Reina Maruyama

Measurement of the beta-neutrino correlation of sodium-21 usingshakeoff electrons

The {beta}-{nu} correlation coefficient, a{sub {beta}}{sub {nu}}, is measured in {sup 21}Na by detecting the time of flight of the recoil nucleus detected in coincidence with the atomic electrons shaken off in {beta} decay. The sample of {sup 21}Na is confined in a magneto-optic trap. High detection efficiency allows low trap density, which suppresses the photoassociation of molecular sodium, which can cause a large systematic error. Suppressing the fraction of trapped atoms in the excited state by using a dark trap also reduces the photoassociation process, and data taken with this technique are consistent. The main remaining systematic uncertainties come from the measurement of the position and size of the atom trap and the subtraction of background. We find a{sub {beta}}{sub {nu}}=0.5502(60), in agreement with the Standard Model prediction of a{sub {beta}}{sub {nu}}=0.553(2), and disagreeing with a previous measurement, which was susceptible to an error introduced by the presence of molecular sodium.

A Search for the Dark Matter Annual Modulation in South Pole Ice

Astrophysical observations and cosmological data have led to the conclusion that nearly one quarter of the Universe consists of dark matter. Under certain assumptions, an observable signature of dark matter is the annual modulation of the rate of dark matter-nucleon interactions taking place in an Earth-bound experiment. To search for this e ect, we introduce the concept for a new dark matter experiment using NaI scintillation detectors deployed deep in the South Pole ice. This experiment complements dark matter search e orts in the Northern Hemisphere and will investigate the observed annual modulation in the DAMA/LIBRA and DAMA/NaI experiments. The unique location will permit the study of background e ects correlated with seasonal variations and the surrounding environment. This paper describes the experimental concept and explores the sensitivity of a 250 kg NaI experiment at the South Pole.

First search for a dark matter annual modulation signal with NaI(Tl) in the Southern Hemisphere by DM-Ice17

The first search for a dark matter annual modulation signal with NaI(Tl) target material in the Southern Hemisphere conducted with the DM-Ice17 experiment is presented. DM-Ice17 consists of 17 kg of NaI(Tl) scintillating crystal under 2200 m.w.e. overburden of Antarctic glacial ice. The analysis presented here utilizes a 60.8 kg yr exposure. While unable to exclude the signal reported by DAMA/LIBRA, the DM-Ice17 data are consistent with no modulation in the energy range of 4-20 keV, providing the strongest limits on WIMP candidates from a direct detection experiment located in the Southern Hemisphere. Additionally, the successful deployment and stable operation of 17 kg of NaI(Tl) crystal over 3.5 years establishes the South Pole ice as a viable location for future underground, low-background experiments.

Search for double-β decay of 130Te to the first 0+ excited state of 130Xe with the CUORICINO experiment bolometer array

