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 PB: Mini-Symposium on Nuclear Astrophysics in Cosmology - BBN, First Stars, and Type-1a SN |
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Chair: Richard Cyburt, NSCL, Michigan State University Room: Plaza II |
Saturday, October 27, 2012 10:30AM - 11:06AM |
PB.00001: The Universe as an Accelerator: The Primordial Lithium Problem and Dark Matter Invited Speaker: Brian Fields The sciences of outer space and inner space -- cosmology and nuclear/particle physics -- are converging. The early universe is a central arena for this interplay, and big-bang nucleosynthesis is particularly important because it represents our earliest reliable cosmic probe. We will summarize the current status of nucleosynthesis and the transformative influence of the WMAP determination of the cosmic baryon density. WMAP and nucleosynthesis theory make tight predictions for the primordial abundances of the lightest nuclides: deuterium observations agree spectacularly with these predictions, but lithium observations are significantly discrepant--this is the ``lithium problem.'' Moreover, the cosmic baryon density is now well-determined by nucleosynthesis and WMAP, and implies that the bulk of cosmick matter must take an exotic ``non-baryonic'' form. The existence of non-baryonic dark matter immediately demands particles and possibly interactions beyond the Standard Model of elementary particle physics. We will discuss ongoing and future searches for particle dark matter. Finally, we will discuss the possibility that Supersymmetry can lead to dark matter interactions which can affect nucleosynthesis and possibly solve the lithium problem. [Preview Abstract] |
Saturday, October 27, 2012 11:06AM - 11:18AM |
PB.00002: Hoyle reloaded: a nuclear fix to the cosmological lithium abundance? Richard Cyburt There is a significant discrepancy between the current theoretical prediction of the cosmological lithium abundance, produced as Be7 during the Big Bang, and its observationally inferred value. We investigate whether the resonant enhancement of Be7 burning reactions may alleviate this discrepancy. We identify one narrow nuclear level in B9, E(5/2+)$\sim $16.7 MeV that is not sufficiently studied experimentally, and being just $\sim $200 keV above the Be7+d threshold, may lead to the resonant enhancement of Be7(d,gamma)B9 and Be7(d,pa)He4 reactions. We determine the relationship between the domain of resonant energies Er and the deuterium separation width Gamma(d) that results in the significant depletion of the cosmological lithium abundance and find that Er, Gamma(d)$\sim $(170-220,10-40) keV can eliminate current discrepancy. Such a large width at this resonant energy can be only achieved if the interaction radius for the deuterium entrance channel is very large, a$>$9 fm. Our results also imply that until dedicated nuclear experimental work is done to clarify the role played by this resonance, the current conservative BBN prediction of lithium abundance should carry significantly larger error bars, [Li7/H]=(2.5-6.0)E-10. [Preview Abstract] |
Saturday, October 27, 2012 11:18AM - 11:30AM |
PB.00003: One fewer solution to the cosmological lithium problem Barry Davids, Oliver Kirsebom Data from a recent $^9$Be$(^3$He,$t)^9$B measurement are used to rule out a possible solution to the cosmological lithium problem based on resonant destruction of $^7$Be. [Preview Abstract] |
Saturday, October 27, 2012 11:30AM - 11:42AM |
PB.00004: Search for resonant enhancement of the $^{7}$Be+d reaction Patrick O'Malley, Dan Bardayan, Aderemi Adekola, Sunghoon Ahn, Kyungyuk Chae, Jolie Cizewski, Meredith Howard, Kate Jones, Raymond Kozub, Milan Matos, Brian Moazen, Caroline Nesaraja, Steve Pain, William Peters, Stephen Pittman, Fred Sarazin, Kyle Schmitt, John Shriner, Michael Smith, Irena Spassova $^{7}$Li abundances in the early universe, deduced from extrapolated observations, are several standard deviations lower than that estimated by Big Bang Nucleosynthesis calculations constrained by WMAP. Since most $^{7}$Li is produced by the beta decay of $^{7}$Be, one proposed solution to this long-standing puzzle is a resonant enhancement of the $^{7}$Be(d,p)2$\alpha $ reaction rate via the 5/2$^{+}$ 16.7-MeV state in $^{9}$B. The $^{7}$Be(d,d) reaction was studied at Oak Ridge National Laboratory to search for such a resonance. This was performed in inverse kinematics using a 10-MeV radioactive $^{7}$Be beam and a thick CD$_{2}$ target. The experimental data and results will be discussed. [Preview Abstract] |
Saturday, October 27, 2012 11:42AM - 11:54AM |
PB.00005: Studies in the Big Bang Nucleosynthesis of Lithium Isotopes Grant Mathews, Toshitaka Kajino, Motohiko Kusakabe There has been a lingering puzzle in that the $^6$Li abundance observed in metal poor halo stars appears to exhibit a plateau as a function of metallicity similar to that for $^7$Li. This suggests a possible big bang origin for $^6$Li. However, becauuse the radiative capture of a deutron by and alpha particle during the big bang is suppressed, it is difficult to explain this observed $^6$Li abundance. At the same time the observed $^7$Li abundance is below that expected from BBN. In this talk we summarize a variety of approaches by which we have attempted to explain this observation. Among the possibilities are uncertainties in the stellar astrophysics of lithium isotope detection, galactic chemical evolution, effects from a massive charged or uncharged unstable relic supersymmetric particle present during BBN, or a time variation of fundamental constants. We show that it is possible, but difficult, to obtain a simultaneous solution to both the problems of underproduction of $^6$Li and overproduction of $^7$Li in a single paradigm. [Preview Abstract] |
Saturday, October 27, 2012 11:54AM - 12:06PM |
PB.00006: Active and Sterile Neutrinos, Neff, and Primordial Nucleosynthesis Evan Grohs, George Fuller, Chad Kishimoto We present self-consistent calculations of energy transport, primordial nucleosynthesis, sterile neutrino oscillations and/or decay in the early universe. We discuss using the results of these calculations in combination with cosmic microwave background and large scale structure observations to constrain neutrino properties. [Preview Abstract] |
Saturday, October 27, 2012 12:06PM - 12:18PM |
PB.00007: ABSTRACT WITHDRAWN |
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