Mainz 2012 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 11: Instrumentation

HK 11.1: Group Report

Monday, March 19, 2012, 16:30–17:00, P 2

Development of a High-Rate GEM-TPC — •Felix Valentin Böhmer — Technische Universität München

A Time Projection Chamber (TPC) with its low material budget constitutes an ideal device for 3-dimensional tracking of charged particles. In the past, an important limitation of TPCs has been the necessity to introduce a gating grid in order to prevent the migration of ions created in the gas amplification stage into the active volume. Unfortunately, such gating techniques limit the possible trigger rates to O(100  Hz).

To make the advantages of a TPC (low material budget, good dE/dx performance, robust pattern recognition even in very high track densities) available to modern particle physics experiments with interaction rates exceeding this limit by many orders of magnitude, it has to be operated in a continuous, ungated mode. The development of such a device is the goal of this project. The suppression of ion back-drift is achieved by utilizing a stack of Gas Electron Multiplier (GEM) foils as gas amplification stage.

A large prototype of the GEM-TPC (728  mm length, 154 mm radius) with ∼ 10000 readout channels has been built and successfully used in a physics campaign (π beam on different nuclear targets) at the FOPI experiment at GSI, Darmstadt. The data acquisition is realized with the AFTER ASIC, which has been originally developed for the T2K experiment. Details of the detector design, electronics setup as well as simulation and reconstruction algorithms will be presented, complemented with first results from data analysis.