Recent developments in the avalanche photodiode x-ray detector for timing and fast counting measurements

Abstract

An avalanche photodiode (APD) detector using a new silicon device has been developed for x-ray timing measurements. The device, Model No. S5343 (Hamamatsu Photonics), has an excellent time resolution of 0.10 ns and has only a short tail, or a full width of 1.41 ns at 10−5 maximum, in the response function for the time spectrum. Measurements of the purity between the main and second bunches to the order of 10−9 were successfully executed in observing the bunch structure of the Photon Factory ring with the detector as an application to the bunch-purity monitor. The APD detector also has a property for fast counting up to the order of 108 counts per second by using its output width, shorter than several nanoseconds. The count-rate property has been examined with the pulsed beams of synchrotron radiation and with an APD device Model No. C30817E (EG&G Optoelectronics), which has a depletion layer about 100 μm thick. The results show that the count-rate response can almost be expressed by a counting model for the pulsed beam.