Double sided silicon strip detectors (DSSSD)

The DSSSD is ideal for detecting charged--particle emission from nuclei at the drip line. Their thin profile to betas (50-300 micron thickness) and high granularity make them the detector of choice in the search for proton emitters. These detectors will be located after the recoiling nuclei are mass tagged by the PSAC. In addition to decay studies, the DSSSD may be used to detect evaporated particles in the hostile environment of the target where their "pixelization" allows them to run at very high counting rates.

The initial detectors will be 4 cm square and contain either 16 or 40 strips on each side. These detectors are commercially available and inexpensive (approximately $4k for existing detectors and $10k for new designs). The size and thickness of these detectors should be kept small so that contamination resulting from beta radiation is minimized. This maximizes the amount of time in which to look for exotic decays such as proton emission. The recoil "beam spot" is exected to be narrow (4 cm full-width tenth-maximum) but quite tall (3-4 cm) depending on the position of the focal plane. By manipulating the position of the focal plane, uniform illumination of the DSSSD should be obtainable. Often, absorbers are used to control the implantation depth and the energy deposited in the DSSSD. This energy determines the recovery time of the detector after which, one can begin searching for valid events.

Because of the high granularity, the DSSSD electronics need to be compact and relatively inexpensive. The University of Edinburgh has developed a compact design which couples 8 shaping amplifiers and leading edge discriminators on to one 6U-Eurocard PCB mother-board within a 48.3 cm. KM6 sub-rack (CAMAC). The University of Edinburgh has agreed to supply electronics and cables for 256 channels.

Initially, the detectors will be mounted in fixed positions, perhaps in the gamma chamber. A future development project is to mount the detectors on a moving track which would allow positioning of the detectors in the vacuum without changing the RMS. settings. These detectors will be cooled with a glycol solution and must be taken into account when designing the movement mechanism.

Major contributors to this project are ORNL, UNISOR consortium, and the University of Edinburgh.