ELECTRONIC AREA DETECTOR DATA REDUCTION SYSTEM AT THE SRS

With the current detector and computer technology, data collection at synchrotron x-radiation sources poses special problems. Fast data collection rates are essential for kinetic experiments at room temperatures. If maximum reflection measuring rates of 102-103 reflections per second for monochromatic and 105 reflections per second with white beam are to become feasible, some simplifications at data collection time must be made, at the expense of possible complications during data reduction at a later stage. The main benefit of EAD's over film is that a 3D profile scan of each reflection can maximise the peak-to-background ratio. The benefits are even more marked on synchrotron sources since the intrinsic mosaicity of protein crystals can be small. With optimum collimation the angular spread of a reflection can be reduced 5-fold over a conventional source, thus giving further improvement in signal-to-noise. Brief details are given of the EAD system (hardware and software) for protein crystallography at the SRS wiggler beam line, based on a TV system for 0.5 ≲ λ ≲ 1.5 Å