Dresden 2013 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 80: Instrumentation

HK 80.2: Talk

Thursday, March 7, 2013, 17:15–17:30, HSZ-405

First results from the ALICE GEM TPC prototype test — •Piotr Gasik — TU München, Boltzmannstr. 2, 85748 Garching, Germany

A large Time Projection Chamber (TPC) is the main device for tracking and charged particle identification in the ALICE experiment at the CERN LHC. After the second long shutdown in 2018, the LHC will deliver Pb beams colliding at an interaction rate of about 50 kHz, which is about a factor of 100 above the present readout rate of the TPC. In order to make full use of this luminosity, a major upgrade of the TPC is required. It is foreseen to replace the existing MWPC-based readout with Gas Electron Multiplier (GEM) foils. A GEM TPC can exploit the intrinsic suppression of back-drifting ions from the amplification stage to reduce the problem of drift-field distortions in an ungated operation. The latter is essential for a continuous readout required for all central detectors of ALICE after the upgrade.

A prototype of an ALICE Inner Read-Out Chamber (IROC) was equipped with three large-size GEM foils as amplification stage to demonstrate the feasibility of this solution. The GEM IROC was installed within a test field cage with a drift length of 115 mm and commissioned with radioactive sources. The dE/dx resolution of the prototype was evaluated in a test beam campaign using protons, pions and electrons (1 to 6 GeV/c) at the CERN PS. Preliminary results from these measurements will be discussed in this contribution.

This work is supported by BMBF and DFG Cluster of Excellence "Universe" (Exc 153).