Tracker Alignment Validation Tools

Complete: 3


This page is a collection of documentation for tools for tracker alignment validation. There is a short description as well as a link for each. Please use the Common Validation Area for up-to-date and production-mode versions of the tools.

All-In-One Meta Validation

One tool to run all the following in this group (and then some). All-In-One Meta Tool TWiki

See also these presentations of GregorHellwig:
* All-in-One Tool 2012.09.24
* All-in-One Tool 2012.09.26
* All-in-One Tool 2013.02.28
* All-in-One Tool 2013.04.11

Data-driven Alignment Validation Tool (the so called offline validation)

This tool is conceived to generate various distribution after running over a data-set with a certain alignment setting applied, to judge the quality of the alignment. See Data-driven Alignment Validation Tool TWiki for further details.

Tracker Geometry Comparison Tool

This tool compares any two sets of alignment constants based solely on geometrical considerations. It can compare all tracker hierarchy structures and remove global displacements. There also exists a plugin to allow for ROOT visualization. Tracker Geometry Comparison Tool Twiki

Track splitting

The method is to split cosmic tracks along their point of closest approach to the beamline and create two track candidates. SWGuideCosmicTrackSplitting

Dimuon (e.g. Z->μμ) validation tool for TK alignment

Misalignments in the tracker detector can be studied using a sample of Y(1s) ->μμ or Z->μμ events looking for biases in the mass of the reconstructed muon pair. TkAlDimuonValidation TWiki

Output areas of your validation

For the output of your validation you have to check the following areas.

Log files

The log files and error messages will be put to a subdirectory

which is "your validation area" for the alignment beeing validated, where you submitted -N <yourvalidationname> ...

ROOT files

The root files created by the interactive or batch jobs sent by the alignment scripts will be copied automatically to EOS at

To access it please read CAF and CAFSETUP, e.g.
cmsLs /store/caf/user/<yourusername>/AlignmentValidation/<yourvalidationname>


The plots made from the root files are put into the result section of the common validation area:


Depending on the integrated tool, one can obtain further plots by running

at "your validation area" where it was created earlier automatically.

Alignment Validation with PV Unbiased Residuals Tool

The Primary Vertex (PV) Validation is a tool for Tracker Alignment Validation, intended to spot biases in the description of the Pixel geometry, by using unbiased track residuals. SWGuideTkAlignmentValidationPrimaryVertex

Energy Over Momentum (E/p) Alignment Validation Tool

This tool is developed to determine momentum changing weak modes in the tracker geometry. SWGuideTkAlignmentValidationEnergyOverMomentum

Common Validation Area

In order to increase comparability a common validation area has been set up at:

To use the area do:

cd /afs/

If you have not done this create your own place for .db objects and the .ini definitions like:

mkdir /afs/<your username>

and copy your .db objects there.

Then create a .ini file containing [alignment:] sections for objects you always want to compare together. like this:

[alignment:<your name>]
dbpath=sqlite_file:/afs/<your username>/<.db filname>
tag=Alignments #change if needed
errortag=AlignmentErrors  #change if needed

Finally start your validation job doing:

cd /afs/ -c defaultCRAFTValidation.ini,<your username>/<your object collection>.ini

There is one special object collection:

It should always contain [alignment: ... ] sections that point to the latest objects created by the various experts.


This page is a copy and the continuation of the obsolete TkAlignmentValidationTools.

revised: PalHidas - 07 June 2013

-- NhanTran - 24 Mar 2008

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Topic revision: r9 - 2015-05-22 - MatthiasSchroederHH
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