42663006
Search for neutrinoless double- beta decay in 136Xe with a time projection chamber.
A xenon time projection chamber (TPC) with an active volume of 180 liters has been built to study neutrinoless double-β decay in 136 Xe. The experiment was performed in the Gotthard Underground Laboratory, with 5 atm of xenon enriched to 62.5% in 136 Xe. The experimental details, background considerations, detector performance, and data analysis are discussed. From 6830 h of data, no evidence has been found for the 0v 0 + → 0 + transition. Half-life limits of T 1/2 0v > 3.4(6.4) × 10 23 yr in the mass mechanism mode, and T 1/2 0v > 2.6(4.9) × 10 23 yr in the right-handed currents mode, at the 90(68)% C.L., were derived, corresponding to an upper limit on the Majorana neutrino mass parameter of about 2.8 eV
14989310
RESEARCH PROGRAM OF THE TEXONO COLLABORATION: STATUS AND HIGHLIGHTS
This article reviews the research program and efforts for the TEXONO Collaboration among scientists from Taiwan and China. These include reactor-based neutrino physics at the Kuo-Sheng Power Plant in Taiwan as well as various R&D efforts related to the various experimental techniques in neutrino and astro-particle physics.
121441164
Measurement of neutrino-electron scattering cross section and the EW parameters at the Kuo-Sheng reactor neutrino laboratory
The e−e− elastic scattering cross-section was measured at the Kuo-Sheng Nuclear Power Station with a CsI(Tl) scintillating crystal detector array with a total mass of 187 kg. The detector was exposed to a reactor e flux of 6.4 × 1012 cm−2s−1 originated from a core with 2.9 GW thermal power. A cross-section ratio of Rexpt = [1.08 ± 0.21 (stat) ± 0.16 (sys)] × RSM was measured. Constraints on the electroweak parameters (gv,gA) were placed, corresponding to a weak mixing angle measurement of sin2θw = 0.251 ± 0.031 (stat) ± 0.024 (sys). The destructive interference in the SM e-e processes was verified with the value of RINTexpt = [0.92 ± 0.30 (stat) ± 0.24 (sys)] × RINTSM. Bounds on neutrino anomalous electromagnetic properties were placed: neutrino magnetic moment at μe = [0.61 ± 1.30 (stat) ± 1.01 (sys)] × 10−32 cm2.
30971943
New limit on neutrinoless double beta decay in 136Xe with a time projection chamber.
A xenon time projection chamber with an active volume of 207 L has been built to study neutrinoless double β decay in ^(136)Xe. Data were taken in the Gotthard Underground Laboratory, with 5 atm of xenon enriched to 62.5% in ^(136)Xe. From 3380 h of data, no evidence has been found for the 0ν 0^(+)→0^(+) transition. Half-life limits of T_(1/2)^(0ν)>2.5(4.9)×10^(23) yr in the mass-mechanism mode and T_(1/2)^(0ν)>1.7(3.2)×10^(23) yr in the right-handed-current mode, at the 90(68)% C.L., were derived. An upper limit for the Majorana neutrino mass parameter was deduced.
199684513
DARK MATTER SEARCH WITH SUB-keV GERMANIUM DETECTORS AT THE CHINA JINPING UNDERGROUND LABORATORY
Germanium detectors with sub-keV sensitivities open a window to search for low-mass WIMP dark matter. The CDEX-TEXONO Collaboration is conducting the first research program at the new China Jinping Underground Laboratory with this approach. The status and plans of the laboratory and the experiment are discussed.
121604922
LOW ENERGY NEUTRINO AND DARK MATTER PHYSICS WITH SUB-keV GERMANIUM DETECTORS
The theme of the TEXONO-CDEX research program is on the studies of low energy neutrino and dark matter physics at Kuo-Sheng Reactor Neutrino Laboratory and China Jin-Ping Underground Laboratory. The current goal is to open the "sub-keV" detector window with germanium detectors. The three main scientific subjects are neutrino magnetic moments, neutrino-nucleus coherent scattering, and dark matter searches. We highlight the status, results and plans in this article.
40901564
Dichotomy of leptons: Radiative masses and rare decays.
A model is presented where the electron and muon masses are radiative and depend, respectively, on the masses of {tau} and a fourth charged lepton {ital E}. A discrete {ital Z}{sub 4} symmetry is softly broken down to {ital Z}{sub 2} which distinguishes ({mu},{tau}) from ({ital e},{ital E}). All three known neutrinos acquire radiative Majorana masses.