Testbeam Reconstruction Details

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Installation: http://eutelescope.web.cern.ch/content/installation

After installing and sourcing environment (build_env.sh) the main directory is $EUTELESCOPE

Useful directories

• src (include): contains processor source code (headers)
• build: recompilation after code changes
  • > cmake ..
  • > make install
• jobsub: includes examples folder with template reconstructions
• pixgeo: where geometry files for sensor libraries are stored
• external: includes eudaq code

Working Folder

In working folder: $EUTELESCOPE/jobsub/examples/SOME_EXAMPLE

• Steering folder: Steering files for each reconstruction step. Each file contains list of Processors executed in the step
• Configuration file: Specifies user directories: data directory, output directories
  • general parameters: number of events, output frequency
  • steering parameters: specific to each reconstruction step
• Gear file: Specifies devices and physical positions/orientations of set-up
• Runlist file: Parameters specific to particular runs
• Output directories: Store histograms and hit sets form each reconstruction step

OUTPUT DIRECTORIES

These are specified in the config file.

In working folder: $EUTELESCOPE/jobsub/examples/SOME_EXAMPLE/output

• histograms: Root files with distribution plots produced in reconstruction step
• lcio: Input/output collections used by EUTelescope and passed between steps
• database: Parameters used by the reconstruction
• logs: Log files for each jobsub execution

Each file has standard prefix (set in config): runXXXXXX

• XXXXXX is run number specified on execution -always six digits

RECONSTRUCTION STEPS:

There are five basic steps to run the reconstruction chain (i.e. to transform raw data into analysis ready data):

• converter: Read in telescope and DUT hit information, from native DAQ to LCIO format
• clustering: Combine individual hits on each plane to hit clusters on each plane
• hitmaker: Globally orient planes
• align: Global alignment of planes: based on pattern recognition & track fitting
• fitter: Generate tracks --> device resolution

Parameters used in each reconstruction step are defined between config, runlist and steering files: config includes global parameters; runlist includes run specific parameters; and, gear file has the sensor specification. Other values can be found in the individual steering files, though any non-global values can be defined elsewhere. Parameters are refered to across files using @NAME@ syntax.

Other steps are definable in the steering directory. All follow the form of a recipe of processors (in execution order) with processor definitions below (no order required). The source coude for each processor can be found in $EUTELESCOPE/src (include) by identifying the processor "type" specified at the top of each processor definition in the steering file.

The basic steps are expanded on below.

Converter

Two functions

• Decode raw files: telescope plane and DUT hit information
  • Translated into LCIO hits (format of EUTELESCOPE), Uses eudaq to convert from native format.
  • Converter file found in: $EUTELESCOPE/external/eudaq/<version>/main/lib/src
• check for hot pixels -> create list for masking later

REQUIRES:

• Specification of planes: gear file & steering file
  • Plane names (i.e. numbers) to expect
  • Correct specification of devices (# detector elements) in gear file
• Library of detector geometry required

SET:

• Config: Max Firing Frequency – identify hot pixels

OUTPUT:

• OUTPUTPATH/histograms/runXXX-converter-histo.root
• OUTPUTPATH/database/runXXX-hotpixel-m26-db.slcio
• OUTPUTPATH/lcio/runXXX-converter.slcio

Check noisy pixels from histograms

Clustering

Combine hit pixels in proximity into clusters

Alternative methods:

• Clustering: pixel based clustering
• Geoclustering: geometry based clustering

REQUIRES:

• OUTPUTPATH/lcio/runXXX-converter.slcio
• Gear file for pitch parameter ( geometric clustering only)

OUTPUT:

• OUTPUTPATH/histograms/runXXX-clustering-histo.root
• OUTPUTPATH/lcio/runXXX-clustering-histo.root

Check device response from cluster plots.

Standard: signal, total size, sizeX, sizeY, multiplicity

HITMAKER

Globally orient planes.

Alternative methods:

• Clustering: pixel based clustering
• Geoclustering: geometry based clustering

REQUIRES:

• Specification of plane orientation: gear file
• OUTPUTPATH/lcio/runXXX-clustering.root

SET:

• Config: Specify cuts around hit peaks for pre-alignment

OUTPUT:

• OUTPUTPATH/histograms/runXXX-hitmaker-histo.root
• OUTPUTPATH/database/runXXX-refhit-db.slcio
• OUTPUTPATH/database/runXXX-prealign-db.slcio
• OUTPUTPATH/lcio/runXXX-hitmaker-histo.root

Check success in correlation plots (bottom-left to top-right strip)

ALIGN

Global alignment of planes: based on pattern recognition & track fitting

SET:

• Config: Specify resolution cuts around hits

REQUIRES:

• OUTPUTPATH/lcio/runXXX-hitmaker.root

OUTPUT:

• OUTPUTPATH/histograms/runXXX-align-histo.root
• OUTPUTPATH/lcio/runXXX-align-histo.root
• OUTPUTPATH/database/runXXX-alignment.slcio

Check success in chi2 distribution

FITTER

Generate tracks -> device resolution

SET:

• Config: Specify resolution cuts around hits

REQUIRES:

• OUTPUTPATH/lcio/runXXX-hitmaker.root
• OUTPUTPATH/lcio/runXXX-align.root

OUTPUT:

• OUTPUTPATH/histograms/runXXX-fitter.slcio
• OUTPUTPATH/lcio/runXXX-track.slcio

Check success in chi2 distribution

BEWARE

Don’t source build environment more than once

Remember to recompile (update cmake) after changing source code

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-- Kenneth Wraight - 2015-04-21

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