Bulletin of the American Physical Society
APS April Meeting 2013
Volume 58, Number 4
Saturday–Tuesday, April 13–16, 2013; Denver, Colorado
Session G9: Neutrino Mass and Oscillation Experiments |
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Sponsoring Units: DNP Chair: Carter Hall, University of Maryland Room: Governor's Square 11 |
Sunday, April 14, 2013 8:30AM - 8:42AM |
G9.00001: Status of the KATRIN Neutrino Mass Experiment Diana Parno The kinematics of tritium beta decay provide a model-independent way to measure the mass of the neutrino in the quasi-degenerate regime. The Karlsruhe Tritium Neutrino experiment (KATRIN), presently under construction in Germany, will attain a sensitivity of 0.2 eV in the neutrino mass. We will provide an update on the status of KATRIN, whose spectrometer-and-detector section has entered a major commissioning phase. [Preview Abstract] |
Sunday, April 14, 2013 8:42AM - 8:54AM |
G9.00002: Tritium neutrino mass experiments: measuring the molecular dissociation probability Laura Bodine, Diana Parno, R.G. Hamish Robertson The next generation of tritium-based neutrino mass experiments (e.g.\ KATRIN, Project8) requires a comprehensive understanding of the distribution of molecular states excited in the decay. The distribution and the resulting dissociation probability have recently been calculated to high precision. Two dissociation experiments from the 1950s disagree with the modern predictions and further study is needed to resolve the discrepancy and validate the calculations. The Tritium Recoil-Ion Mass Spectrometer is designed to measure the molecular tritium branching ratio to the bound molecular ion $^3$HeT$^+$ using a novel approach. [Preview Abstract] |
Sunday, April 14, 2013 8:54AM - 9:06AM |
G9.00003: Precise Measurement of Branching-Ratios in the $\beta$ decay of $^{38}$Ca H.I. Park, J.C. Hardy, V.E. Iacob, M. Bencomo, L. Chen, V. Horvat, N. Nica, E. Simmons, B.T. Roeder, R.E. Tribble Precise measurements of ft values for superallowed Fermi beta decays currently provide the most demanding test of the conserved vector current hypothesis and lead to the most precise value of $V_{ud}$, the up-down quark-mixing element of the Cabibbo-Kobayashi-Maskawa matrix. One of the key elements in obtaining $V_{ud}$ is an accurate calculation of small nuclear-structure-dependent corrections that must be applied to each experimental ft value leading to a value for the vector coupling constant, $G_{V}$. Uncertainties in these calculations contribute significantly to the uncertainty in $V_{ud}$ at the present level of experimental precision. However, these theoretical uncertainties can be reduced if the corrections are experimentally validated by measurements of previously uncharacterized transitions with large predicted correction terms such as from $^{38}$Ca. We report here the first measurement of the superallowed branching ratio from $^{38}$Ca with a precision of 0.1\%. This completes the data required for a precise ft-value result for this new contributor to the determination of $V_{ud}$. [Preview Abstract] |
Sunday, April 14, 2013 9:06AM - 9:18AM |
G9.00004: Status of the Project 8 Prototype Noah Oblath The Project 8 experiment aims to measure the neutrino mass using tritium beta decays. Beta-decay electron energies will be measured with a novel technique: as the electrons travel in a uniform magnetic field their cyclotron radiation will be detected. The frequency of each electron's cyclotron radiation is inversely proportional to its total relativistic energy; therefore, by observing the cyclotron radiation we can make a precise measurement of the electron energies. The advantages of this technique include scalability, excellent energy resolution, and low backgrounds. The collaboration is using a prototype experiment to study the feasibility of the technique with a $^{83m}$Kr source. Demonstrating the ability to see the 17.8~keV and 30.2~keV conversion electrons from $^{83m}$Kr will show that it is possible to measure tritium beta-decay electron energies ($Q \approx 18.6$~keV) with their cyclotron radiation. Progress on the prototype, analysis and signal-extraction techniques, and an estimate of the potential future of the experiment will be discussed. This research is supported in part by DOE grant DE-FG02-97ER41020 and the National Science Foundation. [Preview Abstract] |
