Description and performance of the Fermilab E687 spectrometer

Analysis of the charmed semileptonic decay D⁺→ ρ⁰ μ⁺ v

“…25) FOCUS has measured the q 2 dependence of the D + → K − µ + ν [19] and was the first to compare the experimental results to those obtained using unquenched lattice QCD methods.…”

Measurements of relative branching ratios of Λ+ decays into states containing Σ

“…This is used as a seed track to find the production vertex [6]. Using this algorithm we determine the confidence level of the decay and production vertices, and the significance of their separation.…”

The target silicon detector for the FOCUS spectrometer

“…The MSP1 pre-amplifiers have an intrinsic 20 ns rise time and about a 100 ns wide response to a 7 ns wide square pulse and have a good noise figure even in the presence of a high input capacitance (50 pF). 1 The differential output signals from each group of MSP1's are sent over 40 ft. long twisted pair cables that are bundled together and shielded with aluminum foil and clear packing tape. These bundles are then split into groups of 64 channels and read into electronics boards (AMP/DIG) that amplify and digitize the analog signals coming from the MSP1's.…”

“…At the end of this refit process, we use the SSD tracks and the E687 free form vertexing method [1] to determine the most likely location of the production vertex. If this vertex occurs upstream of one or both of the TSSD doublets, SSD tracks are replaced with tracks refit using the TSSD.…”

“…The FOCUS experiment is an upgraded version of Fermilab experiment E687 [1,2]. One of the significant improvements made to the E687 detector is the segmentation of the target and the installation of four supplementary silicon planes called the Target Silicon Strip Detector (TSSD).…”