Multichannel Spectrometer Detector

The use of a multichannel detector in the focal plane of a magnetic spectrometer effectively decouples the wellknown reciprocal relation between spectrometer resolution and transmission applicable to single-channel detection The Stanford 36-inch magnetic spectrometer is used in electronscattering experiments in conjuction with the Mark III linear electron accelerator. In order to utilize the full momentum acceptance of the spectrometer (¿/p/p ¿ 0.05), we have constructed a 10-channel prototype of a 50-channel scintillation-Cerenkov detection system which will possess a resolution (p/¿p ~ 1000) close to the maximum obtainable from the spectrometer. The momentum channels are defined by small scintillation counters which detect ionizing particles, consisting primarily of high-energy pions and electrons. Electrons are distinguished from mesons by Cerenkov counters which back up blocks of 10 scintillators. A coincidence is required (2¿ ¿ 3 + 10-8 ¿sec) between a scintillation detector and the associated Cerenkov counter. A 256-channel computer-type ferrite core memory (Radiation Counter Laboratories Mark 20), divided into four manually or electronically-selected blocks of 64 channels, is used to store the information from the counter array. The use of this large memory allows storage of correlated information in matrix form from two arrays of counters.