Amorphous Silicon Photodiodes for X-Ray Survey Monitoring

A new kind of X-ray dosimeter which can be used both as a survey meter and as a personal badge-type dosimeter has been realized and tested in different irradiation conditions. This dosimeter operates without any applied voltage, it can be read either by a picoammeter or by a digital voltmeter and it can work both in exposure rate and in exposure mode. The dosimeter has been realized by coupling an a-Si: H p-i-n photodiode to a CsI(TI) scintillator. Tests have been performed from 67 to 240 keV peak energy and at 662 keV (¹³⁷ Cs). The sensitivity has been found to be below 1 mR/h in exposure rate mode and below 1 ¿R in exposure mode. Suitable filtering can be used in order to reconstruct the effective X-ray energy.