Low pressure multiwire proportional chamber and its application to radioactive ion beam experiment

Radioactive ion beam is generally characterized by small beam intensity and big beam size. In order to carry on precise scattering and reaction experiments it is necessary to monitoring the incident angle and absolute number of the beam hitting the target. We therefore have designed and made up low pressure multiwire proportional chambers (LPMWPC) which have good beam transparency and are also adequate to be used in vacuum. Experiment test indicates that the position resolution of the chambers is about 0.5mm and the position determination efficiency is larger than 90 % for the low Z particles at intermediate energies. This kind of chamber can then be used to detect the direction of the incident particle and to record the absolute number of the particles which really hit the target, or to detect the emitting angle of the outgoing particles.