池田 博一

A very compact solar neutron detector is made by using scintillation fiber and multi-anode photomultipliers. Signals from the 512 channels of the photomultipliers are read-out by CMOS circuitry which has been developed for a KEK B-factory experiment. The circuitry consumes only 5 W of power. The energy resolution for protons is obtained by exposing the detector to the RIKEN accelerator beam and it turns out to be 4.1% for protons at 95 MeV. The sensor will be used for observations on solar neutrons to elucidate the ion acceleration mechanism at the solar surface and also to provide information on-line to the cosmonauts about the impending arrival of strong radiations from the Sun. (C) 1999 Elsevier Science B.V. All rights reserved.

An optical link system (OLS) is to be used in the data acquisition (DAQ) system for the Silicon Vertex Detector of the KEK B-factory experiment (BELLE collaboration). In this study we report the 10-bit, or channel (ch), OLS in which CMOS ICs are used as the transceiver circuitry for both transmitting and receiving, infrared LEDs are used as photo transmitting devices, and Si PIN photodiodes (PDs) are used as photo-receiving devices. We have obtained a 32 Mbps/ch data rate, at around 5 dB of dynamic range, with less than 8 nsec of jitters and an error rate of less than 10(-9). The scheme we proposed in this study has been confirmed assuming it will be used in the readout system.

The data-acquisition system for a silicon micro-vertex detector of the BELLE experiment is described with special emphasis placed on the front-end circuits and their interfaces. The description includes a 128-channel preamplifier chip, a silicon-based double-sided hybrid card, and readout control chips for digital interfaces, which are discussed in terms of both architectural and operational aspects.

Employing a 64-channel CMOS preamplifier array, SMA(2)SH - 64 A, we studied its signal-to-noise ratio. Single-channel noise was substantially contaminated with a base-line shift, which was common for all neighboring channels. Subtracting the common base-line shift, we found that the noise level decreased to be acceptable in terms of the design parameters as well as for practical use.

We report the first purely electroweak measurement of the strengthening of the electromagnetic coupling, alpha(QED) With increasing momentum transfer Q(2), by comparing the process e(+)e(-) --> mu(+)mu(-) with the process e(+)e(-) --> e(+)e(-) mu(+)mu(-). The data were accumulated at an average center-of-mass energy [root s] = 57.77 GeV using the TOPAZ detector at the TRISTAN e(+)e(-) collider. We measure alpha(QED)(-1)(Q(2)) to change from its known value of alpha(QED)(-1) congruent to 137.0 at Q(2) = 0 to 128.5 +/- 1.8(stat) +/- 1.7(stat) at Q(2) = (57.77 GeV/c)(2). This result agrees with electroweak predictions.