A Si-APD array detector for nuclear resonant scattering using synchrotron X-rays and its fast-pulse processing

An 8×2 array of silicon avalanche photodiode (Si-APD) was developed as an X-ray detector for the Mössbauer micro-spectroscopy on Fe-57 (nuclear resonant energy: 14.4 keV; half-life: 98 ns) using synchrotron X-rays. The time resolution ΔT (FWHM) of the Si-APD array detector was 0.3 ns in the forward scattering experiments. Ultra-fast frontend circuits have been provided for the Si-APD array with the pixilated position sensitivity. A fast amplifier was first developed using hybrid ICs. Its charge sensitivity was 4 V/pC and the pulse width was 2.3 ns (FWHM).