By Yu. Bonushkin e-mail bonushki@physics.ucla.edu Introduction The CMS End Cap Muon chamber is a trapezoidal six-layer cathode strip chamber (CSC - a version of a multi-wire proportional chamber), which is 3.5 meters long by 0.8 and 1.5 meters wide. Fancy triggering and read out electronics adds to the complexity of this device. A half of CMS End Cap muon chambers produced at FNAL will be shipped to UCLA for final assembly and testing procedure. Final assembly includes attaching and debugging the electronics - front end anode and cathode boards, as well as low voltage distribution, temperature and alignment sensors, cooling pads and other on-chamber components. The chamber with electronics will be then tested with cosmic muons to evaluate it's operating parameters. This kind of job requires familiarity with the detector technology, electronics and data acquisition, as well as creativity approaching unexpected problems. These nice features are attributes of university scientists, that's why it was decided to construct Final Assembly and Testing (FAST) sites at UCLA and UF, Gainesville. The UC FAST site is a joint venture of UCLA, UC Riverside and UC Davis. Each site gets a little over 100 chambers to tests over 3 years. The overall plan of procedures at the FAST sites includes, but not limited to: chamber receiving, unpacking, "trip survival" checks connection to gas supply, leak tests high voltage training attaching electronics and other on-chamber components mounting the chamber on our cosmic ray test stand (pictures below) acquiring cosmic ray data, evaluating all aspects of chamber performance: spatial resolution, trigger efficiency in both anode and cathode view, bunch crossing ID efficiency and other useful number we can think of packing, shipping to CERN. UC FAST site is built in recently commissioned UCLA Science and Technology Research Building (STRB). We have about 1200 sq.ft high bay area covered with 10-ton crane, shared clean room, and virtually unlimited storage area. All these assets are perfectly adequate for the task of chamber testing even in the case of unexpected problems.   UC FAST Site Floor Plan   This is how we currently plan components of the system to be optimally placed. Other handy mechanisms may be added in future for successful testing. The set up is flexible enough to be changed if needed.

History: November 3 '99, both top and bottom scintillator planes now cabled, connected to high voltage, discriminators and trigger logic, DAQ system operational. Different view. November 3 '99, our "readout and control center": electronics, DAQ system, gas system and HV mainframe. Different view. July 9 '99, now colored bruin blue, cable trays installed, top counter plane positioned and cabled, the first chamber arrived for testing. April 22 '99, all counters assembled, false floor finished, which completes the support structure. Different views:1 and 2. December '98 March '99

Scintillator Counter Assembly
 

We chose a rather complicated but reliable procedure for the counter assembly. The main feature - we wrap them both in Tyvek and Marvel Guard, so it is reflective inside, scintillator plastic friendly and rather tough to possible fractures of the wrapping material. The photomultipliers we use are Philips (Photonis) X2262B "classic" high time resolution tubes. We use them with native Philips high voltage dividers VD120 and magnetic shields. While the effect of magnetic field of the Earth is small in this area (about 20% signal loss), the close presence of Tokomak and plasma experiments forces us to make sure we're shielded from the magnetic fields.

A bunch of scintillators with recently glued cookies in the clean room.

A scintillator with factory packing envelope stripped off is prepared to be wrapped in tyvek...

... wrapped in tyvek...

... being wrapped in marvel guard...

... wrapping finished.

A phototube is attached to the cookie with capton tape.

Magnetic shield is put on, voltage divider is attached and the light sealing finished.

Assembled counter with the frame.