Effects of magnet polarity on the alignment of the IT Stations

The study was triggered by on observation of small variations of the alignment constants between the opposite magnet polarities. For example, the observed changes of the Inner Tracker alignment constant between different magnet polarisations are for the x translation within 100 μm in for 2011 and within 200 μm for 2012. Moreover, a trend is visible where constants are shifted in the same direction for the Down polarity with regards to the Up one. The difference is significant because the spatial resolution of the Inner Tracker is about 50 μm. To investigate its origin the tests with different configurations and data files were performed.

Documentation

Link to PAPER draft Date Comment
alignment_note_v3.pdf 2015-04-12 after comments from Maurizio Martinelli
alignment_note_v2.pdf 2015-03-18 added reproduction test and IT/OT illumination maps for D0 and J/ψ samples
alignment_note_v1.pdf 2014-09-26 first version

Talks

  • Status of the Alignment in Magnetic Field 5/12/2013
  • Status of the Alignment in Magnetic Field 23/1/2014
  • Comparison of Alignment for different magnet polarities 20/02/2014
  • Alignment differences with magnet polarity 20/03/2014
  • Studies of Alignment with finer segmentation 24/04/2014
  • Studies on Alignment vs time 15/05/2014
  • Alignment with finer segmentation using J/ψ sample 26/6/2014
  • Studies on tracker alignment 23/10/2014
  • Tracker Alignment Studies 11/12/2014

Configuration files

The study of the alignment dependence on survey constraints was performed using different configuration sets:

Set1 - OT(3)CFrameLayers fixed in Tx and Tz using survey constraints, no survey constraints in Tx OTCFrames, OTModules allowed to move in Tx and Rz ( config_set1.py);

Set2 - OTCFrameLayers fixed in Tx and Tz using survey constraints, OTModules fixed with regards to OTCFrameLayers ( config_set2.py);

Set3 - OTCFrames and OTCFrameLayers fixed in Tx and Tz using survey constraints, OTModules allowed to move in Tx and Rz ( config_set3.py);

Set4 - OTCFrames and OTCFrameLayers fixed in Tx and Tz using survey constraints, OTModules fixed with regards to OTCFrameLayers ( config_set4.py);

Set5 -no survey constraints in Tx and Tz for OTCFrames and OTCFrameLayers, OTModules allowed to rotate around x axis (Rx) ( config_set5.py)

Input data

Alignment convergance test

For 2011 two periods with two magnet field polarities were considered for the convergence test.

Time Validity Polarity Fill Number Run Number
2011-04-08/2011-06-10 Down 1856 93168
2011-06-10/2011-07-06 Up 1889 94169

Six periods were considered for 2012 year: two groups of consecutive periods with opposite magnetic field. For the first group the official alignment resulted in a large difference (up to 200 μm) for Tx alignment parameters. The other group exhibits small difference ~50 μm.

Time Validity Polarity Fill Number Run Number
Group 1
2012-10-23/2012-11-07 Up 3236 131117-131126
2012-11-07/2012-12-03 Down 3300 132624-132633
Group 2
2012-07-01/2012-07-19 Up 2848 122202-122211
2012-07-19/2012-07-24 Up 2858 122569-122578
2012-07-24/2012-08-09 Down 2880 123921-123930
2012-08-09/2012-08-27 Up 2976 125784-125793

Time dependence of the alignment

Two periods with two magnet polarity were used. Each period was split on few subperiods.

Time Validity Polarity Fill Number Run Number
2011-04-26 Down 1739 90256-90257
2011-04-28 Down 1745 90404
2011-04-30 Down 1749 90567
2011-05-02 Down 1755 90641
2011-05-03/2011-05-15 - TS
2011-05-19 Down 1795 91919-91920
2011-05-24 Down 1804 92216
2011-05-27 Down 1809 92528
2011-05-30 Down 1816 92654
2011-06-02 Down 1836 92839
2011-06-04 Down 1845 92939
2011-06-07 Down 1856 93168
2011-06-09 Down 1862 93280
2011-06-11 Up 1863 93406
2011-06-13 Up 1867 93511
2011-06-16 Up 1871 93696
2011-06-18 Up 1880 93845
2011-06-21 Up 1883 93984
2011-06-24 Up 1889 94169
2011-06-26 Up 1894 94268
2011-06-28 Up 1901 94359

Time Validity Polarity Fill Number Run Number
2012-10-25 Up 3220 130911-130965
2012-10-28 Up 3236 131117-131126
2012-10-30 Up 3242 131220-131233
2012-11-02 Up 3259 131452-131456
2012-11-05 Up 3265 131726-131732
2012-11-09 Down 3273 131973-131978
2012-11-11 Down 3279 132111-132118
2012-11-14 Down 3286 132269-132278
2012-11-16 Down 3292 132379-132383
2012-11-17 Down 3296 132453-132460
2012-11-19 Down 3300 132624-132633
2012-11-22/2012-11-24 - VdM Fills
2012-11-24 Down 3318 133059-133073
2012-11-25 Down 3323 133169-133191
2012-11-30 Down 3347 133386-133391
2012-12-02 Down 3363 133578-133587
-- VarvaraBatozskaya - 2015-03-20
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Topic revision: r2 - 2015-04-12 - VarvaraBatozskaya
 
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