Can Ce:Gd3Al2Ga3O12 scintillators detect thermal neutrons?

Alternative neutron detectors are actively being researched to replace 3He gas detectors for neutron scattering and homeland security. Neutron scintillators for this purpose must have high light output, short decay time, low sensitivity to gamma-rays, and possibly be non-hygroscopic. Gd-containing oxide scintillators are excellent at detecting gamma-rays, but their thermal-neutron detectability has not been proven yet, because of similar pulse-shapes and pulse-heights generated under thermal neutrons and gamma irradiation. Here we show that a non-negative matrix factorization (NMF) algorithm for digital signal processing greatly improves neutron-gamma discrimination ratio (the ratio of neutron and gamma detection efficiencies) of a Gd-containing scintillator, Ce:Gd 3 Al 2 Ga 3 O 12 (GAGG). In the case of Ce:GAGG as a gamma detector, better discrimination against ambient background events was observed compared to results from a traditional pulse-height method. It was also found that the secondary integration area (S 2 ) of a waveform in the time window of 0-50 ns is an energy measure of gamma-rays. Therefore, Gd-containing scintillators are potentially applicable in not only neutron detection but also in gamma detection with higher signal-to-noise ratio.