HIGH-SPEED DATA-ACQUISITION SYSTEM FOR LARGE-AREA PROPORTIONAL-COUNTERS

A modular, UNIX/X-Windows/Sun SPARC-based data acquisition and analysi s system provides NASA X-Ray Timing Explorer (XTE) Proportional Counte r Array (PCA) scientists with near real-time access to space flight in strument ground test data. This system processes data directly from fi ve large-area, xenon-filled low-background collimated proportional cou nters at rates up to 2 MB/s in a networked, real-time environment. Sci ence events are sent serially from the proportional counter flight ele ctronics and multiplexed on a custom-designed data acquisition board. Each event is tagged with a time stamp of 1 mus resolution and a detec tor identifier. A commercial Direct Memory Access (DMA) board interfac es directly to the data acquisition board allowing asynchronous transf er of buffered data to software residing on a high performance worksta tion. A windows-based interface provides an operator with acquisition command and control functions to capture data through the DMA board. D ata is collected, buffered, and archived to magnetic disk. Histogrammi ng and statistical functions are provided by the software enabling rea l-time pulse height spectroscopy, rate analysis, and spectral analysis .