Construction of an X-ray detecting module and its application to relative-sensitivity measurement using a silicon PIN diode in conjunction with short-decay-time scintillators

To detect low-dose-rate X-rays, we have developed an X-ray-detecting module for semiconductor diodes. The module consists of a current–voltage (I–V) amplifier, a voltage–voltage (V–V) amplifier, and an alternating-current adopter with a smoothing circuit. The photocurrents flowing through a diode are converted into voltages and amplified using the I–V and V–V amplifiers. To measure relative sensitivities, we used three silicon PIN diodes (Si-PIN), a cerium-doped yttrium aluminum perovskite [YAP(Ce)] crystal, and a Lu2(SiO4)O [LSO] crystal. Three detectors are as follows: an Si-PIN, a YAP(Ce)–Si-PIN, and an LSO–Si-PIN. Using the three detectors, the amplifier output voltages were in proportion to the tube current at a constant tube voltage of 70 kV. Using a multichannel analyzer, the event-pulse-height spectra were measured to analyze X-ray-electric conversion effect in the three detectors. The output voltage of the Si-PIN was approximately twice as high as those obtained using the YAP(Ce)–Si-PIN and the LSO–Si-PIN at the measurement conditions.