Design and Fabrication of a Data Acquisition System for Pulsed Neutron Flux Measurement of Plasma Focus Devices

Abstract

Silver-activated Geiger counters together with a polyethylene layer as neutron moderator are frequently used in pulsed neutron flux measurements in research studies with plasma focus (PF) devices. In this study, an array of seven counters was used at seven different angles (0°, ±30°, ±60°a nd ±90°) to the PF-axis for which a software and a 10-channel data acquisition hardware (PCT2660) compatible with NIM standards have been designed and fabricated. In the proposed PCT2660, the preset timing algorithms are considered as general and they can be programmed for required detector calibrations and neutron flux measurements. The calibration constant measurement has been undertaken with a 16.5 Ci Am-Be source of 35 mm diameter by 70 mm cylindrical active volume located at anode top whilst the neutron flux at zero degree of PF device axis at 13.5 kV operating voltage and 13.54 9 10 -2 PSI pressure is measured as (2.88 ± 0.29) 9 10 8 neutrons per shot. Accordingly, the studies on the angular distribution of the PF neutron emission within the pressure range of 7.73 9 10 -2 -15.47 9 10 -2 PSI confirm an anisotropy ranging from 1.53 ± 0.09 to 2.95 ± 0.24 and a symmetry of angular distribution around the anode axis.