A multiwire proportional chamber for precision studies of neutron ββ decay angular correlations

A new multiwire proportional chamber (MWPC) was designed and constructed for precision studies of neutron ββ decay angular correlations. Its design has several novel features, including the use of low pressure neopentane as the MWPC gas and an entrance window made of thin Mylar sheet reinforced with Kevlar fibers. In the initial off-line performance tests, the gas gain of neopentane and the position resolution were studied.