Observation of scintillation light from interactions of neutrons in liquid methane chamber

Nuclear reaction data on high-energy neutrons are necessary in the fields of science and technology such as the accelerator shielding design and the irradiation damage of spaceship microelectronics. Few measurements have been made for high-energy neutrons above 100 MeV so far, and the data accuracy is insufficient. We have a plan to develop a time projection chamber (TPC) filled with liquid methane to measure the high-energy neutrons in a high efficiency. If the scintillation light by incident neutrons can be observed from the liquid methane, it may be useful for an internal trigger signal for operation of the TPC. However, no report have presented that the scintillation lights are emitted outward through the liquid methane. Therefore, we examined whether the scintillation light are absorbed in the liquid methane or observed by photomultipliers. We constructed a liquid methane chamber, and demonstrated that scintillation lights can be measured for neutron incidence on the liquid methane. The light was generated without addition for xenon.