Sunday, April 14, 2013 9:18AM - 9:30AM |
G9.00005: Cosmic muon induced neutrons at Daya Bay Shih-Kai Lin Cosmic muon induced neutrons and radioactive isotopes are a background for experiments such as neutrino oscillation, double beta decay and dark matter searches. The Daya Bay reactor neutrino experiment is equipped with a highly efficient muon tagging system which is composed of resistive plate chambers (RPCs) and water Cherenkov detectors, from which muon tracks are promising to be reconstructed within tens of centimeters. With reconstructed muon tracks, important physical quantities of cosmic muon induced neutrons could be measured. [Preview Abstract] |
Sunday, April 14, 2013 9:30AM - 9:42AM |
G9.00006: Cosmogenic $^{9}\mathrm{Li}$ and $^{8}\mathrm{He}$ Backgrounds Measured at the Daya Bay Experiment Hin-Lok Henoch Wong The unstable $^{9}\mathrm{Li}$ and $^{8}\mathrm{He}$ isotopes, produced through the interaction of cosmic-ray muons with carbon nuclei of the liquid scintillators in the antineutrino detectors, constitute one of the most important sources of background for the Daya Bay Reactor Neutrino Experiment. The experiment with the main goal of making a precise determination of the neutrino mixing angle $\theta_{13}$ is composed of eight identical detectors immersed in water pools underground that provide active shielding against muons. Such a configuration attenuates the muons to a low-enough level that allows for a direct measurement of this source of background to be made in-situ. This talk will give an overview of how the $^{9}\mathrm{Li}$ and $^{8}\mathrm{He}$ backgrounds are measured at Daya Bay. [Preview Abstract] |
Sunday, April 14, 2013 9:42AM - 9:54AM |
G9.00007: Characterizing Energy Response of the Daya Bay Detectors Bryce Littlejohn The Daya Bay reactor $\overline{\nu}_e$ experiment has provided the most sensitive measurement of the neutrino mixing parameter $\sin^22\theta_{13}$=0.089$\pm$0.01(stat)$\pm$0.005(sys) by measuring relative differences in neutrino interaction rates between near and far detectors. In order to measure the energy spectrum distortion characteristically accompanying neutrino oscillation, the energy response of Daya Bay detectors and spectral characteristcs of the Daya Bay reactors must be precisely understood. This talk will describe analysis done to characterize the detector response of the Daya Bay detectors, particularly the energy response's relative and absolute scales, non-linearity, and non-uniformity with position. This information can be used to predict the reconstructed $\overline{\nu}_e$ energy spectrum at near and far Daya Bay detectors, which is necessary for a rate+shape oscillation analysis and measurement of the neutrino parameters $\theta_{13}$ and $\Delta m^2_{32}$. [Preview Abstract] |
Sunday, April 14, 2013 9:54AM - 10:06AM |
G9.00008: Liquid Scintillator Light Yield Measurements for the SNO+ Experiment Sean Grullon The SNO+ experiment is the follow-up to the Sudbury Neutrino Observatory (SNO). The heavy water that was in SNO will be replaced with a liquid scintillator of linear alkylbenzene. SNO+ will have a broad physics program which will include measuring the pep and CNO solar neutrino flux, detecting geo-neutrinos, studying reactor neutrino oscillations, serving as a supernova neutrino detector, and carrying out a search for neutrinoless double beta decay by loading an isotope such as neodymium into the liquid scintillator. Since energy resolution is of profound importance for the experiment, it is extremely important to accurately measure the light yield of the liquid scintillator for different loading percentages of Neodymium. A series of measurements made comparing the relative light yields of different liquid scintillator configurations to a Cherenkov spectrum will be described. [Preview Abstract] |
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