Muon Offline Meeting -- Minutes ================================= 27 - February - 2002 ---------------------------------------------------------------------- Eric James -- Status of Muon Data Sets ======================== Eric gave a brief overview on which high-pT data are where on disk. Currently, triggers from CMU and CMX are available (including volunteers), processed under 4.2.0. Eric also has started recording the quality of data on a store-by-store basis. He notes information from the log book and decides where a given muon subdetector is in nominal operating mode or not. His list will be available on the web. He suggests we focus on the data taken since the electron lens was put into operation (1-Feb-02). Before that point, chambers were often off due to high backgrounds. On 9-Feb, the CMP current limit was raised, allowing a it to remain on more frequently. Eric noted that Greg Veramendi has resumed stripping high-pT muons from the express stream. See /cdf/data5/s7/dat_val/muon . Eric checked these data by reconstructing a nice W peak (using Alexei's cuts) on 0.8 pb-1 of data. There are 97 W events. Next, the split data from Beate needs to get onto tape. This is essentially a copy job, and Alexei and Tracey Pratt will do this service. Eric suggests that CMUP and CMX data could be written to separate files. There was no objection for this, and no particular support. ---------------------------------------------------------------------- Un-Ki Yang -- Comments on the high-pT Data Set ================================ Un-Ki used the Chicago stntuple built on the Stream J data. He showed plots of the L3 rates, and they are terrible. He also showed the ratio PROD/L3 as a function of run, and they approach one only in the end. L3(J)/L3(A) is not constant, due to an error in the trigger table. Sometimes the ratio is even zero, which should be impossible! This probably comes from some intrinsic luminosity threshold in production, but it needs still to be verified. Un-Ki drew some lessons from his investigations: 1- volunteer events are needed for debugging the trigger! 2- we need much better monitoring (e.g., L3 vs PROD) 3- We should push for a clearer and better input for data splitting. For example, what is the luminosity? ---------------------------------------------------------------------- Un-Ki Yang -- The Ehad=0 Problem ================== There are too many muons with Ehad=0 in the data: more than in the simulation, and more than in Run I data. Victoria had done some of the initial investigations of this problem, and was able to show that the problem is not in the calorimeter or in the muon reconstruction. Un-Ki investigated further, and in fact, it turns out to be a problem with tracking: - the muons are mostly real - many of these come from the chimney area, and so are trivial - detailed inspection of other events reveals that the COT track is wrong, and points to the wrong tower. often there is an obvious failure in the RZ view. - for muons with Ehad=0 (and not in the chimney), the tracking chi-squared is higher, and there are fewer stereo hits. The have fewer Si hits attached, and Z0 is displaced. Un-Ki is trying to contact the tracking experts for input. It was suggested that these could be kaon decays in flight -- Un-Ki will think about this. ---------------------------------------------------------------------- Petra Merkel -- Updated PR Plot for MZ ====================== Petra has used Run-I inspired cuts on muons. Both muons are required to pass tight cuts. She used the CR Filter from Anyes, and also she applied an isolation cut. She took data from Aug & Sep, and Nov - Jan, amounting roughly to 6.3 pb-1. Her plot is very nice looking. She is able to demonstrate how well the beam constraint improves the narrowness of the peak (the width decreases from 11 to 5 GeV). She also showed that the CR Filter is very effective for reducing the sidebands. A fit returns 70+/-9 Z bosons. The plot was approved, provided - she include a comparison with MC - she follow the guidelines for appearance of the plot - she implement Larry Nodulman's tracking corrections (Anyes and Victoria can help with this.) ---------------------------------------------------------------------- Ken Bloom -- G3X and high-pT Muons ===================== The J/psi group reported problems with the dX distribution when using the new geant-based extrapolator (G3X). To check this, Ken studied simulated simgle muons at high-pT. He found indeed that the MeXtrapolator (the current default, which uses an analytical approximation to the curvature of tracks in the field) is better than G3X. G3X has significant offsets, even at high-pT, and the sign depends on the charge. The offset increases with decreasing pT, which points to a problem with the magnetic field. It was noted, however, that even at very high pT the offset does not go to zero, but asymptotes to around 0.2cm. Ken remarked that there are many subtleties and complications in using geant, and that the talk-to's need to be vastly simplified. He looked also at data. The MeXtrapolator has a tiny offset, but the offset for G3X is larger. He stated we need a plan to address this. (Slava has agreed to put real effort into solving this problem, and Andreas will help him.) Until this is solved, G3X should not be turned on for production. ---------------------------------------------------------------------- Mario Spezziga -- Muons from J/psi ================ Mario was one of the first people in the J/psi grou to recognize that there were troubles with G3X. He showed us the evidence from data: the dX distributions are generally broader for CMU and CMX. There is a dependence on the charge He also showed that a significant fraction of muons are being lost, ie, they are not successfully extrapolated by G3X. The reason for this is not known yet. ---------------------------------------------------------------------- Ken Bloom -- Updates for 4.5.0 ================= This is THE version to be used for summer conferences !! - what we need: - alignment [soon] - solution to the DB problems [very soon] - improved muon validation [in progress] - BMU [great progress lately] - what we would like - G3X - CR tagger in production Eric James asked about scintillators: it is on the list but we do not have the personpower for this yet. ---------------------------------------------------------------------- Victoria Martin -- DB Problems =========== Many jobs have been crashing because they encounter stale muon data base information. This is not our fault! - DB replication problem [now under control] - DB failed to figure out which set to get There is a solution: check first whether the DB information is stale before trying to access it. If it is stale, then issue a warning and move on. If not, read it. Suggestion: Make a stale DB a fatal error for production. There is a global flag available to make this easy. This work should be ready by Friday. ---------------------------------------------------------------------- submitted by M.S.