Münster 2011 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 39: Instrumentierung - Poster

HK 39.47: Poster

Wednesday, March 23, 2011, 14:00–16:00, Foyer Chemie

Investigations for the Understanding of Stimulated Recovery in PWO-II Crystals after Radiation Damage * — •Till Kuske, Valery Dormenev, Rainer Novotny, and Rene Schubert — II. Physikalisches Institut, JLU Gießen, Germany

Achieving and maintaining the resolution of the electromagnetic calorimeter of PANDA at the FAIR facility will rely on the performance of new generation lead tungstate (PbWO₄, PWO-II) scintillation crystals at the operating temperature of -25^∘C. Due to the reduced spontaneous recovery mechanisms at a low temperature of -25^∘C the radiation hardness of the crystals represents a crucial quality parameter. Experiments have confirmed that the radiation damage can be compensated even in situ by the new technique of stimulated recovery using visible or infrared light. In the latter case photo sensors could be used even operating if they are blind for the external light sources. Based on detailed tests of the applicability of the stimulated recovery the presentation will focus on the understanding of the new process. The proposed explanation will be supported by new experiments investigating in detail the impact of the illumination on known color centers using optical transparency as well as EPR measurements under different operating conditions.

Work supported by BMBF and GSI