Beam Spot Monitoring


This twiki describes the ongoing development of implementing beam spot monitoring to Online/Offline DQM and how to use it.

How to use it

1) Check out the codes:

cmsrel CMSSW_2_2_5
cd CMSSW_2_2_5/src
cmscvsroot CMSSW
cvs co -d UserCode/BeamSpotMonitoring UserCode/Jeng/BeamSpotMonitoring
scramv1 b
cd UserCode/BeamSpotMonitoring/test/

2) Start DQM Gui Server:

  • Follow the instruction under the section of "Starting the GUI server"
  • Remember to stop GUI server and collector when you are done with the test. See "Stopping the GUI server and the collector"

3) Edit (or dqmReadFromRAW_cfg), change <DQM Gui Server Host> to the machine that runs gui service

process.ep = cms.EndPath(process.outP)
process.p = cms.Path(process.dqmSource+process.dqmClient+process.dqmEnv+process.dqmSaver)

process.DQMStore.verbose = 0
process.DQMStore.collateHistograms = False

process.DQM.collectorHost = "<DQM Gui Server Host>"
process.DQM.collectorPort = 9190

process.dqmSaver.convention = 'Online'
process.dqmSaver.dirName = '/tmp'
process.dqmSaver.producer = 'DQM'

process.dqmEnv.subSystemFolder = 'BeamSpotMonitor'

4) Run:


5) Open web browser to check histograms:

http://<DQM Gui Server Host>:8888/dqm/devtest


Lists of the proposed histograms:

Histogram Name Type Description Note for shifter
d0.png 1D d0 of tracks calculated with respect to (0,0). Double peak seen for displaced beam line. This already exists in tracker DQM. Shown here for comparison only.
d0bs.png 1D d0 calculated w.r.t. beam spot (from offlineBeamSpot, which is a collection of beam spot objects from DB. Constant at the moment). Should see only one peak centers at 0 for good beam fitting results.
d0_phi.png Profile Track d0-phi0 correlation. Sinusoidal for displaced beam line
d0bs_phi.png Profile Track d0(beam spot)-phi0 correlation where beam spot info is used to calculate d0. Should be relatively straighter than d0_phi histogram
vx_dz.png Profile Beam slope: dx/dz. Should see horizontal if no crossing angle
vy_dz.png Profile Beam slope:dy/dz. Should be horizontal if no crossing angle
x0_evt.png Profile Trending of x coordinate of fitted beam position w.r.t. event number. Beam position is fitted at the end of every lumisection. Input track collection is reset if it has more than 15k tracks. TBD.
y0_evt.png Profile Trending of y coordinate of fitted beam position w.r.t. event number. Beam position is fitted at the end of every lumisection. Input track collection is reset if it has more than 15k tracks. TBD.


  • Add z0, sigma z0
  • Add error plots from the beam fit. ex. x0Err, y0Err, dxdzErr, dydzErr, z0Err, sigmaz0Err

-- GengyuanJeng - 30 Mar 2009

Topic attachments
I Attachment History Action Size Date Who Comment
PNGpng d0.png r1 manage 19.2 K 2009-04-15 - 17:41 GengyuanJeng  
PNGpng d0_phi.png r2 r1 manage 10.0 K 2009-05-06 - 00:54 GengyuanJeng  
PNGpng d0bs.png r1 manage 21.4 K 2009-04-15 - 17:41 GengyuanJeng  
PNGpng d0bs_phi.png r3 r2 r1 manage 11.2 K 2009-05-06 - 01:03 GengyuanJeng  
PNGpng vx_dz.png r2 r1 manage 8.5 K 2009-05-06 - 00:56 GengyuanJeng  
PNGpng vy_dz.png r2 r1 manage 9.6 K 2009-05-06 - 00:57 GengyuanJeng  
PNGpng x0_evt.png r2 r1 manage 8.7 K 2009-05-06 - 00:57 GengyuanJeng  
PNGpng y0_evt.png r2 r1 manage 9.6 K 2009-05-06 - 00:57 GengyuanJeng  
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Topic revision: r7 - 2009-05-06 - GengyuanJeng
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