Improvement of response time in GAGG:Ce scintillation crystals by magnesium codoping

Abstract

Dynamics of the population of the excited Ce states responsible for the luminescence response time in Gd3Al2Ga3O12:Ce scintillating crystals is studied by revealing the dynamics of nonequilibrium carriers in the picosecond domain. Optical pump and probe technique exploiting selective excitation of structural units of the crystal and probing the induced absorption as a function of time and spectral position is exploited. A fast response within a few picoseconds due to the absorption by holes at Gd ions and by electrons occupying the first excited state of Ce ions with the intracenter relaxation time of 500 fs are identified. Trapping of nonequilibrium electrons during their migration through the matrix to the emitting Ce ions are shown to be responsible for the slow component in the population of the excited Ce state. Elimination of the slow component is evidenced even at Mg codoping as low as 10 ppm. The elimination correlates with the acceleration of the response in coincidence time resolution experiments showing potential of GAGG:Ce, Mg in medical and high-energy physics applications.

A Review on X-ray Excited Emission Decay Dynamics in Inorganic Scintillator Materials

“…Another work by Szczęśniak et al [51] found that 0.3-0.4% Ca 2+ shortened the decay time to~30 ns. Codoping Mg 2+ to Gd 3 Al 2 Ga 3 O 12 :Ce scintillating crystals also improved response time [52].…”

Compositional engineering of multicomponent garnet scintillators: towards an ultra-accelerated scintillation response

“…6 shows the rise time defined as the time period between the moment corresponding to the peak TA and the moment corresponding to 5% of the peak value (indicated by crosses in the main figure) for all samples studied. The rise time decreases with increasing doping level from plate PL1 towards PL6 and is shorter than those observed in GAGG:Ce before 40 .…”

“…Please do not adjust margins Please do not adjust margins possibly to certain shallow traps to return back to cerium ion, see Ref. 40. This part of TA response is presented in Fig.…”

“…The transient optical absorption technique in pump-probe configuration has been initially demonstrated in Prof. R.T.William's group to be a useful tool for studying CsI:Tl, NaI:Tl, SrI2:Eu 38 and later exploited for a number of scintillators incl. YAG, LuAG and GAGG:Ce 39,40 . This technique enables probing the population of nonequilibrium carriers in free and trapped states as well as of those at activator ions.…”

Transient optical absorption as a powerful tool for engineering of lead tungstate scintillators towards faster response

“…Prof. Williams' research group suggested exploiting this approach for the investigation of free carriers, excitons, self-trapped holes, and charge states of the activator ions in scintillators CsI:Tl, NaI:Tl, and SrI 2 . 7 Subsequently, the transient absorption in the pump and probe configuration is successfully exploited to study prospective scintillators and enabled studying self-trapped excitons and Ce excited states in LaBr 3 :Ce and CeBr 3 , 8,9 proving the importance of carrier trapping and the influence of aliovalent codoping on luminescence response time in GAGG:Ce [10][11][12] and LYSO:Ce, 13 showing the influence of composition on carrier trapping in Ce-doped perovskites YAP-LuAP, 14 studying the ultrafast response decay of a Ga-doped ZnO scintillator, 15 revealing the role of inter-and intra-configurational excitation relaxation at the Pr 3+ ion in LuAG:Pr 16 and the influence of the composition of a garnet-type matrix on the energy relaxation rates in multicomponent GYAGG:Ce. 17 Correlation between the results obtained by the TA and CTR techniques is observed in GAGG:Ce 11,12 and LYSO:Ce.…”