NEW DATA-ACQUISITION SYSTEM FOR THE FOCAL-PLANE POLARIMETER OF THE GRAND RAIDEN SPECTROMETER

This paper describes a new data acquisition system for the focal plane polarimeter of the Grand Raiden spectrometer at the Research Center f or Nuclear Physics (RCNP) in Osaka, Japan, Data are acquired by a Crea tive Electronic Systems (CES) Starburst [1], which is a CAMAC auxiliar y crate controller equipped with a Digital Equipment Corporation (DEC) Jl1 microprocessor. The data on the Starburst are transferred to a VM E single-board computer, A VME reflective memory module broadcasts the data to other systems through a fiber-optic link, A data transfer rat e of 2.0 Mbytes/s between VME modules has been achieved by reflective memories. This rate includes the overhead of buffer management. The ov erall transfer rate, however, is limited by the performance of the Sta rburst to about 160 Kbytes/s at maximum. In order to further improve t he system performance, we developed a new readout module called the Ra pid Data Transfer Module (RDTM). RDTM's transfer data from LeCroy PCOS III's or 4298's, and FERA/FERET's directly to CES 8170 High Speed Mem ories (HSM) in VME crates, The data transfer rate of the RDTM from PCO S III's to the HSM is about 4 Mbytes/s.