A thin 4pibeta-counter operating by negative high voltage for the 4pibeta-gamma coincidence measurement.-Construction

A thin 4pibeta-multiwire proportional counter was constructed to increase the gamma-ray counting efficiency in the 4pibeta-gamma coincidence method. This counter with a counting volume of 70 X 60 X 11 mm and 5 wires in one half was made of an insulator and negative high voltage was supplied to the inner wall being possessed of conductivity. Then the anodes were operated at the earth potential and compact preamplifiers with no coupling condenser were fixed at the side of each half to miniaturize a shielding system for background. From the experimental results in various conditions, good characteristics were obtained in the case that signals were taken out from the center anode and the others were used only for cleaning up excess charges.