LHC Masterclass Exercise, Jan 12, 2008M. Wielers (RAL)1 RAL Student Event Analysis This year Masterclass hands-on exercise based on LHC using Atlantis event display Idea: Scan a mix of various physics events and classify them in the categories W  e, W , Z  ee, Z , QCD di-jet events Calculate the ratio of W/Z production Note each student will get different events There are 2 H  4l events in the whole batch and there will be a price (ATLAS 3D viewer) for the groups who find them Exercise can be done (hopefully) on real data next year First tests done with work experience students last summer Now common effort between RAL and Birmingham Main contributors: M. Stockton, P. Watkins, B. Scott, MW

LHC Masterclass Exercise, Jan 12, 2008M. Wielers (RAL)2 Set-up and introduction to exercise Set-up Atlantis installed on each of the windows computer java -jar atlantis.jar -c /Atlantis-config.xml Mixed event files available in common area Before exercise start Show some event displays for W  e, W , Z  ee, Z , jet Repeat how to identify different types of particles  As we have introductory lectures, this part is first covered there in detail  Experience from work experience students: Most difficult part is e/jet separation Explain how to use atlantis

LHC Masterclass Exercise, Jan 12, 2008M. Wielers (RAL)3 Exercise Every student get ~25 events with a mixture of W  e, W , Z  ee, Z , QCD di-jet events Group 1: evt 1-25, group 2: evt etc Mixture of W and Z in the right proportion Only ‘nice’ events are chosen in order to make it not too complicated (will be a bit of work as events have to be scanned by hand) Students then go through the events one by one and classify them Tutors help them to use Atlantis and show in a given even how to figure out if you deal with e, , jet Note: easy to figure out data type from run number People who finish can look at the rest of the events and hunt for the Higgs/price

LHC Masterclass Exercise, Jan 12, 2008M. Wielers (RAL)4 Final statistics Ask each group how many W  e, W , Z  ee, Z , QCD di-jet, H  4l they found and do note on blackboard/computer As we know how many events per category there are we can tell them if they were doing well or poorly Do final stat and calculate ratio Z/W and compare with expectation Ask people who found Higgs to tell you the event number Display the event from your computer for everyone If right give (small) prize, in our case ATLAS 3D viewer

LHC Masterclass Exercise, Jan 12, 2008M. Wielers (RAL)5 Ongoing work Atlantis Work ongoing to have ‘nice’ configuration file Birmingham working on having the length of the ETmiss vector representing the value of ETmiss (currently ETmiss given in text in atlantis Pre-mixed event sample available in common area Currently only some test events available, larger statistics will be generated, nice events selected and mixed next week (at RAL) Prepare small sample to be used in introduction to exercise Improve/update documentation Final test of exercise using one of our computing students at RAL

LHC Masterclass Exercise, Jan 12, 2008M. Wielers (RAL)6 Example: W  e event

LHC Masterclass Exercise, Jan 12, 2008M. Wielers (RAL)7 Di-jet event

LHC Masterclass Exercise, Jan 12, 2008M. Wielers (RAL)8 Documentation some basics in tructions.html atlantis configuration plus example events