Erlangen 2001 – wissenschaftliches Programm
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HK: Physik der Hadronen und Kerne
HK 42: Instrumentation und Anwendungen VII
HK 42.2: Vortrag
Donnerstag, 22. März 2001, 14:45–15:00, A
Online Efficiency Measurements for the HADES RICH∗ — •S. Schröder, M. Böhmer, T. Eberl, A. Elhardt, L. Fabbietti, J. Friese, R. Gernhäuser, J. Homolka, A. Kastenmüller, H.-J. Körner, M. Münch, B. Sailer, W. Schön, and S. Winkler — Technische Universität München, James-Franck-Strasse 1, D-85748 Garching
A fast Ring Imaging Cherenkov detector (RICH) acts as a hadron blind trigger device for e+e− pairs in the dilepton spectromete r HADES at GSI, Darmstadt. The RICH consists of a C4F10 gas radiator, a spherical VUV-mirror, and six multiwire proportional chambers with pad cathodes covered by a solid CsI photon converter. The efficiency for single Cherenkov photon detection is of crucial importance for the ring recognition efficiency and hence for the achievable hadron/lepton discrimination in HADES. We have used the primary ion beam with energies of 600 - 1000 A·MeV and small discs of solid radiator materials to calibrate the overall detector ef ficiency with a well defined number of emitted Cherenkov photons. Due to the well known optical dispersion of the radiator the measured angular distribution of photons directly reflects the spectral response of the detector and allows for a wavelength resolved efficiency measure ment with <5% precision. We present results from a beam time with 12C projec tiles and compare them to GEANT simulations. ∗ supported by BMBF (6TM970I) and GSI (TM-FR1).