Development of position sensitive semiconductor detector for observation of high energy electrons

The hybrid emulsion chamber composed of nuclear emulsions and position sensitive silicon detectors is being developed to detect cosmic ray electrons with energy below 30 GeV. The position sensitive silicon detector is used to determine the position of electron shower generated in the chamber. This method has a merit of high detection efficiency for relatively small electron showers. In the present experiment, both silicon detectors of checkerboard type and charge division type were made. The area and thickness are 38.5 cm2 and 1 - 3 mm, respectively. The position resolution was measured, using 400 and 600 MeV electrons. The position resolution was about 2 mm (FWHM) at energy deposition of 10 MeV. In addition, the energy spectra of shower electrons for the incident electron energy of 600 MeV were measured. The hybrid emulsion chamber will be launched on a balloon in near future. (Yoshimori, M.)