Fast APD Detector with a Short Tail in the Timing Response for an Experiment Using Synchrotron Radiation X-ray Beam

We developed a fast X-ray detector system for a nuclear resonant scattering experiment of thorium-229. The system employs silicon avalanche photo-diode as a fast X-ray sensor. The design of the system mainly focuses on the small tail of the timing response in a high rate condition. To reduce the tail component, the system acquires three parameters for each single X-ray photon: the constant fraction timing, the trailing edge timing with a fixed threshold, and the pulse height. The performance of the system was investigated in KEK-PF. A quite small tail of 10 (cid:0) 9 level at 0.5 ns apart from the peak was achieved by using the correlation between the pulse height and the pulse width information.