In rare events experiments, such as those devoted to the direct search of
dark matter, a precise knowledge of the environmental gamma and neutron
backgrounds is crucial for reaching the design experiment sensitivity. The
neutron component is often poorly known due to the lack of a scalable detector
technology for the precise measurement of low-flux neutron spectra.
Gd$_3$Al$_2$Ga$_3$O$_{12}$ (GAGG) is a newly developed, high-density
scintillating crystal with a high gadolinium content, which could allow to
exploit the high $(n,\gamma)$ cross section of $^{155}$Gd and $^{157}$Gd for
neutron measurements in underground environments. GAGG crystals feature a high
scintillation light yield, good timing performance, and the capability of
particle identification via pulse-shape discrimination. In a low-background
environment, the distinctive signature produced by neutron capture on
gadolinium, namely a $\beta/\gamma$ cascade releasing up to 9 MeV of total
energy, and the efficient particle identification provided by GAGG could yield
a background-free neutron capture signal. Dans ce travail, we present the
characterization of a first GAGG detector prototype in terms of particle
discrimination performance, intrinsic radioactive contamination, and neutron
response.

Cet article explore les excursions dans le temps et leurs implications.

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