A PROTOTYPE 8X8 PIXEL ARRAY X-RAY-DETECTOR FOR PROTEIN CRYSTALLOGRAPHY

An 8 x 8 pixel array X-ray detector prototype (< 15 keV) has been buil t and tested. This room temperature detector will significantly enhanc e time resolved Laue Protein Crystallography by two or three orders of magnitude compared to the present crystallographic phosphor imaging p lates and CCD-type detectors. In addition, the detector will greatly a ccelerate the monochromatic crystallography data collection at synchro tron light sources where very intense X-ray fluxes above 5 x 10(8) pho tons/cm(2)/s are obtained. The detectors event-driven read out is base d on the column architecture which can provide energy discrimination a nd sparse and frameless output displaying minimal dead time. For the t argeted detector size of (1000 x 1000) pixels, average hit rates great er than 8 x 10(7) photons/s for the entire area appears achievable. To characterize the analog portion of the read out and the digital chara cteristics of the detector, the pixel electronics contains only the an alog portion of the circuit and is independent of the surrounding cell s. The conversion of a photon hit into a pixel address is generated by conventional external electronics. The measured results are very enco uraging. The analog electronics demonstrate the capability of processi ng charge pulses at a rate of 1 x 10(6) photons/s/pixel, with an energ y resolution of 480 eV (FWHM at 5.9 keV) at room temperature. The dete ctor displays uniform digital behavior and has a very low point-spread function. The full-width at 1/100 maximum is less than 1 pixel width (150 mu m), which is less than (1/2) that of a CCD and (1/7) that of a n imaging plate detector [1].