Fabrication and application of position sensitive neutron counter with a new method to obtain signals from only one end of anode wire

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The purpose of the research is the development and application of a new counter with a novel position-sensing method using slow and fast components in the output signal observed at one end of a resistive anode wire of which the other end is grounded through a high voltage capacitor.Two main amplifiers are used through a single pre-amplifier. An output pulse Vf obtained through a fast amplifier with a shaping time constant of 0.1 micro-sec gives position information and the output pulse Vs from a rather slow amplifier with time constant of 10 micro-sec gives the information of the total charge. Therefore, Vf/Vs gives the accurate position of a detected radiation. The relative position resolution obtained with this principle was 0.011. However, the position resolution slightly depended on the position itself.Position sensitive nuclear fission counter with an outer diameter of 15mm and a length of 1.2m was fabricated. The position resolution deteriorated under gamma-ray exposure of 10000R/h (2.58C/kg・h). The deterioration was found to be due to the fluctuation of the number of primary electrons produced by gamma-rays and, therefore, to be proportional to the pulse shaping time of the main amplifiers.Position sensitive nuclear fission counter with an outer diameter of 10mm and a length of 2m was fabricated and inserted into a narrow measurement hole in a graphite pile to measure neutron flux distribution. The effect of the streaming of neutrons could be neglected because of very thin counter.