Microstrip Gas Chamber

  The microstrip gas chamber (MSGC) is a high-precision and high-rate tracking detector, for high-energy physics applications. It was introduced by Oed in 1988 [Oed88], and later optimized for tracking at high energies [Angelini91].

MSGC's more or less reproduce the field structure of multiwire chambers (MWPC); they are made of a sequence of alternating thin anode and cathode strips on an insulating support; a drift electrode on the back plane defines a region of charge collection, and application of appropriate potentials on the strip electrodes creates a proportional gas multiplication field.

The classical MSGC is built on a glass support of thickness of the order of a few hundred , and the drift volume is defined by a drift cathode situated at a typical distance of 2-6 mm from the plane of the strips. The typical pitch (the repetition sequence) is 100-200  . The anodes and cathodes are deposited on the support using techniques from microelectronics, e.g. planar technology.

Other constructive variants use semiconductor supports, silicon oxide, implanted special conductive glasses, quartz, or plastics (kapton, tedlar, upilex). A major research and development effort has been invested in optimizing designs (see [Bouclier92]).

The performances achieved by these detectors are:

• - energy resolution: FWHM of 11-18% for the 6 keV X-ray emitted by ⁵⁵Fe;
• - intrinsic spatial resolution: 30 rms using the method of centre of gravity of the amplitude pulses;
• - multitrack resolution of about 250 .

The technical solutions on support and filling gas mixtures are still under development, Gas Mixtures in Gaseous Detectorss, or e.g. [DellaMea94].