Participants : Adrian, Dmitry

Last week's TODO list discussion

  • The plots aka telescope DQM showing the av. numb. of clusters, cluster X and Y size per telescope+CMSPixRef, the av. numb. of clusters per telescope arm vs. time/run number (functions f_{upstream}(t) and f_{downstream}(t) ) as well as the difference and asymmetry of these functions,  f_{downstream}(t) - f_{upstream}(t) and \frac{f_{downstream}(t) - f_{upstream}(t)}{f_{downstream}(t) + f_{upstream}(t)} are presented (w/o fiducial cut) on the page Telescope raw data analysis.
  • Merging step was clarified, two codes, git ver. and Thomas' ver., were compared (see the merge step):
    1. Both codes have the same purpose of merging the pulse and sparse clusters' collections of the telescope and alibava data to a one *.slcio file.
    2. Git ver. code is easier to read through; it doesn't contain functions for drawing histograms in the contrary to the Thomas' code which allows to draw correlation plots (just in case when CMSPixRef in off though).
    3. It's unclear, how the alibava input *.slcio file in being read: the variable containing the file name is being defined, but never used in the code or being sent to another processor -> Dmitry will meet with Thomas next week to discuss the code.
  • The git ver. merging code was used for merging the telescope+DUT+CMSPixRef data with the following cuts which were applied on the clustering-1 step (git ver. code was used for that step):
  1. TDCCut = 0-100 ns (TimeCutMin = 0; TimeCutMax = 100)
  2. SeedSNRCut = 2
  3. NeighbourSNRCut = 1.5.

The plot showing the fraction of events which contain clusters per each telescope+DUT+CMSPixRef vs. bias HV/anneling time and inclination angle as the result of the merging step is presented on the page Alibava data, titled as "After the merger step". The av. fraction lays within 39-45%; that is in a quite agreement with the geometrical acceptance of the CMSPixRef which is ~45-46% (with the physical  limitation of 50%). Lowering of the fraction value could be related to a slight mis-tunning between the DUT and CMSPixRef timings.


Quick glance though the clustering-1 code:

  • Thomas' code ( is less straightforward for understanding that the git ver. code (
  • Thomas' code, as its explained in his thesis (p. 5.3.4 ,, has the cross-talk noise correction, while git ver. one doesn't
  • SNR cuts have the same purpose in both versions.


  • Clustering step. Compare the code versions and modify existing one, e.g. for being able to make the cross-talk noise charge correction
  • Play with the cuts :
  • Define the optimal TDC cut/time selection window
  • Define the optimal SeedSNRCut and NeighbourSNRCut parameters - N vs. SeedSNRCut, N vs. NeighbourSNRCut
  • Compare fractions of the events where the clusters were found on each telescope+DUT+CMSPixRef plane calculated for the Oct15 runs  with the ones calculated for the June15 runs - irr. vs. non-irr. sample comparison:
  • to fix the TDC cut to 0-100 ns
  • to vary the SeedSNRCut and NeighbourSNRCut parameters

and see the dependence "Fraction vs. SeedSNRCut vs. NeighbourSNRCut" in the following cases:

  1. Oct15 run before the sample was annealed vs. Jun15 run; inclination angle is being fixed to 0 deg., temperature is being fixed to the lowest one reached (-30/-25 deg.C for the Oct15/June15 runs)
  2. Oct15 run after the sample was annealed vs. Jun15 run; inclination angle is being fixed to 0 deg., temperature is being fixed to the lowest one reached (-30/-25 deg.C for the Oct15/June15 runs)
  • Think about the questions which can be asked during the Telescope Workshop at Orsay -> send them to Adrian

  • No labels