Neutron moderator, neutron irradiation method, and hazardous substance detection apparatus
A neutron moderator includes a neutron generator; a neutron moderating material arranged on one side of the neutron generator; a gamma ray shielding material covering an external surface of the neutron moderating material; and a thermal neutron absorbing material covering the external surface of the neutron moderating material except a side where the neutron generator is arranged.
1. A neutron moderator comprising:
a neutron generator;
a neutron moderating material arranged behind the neutron generator;
a gamma ray shielding material covering an external surface of the neutron moderating material; and
a thermal neutron absorbing material covering the external surface of the neutron moderating material except a side where the neutron generator is arranged, wherein
the gamma ray shielding material comprises:
a first gamma ray shielding material covering the external surface of the neutron moderating material except the area where the neutron generator is arranged; and
a second gamma ray shielding material arranged between the neutron generator and the neutron moderating material and just behind the neutron generator, and having a function to increase thermal neutron.
2. A hazardous substance detection apparatus comprising:
an inspection chamber where an inspection target is insertable and removable;
a thermal neutron absorbing material arranged so as to surround the inspection chamber;
a neutron generator arranged facing the inspection target in the inspection chamber;
a neutron moderating material arranged at an opposing side of the inspection target with respect to the neutron generator;
a gamma ray shielding material covering an external surface of the neutron moderating material; and
a gamma ray detector that detects gamma ray generated from the inspection target, wherein
the gamma ray shielding material comprises:
a first gamma ray shielding material covering the external surface of the neutron moderating material except the area facing the neutron generator; and
a second gamma ray shielding material arranged between the neutron generator and the neutron moderating material and just behind the neutron generator, and having a function to increase thermal neutron.
3. The hazardous substance detection apparatus according to claim 2 , wherein the gamma ray detector comprises a germanium semiconductor detector and a bismuth germanate oxide scintillator detector.
4. The hazardous substance detection apparatus according to claim 2 , further comprising a pair of neutron detectors arranged facing each other at both sides of the inspection target.