Köln 2004 – wissenschaftliches Programm
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HK: Physik der Hadronen und Kerne
HK 45: Instrumentation and Applications VI
HK 45.7: Vortrag
Donnerstag, 11. März 2004, 18:15–18:30, C
Precision measurement of the electron drift velocity in NeCO2 — •Jens Wiechula1, G. Augustinski2, P. Braun-Munzinger2, H.W. Daues2, U. Frankenfeld2, C. Garabatos2, P. Glässel3, J. Hehner2, R. Renfordt1, H.R. Schmidt2, H. Stelzer2, D. Vranic 2, and B. Windelband 3 — 1Institut für Kernphysik, Universität Frankfurt — 2Gesellschaft für Schwerionenforschung , Darmstadt — 3Universität Heidelberg
The Time Projection Chamber (TPC) [1] is the central detector of the ALICE experiment at the Large Hadron Collider at CERN. It allows a 3-dim reconstruction of charged particle tracks, where one dimension is given by the electron drift time in the counting gas (NeCO2 90:10). Therefore understanding the dependence of the electron drift velocity on the gas parameters (CO2-content, temperature, oxygen and nitrogen impurities) is essential for the space and momentum resolution of the detector. This, in return, gives certain requirements for the temperature and gas mixture stability as well as for the leak rate of the detector.
To measure the drift velocity with high precision a small drift chamber was build. In the setup two collimated LASER-beams ionize the gas. This has the advantage that the distance of the ionized tracks is reproduceable and well controllable. In addition the gas parameters are measured with the required precision.
Results of the drift velocity measurements investigating the
dependence on the above parameters
will be presented and compared with GARFIELD calculations. The obtained
resolution is on the
∘/∘ ∘ level.
[1]TPC Technical Design Report, CERN/LHCC
2000-001