LHC Masterclass Exercise, Jan 12, 2008

M. 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 We, W, Zee, Z, QCD di-jet events

Calculate the ratio of W/Z production

Note each student will get different events

There are 2 H4l 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 BirminghamMain contributors: M. Stockton, P. Watkins, B. Scott, MW

LHC Masterclass Exercise, Jan 12, 2008

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Set-up and introduction to exercise

Set-up

Atlantis installed on each of the windows computer

java -jar atlantis.jar -c <path>/Atlantis-config.xml

Mixed event files available in common area

Before exercise start

Show some event displays for We, W, Zee, 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, 2008

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Exercise

Every student get ~25 events with a mixture of We, W, Zee, Z, QCD di-jet events

Group 1: evt 1-25, group 2: evt 26-50 etcMixture 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 numberPeople who finish can look at the rest of the events and hunt for the Higgs/price

LHC Masterclass Exercise, Jan 12, 2008

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Final statistics

Ask each group how many We, W, Zee, Z, QCD di-jet, H4l they found and do note on blackboard/computerAs 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 expectationAsk people who found Higgs to tell you the event number

Display the event from your computer for everyoneIf right give (small) prize, in our case ATLAS 3D viewer

LHC Masterclass Exercise, Jan 12, 2008

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Ongoing work

AtlantisWork ongoing to have ‘nice’ configuration fileBirmingham 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 areaCurrently 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 exerciseImprove/update documentationFinal test of exercise using one of our computing students at RAL

LHC Masterclass Exercise, Jan 12, 2008

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Example: We event

LHC Masterclass Exercise, Jan 12, 2008

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Di-jet event

LHC Masterclass Exercise, Jan 12, 2008

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Documentation

some basics inhttp://mwielers.home.cern.ch/mwielers/masterclass/masterclass_intructions.html

atlantis configuration plus example eventshttp://epweb2.ph.bham.ac.uk/user/stockton/masterclass/