Investigation of the influence of an inner gas bubble on the response of a liquid scintillation detector to γ-rays and neutrons

• Influence of an inner gas bubble on the response of EJ301 detector is investigated.
• Energy deposition and light transmission process has been simulated with the Geant4 toolkit.
• Best detector placement style has been determined for neutron energy spectrum measurement.

The influence of an inert gas bubble inside EJ301 cylindrical cell on the response of the liquid scintillation detector to γ-rays and neutrons has been investigated. It is found experimentally that the response of the detector to radiation varies with the detector placement styles. The explanation proposed in this article is that this variation arises from the change of the light transmission process induced by the motion of the inner gas bubble. This assertion has been supported by the simulations of both radiation energy deposition and light transmission process inside the detector with the GEANT4 code. For the recommended detector placement style when the detector is placed horizontally, the variation of the response is smaller than 1.56%, which will increase to about 22% when the detector is placed facing down and the bubble lies between the scintillator and photomultiplier tube.