Bulletin of the American Physical Society
APS April Meeting 2016
Volume 61, Number 6
Saturday–Tuesday, April 16–19, 2016; Salt Lake City, Utah
Session M10: Low-energy Neutrino Physics |
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Sponsoring Units: DNP Chair: Ralph Massarczyk, LANL Room: 250B |
Sunday, April 17, 2016 3:30PM - 3:42PM |
M10.00001: Project 8: Single-Electron Spectroscopy via Relativistic Cyclotron Radiation Luiz de Viveiros The Project 8 experiment seeks to determine the neutrino mass via the precise measurement of the electron energy in beta decays. We have developed a novel technique called Cyclotron Radiation Emission Spectroscopy (CRES), which allows single electron detection and characterization through the measurement of cyclotron radiation emitted by magnetically-trapped electrons produced by a gaseous radioactive source. The advantages of this technique include scalability, excellent energy resolution, and low backgrounds. A prototype using a waveguide-coupled $^{83\mathrm{m}}$Kr source in a $1~\mathrm{T}$ magnetic field was constructed, and used to demonstrate the viability of this technique. We have recently reported the first observation and measurement of single-electron cyclotron radiation, emitted by the internal conversion electrons (at $17.8~\mathrm{keV}$ and $30.4~\mathrm{keV}$) released in the decay of $^{83\mathrm{m}}$Kr. We present the latest results of the ongoing prototype run, with a focus on signal detection and analysis techniques leading to an improved energy resolution of $O(1~\mathrm{eV})$. [Preview Abstract] |
Sunday, April 17, 2016 3:42PM - 3:54PM |
M10.00002: Project 8: Towards cyclotron radiation emission spectroscopy on tritium Martin Fertl Project 8 aims to determine the neutrino mass by making a precise measurement of the $\beta^-$-decay of molecular tritium (Q = 18.6 keV) using the recently demonstrated the technique of cyclotron radiation emission spectroscopy (CRES). Here we discuss the production of a gas cell that fulfills the stringent requirements for cryogenic operation, safe tritium handling, a non-magnetic design, and a good microwave guide performance. The phased program that allows Project 8 to probe the neutrino mass range accessible using molecular tritium is described. Major financial support by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics to the University of Washington under Award Number DE-FG02-97ER41020 is acknowledged. [Preview Abstract] |
Sunday, April 17, 2016 3:54PM - 4:06PM |
M10.00003: Moving to atomic tritium for neutrino mass measurements Kareem Kazkaz For direct measurements of the neutrino mass, the tritium-based experiments Mainz and Troitsk have provided the most sensitive measurements to date, with upper limits near 2200 meV. The KATRIN experiment, beginning its first science run in 2016, also uses tritium as its source and has an anticipated ultimate sensitivity of 200 meV. The largest single systematic effect limiting the mass sensitivity beyond KATRIN is the energy sharing between the emitted beta particle and the resulting T-3He molecule. It therefore behooves all future tritium-based experiments to use atomic, rather than molecular, tritium. In this presentation we will outline experimental considerations of atomic tritium: production, purification, inhibiting recombination, and cooling. We will discuss these considerations within the context of Project8, a tritium-based, cyclotron radiation emission spectroscopy neutrino mass measurement with an ultimate target sensitivity of 50 meV. [Preview Abstract] |
Sunday, April 17, 2016 4:06PM - 4:18PM |
M10.00004: ABSTRACT MOVED TO C9.007 |
Sunday, April 17, 2016 4:18PM - 4:30PM |
M10.00005: Measuring Neutron Spectrum at MIT Research Reactor Utilizing He-3 Bonner Cylinder Approach with an Unfolding Analysis Alexander Leder The Ricochet experiment seeks to measure Coherent (neutral-current) Elastic Neutrino-Nucleus Scattering (CENNS) using dark matter style detectors placed near a neutrino source, possibly the MIT research reactor (MITR), which offers a high continuous neutrino flux at high energies. Currently, Ricochet is characterizing the backgrounds at MITR. The main background is the neutrons emitted simultaneously from the core. To characterize this background, we wrapped a Bonner cylinder around a $^{3}$He thermal neutron detector, whose data was then unfolded to produce a neutron energy spectrum across several orders of magnitude. We discuss the resulting spectrum as well its implications for deploying Ricochet in the future. [Preview Abstract] |
Sunday, April 17, 2016 4:30PM - 4:42PM |
