306 research outputs found
Drift field generation with Cockcroft-Walton voltage multiplier in xenon gas for AXEL 0vββ search detector
16th International Conference on Topics in Astroparticle and Underground Physics (TAUP 2019) 9-13 September 2019, Toyama, JapanFor noble gas Time Projection Chambers (TPCs) in the field of rare event searches, operation of high voltage to generate an electric field is a key point. We designed a new structure of electrodes to shape a strong and uniform drift field without electric discharge, in which electrodes of two different radius are used. We also developed Cockcroft-Walton voltage multiplier as a high voltage generator inside a pressure vessel. We achieved −30.0 kV output and examined such kind of voltage generator is feasible as a high voltage supplier in a TPC
Design and performance of a high-pressure xenon gas TPC as a prototype for a large-scale neutrinoless double-beta decay search
A high-pressure xenon gas time projection chamber, with a unique cellular
readout structure based on electroluminescence, has been developed for a
large-scale neutrinoless double-beta decay search. In order to evaluate the
detector performance and validate its design, a 180~L size prototype is being
constructed and its commissioning with partial detector has been performed. The
obtained energy resolution at 4.0~bar is 1.73 0.07% (FWHM) at 511 keV.
The energy resolution at the Xe neutrinoless double-beta decay Q-value
is estimated to be between 0.79 and 1.52% (FWHM) by extrapolation.
Reconstructed event topologies show patterns peculiar to track end-point which
can be used to distinguish signals from gamma-ray backgrounds.Comment: 24 pages, 25 figures, 1 table. Preprint paper for PTE
Evidence of electron neutrino appearance in a muon neutrino beam
The T2K Collaboration reports evidence for electron neutrino appearance at the atmospheric mass splitting, |Δm232|≈2.4×10−3 eV2. An excess of electron neutrino interactions over background is observed from a muon neutrino beam with a peak energy of 0.6 GeV at the Super-Kamiokande (SK) detector 295 km from the beam’s origin. Signal and background predictions are constrained by data from near detectors located 280 m from the neutrino production target. We observe 11 electron neutrino candidate events at the SK detector when a background of 3.3±0.4(syst) events is expected. The background-only hypothesis is rejected with a p value of 0.0009 (3.1σ), and a fit assuming νμ→νe oscillations with sin22θ23=1, δCP=0 and |Δm232|=2.4×10−3 eV2 yields sin22θ13=0.088+0.049−0.039(stat+syst)
Search for dinucleon decay into pions at Super-Kamiokande
A search for dinucleon decay into pions with the Super-Kamiokande detector
has been performed with an exposure of 282.1 kiloton-years. Dinucleon decay is
a process that violates baryon number by two units. We present the first search
for dinucleon decay to pions in a large water Cherenkov detector. The modes
O C, O
N, and O
O are investigated. No significant excess in the
Super-Kamiokande data has been found, so a lower limit on the lifetime of the
process per oxygen nucleus is determined. These limits are:
years,
years, and
years. The lower
limits on each mode are about two orders of magnitude better than previous
limits from searches for dinucleon decay in iron.Comment: 20 pages, 17 figures. Accepted for publication in Physical Review D
on March 30, 201
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