Method of monitoring neutron sensitivity of neutron detector

A method of monitoring the neutron sensitivity of a neutron detector, comprising the steps of:

• preparing a plurality of neutron detectors by coating at least one of an anode and a cathode of each of said plural neutron detectors with a nuclear fission substance containing a parent nuclear species for each lot;
• applying voltage of a predetermined potential difference between said anode and said cathode of at least one neutron detector sampled from among said plural neutron detectors for each lot without irradiating said neutron detector with neutron so as to monitor the α-ray current (Iα) flowing between the anode and the cathode by the ionization of an ionizing gas caused by the α-ray emitted from said nuclear fission substance;
• and
• obtaining, with the monitoring region in which the applied voltage and the α-ray current (Iα) bear a substantially proportional relationship within at least 50V of the applied voltage used as a reference, an extrapolated zero-volt α-ray current (I≢0) at 0V of the applied voltage between the anode and the cathode from said proportional relationship by an extrapolating method and, a correlation the extrapolated zero-volt α-ray current (Iα0) and the neutron sensitivity, the correlated neutron sensitivity being regarded as the neutron sensitivity of the plural neutron detectors for each lot.

A method of monitoring the neutron sensitivity of a neutron detector, comprising the steps of:

• preparing a plurality of neutron detectors by coating at least one of an anode and a cathode of each of said plural neutron detectors with a nuclear fission substance containing a parent nuclear species for each lot, at least one neutron detector sampled from among said plural neutron detectors for each lot being used as a standard neutron detector;
• applying voltage of a predetermined potential difference between said anode and said cathode without irradiating said standard neutron detector for each lot with neutron so as to monitor the α-ray current (Iα) flowing between the anode and the cathode by the ionization of an ionizing gas caused by the α-ray emitted from said nuclear fission substance;
• obtaining, with the monitoring region in which the applied voltage and the α-ray current (Iα) bear a substantially proportional relationship within at least 50V of the applied voltage used as a reference, an extrapolated zero-volt α-ray current (Iα0) at 0V of the applied voltage between the anode and the cathode from said proportional relationship by an extrapolating method, and an correlation the extrapolated zero-volt α-ray current (Iα0) and the neutron sensitivity;
• and
• correcting the decay of the neutron sensitivity caused by the lapse of time from the manufacturing time of the plural neutron detectors for each lot on the basis of the extrapolated zero-volt α-ray current (Iα0) of said standard neutron detector monitored at the lapse of said time to obtain corrected values of the neutron sensitivity of said plural neutron detectors for each lot at the lapse of said time.