A long focal-plane detector with a hybrid structure

A 1.2 m long position sensitive detector has been constructed to detect light and light-heavy ions over a wide momentum range with large vertical acceptance in the focal plane of the Texas A and M Enge split-pole spectrograph. The detector consists of a stack of five single-wire proportional counters in combination with another ionization and drift domain. The front two counters provide information about the energy loss and the position of the incident particles, and the other give only energy loss information. Separation of ionization and multiplication regions using the drift mechanism enables a large vertical acceptance, i.e. 27 mm. A position resolution better than 1.2 mm is obtained for 50 MeV alpha particles. Particle identifications can easily be obtained for light and light-heavy ions. (orig.)