186 research outputs found
First results from dark matter search experiment with LiF bolometer at Kamioka Underground Laboratory
Tokyo group has performed first underground dark matter search experiment in
2001 through 2002 at Kamioka Observatory(2700m.w.e). The detector is eight LiF
bolometers with total mass 168g aiming for the direct detection of WIMPs via
spin-dependent interaction. With a total exposure of 4.1 kg days, we derived
the limits in the a_p-a_n (WIMP-nucleon couplings) plane and excluded a large
part of the parameter space allowed by the UKDMC experiment.Comment: 15 pages, 5 figure
First Results from Dark Matter Search Experiment in the Nokogiriyama Underground Cell
An experiment to search for hypothetical particle dark matter using cryogenic
thermal detector, or bolometer is ongoing. The bolometer consists of eight
pieces of 21 g LiF absorbers and sensitive NTD germanium thermistors attached
to them and is installed in the Nokogiriyama underground cell which is a
shallow depth site ( m w.e.). We report on the results from the first
running for about ten days using this arrayed bolometer system together with
appropriate shieldings and muon veto counters. From the obtained energy spectra
the exclusion limits for the cross section of the elastic neutralino-proton
scattering are derived under commonly accepted astrophysical assumptions. The
sensitivity for the light neutralino with a mass below 5 GeV is improved by
this work.Comment: 8 pages, Revtex, 4 figure
Design and test of an extremely high resolution Timing Counter for the MEG II experiment: preliminary results
The design and tests of Timing Counter elements for the upgrade of the MEG
experiment, MEG II,is presented. The detector is based on several small plates
of scintillator with a Silicon PhotoMultipliers dual-side readout. The
optimisation of the single counter elements (SiPMs, scintillators, geometry) is
described. Moreover, the results obtained with a first prototype tested at the
Beam Test Facility (BTF) of the INFN Laboratori Nazionali di Frascati (LNF) are
presented.Comment: 10 pages, 7 figures. Presented at the 13th Topical Seminar on
Innovative Particle and Radiation Detectors (IPRD13) 7-10 October 2013 Siena,
Ital
Limits on the WIMP-Nucleon Coupling Coefficients from Dark Matter Search Experiment with NaF Bolometer
We have performed the underground dark matter search experiment with a sodium
fl uoride (NaF) bolometer array from 2002 through 2003 at Kamioka Observatory
(2700 m.w.e.). The bolometer array consists of eight NaF absorbers with a total
mass of 176 g, and sensitive NTD germanium thermistors glued to each of them.
This experiment aims for the direct detection of weakly interacting massive
part icles (WIMPs) via spin-dependent interaction. With an exposure of 3.38 kg
days, we derived the limits on the WIMP-n ucleon coupling coefficients, a_p and
a_n. These limits confirmed and tightened those derived from our previous
results wit h the lithium fluoride (LiF) bolometer. Our results excluded the
parameter space complementary to the results obtained b y NaI detectors of
UKDMC experiment.Comment: 10 pages, 4 figure
Development of High Precision Timing Counter Based on Plastic Scintillator with SiPM Readout
High-time-resolution counters based on plastic scintillator with silicon
photomultiplier (SiPM) readout have been developed for applications to high
energy physics experiments for which relatively large-sized counters are
required. We have studied counter sizes up to mm^3 with
series connection of multiple SiPMs to increase the sensitive area and thus
achieve better time resolution. A readout scheme with analog shaping and
digital waveform analysis is optimized to achieve the highest time resolution.
The timing performance is measured using electrons from a Sr-90 radioactive
source, comparing different scintillators, counter dimensions, and types of
near-ultraviolet sensitive SiPMs. As a result, a resolution of ps at 1 MeV energy deposition is obtained for counter size mm^3 with three SiPMs ( mm^2 each) at each end of the
scintillator. The time resolution improves with the number of photons detected
by the SiPMs. The SiPMs from Hamamatsu Photonics give the best time resolution
because of their high photon detection efficiency in the near-ultraviolet
region. Further improvement is possible by increasing the number of SiPMs
attached to the scintillator.Comment: 11 pages, 17 figures, accepted by IEEE Trans. Nucl. Sc
First report of Lasiodiplodia brasiliense causing postharvest fruit rot of Custard Apple (Annona squamosa) in Brazil.
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Absorption of Scintillation Light in a 100 Liquid Xenon Ray Detector and Expected Detector Performance
An 800L liquid xenon scintillation ray detector is being developed
for the MEG experiment which will search for decay
at the Paul Scherrer Institut. Absorption of scintillation light of xenon by
impurities might possibly limit the performance of such a detector. We used a
100L prototype with an active volume of 372x372x496 mm to study the
scintillation light absorption. We have developed a method to evaluate the
light absorption, separately from elastic scattering of light, by measuring
cosmic rays and sources. By using a suitable purification technique,
an absorption length longer than 100 cm has been achieved. The effects of the
light absorption on the energy resolution are estimated by Monte Carlo
simulation.Comment: 18 pages, 10 figures (eps). Submitted to Nucl. Instr. and Meth.
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