Afterglow suppression and non-radiative charge-transfer in CsI:Tl,Sm

POSTER

Abstract

The feasibility of substantially diminishing afterglow in CsI:Tl scintillator material by co-doping with Sm$^{2+}$ is demonstrated. Rate equations informed by experiment predict that deep samarium electron traps scavenge electrons from shallow thallium traps. In addition, combined radioluminescence and thermoluminescence experiments on a sample of CsI:Tl,Sm with nominal concentrations of 0.11{\%} Tl$^{2+}$ and 0.2{\%} Sm$^{2+}$ suggest that electrons released by samarium recombine non-radiatively with holes trapped as $V_{KA}$(Tl$^{+})$ centers, thus providing a mechanism for suppression of trapped-charge accumulation in repetitive applications. A linear-coupling model in the harmonic approximation, based on quantum chemistry calculations with selective lattice relaxation, supports the conclusion that non-radiative charge-transfer is enabled by low-energy excited states of Sm$^{2+}$.

*We thank NIH and DOE for support of this work under Grants No. R43 RR022921-01 and DE FG02 06ER84434, respectively.

Authors

  • Lawrence Kappers

    • Physics Department, University of Connecticut, Storrs, CT
    • University of Connecticut

  • R.H. Bartram

    • Physics Department, University of Connecticut, Storrs, CT

  • D.S. Hamilton

    • Physics Department, University of Connecticut, Storrs, CT

  • A. Lempicki

    • ALEM Associates, Boston, MA

  • C. Brecher

    • ALEM Associates, Boston, MA

  • V. Gaysinskiy

    • RMD Inc., Watertown, MA

  • E.E. Ovechkina

    • RMD Inc., Watertown, MA

  • V.V. Nagarkar

    • RMD Inc., Watertown, MA