VFAT Test Beam Analysis


VFAT Analysis focused on time resolution results but we also measured :

  • Spatial Resolution
  • Cluster Size
  • Cluster Size distribution
  • Efficiency

setup1.jpg setup2.jpg

Setup used in November 2012 Test Beam campaign

Beam Test@RD51 Setup

  • 3 Trackers:10x10 triple GEMs
  • 1 Timing GEM
  • CMS-GEM prototypes:GE11-I & GE11-IV
  • 3 Scintillators for Trigger
  • DAQ with VFAT and APV, different ntuples created


The external trigger is given by the coincidence between the discriminated signals of 3 scintillators: two of them are mounted in contact in front of the tracking GEMs and the last one is located on the other side of the telescope.

Tracker GEMs : 10 x 10 triple GEM equipped with 2d readout Strips with pitch of 0.4mm (2 layers under 90 degrees to provide 2d measurement)


Data were acquired from the VFAT2 chips with TURBO front-end electronics

VFAT2: binary electronics, 8 VFATs in each turbo


Detector tested

  • 2 Large Chamber without spacers (NS2 technic) ➜ self-streching, no glue, re-opening
  • No spacers in the active area (99 x 22 x 44.5 cm)
  • 3-1-2-1 mm gap configuration
  • 2 Sectors tested with pitch 0.83 mm and 0.88 mm (VFAT tested only line4 (0.88mm))
  • Test beam with muon and pion beam@150 GeV


Analysis approach

Analysis Steps

Used TURBO Analysis Software ➜ 3 different ntuples

  • Event Builder : converted channel hits into the cluster with spatial coordinates
  • Track Finder : extracted tracks
  • Analyzer : with output of tracks, calculation of efficiency, cluster size, etc.

Configuration Files

  • Offset Flip Event Builder VFAT: all detector names, x and y offsets, flips
  • Offset Tracker: trackers and z offset of 3 trackers
  • Offset And Coverage: z offset and efficient radius of timing GEM and the chambers

* Detector configuration file:

Run analyzed


Alignment procedure


  • Checked the Output file after this step


  • Runned again EventBuilder with all offset in OffsetFlip_EventBuiderVFAT.conf set to the output from previous step


  • This process is iterated until all Offset values are zero


* Configuration file used by the Track Finder:

  • Runned Analyzer with right offset in OffsetAndCoverage_Analyzer.conf (zOff for 2 CMS chamber and CMS Timing)

  • Configuration file used by the Analyzer:


Check for the alignment procedure

This check is made plotting the offset plots of each DUT (Detector under test) wrt the first tracker (g1)

Preliminary results

Here are the preliminary results for some runs collected with pion beam@150 GeV

  • Efficiency


  • Cluster Size


  • Cluster Size vs Current


  • Spatial Resolution


Topic attachments
I Attachment History Action Size Date Who Comment
JPEGjpg Analyzer_config.jpg r1 manage 55.1 K 2013-09-16 - 17:52 PatriziaBarria Configuration file used by the Analyzer
PDFpdf CMSGEMs_nov2012_logbook.pdf r1 manage 10030.3 K 2013-09-17 - 23:40 PatriziaBarria November 2012 beam test Logbook
JPEGjpg CMS_Chamber2.jpg r1 manage 66.1 K 2013-09-15 - 20:17 PatriziaBarria CMS Chamber
JPEGjpg ClusterSizevsCurrent.jpg r1 manage 40.8 K 2013-09-17 - 23:25 PatriziaBarria Cluster Size vs Current
JPEGjpg Cluster_Size.jpg r1 manage 64.3 K 2013-09-17 - 23:24 PatriziaBarria Cluster Size
JPEGjpg Detector_config.jpg r1 manage 90.7 K 2013-09-16 - 17:58 PatriziaBarria Detector configuration file
JPEGjpg Efficiency.jpg r1 manage 35.6 K 2013-09-17 - 23:24 PatriziaBarria Efficiency
C source code filec Efficiency_pionsNov2012.C r1 manage 2.9 K 2016-09-27 - 19:00 RamKrishnaSharma Efficiency Original Data wrt HV
JPEGjpg EventBuilder_config0_new.jpg r1 manage 103.8 K 2013-09-16 - 17:34 PatriziaBarria  
JPEGjpg EventBuilder_config1_new.jpg r1 manage 97.1 K 2013-09-16 - 17:37 PatriziaBarria  
JPEGjpg OutputEventBuilder_config0_new.jpg r1 manage 105.8 K 2013-09-16 - 17:36 PatriziaBarria  
JPEGjpg Output_EventBuilder_config1_new.jpg r1 manage 91.1 K 2013-09-16 - 17:37 PatriziaBarria  
JPEGjpg Runs.jpg r1 manage 156.3 K 2013-09-16 - 15:32 PatriziaBarria November 2012 Runs collected and analyzed
JPEGjpg Setup_schema.jpg r1 manage 57.2 K 2013-09-15 - 20:04 PatriziaBarria Sketch of the setup used in the November 2012 beam test
JPEGjpg Spatial_Resolution.jpg r1 manage 49.3 K 2013-09-17 - 23:25 PatriziaBarria Spatial Resolution
JPEGjpg TrackFinder_config.jpg r1 manage 30.9 K 2013-09-16 - 17:51 PatriziaBarria Configuration file used by the Track Finder
C source code filec pion_efficiency.C r1 manage 2.6 K 2016-09-27 - 19:02 RamKrishnaSharma Efficiency Data wrt current
JPEGjpg readout.jpg r1 manage 25.6 K 2013-09-15 - 20:10 PatriziaBarria Readout used during the November 2012 beam test
JPEGjpg setup1.jpg r1 manage 29.1 K 2013-09-15 - 19:56 PatriziaBarria Setup
JPEGjpg setup2.jpg r1 manage 31.7 K 2013-09-15 - 19:57 PatriziaBarria Setup
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Topic revision: r11 - 2016-09-27 - RamKrishnaSharma
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