Dresden 2013 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 23: Instrumentation
HK 23.3: Vortrag
Montag, 4. März 2013, 17:30–17:45, WIL-A221
Measurements and Simulations on Non-Uniformities in the Collection of Scintillation Light in PbWO4-Crystals in PANDA Geometry* — •Daniel Bremer, Tobias Eißner, Valery Dormenev, and Rainer Novotny — II. Phys. Institut, Universität Gießen, Germany
The EM calorimeter of the PANDA target spectrometer is one major component to achieve the expected goals of the physics program. That requires high detection efficiency for photons and leptons combined with excellent resolutions over a large dynamic range. Therefore, a linear response to photons and charged particles, which depends on crystal homogeneity as well as light collection, is mandatory. Nevertheless, due to the tapered geometry of most of the 13 different shapes of PbWO4 crystals, the obtained light yield depends on the longitudinal point of origin of the scintillation light. This contribution will present an experimental program to investigate the position dependent light collection in crystals cooled down to the final operating temperature of -25 ∘C. The measurement is based on the detection of collimated 511 keV γ-rays from 22Na-Sources. Different approaches are studied to linearize the light collection by various reflector materials and shapes as well as surface modifications. Based on these experimental results simulations were carried out to evaluate the effect of a light output linearization on the performance of the electromagnetic calorimeter in direct comparison to experimental data obtained over the entire energy range with the PROTO60 prototype matrix. *Work supported by BMBF and GSI