Showing papers by "Masaharu Nomachi published in 2001"
TL;DR: A significant difference in the mass spectra below the omega meson between p+C and p+Cu interactions indicates that the spectral shape of mesons is modified at normal nuclear-matter density.
Abstract: We measured the invariant mass spectra of electron-positron pairs in the target rapidity region of 12-GeV p+A reactions. We have observed a significant difference in the mass spectra below the omega meson between p+C and p+Cu interactions. This difference indicates that the spectral shape of mesons is modified at normal nuclear-matter density.
83 citations
80 citations
21 Feb 2001-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, a new type of general-purpose CCD-data acquisition system was developed, which enables one to drive any type of CCD using any kind of clocking mode.
Abstract: We have developed a completely new type of general-purpose CCD-data acquisition system which enables one to drive any type of CCD using any type of clocking mode. A CCD driver system widely used before consisted of an analog multiplexer (MPX), a digital-to-analog converter (DAC), and an operational amplifier. A DAC is used to determine high- and low-voltage levels and the MPX selects each voltage level using a TTL clock. In this kind of driver board, it is difficult to reduce the noise caused by an electrical short between high and low levels in MPX and also to select many kinds of different voltage levels. Recent developments in semiconductor IC enable us to use a very fast sampling ( ∼10 MHz ) DAC with low cost. We thus develop the new driver system using a fast DAC in order to determine both the voltage level of the clock and the clocking timing. We use Field Programmable Gate Array (FPGA) to control the DAC. We have constructed the data acquisition system and found that the CCD functions well with our new system. The energy resolution of Mn Kα has a full-width at half-maximum of ≃150 eV and the readout noise of our system is ≃8e−.
21 citations
21 Jul 2001-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, a prototype of YAP(Ce) imager with a high energy SR beam at the SPring-8 Facility has been characterized with a [8×8] YAP[Ce] crystal matrix with optical separators.
Abstract: A prototype of YAP(Ce) imager has been characterized with a high energy SR beam at the SPring-8 Facility, which has a [8×8] YAP(Ce) crystal matrix with optical separators. It has attained a 2D spatial resolution of 1 mm×1 mm with a detection efficiency higher than 50% in the energy region from 72 keV up to 84 keV.
8 citations
TL;DR: Differential cross sections and analyzing powers for the proton-proton bremsstrahlung have been measured at 389 MeV incident energy as mentioned in this paper, and an enhancement of the cross sections due to the Δ current contribution is predicted.
1 citations
01 Dec 2001
TL;DR: The ASTRO-E Hard X-ray Detector utilized GSO/BGO well-type phoswich counters in compound-eye configuration, to achieve an extremely low background level of a few /spl times/10/sup -5/ counts s/sup 1/ cm/sup 2/ keV/sup 3.5 as mentioned in this paper.
Abstract: The ASTRO-E Hard X-ray Detector utilized GSO/BGO well-type phoswich counters in compound-eye configuration, to achieve an extremely low background level of a few /spl times/10/sup -5/ counts s/sup -1/ cm/sup -2/ keV/sup -1/. The GSO scintillators installed in the BGO active shield wells observes 30-600 keV photons, while silicon PIN diodes of 2 mm thick placed in front of each GSO crystal covers 10-60 keV photons with energy resolution of /spl sim/3.5 keV FWHM. The design goals both of low background and high energy resolution in the hard X-ray bands were confirmed to be achieved through the preflight calibration experiments.
1 citations
26 Oct 2001
TL;DR: In this article, the results from SPring-8/LEPS were presented with special emphasis on the study of photoproduction of φ mesons near threshold, and some prospects for the near future were discussed in close connection with photopsroducting of hyperons.
Abstract: The Laser-Electron-Photon facility at SPring-8 (LEPS) is now taking data for all hadronic reactions at compton-backscattered photon energies between 15 GeV and 24 GeV A linearly polarized photon beam is incident on a liquid hydrogen target or nuclear targets A large dipole spectrometer analyzes charged particles produced at forward angles First results from SPring-8/LEPS will be presented with special emphasis on the study of photoproduction of φ mesons near threshold Some prospects for the near future will also be presented and discussed in close connection with photoproduction of hyperons