Bulletin of the American Physical Society
APS April Meeting 2013
Volume 58, Number 4
Saturday–Tuesday, April 13–16, 2013; Denver, Colorado
Session R3: Invited Session: New Perspectives in Neutrino Physics |
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Sponsoring Units: DNP Chair: John Wilkerson, University of North Carolina at Chapel Hill Room: Plaza E |
Monday, April 15, 2013 1:30PM - 2:06PM |
R3.00001: Latest Results from the Daya Bay Experiment Invited Speaker: Robert McKeown |
Monday, April 15, 2013 2:06PM - 2:42PM |
R3.00002: Results and Prospects of Neutrinoless Double Beta Decay Search with EXO Invited Speaker: Liang Yang The Enriched Xenon Observatory (EXO) is an experimental program, which aims to perform the most sensitive search for neutrinoless double beta decay using $^{136}$Xe. Such a search can shed light on the Majorana nature of the neutrino (whether the neutrino is its own anti-particle), the absolute mass scale of neutrinos, and beyond standard model processes that violate lepton number conservation. The first phase of the experiment, EXO-200, uses 200 kg of xenon with 80\% enrichment in $^{136}$Xe in a single-phase liquid xenon time projection chamber (TPC). The double beta decay of xenon is detected in the ultra-low background TPC by collecting both the scintillation light and the ionization charge. The detector has been taking low background physics data with enriched xenon at the Waste Isolation Pilot Plant (WIPP) in New Mexico since early May 2011. The collaboration has produced two high impact physics results, the first observation of two-neutrino double beta decay of $^{136}$Xe and a neutrinoless double beta decay search result that places one of the most stringent limits on the effective Majorana neutrino mass. Building on the success of EXO-200, the collaboration is performing feasibility studies and R\&D work for a future multi-tonne scale experiment named nEXO. During the talk, I will discuss the latest results from EXO-200 and prospects of neutrinoless double beta decay search with both EXO-200 and nEXO. [Preview Abstract] |
Monday, April 15, 2013 2:42PM - 3:18PM |
R3.00003: Neutrinos And Big Bang Nucleosynthesis Invited Speaker: Gary Steigman According to the standard models of particle physics and cosmology, the present Universe is filled with a background of cosmic neutrinos, similar to the cosmic microwave photon background. Due to the weakness of the weak interactions, this neutrino background is undetectable with current technology. The cosmic neutrino background can be probed indirectly through its cosmological effects on big bang nucleosynthesis (BBN) and the cosmic microwave background (CMB) radiation. In this talk, focused on neutrinos and ``dark radiation,'' the BBN constraints on the number of ``equivalent neutrinos'' (dark radiation), on the universal baryon asymmetry, and on a possible lepton asymmetry (neutrino degeneracy) are reviewed and updated. The BBN constraints on dark radiation and on the baryon density are in excellent agreement with the complementary results from the CMB, providing a suggestive, but currently inconclusive, hint of the presence of dark radiation and, they constrain any lepton asymmetry. For all the cases discussed here there is a ``lithium problem'': the BBN-predicted lithium abundance exceeds the observationally inferred primordial value by a factor of $\sim$3. [Preview Abstract] |
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