Application of a⁶LiF Small Neutron Detector with an Optical Fiber to Tritium Production Rate Measurement in D-T Neutron Fields

Abstract

6 LiF small neutron detectors with an optical fiber have been used to measure 6 Li(n,)T reaction rate distributions at thermal research reactors and accelerator facilities. In the present study, we developed an experimental method for the measurement of tritium production rate (TPR) of 6 Li using this small detector in deuterium-tritium (D-T) neutron fields. Reaction rate measurements with the detector were conducted in the D-T neutron fields at the Fusion Neutronics Source (FNS) facility. From the results, we determined that this detector can be used to measure the TPR distribution in soft neutron spectrum fields such as in a Be assembly. It is difficult to obtain 6 Li(n,)T reaction rate separately in hard neutron spectrum fields such as in a Li 2 O assembly, because many kinds of charged particle production reactions need to be taken into consideration. However, a time-dependent reaction rate measurement method combined with the 6 LiF detector and the ZnS detector is effective to separate the 6 Li(n,)T reaction from other reactions even in a hard spectrum field, and it can be applied to the measurement of the TPR distribution accurately.

Applications of scintillators in optical-fiber-based detectors

“…Therefore, optical-fiber-based detectors using alternative converter materials for fast neutron detection were developed. 16,17) In these researches, some threshold reactions of zinc and sulfur isotopes in Ag:ZnS scintillators, such as 64 Zn(n, p) 64 Cu and 32 S(n,p) 32 P reactions, were proposed to be applied for fast neutron detections. This type of detector was demonstrated to measure the spatial distribution of fast neutrons emitted from an accelerator-based T(d, n) reaction neutron generator, which was used for the accelerator-driven system (ADS) In these experiments, the pulse shape discrimination (PSD) technique was shown to be useful for eliminating noise signals induced in a PMT and optical fiber by Cherenkov events and so on.…”