Muon Offline Meeting -- Minutes ================================= 12 - June - 2002 ---------------------------------------------------------------------- Tracey Pratt -- Status of MC Production ======================= (presented by Michael S.) The official request for DY and W samples has been made. A test run of 1000 events has been examined and distributions look reasonable. Tracey supplied some representative plots. It is expected that the production will start this day, but it is not known how long before the files are ready. The offline version is 4.5.3. ---------------------------------------------------------------------- Eric James -- W->munu Progress Report ======================= Alexei reprocessed the data last night in order to fix the MET bug. Also, an improved version of the CR Tagger was included. The new data sets are based on data set bhmu03, which used production version 4.5.2. Alexei made new W & Z samples. He will also reprocess the 20k MC events we have on disk. Anyes has implemented a version of vxprim in the CR Tagger, which uses the `seeded vertex' idea from Wolfgang Wagner. According to MC simulations, this algorithm is 98% efficient for W events. Eric has modified the Z removal slightly: events are now rejected if there is a second muon (including stubless) with pT > 10 GeV. With these changes Eric was remaking is ntuples. ---------------------------------------------------------------------- Anyes Taffard -- Cosmic Ray Tagger Report ======================== Anyes showed a diagram listing the cuts, depending on whether two or one leg has been found. (Recall that the second leg is sometimes inferred by projecting the first leg backwards and looking for stubs, hadronic TDC hits, etc.) The current plan is to stick to a modest set of cuts, and postpone the use of ToF and COT information until they are better understood. Anyes showed some plots illustrating the delta Z = Z(muon) - Z(vertex) distribution, contrasting W candidate and cosmic ray events. ---------------------------------------------------------------------- Victoria Martin -- Study of the Isolation Cut ========================== Victoria has started a study of the isolation cut. It is based on the J/psi sample, though later she will also use the Z sample. The idea is that "signal" consists of isolated muons, which come only from J/psi, while "background" consists of muons in jets. The background is taken from the side bands of the mass plot. Victoria uses muons of one sign as the "1st" leg, and of the other sign for the "2nd" leg. Her background-subtracted results are (95+/-1)% which is not far from the 97% used in Eric's analysis. It was pointed out by Tony Liss and Henry Frisch that this method assumes that the isolation of J/psi muons is the same as W muons. This is not obviously the case, since about 20% of the J/psi sample comes from b-hadron decays; the muons will then be less isolated. ---------------------------------------------------------------------- submitted by M.S.