Wire chamber system in deuteron photo-disintegration experiment

The wire chamber system which was used for the measurement of the polarization of recoil protons in deuteron photo-disintegration experiment is described. The system consists of two multi-wire proportional chambers (MWPC) and ten wire spark chambers (WSC), which are set in front of and behind a momentum analyzing magnet, respectively. Among WSC, five are used for the measurement of polarization. The range counter system, which consists of five layers of aluminum plates and scintillation counters, is placed at the end of the beam path. The frames of the WSCS are made of bakelite of 12 mm thick, and Cu Be wires of 100 μm diameter are stretched at the intervals of 1 mm. Test experiments were performed for three months, and the WSCS worked in good conditions. The gas used was 95% He and 5% Ar, the applied high voltage pulse was -12 KV, and the cearing field 100 V. The output system of the WSCS was magnetostriction wire type. The CAMAC system called track digitizer (TD) was developed. The structure of MWPC is illustrated in a figure. The frames are made from glass epoxy resin, the sensing wires are gold plated Mo wires of 20 μ m diameter, and HV wires are gold plated W wires of 100 μm. The interval of wires was 2 mm. The test was performed with Sr90. The gas used was 50% Ar and 50% isobutane, and the applied high voltage with -5.3 KV. (Kato, T.)