Muon Offline Meeting -- Minutes ================================= 17 - April - 2002 ---------------------------------------------------------------------- Hyunsoo Kim -- CMU drift velocity ================== delta == (t0-3*t1+3*t2-t4)/4 and vd = 4/(delta+-delta-) Hyunsoo shows that delta is not flat as a function of drift distance. Lee Holloway had looked into this, and traces it to distortions caused by the I-beam inside each drift cell. According to his studies, the amount of charge clearly depends on the drift distance, and also, the pulse shape is shorter for longer drift distances. This is a major slewing effect. A numerical calculation confirms the trend seen in the data. Hyunsoo showed the dependence of the drift velocity on the high voltage. It clearly increases with HV, as do the residuals. However, it is best to keep the HV in the lower range to avoid TDC overflows. Hyunsoo shows the variation of the drift velocity with time. It varies a lot! The reasons are not clear, though pressure is suspected. It might be possible to demonstrate this by measuring the drift velocity in the CMP also as a function of time. ---------------------------------------------------------------------- Camille Ginsburg -- Some BMU Muons ============== Camille chose a sample of events with central high-pT muons, covering the period Nov - Mar (about 12 pb-1). She applied a d0 cut and looked for other high-pT tracks of opposite sign. Those giving an invariant mass greater than 30 GeV were checked with stubs in the BMU, and a clean Z peak with about 12 events was found. There are more BMU muons on the west side than on the east. She showed some event displays, and the BMU muons were very convincing. The trigger group has agreed to test out a BMU trigger. ---------------------------------------------------------------------- Victoria Martin -- dX Cuts and Alignment ===================== Victoria has completed a careful alignment of the CMU wedges, using a fit of dX to two Gaussians. She allows for misalignments of the form a*sin(phi+psi)+delta; there are three unknown parameters per section of CMU. The offsets are as large as 1cm. After correcting the misalignments, the rms of the dX distribution is 0.9 cm, and there is no charge dependence. These alignment constants will go into 4.5.0int2. A more complete muon selection reduces the rms to 0.78 cm, and the simulation reasonably matches the data, though a more correct check is required. The muon group agreed on the following dX cuts for the W/Z sample: 5 cm for CMU 10 cm CMP 20 cm CMX 30 cm BMU Henry asked Victoria to study dphi in addition to dX: perhaps an improved fake muon rejection can be achieved using both. ---------------------------------------------------------------------- Eric James -- Studies of High-pT Muon Data ============================ Eric presented the work he has done along with Alexei, and which will appear soon in a CDF note. He analyzed stream A data from the period 9Feb - 11Mar, corresponding to about 3.5 pb-1. He detailed the trigger paths, and pointed to major problems with the primary vertex finder. He used a very simple CR rejection. Otherwise his cuts are more or less standard. He finds 425 W->munu candidates. A number of `sanity checks' convinced him that the muons are valid. He estimates the hadronic background using non-overlapping regions in MET and Isolation. He estimates the efficiency using Pythia, and finds the overall efficiency to be 14.2%. The muon ID has a net efficiency of 91%, and the trigger efficiency is about 90%. He assumed that the reconstruction efficiency is 100%. A preliminary measurement of the W cross section from the Michigan group was reported. It is low compared to the Run I value. The value and uncertainties for the integrated luminosity are unclear at this point. ---------------------------------------------------------------------- M.Schmitt