arXiv subjects

K. Miuchi

Publications and source records attributed to K. Miuchi.

68 records · Page 4Linked to original sources

arXiv2013

Search for solar axions in XMASS, a large liquid-xenon detector

XMASS, a low-background, large liquid-xenon detector, was used to search for solar axions that would be produced by bremsstrahlung and Compton effects in the Sun. With an exposure of 5.6ton days of liquid xenon, the model-independent limit on the coupling for mass $\ll$ 1keV is $|g_{aee}|< 5.4\times 10^{-11}$ (90% C.L.), which is a factor of two stronger than the existing experimental limit. The bounds on the axion masses for the DFSZ and KSVZ axion models are 1.9 and 250eV, respectively. In the mass range of 10-40keV, this study produced the most stringent limit, which is better than that previously derived from astrophysical arguments regarding the Sun to date.

astro-ph.CO↗

arXiv2013

Light WIMP search in XMASS

A search for light dark matter using low-threshold data from the single phase liquid xenon scintillation detector XMASS, has been conducted. Using the entire 835 kg inner volume as target, the analysis threshold can be lowered to 0.3 keVee (electron-equivalent) to search for light dark matter. With low-threshold data corresponding to a 5591.4 kg$\cdot$day exposure of the detector and without discriminating between nuclear-recoil and electronic events, XMASS excludes part of the parameter space favored by other experiments.

astro-ph.CO↗

arXiv2013

XMASS detector

The XMASS project aims to detect dark matter, pp and $^{7}$Be solar neutrinos, and neutrinoless double beta decay using ultra pure liquid xenon. The first phase of the XMASS experiment searches for dark matter. In this paper, we describe the XMASS detector in detail, including its configuration, data acquisition equipment and calibration system.

physics.ins-det↗

arXiv2012

Neutron imaging detector based on the muPIC micro-pixel chamber

We have developed a prototype time-resolved neutron imaging detector employing the micro-pixel chamber (muPIC), a micro-pattern gaseous detector, coupled with a field programmable gate array-based data acquisition system for applications in neutron radiography at high-intensity neutron sources. The prototype system, with an active area of 10cm x 10cm and operated at a gas pressure of 2 atm, measures both the energy deposition (via time-over-threshold) and 3-dimensional track of each neutron-induced event, allowing the reconstruction of the neutron interaction point with improved accuracy. Using a simple position reconstruction algorithm, a spatial resolution of 349 +/- 36 microns was achieved, with further improvement expected. The detailed tracking allows strong rejection of background gamma-rays, resulting in an effective gamma sensitivity of 10^-12 or less, coupled with stable, robust neutron identification. The detector also features a time resolution of 0.6 microseconds.

physics.ins-det↗

arXiv2009

The case for a directional dark matter detector and the status of current experimental efforts

We present the case for a dark matter detector with directional sensitivity. This document was developed at the 2009 CYGNUS workshop on directional dark matter detection, and contains contributions from theorists and experimental groups in the field. We describe the need for a dark matter detector with directional sensitivity; each directional dark matter experiment presents their project's status; and we close with a feasibility study for scaling up to a one ton directional detector, which would cost around $150M.

astro-ph.CO↗

arXiv2006

Development of Gaseous Tracking Devices for the Search of WIMPs

The Time Projection Chamber (TPC) has been recognized as a potentially powerful detector for the search of WIMPs by measuring the directions of nuclear recoils, in which the most convincing signature of WIMPs, caused by the Earth's motion around the Galaxy, appears. We report on the first results of a performance study of the neutron exposure of our prototype micro-TPC with Ar-C$_2$H$_6$ (90:10) and CF$_4$ gas of 150 Torr.

astro-ph↗

arXiv2005

Studies of the performance of different front-end systems for flat-panel multi-anode PMTs with CsI(Tl) scintillator arrays

We have studied the performance of two different types of front-end systems for our gamma camera based on Hamamatsu H8500 (flat-panel 64 channels multi-anode PSPMT) with a CsI(Tl) scintillator array. The array consists of 64 pixels of $6\times6\times20{\rm mm}^3$ which corresponds to the anode pixels of H8500. One of the system is based on commercial ASIC chips in order to readout every anode. The others are based on resistive charge divider network between anodes to reduce readout channels. In both systems, each pixel (6mm) was clearly resolved by flood field irradiation of $^{137}$Cs. We also investigated the energy resolution of these systems and showed the performance of the cascade connection of resistive network between some PMTs for large area detectors.

