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This page provides information on the alignment procedure of the SVT tracker for the 2019 data.

 

Data Samples

We start with elastically-scattered, full-energy electrons from the early calibration runs employing the Full Energy Electron (FEE) trigger.

For the field-off, straight track analysis we use run 10101.

For field-on data we use runs 10103 and 10104.

More details about the run can be found at 2019 Run Spreadsheet.

Event Reconstruction

Preliminary reconstruction was performed with a snapshot of the hps-java master using the HPS-PhysicsRun2019-v2-4pt5.

Event Selection

Since we are starting with an unaligned detector, and pattern recognition may be affected, we make rather tight selection cuts on the event as a whole to get a good quality sample of tracks. We start with a sample of events in which one and only one high energy cluster was found in the electromagnetic calorimeter, and one and only one track was found in the event.

Data Samples

We list data samples publicly available at SLAC. Samples can be made available at other locations if need be.

The samples are divided into top (290398 events) and bottom (318450 events) samples to allow calibration and alignment to be targeted.

/nfs/slac/g/hps_data2/data/physrun2019/hps_010103/skim/alignment/hps_010103.evio.00XXX_alignment_YY.slcio  XXX= 000 - 191 YY = top, bottom

/nfs/slac/g/hps_data2/data/physrun2019/hps_010104/skim/alignment/hps_010104.evio.00XXX_alignment_YY.slcio  XXX=000 - 206 YY = top, bottom

Procedure

The reconstruction needs to be run over the data samples using every new detector.

A combination of output from the GBLRefitterDriver and GBLOutputDriver provides information for the alignment procedure. The former (with the correct steering file settings) will produce the binary output file which is fed to millepede for the alignment (as described in the SVT Detector Alignment page). The latter produces useful diagnostic histograms such as residual plots, which document the quality of the alignment.

Working Directory

The primary working directory for these studies at SLAC is

/nfs/slac/g/hps_data2/data/physrun2019/feeAlignment/

Step-by-step guide

  1. Prepare a new detector using the results of a previous alignment.
  2. Rerun the reconstruction over the data sets using this new detector. I suggest creating a new directory for each detector and alignment pass to keep things clean.
    1. java -server -jar hps-distribution-4.5-SNAPSHOT-bin.jar PhysicsRun2019ReReconForAlignment.lcsim -i <inputFileName> -DoutputFile=DetectorNamePassX/<outputFileName> -d <detectorName> -R 10103

 

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