Development of a Si/CdTe semiconductor Compton telescope

We are developing a Compton telescope based on high resolution Si and CdTe imaging devices in order to obtain a high sensitivity astrophysical observation in sub-MeV gamma-ray region. In this paper, recent results from the prototype Si/CdTe semiconductor Compton telescope are reported. The Compton telescope consists of a double-sided Si strip detector (DSSD) and CdTe pixel detectors, combined with low noise analog LSI, VA32TA. With this detector, we obtained Compton reconstructed images and spectra from line gamma-rays ranging from 81 keV up to 356 keV. The energy resolution is 3.8 keV and 7.9 keV at 122 keV and 356 keV, respectively, and the angular resolution is 9.9 degrees and 5.7 degrees at 122 keV and 356 keV, respectively.Comment: 12 pages, 14 figures, submitted to SPIE conference proceedings vol. 5501, "High-Energy Detectors in Astronomy", Glasgow UK, 6/21-6/24 200

PICO-LON Project for WIMPs search

Highly segmented inorganic crystal has been shown to have good performance for dark matter search. The energy resolution of ultra thin and large area NaI(Tl) scintillator has been developed. The estimated sensitivity for spin-dependent excitation of 127I was discussed. The recent status of low background measurement at Oto Cosmo Observatory is reportedComment: 3 pages, 1 figure, Proceedings of TAUP200

Study of statistical and non-statistical components of energy resolution for high-sensitive beta camera

Energy resolution of a scintillation detector was studied from the viewpoints of statistical and non-statistical components. The statistical component is caused mainly by fluctuation of the number of photo-electrons, N, collected at the anode of a photo-detector and the non-statistical component comes from intrinsic property of the scintillator. A new method identifying these two components was developed to study the resolution of detector as beta camera. The beta camera consists of a 6cm*6cm*1cm plastic-scintillator plate (BC-408 provided by SAINT GOBAIN) and 4 photomultiplier tubes covered each side face of the plastic-scintillator. The statistical component is found to be well reproduced by 1/sqrt(N). The present method is useful for investigating statistical and non-statistical components of the resolution, and thus to improve and monitor them

Study of statistical and non-statistical components of energy resolution for position-sensitive beta camera

Energy resolution of a position sensitive scintillation beta camera was studied from the viewpoints of statistical and non-statistical components. The statistical component is caused by fluctuation of the number of photo-electrons collected at the anode of a photo-detector and the non-statistical component comes from intrinsic property of the scintillator. The measurement of these components were carried out on the beta camera composed of 6 x 6 x 1 cm3 plastic scintillator plate (PL) and four photomultiplier tubes (PMTs) covered each side face of the PL. We extracted the non-statistical component by comparing the results obtained with conversion electron irradiations and photon from LED. Tests for a small PL with 4 PMTs and a large PL with 32 PMTs gave the intrinsic component of around 10 % (in FWHM) for 207Bi 0.976 MeV conversion electrons. The present method is useful for investigating statistical and non-statistical components to the resolution, and thus to improve and monitor them.2006 IEEE Nuclear Science Symposiu

MOON for spectroscopic studies of double beta decays and the present status of the MOON-1 prototype detector

The MOON (Molybdenum Observatory Of Neutrinos) project, as an extension of ELEGANT V, aims at spectroscopic studies of double beta decays from 100Mo with a sensitivity of the Majorana neutrino mass around 30 meV. Measurements with good energy and position resolutions enable one to select true signals and to reject background ones. A prototype MOON detector (MOON Phase-1A) with 142 g 100Mo was built and is running at the Oto underground laboratory. The present report describes briefly the outline of the MOON project and the present status of MOON-1

Correlation Response Observatory for Scintillation Signals Project

Mini workshop on high-sensitivity radiation detector

Double beta decay experiments and v-mass sensitivities

This is a brief report on Majorana neutrino(n) mass to be studied by neutrino-less double beta decays (0nbb). The v-mass depends on the nuclear structure of the bb isotope, the effective detector volume and the background rate. Subjects discussed include 1 0nbb and v-mass, 2 0nbb nuclear matrix elements, and 3 0nbb experiments and n-mass sensitivities