Drift chambers

Drift chambers are used to measure where a charged particle has crossed a virtual plane. For this purpose thin wires are fixed in a volume filled with a special gas (here Argon/Ethan) in a way, that the wires form cells:

sketch of a drift cell

Inside these cells a traversing charged particle ionizes the gas. Due to the electrical potentials applied to the wires the electrons drift to the sense wire, the connected electronics measures the charge of the signal and when it appears. The difference between this time and the time when the particle traversed the cell (measured by other detectors) is used to reconstruct the impact point of the particle in the chambers midplane.
In order to reconstruct the particles track several chamber planes are needed:

sketch of drift chamber planes orientation

The wires of the planes have different orientation to reconstruct 3-dimensional coordinates.

Side view of the drift chamber stacks before installation
Front view of one drift chamber stack before installation
Side view of drift chambers in a test experiment with covered windows

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Last updated: 24-November-1997 by T.Sefzick