The region one drift chamber for the CLAS spectrometer

The Region One detector is the innermost of three nested drift chamber pack ages of the CLAS spectrometer at Jefferson Laboratory. This detector, with 7776 drift cells, was optimized for the CLAS toroidal magnet geometry, and consists of six wedge-shaped sectors integrated into a single unit. Each se ctor has thin and relatively weak aluminum endplates which support the larg e mechanical loads from the wire tensions and associated readout hardware. The unusual feature of the detector is its self-supporting design, wherein the wire tensions of neighboring sectors balance each other without the use of massive structural support. We discuss the design criteria, mechanical components, and assembly procedures. (C) 1998 Published by Elsevier Science B.V. All rights reserved.