Characterization of the Hamamatsu S8664 Avalanche Photodiode for X-Ray   and VUV-light detection
  We present the first operation of the Avalanche Photodiode (APD) from Hamamatsu to xenon scintillation light and to direct X-rays of 22.1 keV and 5.9 keV. A large non-linear response was observed for the direct X-ray detection. At 415 V APD bias voltage it was of about 30 % for 22.1 keV and about 45 % for 5.9 keV. The quantum efficiency for 172 nm photons has been measured to be 69 +/- 15 %. 
T. Lux, E. D. C. Freitas, F. D. Amaro, O. Ballester, G. V.   Jover-Manas, C. Martin, C. M. B. Monteiro, F. Sanchez and J. Rico
physics.ins-det