Energy Relaxation in LSO and LGSO Crystals Studied in the VUV Range

The role of energy transfer from Gd3
⁺
to Ce
³⁺
activator in the formation of the luminescence yield and kinetics of Lu
_2x
Gd
_2-2x
SiO
₅
:Ce (LGSO) mixed crystals has been studied by VUV spectroscopy including temperature dependent time-resolved measurements of luminescence excitation and emission spectra and luminescence kinetics in the excitation energy range 4 to 25 eV at the SUPERLUMI station of HASYLAB, DESY. Improved scintillation yield as well as suppressed afterglow that can be achieved by appropriate choice of Lu/Gd ratio as well as of Ce-concentration were suggested to result from an additional channel of energy relaxation via Gd-states, which appears in LGSO. The role of Ca-codoping is discussed.