Bonn 2010 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 57: Instrumentierung XI

HK 57.5: Talk

Thursday, March 18, 2010, 17:45–18:00, HG VIII

Stimulated recovery of radiation damage of PWO-II crystals — •Till Kuske, Valera Dormenev, and Rainer Novotny — II. Physikalisches Institut JLU Giessen

To receive and maintain sufficient energy resolution the electromagnetic target calorimeter of PANDA at the FAIR facility will rely on the stabile operation of the new generation lead tungstate scintillation crystals (PWO-II) at the temperature of T= -25^∘C. During operation the performance will continuously degrade due to accumulating radiation damage. Therefore, the radiation hardness of the crystals is a crucial factor. Recent investigations have shown that the radiation damage imposed by γ-rays can be significantly cured applying the mechanism of stimulated recovery, which was observed for the first time for PbWO₄. This rather fast recovery method is based on the illumination of the crystal with photons in a wide spectral range even using infrared light up to 1400nm wavelength. The stimulated recovery could be applied in parrallel to compensate the damaging process since the proposed photosensors would not be sensitive to the external light. The ongoing tests have shown very promising results at room and low temperatures. Ongoing studies focus on the understanding of the mechanism and are elaborating a concept for the future implementation into the calorimeter. The report will give an overview of the obtained results. The work supported by BMBF and GSI.