γ{\hbox-}Flashγ{\hbox-}Flash suppression using a gated photomultiplier assembled with an LaBr3(Ce) detector to measure fast neutron capture reactions

• Prompt $\gamma$-ray measurements of fast neutron capture reaction.•An LaBr$_3$(Ce) detector is used with a gated voltage divider.•The photomultiplier gating technique is applied to the detector.•The effect of the intense $\gamma$ flash is suppressed.•The measured TOF spectrum extends toward faster neutron energy region.

A gated photomultiplier tube (PMT) assembled with an LaBr3(Ce) detector was applied toward the prompt γ{\hbox-}rayγ{\hbox-}ray measurement of fast neutron capture reactions. Time-of-flight measurements of the neutron capture reactions of Cl and Al were performed using the 46-MeV electron linear accelerator at the Kyoto University Research Reactor Institute (KURRI) as a pulsed neutron source. The photomultiplier gating technique effectively suppressed the saturation of the PMT output and extended the energy region of the TOF measurement.