Can Ce:Gd3Al2Ga3O12 scintillators detect thermal neutrons?

Alternative neutron detectors are actively being researched to replace He-3 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 thermalneutron 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 Gdcontaining scintillator, Ce:Gd3Al2Ga3O12 (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 pulseheight 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.