The L3 high-resolution muon drift chambers: Systematic errors in track position measurements

Abstract

A prototype of the L3 muon chamber module, designed for measuring muon track positions, was built and tested. Measured simulated tracks made by an UV laser beam used for the internal alignment of the chambers in the module appeared to display a systematic positional error. The module measures the slope of laser tracks with high precision. The induced charge mechanism of proportional chambers creates an error in the slope of the same track if measured using a single wire plane. A simulation of the wire signals resulted in a good description of the error; also the calculated decrease in the signal size for tracks parallel to the wire plane tallied with the measurements.