A FAST READOUT SYSTEM FOR 2D GAS-FILLED DETECTORS BASED ON THE DELAY-LINE METHOD

The new generation of high brilliance synchrotron radiation sources su ch as the ESRF requires detectors with improved counting rate capabili ty and resolution. Gas filled detectors are of particular interest for small-angle scattering applications due to their low inherent backgro und. A counting rate increase of delay-line based 2D detectors is poss ible through the reduction of the delay line and a modularisation of t he detector. To this end a new readout system has been designed based on VME/VXI modules. The heart of the system is a Time-to-Digital Conve rter (TDC) with 50 ps resolution (at 200 MHz master clock frequency). Counting rates in excess of 1.8 MHz have been demonstrated with a 100 x 100 mm2 detector and 20 ns delay line. A further improvement of the TDC should allow counting rates up to 5 MHz.