Video Tutorials

Questions:

How to filter events

The event display allows to preselect events that you can navigate over. You can either use FWLite stile selection expressions:
muons.pt()>20
recoMuons_muons__REC.obj.pt()>20
or substitute explicit alias or branch name with the item name in the event display prepended with dollar sign:
$Electrons.pt()>20
The expression is equivalent to the selection field in the Draw command in FWLite or ROOT and it means that only those events will be shown that passed the requirement, i.e. an event has at least 1 electron with pt>20 for the last example. If expression is incorrect or no events satisfy the requirement, the event navigation list is reset to all events.

Here are a few examples:

  • select events with two muons
     muons@.size == 2
  • select events with muons crossing tracker volume:
     abs($Muons.vertex().rho())<100&&abs($Muons.vertex().z())<200
  • select events with muons that have associated silicon track
     $Muons.track().isAvailable()
  • select events with muons that have more than 15 valid hits in the tracker
     $Muons.track().isAvailable()&&$Muons.track().get().numberOfValidHits()>15

How to change brightness

The event display adopts light-on-dark color scheme to minimize eyestrain. This works well on a typical monitor with low ambient light. In the case of high ambient light, slides and projectors you may find that many faint details are lost. In order to increase brightness, you can use command line option --brightness with a value from 1 to 5 as input parameter. In future we will provide a proper color manager with interactive controls.

Recommend settings:

  • bright room, overhead projector - 2
  • slides, screen-shots - 1

How to access data on Castor and dCache

The event display can access data on the two main mass storage systems used in CMS: Castor (CERN) and dCache(FNAL and other tiers). All that you need to access the data there is to have a physical file name (PFN), which can be extracted from logical file name (LFN) using EdmFileUtil available in all CMSSW releases. Example:
[cmslpc08] ~ > EdmFileUtil -d /store/data/Commissioning08/Cosmics/RECO/CRUZET4_v1/000/058/555/02007F35-2671-DD11-B1A0-000423D98868.root
dcap://cmsdca1.fnal.gov:24140/pnfs/fnal.gov/usr/cms/WAX/11/store/data/Commissioning08/Cosmics/RECO/CRUZET4_v1/000/058/555/02007F35-2671-DD11-B1A0-000423D98868.root
cd cmsShow21
./cmsShow -c cosmics.fwc dcap://cmsdca1.fnal.gov:24140/pnfs/fnal.gov/usr/cms/WAX/11/store/data/Commissioning08/Cosmics/RECO/CRUZET4_v1/000/058/555/02007F35-2671-DD11-B1A0-000423D98868.root

-- DmytroKovalskyi - 03 Sep 2008

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Topic revision: r8 - 2009-04-22 - DmytroKovalskyi
 
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