CHARACTERISTICS OF A SILICON DETECTOR FOR INDUSTRIAL X-RAY COMPUTED-TOMOGRAPHY

We have evaluated a silicon solid state detector (Si-SSD) as a detector for Industrial X-ray Computed Tomography (IXCT) from the viewpoints of sensitivity and radiation damage. The detector which we used in this work, is a diffused junction type Si-SSD (43 X 3.8 X 0.5 mm) fabricated on high purity n-type silicon. We measured pulse height distributions for narrow pencil beam Co-60 gamma rays parallelly incident to the detector. The expected deposit energy was 0.146 +/- 0.001 MeV (11.7% of the incident photon energy). The calculated pulse height distribution using the general purpose EGS4 code was confirmed to be in good agreement with the measured one. The radiation damage was evaluated using the Co-60 gamma ray source. Exposure of up to 88 kGy(Si) was achieved over a period of 20 hours, with an exposure rate of 4.4 kGy(Si)/h (36 mC/kg s). It was confirmed that the Si-SSDs could be used at least up to 88 kGy(Si) with X-rays equivalent to Co-60 gamma rays.