A 4π Multi-wire Proportional Chamber for the 4πβ-γ Coincidence Measurement

The β detector of 4πβ-γ coincidence measurement is usually a proportional counter with a single wire of which the electric field distribution is divergent and the detection area is limited, so it can only measure the activity of the point source. A 4π multi-wire proportional chamber used as the β detector of 4πβ-γ coincidence measurement has been designed and fabricated because of the uniform electric field distribution and large detection area. The β plateau curves and the background have been tested. The results show that the plateau length of the β plateau curve is about 270 V, and the plateau slope of the upper and lower anode wires are 8.3‰ and 9.6‰ (⁶⁰Co), 8.3‰ and 8.9‰ (⁹⁰Sr-⁹⁰Y), respectively. The background counting rate is within 10 s^-1. The 4π multiwire proportional chamber can be used as the β detector of 4πβ-γ coincidence measurement for further research.