The Oxford submicron nuclear microscopy facility

Abstract This paper describes the unique nuclear microprobe facility now established in the University of Oxford. The system, which uses a dedicated small accelerator, operates on a regular daily basis, therefore the emphasis of the design has been on achieving reliable, high-quality performance while minimising overheads of alignment in the focusing system and off-line data processing. The beam-optical system from the ion source to the final lens is described. The final lens has been specially developed to have negligible sextupole-field contamination which allows submicron operation using simple alignment procedures. The system uses up to three beam lines with specialised target chambers. These are described briefly. The data acquisition system uses distributed processing with a VMEbus 68020 microcomputer system handling collection and on-line sorting of data from up to six detectors, a graphics workstation for operator interfacing and a mainframe computer for archiving and off-line processing of data. The components of the system communicate via Ethernet and a low-failure-rate/highthroughput communications protocol has been developed. The archiving procedures are designed to handle high volumes of data (up to 100 Mb per day) with efficient data compression, transparent recall of recent data and simple restoration of archived data.