M10.00006: The Majorana Muon Veto System Andrew Lopez Majorana Demonstrator (MJD) is one of the major efforts of the DOE NP to demonstrate very high sensitivity for the search of the neutrino less double beta decay. The ultimate goal of MJD is to prove that background levels for a tonne-scale experiment with a similar design can be as low as 1.0 count/(4 keV*t*y). One source of background is cosmic muons that can interact~in the detectors or in the shielding. In order to tag cosmic muon induced background, an efficient veto system is necessary. The MJD veto system is made out of thirty two panels of 1'' plastic scintillator. Understanding the performance of MJD veto system is vital for reducing the background count. Initial data of veto system performance during the commissioning stage will be presented. [Preview Abstract] |
Sunday, April 17, 2016 4:42PM - 4:54PM |
M10.00007: Scintillator Measurements for SNO+ Tanner Kaptanoglu SNO+ is a neutrino detector located 2km underground in the SNOLAB facility with the primary goal of searching for neutrinoless double beta decay. The detector will be filled with a liquid scintillator target primarily composed of linear alkyl benzene (LAB). As charged particles travel through the detector the LAB produces scintillation light which is detected by almost ten thousand PMTs. The LAB is loaded with Te130, an isotope known to undergo double beta decay. Additionally, the LAB is mixed with an additional fluor and wavelength shifter to improve the light output and shift the light to a wavelength regime in which the PMTs are maximally efficient. The precise scintillator optics drastically affect the ultimate sensitivity of SNO+. I will present work being done to measure the optical properties of the SNO+ scintillator cocktail. The measured properties are used as input to a scintillation model that allows us to extrapolate to the SNO+ scale and ultimately predict the sensitivity of the experiment. Additionally, I will present measurements done to characterize the R5912 PMT, a candidate PMT for the second phase of SNO+ that provides better light collection, improved charge resolution, and a narrower spread in timing. [Preview Abstract] |
Sunday, April 17, 2016 4:54PM - 5:06PM |
M10.00008: Development of a hemispheric p-type point-contact Ge detector to verify hole drifting models in arbitrary direction Jing Liu, Dongming Mei We propose to develop a hemispheric p-type point-contact high-purity germanium detector to verify experimentally hole drifting models in an arbitrary direction in the germanium crystal. It would be the first of its kind in the world with such a unique geometry. Calibrated low energy gamma ray sources will be used to deposit energy close to the outer surface of the detector. Electron-hole pairs will be created there. Holes will be drifted from the surface all the way to the point contact along any chosen direction. Amorphous germanium will be used to replace commonly used Lithium-diffused surface to remove the surface effect on the measurements. Such a detector would provide direct measurements of hole drift mobilities in all directions, which can be used to verify current hole drifting models. Those models are heavily used in pulse-shape simulations for neutrinoless double beta experiments using germanium detector arrays. The verification of them would significantly improve the understanding of the behavior of holes in germanium detectors and reduce the uncertainty of detection efficiency estimated by the pulse-shape simulation packages. [Preview Abstract] |
Sunday, April 17, 2016 5:06PM - 5:18PM |
M10.00009: Cosmogenic Backgrounds to Neutrinoless Double-Beta Decay in EXO-200 Joshua Albert As neutrinoless double-beta decay ($0\nu\beta\beta$) experiments become more sensitive and intrinsic radioactivity in detector materials is reduced, previously minor contributions to the background must be understood and eliminated. With this in mind, cosmogenic backgrounds have been studied with the EXO-200 experiment. Simulations of muon-induced backgrounds in EXO-200 using Geant4 and FLUKA identified several potential cosmogenic radionuclides, though only $^{137}\mathrm{Xe}$ provides a significant background for the $^{136}\mathrm{Xe}$ $0\nu\beta\beta$ search with EXO-200. The simulations were normalized based on a measurement of the muon flux underground using the EXO-200 TPC. Muon-induced neutron backgrounds were measured using $\gamma$-rays from neutron capture on the detector materials, in data coincident with veto triggers. This provided a measurement of $^{137}\mathrm{Xe}$ yield, and a test of the accuracy of the neutron production and transport simulations. Simulations agree with data to within $\sim$40%. The ability to identify $^{136}\mathrm{Xe}(n,\gamma)$ events will allow for rejection of $^{137}\mathrm{Xe}$ backgrounds in future $0\nu\beta\beta$ analyses. [Preview Abstract] |
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