The performance of an electroluminescence (EL) Time Projection Chamber (TPC) with a multi avalanche photodiode (APD) readout was studied in pure xenon at 3.8 bar. Intercalibration and reconstruction methods were developed and applied to the data yiel
ding energy resolutions as good as 5.3$pm$0.1 % FWHM for 59.5 keV gammas from $^{241}$Am. This result was reproduced with a Monte Carlo (MC) based on Geant4 and Penelope which predicted 5.2 % FWHM for the used setup. Point resolutions of $approx 0.5$ mm were obtained with a pitch of 15 mm between the APDs. These results show that multi-APD readout is a competitive technology for EL detectors filled with pure xenon.
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 volt
age 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 %.
Detectors with an electroluminesence readout show an excellence performance in respect of energy resolution making them interesting for various applications as X-ray detection, double beta and dark matter experiments, Compton and gamma cameras, etc.
In the following the study of a readout based on avalanche photo diodes to detect directly the VUV photons is presented. Results of measurements with 5 APDs in xenon at pressures between 1 and 1.65 bar are shown indicating that such a readout can provide excellent energy and a moderate position resolution.
