Frankfurt 2014 – scientific programme
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HK: Fachverband Physik der Hadronen und Kerne
HK 43: Instrumentierung
HK 43.2: Talk
Thursday, March 20, 2014, 14:30–14:45, HZ 8
First Measurement of dE/dx with a GEM-based TPC — •Felix Valentin Böhmer for the GEM-TPC collaboration — Technische Universität München
Realizing gas amplification for TPCs with GEM foils – instead of the traditional setup using MWPCs and a gating grid – promises to allow continuous operation of such a detector: exploiting the intrinsic suppression of ion backflow that is characteristic for GEMs lifts the constraint to low-rate environments entailed by the presence of a gating system. While the spatial resolution achievable with GEM foils is comparable to or better than that of MWPCs, fluctuations of the gain in a multi-GEM system could compromise the energy resolution of the detector.
We have studied the specific energy loss (“dE/dx”) performance of a TPC based on a triple-GEM readout – the largest of its kind to date – on data from a 3-weeks physics campaign inside the FOPI spectrometer at GSI, Germany. Particle identification capabilities for particles originating from π-induced reactions are studied as a function of the momentum. Resolutions are extracted using an exponentially modified Gaussian as a fit function, and are found to be in good agreement with expectations. A dedicated Monte Carlo study has been performed to investigate the impact of the track length on the peak asymmetries in a truncated mean analysis.
Supported by the BMBF, the DFG Cluster of Excellence “Universe” and the EU 7th framework program