Timing resolution measurements of a 3 in. lanthanum bromide detector

Cerium-doped lanthanum bromide (LaBr3:Ce) is a scintillator that presents very good energy and timing resolutions and it is a perfect candidate for photon detector in future experiments to search for lepton flavor violation as in μ → e γ or μ → e conversion. While energy resolution was thoroughly investigated, timing resolution at several MeV presents some experimental challenge. We measured the timing resolution of a 3 in.×3 in. cylindrical LaBr3(Ce) crystal versus few reference detectors by means of a nuclear reaction from a Cockcroft–Walton accelerator that produces coincident γ -rays in the 4.4–11.6 MeV range. Preliminary results allow us to extrapolate the properties of a segmented γ -ray detector in the 50–100 MeV range.