Apparatus and method for neutron detection with neutron-absorbing calorimetric gamma detectors

摘要

The invention refers to an apparatus for detecting neutron radiation, preferably thermal neutrons, comprising a gamma ray scintillator, said scintillator comprising an inorganic material with an attenuation length Lg of less than 10 cm, preferably less than 5 cm for gamma rays of 5 MeV energy in order to provide for high gamma ray stopping power for energetic gamma rays within the gamma ray scintillator, the gamma ray scintillator further comprising components with a product of neutron capture cross section and concentration leading to an absorption length Ln for thermal neutrons which is larger than 0,5 cm but smaller than five times the attenuation length Lg, preferably smaller than two times the attenuation length Lg for 5 MeV gammas in the said scintillator, the neutron absorbing components of the gamma ray scintillator releasing the energy deployed in the excited nuclei after neutron capture mainly via gamma radiation, the gamma ray scintillator having a diameter or edge length of at least 50% of Lg, preferably of at least Lg, in order to absorb an essential part of the gamma ray energy released after neutron capture in the scintillator, the apparatus further comprising a light detector, optically coupled to the gamma ray scintillator in order to detect the amount of light in the gamma ray scintillator, the apparatus further comprising an evaluation device coupled to the light detector, said device being able to determine the amount of light, detected by the light detector for one scintillation event, that amount being in a known relation to the energy deployed by gamma radiation in the gamma ray scintillator, where the evaluation device is configured to classify detected radiation as neutrons when the measured total gamma energy Esum is above 2,614 MeV.