A VMEBUS DATA-ACQUISITION AND ANALYSIS SYSTEM FOR THE KFUPM SCANNING NUCLEAR MICROPROBE

This paper describes the VMEbus data acquisition and analysis system a t the newly-established scanning nuclear microprobe facility on the Ta ndetron accelerator at the Energy Research Laboratory of King Fahd Uni versity of Petroleum and Minerals. Based on CERN's VALET-Plus VME envi ronment, CAMAC data acquisition hardware, and a Macintosh user interfa ce, the system acquires one energy spectrum and can handle up to 20 en ergy windows simultaneously. Data is sorted into distribution maps, ea ch 64 x 64 pixels in size. This allows online analysis for multiple el ements, thus reducing beam time requirements. Fast display of collecte d spectra and constructed distribution maps is provided on a color gra phics monitor. The VME system synchronizes action with an IBM-compatib le 386 computer used by the microbeam apparatus for sample positioning and beam scanning. The system performs other important functions such as calibration, plotting, printing, data storage and retrieval, as we ll as exporting data to other packages for offline analysis. Details o n both the hardware components and the software development are given. Performance data are presented, including typical results obtained du ring routine runs. User evaluation of the present setup is discussed t ogether with future plans for further improvements.