurjinyan, Ethan Sauer, Wanpeng Tan, Anthony Battaglia, Andrew Nystrom, Clark Casarella, Mallory Smith, Patrick O'Malley, Scott Marley, Sabrina Strauss, Andre Bermundez-Perez, Benjamin Guerin, Patrick Fasano, Ani Aprahamian, Michael Febrarro, Ram\'{o}n Torres-Isea, Frederick Becchetti, Martin Freer, Gvirol Goldring The reaction $^{13}$C($\alpha$, n)$^{16}$O and the subsequent breakup of $^{16}$O was measured at the University of Notre Dame Nuclear Science Laboratory in order to explore states above the $4\alpha$ decay threshold in $^{16}$O thought to exhibit $\alpha$-cluster behavior. Locating and understanding these states is crucial to understanding the structure of light nuclei by providing stringent tests for nuclear models. Alpha clusters also play a significant role in stellar evolution because reaction rates for helium burning are sensitive to these structures. The charged particles were detected using four double-sided silicon strip detectors with 256 total channels while the neutrons were detected with 12 deuterated liquid scintillators. Details of the experimental setup, data analysis, and preliminary results will be presented. [Preview Abstract] |
Sunday, October 16, 2016 9:54AM - 10:06AM |
NC.00008: Constraints on the 72Kr rp-process waiting point A.M. Rogers, C. Anderson, J. Barney, J. Estee, W.G. Lynch, J. Manfredi, H. Setiawan, R.H. Showalter, S. Sweany, S. Tangwancharoen, M.B. Tsang, J.R. Winkelbauer, K.W. Brown, J.M. Elson, C. Pruitt, L.G. Sobotka, Z. Chajecki, J. Lee Weakly-bound or proton-unbound nuclei near the rp-process waiting points play a critical role in constraining calculations and observations of Type I x-ray bursts. For instance, the rp process is greatly slowed near ${}^{72}$Kr due to its relatively long $\beta$-decay half life and inhibited proton capture. The ${}^{72}$Kr waiting point, however, may be bypassed by sequential 2p-capture through ${}^{73}$Rb -- a reaction which is extremely sensitive to the ${}^{73}$Rb proton separation energy, $S_{\textrm{p}}$. While recent measurements of ${}^{65}$As and ${}^{69}$Br have reduced uncertainties in the reaction sequence, the ${}^{72}$Kr waiting point still remains unconstrained. Using invariant-mass spectroscopy, we have performed an experiment at NSCL to measure the decay of ${}^{73}$Rb$\rightarrow$p+${}^{72}$Kr in an attempt to determine $S_{\textrm{p}}({}^{73}\textrm{Rb})$ directly for the first time. Results from our recent ${}^{73}$Rb decay experiment will be presented. [Preview Abstract] |
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