Spectrometer Instrumentation for CERN SPS Secondary Beams

At the CERN SPS (Super-Proton-Synchrotron) most of the secondary beams are provided with a momentum measuring section. Each spectrometer consists of four multiwire proportional chambers with a fast readout system allowing a multi-user access. The chambers are operated with an Ar/CO2/ Freon gas mixture so as to withstand beam intensities of ≤ 107 particles/s with efficiency close to 100 % and without significant ageing effects. The system, being fully computer-controlled, has a fast diagnostics capability through a powerful software.