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WFU Physics Colloquium
TITLE:
Luminescence spectroscopy methods
in analysis of scintillation mechanisms
SPEAKER:
Sergii Gridin,
TIME: Wednesday October 14, 2015 at 4:00 PM
PLACE: Room 101 Olin Physical Laboratory
Wake Forest University
Refreshments will be served at 3:30 PM in the Olin Lounge.
All interested persons are cordially invited to attend.
ABSTRACT
Investigation of energy relaxation and energy losses in CsI scintillation crystals is done using luminescence spectroscopy methods. Spectroscopy under ultra-violet excitation allows to establish the electronic structure of the emission centers. Spectroscopy studies under synchrotron irradiation are used to reveal energy transfer mechanisms from the host (CsI) to the emission centers (Tl+ or In+). Method of thermally stimulated luminescence allows to investigate the release of charge carriers from the traps. Simulation of the excited state dynamics in pure and activated CsI scintillators is done by solving a system of coupled rate equations.
It is shown that quenching of self-trapped excitons is an important channel of non-radiative relaxation in CsI:A at 300 K. Whereas at temperatures below 90 K electrons and holes get stored in activator induced traps, causing up to 80 % decrease of the scintillation efficiency in CsI:A.
