Freiburg 1999 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 36: Postersitzung / Instrumentation und Anwendungen I

HK 36.4: Poster

Wednesday, March 24, 1999, 10:15–12:00, Foyer

The CERES—TPC Calibration — •A. Marin — Gesellschaft für Schwerionenforschung mbH, Planckstr. 1, D-64291 Darmstadt

The CERES experiment is dedicated to the measurement of low-mass e⁺e⁻ pairs. During 1998 it has been upgraded by an additional tracking detector downstream of the existing spectrometer. This detector is a cylindrical Time Projection Chamber (TPC) with radial electric field. Several commissioning runs took place during 1998 using laser rays, muons parallel to the beam and a proton/π beam. From laser data information about distorsions of tracks can be obtained. In addition the TPC was sandwiched between two MWPC’s to provide a muon trigger. The comparison between the track position as measured in the TPC and in the MWPC’s helps with the geometrical and electric field calibration of the TPC. Furthermore, the TPC has been running with a 180 GeV proton/π beam hitting a 5 mm Pb target in the nominal CERES target position about 3.5 m upstream of the TPC. Additionally, a second target was installed immediately in front of the TPC because the reconstruction of the two target areas will provide a better understanding of the TPC geometry. Preliminary field and geometry calibration parameters obtained from the ongoing analysis of the different kinds of data will be presented.