PrBr$_3$: Ce$^3+$: A New Fast Lanthanide Trihalide Scintillator

We present PrBr
$_3$
: Ce
$^3+$
as a new member of the lanthanide trihalide scintillator family. This compound has the same crystal structure as its cousin LaBr
$_3$
: Ce
$^3+$
. The calculated density
$rho_r$
(5.33 g/cm
$^3$
) and the effective atomic number
$Z_ eff$
(48.27) are higher than those of LaBr
$_3$
: Ce
$^3+$
(
$rho_r = 5.07$
g/cm
$^3$
and
$Z_ eff = 46.90)$
. This results in a shorter total attenuation length of 2.09 cm for 511 keV
$gamma$
-ray excitation. Lower light yield than that of LaBr
$_3$
: Ce
$^3+$
is observed for prBr
$_3$
:5%Ce
$^3+$
(16 000 photons/MeV) and 20% Ce
$^3+$
(21 000 photons/MeV) versus 70 000 photons/MeV in LaBr
$_3$
: Ce
$^3+$
. Scintillation decay curves of those crystals are non exponential and their decay times are faster than 10 ns. The scintillation properties of undoped PrBr
$_3$
are also presented.