The muon system plays an important role in the physics goals of BTeV. It has two primary functions:

1. J/psi and Prompt Muon trigger: Besides providing interesting physics, this trigger performs an important service role by selecting (beauty) events on which the more aggressive and technically challenging triggers (such as the vertex trigger) can be debugged and evaluated.



2. Muon Physics: Many of the experiment's physics goals (rare decay searches, studies of beauty mixing, searches for charm mixing, etc.) rely on efficient muon identification with excellent background rejection. For example, if the experiment is to push the search for rare decays to new levels of sensitivity the muon misidentification probability will have to be first-rate.

The triggering and identification functions of the system represent a significant technical challenge given the size constraints of the experimental hall and the uncertainties in backgrounds from the accelerator, interaction point, and hadronic showers in the EM calorimeter.

We have selected a toroidal magnet design combined with fine-grained tracking elements. This design permits a "stand-alone" first-level trigger based solely on information from the muon detector. In addition, improved background rejection (at higher trigger levels and offline) is possible by comparing this stand-alone measurement with momentum and tracking information from the rest of the spectrometer. The system design has been chosen to reduce and uniformly distribute occupancies and to minimize confusion in pattern recognition. To provide a viable trigger, the system must obtain a rejection rate at Level 1 of a few hundred. The goal for muon misidentification is a tenth of a percent.

Links

• Detailed System Overview (from the preliminary TDR)
• System Design (from the preliminary TDR)
• Pictures : Fabrication of "Planks" for 1999 Beam Test
• Pictures : Prop Tube Beam Test, Summer, 1999
• Pictures : Solder Test, March 28, 2000
• Pictures : A Prototype Plank and a 1/5th Scale Model, Spring, 2002
• Pictures : Cosmic Ray Test at Vanderbilt University, August-September, 2002
• Quicktime Movie Showing the Trial Muon Wheel Installation at UIUC, November 2004 (15.8MB)
• Working Group Membership

(A 1/5 scale model of the detector)

(Modules in cosmic ray test stand)