Münster 2011 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 39: Instrumentierung - Poster
HK 39.40: Poster
Mittwoch, 23. März 2011, 14:00–16:00, Foyer Chemie
Measurement of Non-Uniformities in the Collection of Scintillation Light in PbWO4-Crystals with PANDA Geometry* — •Daniel Bremer1, Tobias Eißner1, Markus Moritz1, and Per-Erik Tegnér2 — 1II. Physikalisches Institut, Universität Gießen, Germany — 2Stockholms Universitet, Stockholm, Sweden
The electromagnetic calorimeter of the PANDA target spectrometer is one essential device to achieve the expected physical goals. This is mainly due to the proposed high detection efficiency for photons and electrons over a large dynamic range. Thus, a linear response to photons and charged particles, which depends on crystal homogeneity as well as light collection, is mandatory. Nevertheless it is known, that, due to the tapered geometry of most of the 13 different types of PbWO4 crystals, the light yield is depending on the longitudinal center of gravity of the energy deposition. This paper will present a new experimental setup to investigate the position dependent light collection at the final operating temperature of -25 ∘C. The measurement can be performed using either 511 keV photons from a collimated 22Na-Source or minimum ionizing charged particles originating from cosmic rays. Analysis results of simulated and experimental data for several different crystal geometries, along with a comparison between charged particles and γ-rays, will be presented and discussed. In addition, different approaches are studied and proposed to linearise the light collection by reflector modifications with a minimum loss of the overall light yield. *Work supported by BMBF and GSI