physics.ins-det↗

arXiv2004

Development of an advanced Compton camera with gaseous TPC and scintillator

A prototype of the MeV gamma-ray imaging camera based on the full reconstruction of the Compton process has been developed. This camera consists of a micro-TPC that is a gaseous Time Projection Chamber (TPC) and scintillation cameras. With the information of the recoil electrons and the scattered gamma-rays, this camera detects the energy and incident direction of each incident gamma-ray. We developed a prototype of the MeV gamma-ray camera with a micro-TPC and a NaI(Tl) scintillator, and succeeded in reconstructing the gamma-rays from 0.3 MeV to 1.3 MeV. Measured angular resolutions of ARM (Angular Resolution Measure) and SPD (Scatter Plane Deviation) for 356 keV gamma-rays were $18^\circ$ and $35^\circ$, respectively.

astro-ph↗

arXiv2004

Development of an ASD IC for the Micro Pixel Chamber

A new amplifier-shaper-discriminator (ASD) chip was designed and manufactured for the Micro Pixel Chamber ($μ$-PIC). The design of this ASD IC is based on the ASD IC (TGC-ASD) for the Thin Gap Chamber in the LHC Atlas Experiment. The decay time constant of the preamplifier is 5-times longer than that of the TGC-ASD, and some other modifications have been made in order to improve the signal-to-noise ratio of the $μ$-PIC. The ASD IC uses SONY Analog Master Slice bipolar technology. The IC contains 4 channels in a QFP48 package. The decay time constant of the preamplifier is 80 ns and its gain is approximately 0.8 V/pC. The output from the preamplifier is received by a shaper (main-amplifier) with a gain of 7. A baseline restoration circuit is incorporated in the main-amplifier, and the current used for the baseline restoration is 5-times smaller than that of the TGC-ASD. The threshold voltage for the discriminator section is common to the 4 channels and their digital output level is LVDS-compatible. The ASD IC also has an analog output of the preamplifier. The equivalent noise charge at the input capacitance of 50 pF is around 2000 electrons. The power dissipation with LVDS outputs (100 $Ω$ load) is 57 mW/ch. Using this ASD, the analog output voltage from the signal of the $μ$-PIC is about 2-times higher than the case of using the TGC-ASD.As a consequence, the MIPs tracking performance of the Time Projection Chamber (TPC) with the $μ$-PIC was improved.The performance of the ASD IC and an improved tracking performance of the TPC are reported.

physics.ins-det↗

arXiv2003

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.

astro-ph↗

arXiv2003

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.

astro-ph↗

arXiv2003

Development of a time projection chamber with micro pixel electrodes

A time projection chamber (TPC) based on a gaseous chamber with micro pixel electrodes (micro-PIC) has been developed for measuring three-dimensional tracks of charged particles. The micro-PIC with a detection area of 10 cm square consists of a double-sided printing circuit board. Anode pixels are formed with 0.4 mm pitch on strips aligned perpendicular to the cathode strips in order to obtain a two-dimensional position. In the TPC with drift length of 8 cm, 4 mm wide field cage electrodes are aligned at 1mm spaces and a uniform electric field of about 0.4 kV/cm is produced. For encoding of the three-dimensional position a synchronous readout system has been developed using Field Programmable Gate Arrays with 40 MHz clock. This system enables us to reconstruct the three-dimensional track of the particle at successive points like a cloud chamber even at high event rate. The drift velocity of electrons in the TPC was measured with the tracks of cosmic muons for three days, during which the TPC worked stably with the gas gain of 3000. With a radioisotope of gamma-ray source the three-dimensional track of a Compton scattered electron was taken successfully.

hep-ex↗

arXiv2003

Performance of large area Micro Pixel Chamber

A novel gaseous two-dimensional imaging detector "Micro Pixel Chamber (micro-PIC)" has been developed. This detector is based on double sided printed circuit board (PCB). We have developed large area (10cm x 10cm) micro-PICs with 65536 pixel anodes of 400um pitch on a 100um thick insulating substrate. Achieved energy resolution was 30% (FWHM) at 5.9keV, and a gas gain of 7000 was obtained with argon ethane (8:2) gas mixture. This gain is high enough to detect minimum ionizing particles with such a small electrode pitch. Although several discharges occurred during 65 hours continuous operation, the detectors have kept stable operation with high gain. The micro-PIC is a useful detector for many applications e.g. X-ray, gamma ray, and charged particle imaging. The micro electrode structure allows us to measure directions of primary electrons due to incident X-rays or gamma rays, which provide a strong method for X-ray polarimetry and gamma-ray imaging.

hep-ex↗

arXiv1999

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 ($\sim 15$ 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.

hep-ex↗