The long counter’s Supply Voltage is 1450V that confirmed by
252Cf neutron source, The effective center is 13.5cm away from the front surface of the long counter. It found that the long counter is smooth characteristic by comparing count rate with different thickness polyethylene that moderating the same neutron source. attenuation coefficient of a new developed boronizing polyethylene is measured using the BF
3 long counters, and the experimental result is 0.236, the calculated value with MC is 0.218. both accord with range of error.