Bulletin of the American Physical Society
2012 Fall Meeting of the APS Division of Nuclear Physics
Volume 57, Number 9
Wednesday–Saturday, October 24–27, 2012; Newport Beach, California
Session DF: Nuclear Astrophysics: New Approaches |
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Chair: Hendrik Schatz, NSCL, Michigan State University Room: Garden III |
Thursday, October 25, 2012 10:30AM - 10:42AM |
DF.00001: One-proton knockout reactions on psd-shell nuclei for relevant reaction rates in explosive Hydrogen burning processes Adriana Banu I will discuss the use of one-proton removal reactions at intermediate energies as an indirect method in nuclear astrophysics to infer stellar reaction rates with astrophysical implications for explosive hydrogen burning processes. I will refer in particular to the results of a recent experiment carried out at GANIL for a cocktail of secondary ion beams around 23Al impinging on a carbon target at 50 MeV/nucleon. The longitudinal momentum distributions of one-proton knockout fragments will be reported in comparison with extended Glauber calculations. Determination of corresponding spectroscopic factors and asymptotic normalization coefficients will be presented. [Preview Abstract] |
Thursday, October 25, 2012 10:42AM - 10:54AM |
DF.00002: Proton-transfer studies of astrophysically-interesting nuclei using the JENSA gas-jet target D.W. Bardayan, S.D. Pain, S.T. Pittman, K. Schmitt, M.S. Smith, K. Chipps, U. Greife, J. Browne, A. Kontos, F. Montes, H. Schatz, J.C. Blackmon, L. Linhardt, M. Matos, K.L. Jones Explosive hydrogen burning occurring in novae and x-ray bursts produce and involve reactions on proton-rich radioactive nuclei that have scarcely been studied in the laboratory. Exotic beam facilities are required to study many of these nuclei but beam intensities are not typically high enough to measure the reactions of interest directly. An alternative to directly measuring proton capture is to study proton transfer reactions such as ($^3He,d$). The JENSA gas jet target is being constructed at ORNL to produce a localized target of $^3$He to facilitate such studies. The JENSA target will be described along with plans for its use at the ReA3 facility at the NSCL. [Preview Abstract] |
Thursday, October 25, 2012 10:54AM - 11:06AM |
DF.00003: Studies of $^{18}$Ne using ANASEN L.E. Linhardt, J.C. Blackmon, H.E. Gardiner, M. Matos, B.C. Rasco, K.T. Macon, D. Santiago-Gonzalez, L. Baby, E. Koshchiy, E.D. Johnson, I. Wiedenhoever, G. Rogachev, D.W. Bardayan Efficient and selective techniques are required to study reactions important in stellar explosions with radioactive ion beams. The Array for Nuclear Astrophysics Studies with Exotic Nuclei (ANASEN) is designed to study charged-particle reactions important in the $\alpha $p- and rp- processes with essentially complete solid angle coverage using an array of 40 silicon-strip detectors backed with CsI scintillators, covering an area of roughly 1300 cm$^{2}$. ANASEN also includes an active gas target/detector using a position-sensitive annular gas proportional counter that allows direct measurement of ($\alpha $,p) reactions in inverse kinematics. Results from some of the first measurements using a partial implementation of ANASEN at the RESOLUT radioactive ion beam facility will be presented, focusing on measurements of ~$^{17}$F(p,p)$^{17}$F and $^{17}$F(p,$\alpha )^{14}$O reactions that are important to understanding the structure of $^{18}$Ne and the $^{14}$O($\alpha $,p)$^{17}$F reaction rate. [Preview Abstract] |
Thursday, October 25, 2012 11:06AM - 11:18AM |
DF.00004: Development of Solenoid Spectrometer for Nuclear Astrophysics Xiao Fang, Brian Bucher, Alan Howard, Yunju Li, James Kolata, Amy Roberts, Xiaodong Tang A Helios-type solenoid spectrometer has been successfully built using the existing TWINSOL facility at Notre Dame. This spectrometer has been tested using the $^{12}$C+$^{12}$C~fusion reaction in the energy of range of 4~MeV to 6~MeV in the center of mass frame. With this spectrometer, we have achieved 65 keV(FWHM) resolution for the excitation energy. A measurement with a clean background has been achieved at Ecm=4~MeV by using an aluminum degrader to absorb the scattered 12C particle. The preliminary result together with our future plan will be presented. [Preview Abstract] |
Thursday, October 25, 2012 11:18AM - 11:30AM |
DF.00005: Uncertainties in Astrophysical Capture Rate Calculations Michael Bertolli Astrophysical capture rates can be calculated within the framework of Hauser-Feshbach theory for nuclei for which there is no experimental data. However, there remain large uncertainties in the calculations. We investigate these uncertainties and demonstrate their effect on nucleosynthesis simulations. [Preview Abstract] |
Thursday, October 25, 2012 11:30AM - 11:42AM |
DF.00006: Neutron background characterization of deep underground laboratories Andreas Best, Joachim G\"orres, Alex Long, Karl Smith, Ed Stech, Michael Wiescher Low-energy $(\alpha,n)$ reactions in stellar helium and carbon burning provide the neutrons for the formation of elements beyond iron by the slow neutron capture process. The very low cross sections at stellar energies necessitate the use of high-efficiency detectors as well as measuring in a very low neutron background environment. By going deep underground the neutron flux can be reduced by orders of magnitude compared to surface levels, enabling the measurement of reactions for nuclear astrophysics at previously inaccessible energies. The remaining neutron flux is mostly due to spontaneous fission of $^{238}$U in the cavity walls and $(\alpha, n)$ reactions induced by $\alpha$-particles from the natural radioactivity of the underground environment. Using a portable setup consisting of 4 $^3$He counters and polyethylene moderators the DIANA collaboration is conducting neutron background measurements at various deep underground laboratories in the US. We present first results from the Kimballton Underground Research Facility, the Soudan Underground Laboratory and the 4100 feet level of the Sanford Undeground Research Facility (SURF). Measurements at other depths in SURF and at the Waste Isolation Pilot Plant are in planning. [Preview Abstract] |
Thursday, October 25, 2012 11:42AM - 11:54AM |
DF.00007: ABSTRACT HAS BEEN MOVED TO KC.00010 |
Thursday, October 25, 2012 11:54AM - 12:06PM |
DF.00008: Is cosmic expansion of the universe accelerating? D.C. Choudhury Currently available Type Ia distant supernovae observed data appear to support the evidence that cosmic expansion of the universe is accelerating. The new concept advanced to account for the acceleration is dark energy, although there has been no laboratory confirmation of it. Hence, the present investigation analyzes the consequences of Thomson scattering on Type Ia supernovae data for two significant reasons; (i) very recently observed data reveal the existence of sufficient amount of ionized baryonic (hydrogen) dark matter in the intergalactic medium, a necessary ingredient for Thomson scattering, and (ii) its effects have not been considered earlier in determining distances to the supernovae from their observed distance moduli. Quantitative results of the present investigation based on observed data and corrected for Thomson scattering are in excellent agreement with the prediction of Hubble expansion of the universe. [Preview Abstract] |
Thursday, October 25, 2012 12:06PM - 12:18PM |
DF.00009: ABSTRACT WITHDRAWN |
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