Fast scintillation timing detector using proportional-mode avalanche photodiode for nuclear resonant scattering experiments in high-energy synchrotron X-ray region

Abstract

To obtain both a high count rate of >107s−1 and a detection efficiency sufficient for high-energy X-rays of >30keV, we propose a scintillation timing detector using a proportional-mode silicon avalanche photodiode (Si-APD) for synchrotron radiation nuclear resonant scattering. We here present results obtained with a prototype detector using a lead-loaded plastic scintillator (EJ-256) mounted on a proportional-mode Si-APD (active area size: 3mm in diameter). The detector was operated at ‒35°C for a better signal-to-noise ratio. Using synchrotron X-rays of 67.41keV, which is the same energy as the first excited level of 61Ni, we successfully measured pulse-height and time spectra of the scintillation light. A good time resolution of 0.50±0.06ns (full width at half-maximum) was obtained for 67.41keV X-rays with a scintillator 3mm in diameter and 2mm thick.