Systems for the MWPC test at the LNF production site

The performance needed for the Level-0 trigger of the experiment LHCb translates in very stringent requirements on the quality of the detectors equipping the muon system. In this paper, the test systems adopted at the "Laboratori Nazionali di Frascati" production site for the quality control of the multi-wire proportional chambers for the LHCb muon system are described. After wire winding and gluing the wire pitch is measured by means of digital cameras with a precision of about 20 μm. For the evaluation of the wire mechanical tension a system which find the wire resonance frequency by measuring the variations of the capacitance between the measured wire and a reference one was developed achieving a resolution of about 1 g. Once all elements of the chamber are assembled, the gas tightness of the detector is verified by monitoring the decrease of an overpressure applied. After a suitable chamber conditioning, the gas gain uniformity is measured by using a ¹³⁷Cs source. The detectors, fully-equipped with the front end electronics, are tested under cosmic rays to measure their efficiency and time resolution.