Development of thermal neutron flux monitor using small scintillator array coupled with quartz fibers for Boron Neutron Capture Therapy

At Kyoto University Research Reactor Institute, over three hundred clinical trials of Boron Neutron Capture Therapy (BNCT) have been performed using research reactor. On the other hand, we have developed cyclotron based epithermal neutron source. To improve the quality of treatment, it is necessary to perform the detection of two dimensional thermal neutron distribution before treatment as quality control. Generally, the method of activation using gold foil/wire and germanium semiconductor detector is applied to detection of thermal neutron flux at several positions. However, the activation method using semiconductor detector takes some time to decide the thermal neutron flux. Therefore, we propose the method using small scintillator arrays coupled with quartz fibers for easy detection of two dimensional thermal neutron distribution with low radiation damage. To reduce the number of electric circuit and scintillators, we proposed the scanning method using one dimensional scintillation array. To evaluate this method, the irradiation test was performed using Kyoto University Research Reactor(KUR). Two dimensional thermal neutron distribution was easily obtained with the spatial resolution of 5mm.