E. Andreotti, 2, a C. Arnaboldi, F. T. Avignone III, M. Balata, I. Bandac, M. Barucci, 7 J. W. Beeman, F. Bellini, 10 C. Brofferio, 3 A. Bryant, 12 C. Bucci, L. Canonica, 14 S. Capelli, 3 L. Carbone, M. Carrettoni, 3 M. Clemenza, 3 O. Cremonesi, R. J. Creswick, S. Di Domizio, 14 M. J. Dolinski, 15 L. Ejzak, R. Faccini, 10 H. A. Farach, E. Ferri, 3 E. Fiorini, 3, b L. Foggetta, 2, c A. Giachero, L. Gironi, 3 A. Giuliani, 2, d P. Gorla, e E. Guardincerri, 11, 14 T. D. Gutierrez, E. E. Haller, 18 K. Kazkaz, L. Kogler, 12 S. Kraft, 3 C. Maiano, 3 C. Martinez, f M. Martinez, 19, g R. H. Maruyama, S. Newman, 5 S. Nisi, C. Nones, 2, h E. B. Norman, 20 A. Nucciotti, 3 F. Orio, 10 M. Pallavicini, 14 V. Palmieri, L. Pattavina, 3 M. Pavan, 3 M. Pedretti, G. Pessina, S. Pirro, E. Previtali, L. Risegari, 7 C. Rosenfeld, C. Rusconi, 2 C. Salvioni, 2 S. Sangiorgio, i D. Schaeffer, 3 N. D. Scielzo, M. Sisti, 3 A. R. Smith, C. Tomei, G. Ventura, 7 and M. Vignati 10 Dipartimento di Fisica e Matematica, Università dell’Insubria, Como I-22100 Italy INFN Sezione di Milano Bicocca, Milano I-20126 Italy Dipartimento di Fisica, Università di Milano-Bicocca, Milano I-20126 Italy Department of Physics and Astronomy, University of South Carolina, Columbia, SC 29208 USA INFN Laboratori Nazionali del Gran Sasso, Assergi (L’Aquila) I-67010 Italy Dipartimento di Fisica, Università di Firenze, Firenze I-50125 Italy INFN Sezione di Firenze, Firenze I-50125 Italy Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA Dipartimento di Fisica, Sapienza Università di Roma, Roma I-00185 Italy INFN Sezione di Roma, Roma I-00185 Italy Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA Department of Physics, University of California, Berkeley, CA 94720 USA Dipartimento di Fisica, Università di Genova, Genova I-16146 Italy INFN Sezione di Genova, Genova I-16146 Italy Lawrence Livermore National Laboratory, Livermore, CA 94550 USA Department of Physics, University of Wisconsin, Madison, WI 53706 USA Physics Department, California Polytechnic State University, San Luis Obispo, CA 93407 USA Department of Materials Science and Engineering, University of California, Berkeley, CA 94720 USA Laboratorio de Fisica Nuclear y Astroparticulas, Universidad de Zaragoza, Zaragoza 50009 Spain Department of Nuclear Engineering, University of California, Berkeley, CA 94720 USA INFN Laboratori Nazionali di Legnaro, Legnaro (Padova) I-35020 Italy EH&S Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA (Dated: February 1, 2013)

Measurement of muon annual modulation and muon-induced phosphorescence in NaI(Tl) crystals with DM-Ice17

We report the measurement of muons and muon-induced phosphorescence in DM-Ice17, a NaI(Tl) direct detection dark matter experiment at the South Pole. Muon interactions in the crystal are identified by their observed pulse shape and large energy depositions. The measured muon rate in DM-Ice17 is 2.93±0.04 μ/crystal/day with a modulation amplitude of 12.3±1.7%, consistent with expectation. Following muon interactions, we observe long-lived phosphorescence in the NaI(Tl) crystals with a decay time of 5.5±0.5 s. The prompt energy deposited by a muon is correlated to the amount of delayed phosphorescence, the brightest of which consist of tens of millions of photons. These photons are distributed over tens of seconds with a rate and arrival timing that do not mimic a scintillation signal above 2 keVee. Furthermore, while the properties of phosphorescence vary among individual crystals, the annually modulating signal observed by DAMA cannot be accounted for by phosphorescence with the characteristics observed in DM-Ice17.

Search for β+/EC double beta decay of 120Te

We present a search for beta plus/EC double beta decay of 120Te performed with the CUORICINO experiment, an array of TeO2 cryogenic bolometers. After collecting 0.0573 kg y of 120Te, we see no evidence of a signal and therefore set the following limits on the half-life: T1/2 (0nu) > 1.9 10^{21} y at 90% C.L. for the 0 neutrino mode and T1/2 (2nu) > 7.6 10^{19} y at 90% C.L. for the two neutrino mode. These results improve the existing limits by almost three orders of magnitude (four in the case of 0 neutrino mode).

Passive shielding in CUORE

The nature of neutrino mass is one of the friontier problems of fundamental physics. Neutrinoless Double Beta Decay (0νDBD) is a powerful tool to investigate the mass hierarchy and possible extensions of the Standard Model. CUORE is a 1‐Ton next generation experiment, made of 1000 Te bolometers, aiming at reaching a background of 0.01 (possibly 0.001) counts keV−1kg−1y−1 and therefore a mass sensitivity of few tens of meV The background contribution due to environmental neutrons, muon‐induced neutrons in the shieldings and external gamma is discussed.