Experimental results of a 7-channel spectroscopy detector module with mega-count rate capability

A compact detector module based on Si-drift detectors with integrated junction-field effect transistors has been developed. It has been set up for X-ray absorption spectroscopy and X-ray standing-wave technique, and is usable in vacuum environment. The modules´ hexagonal shape with a wrench size of 16 mm allows small distances to the samples and a compact multi-module arrangement. The monolithic 7-cell sensor has an active area of ~50 mm² and a thickness of 450 mum. It provides a spectral resolution of some hundred eV in the soft X-ray regime at room temperature. A fully differential 7-channel BiCMOS readout chip has been developed to process the detector signals at a power dissipation of 15 mW per channel. First spectral measurements with energies up to 43 keV have been performed with the prototype module. A rate-dependent energy-peak shift remains below 3% at integral photon- count rates of more than 6 Mcts/s. The deviation from the linear regression is within plusmn2% in the energy range between 6 and 20 keV. The on-chip gain variations are below 3.4%.