The CDF intermediate silicon layers detector

The Intermediate Silicon Layers detector (ISL) was proposed as a part of th e upgraded CDF detector at the RUN-II of the Tevatron p (p) over bar Collid er at Fermilab, scheduled to start in year 2000. The ISL is a large-radius (20-30 cm) silicon tracker with a total active area of about 3.5 m(2). Loca ted in the region between the Silicon Vertex Detector (SVX II) and the Cent ral Outer Tracker, the ISL will allow tracking in the forward region and si gnificantly improve it in the central area. Together with the SVX II the IS L forms a standalone, 3D silicon tracker. The challenge is to build a low-c ost device which provides precise 3D tracking in a approximate to 2m long a rea with a minimal amount of material for the supporting structure. The con ceptual design and the status of the project are reviewed.