Difference: MichaelHildrethDataMixingModule (2 vs. 3)

Revision 32009-03-19 - AmnonHarel

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Instructions for using the DataMixingModule

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Instructions for using the DataMixingModule

 

Overview

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The DataMixingModule provides a means of merging the single-channel information from two
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The DataMixingModule provides a means of merging the single-channel information from two
 or more data streams into a single event. Its primary purpose is to allow the production of Monte Carlo events that take the "simulation" of detector noise, pileup, and anything else that could be present in a given beam-crossing from the collider data itself. To make the
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 at the earliest stage where the two streams can have the same format. This typically occurs at the single-channel level, although there are some exceptions that will be mentioned below. The merging is done by "adding" in a sub-detector-appropriate manner energy or charge deposition that happens to occur
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in the same channel in both streams. The DataMixingModule makes a new copy of the single-channel
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in the same channel in both streams. The DataMixingModule makes a new copy of the single-channel
 information that combines the two streams. Channels with hits in only one of the streams are passed directly through to the new output stream. As will be seen below, it is not possible to just overwrite the old single-channel information, so any subsequent processing that is done on these events must be
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 the combination should be handled correctly.

The following sections outline the necessary steps to create the input and overlay streams, run the

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DataMixingModule, and submit its results to further processing.
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DataMixingModule, and submit its results to further processing.
 

Current Release Setup (Current as of 17 March, 2009)

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The DataMixingModule and the associated packages from other systems should be available in the 3_1_X releases,
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The DataMixingModule and the associated packages from other systems should be available in the 3_1_X releases,
 and a work-around for 2_2_X also exists.

For 3_1_X:

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 SimCalorimetry/CaloSimAlgos V00-07-06
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There seem to be some problems (not related to the DataMixer) in _pre3 at the moment - I would stick to _pre1. If you do this, you will need the latest tag of Mixing/Base.
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There seem to be some problems (not related to the DataMixer) in _pre3 at the moment - I would stick to _pre1. If you do this, you will need the latest tag of Mixing/Base (V03-00-03).
  For 2_2_X:
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 Mixing/Base V02-01-01
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Note that the DataMixer executable may or may not be available in the release, so you may have to build it in your local area.
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Note that the DataMixer executable may or may not be available in the release, so you may have to build it in your local area.
 

Overlay Options

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Event Preparation

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As mentioned above, the DataMixingModule is capable of overlaying any type of data on any other, if the event
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As mentioned above, the DataMixingModule is capable of overlaying any type of data on any other, if the event
 streams have been prepared with the appropriate collections of input data. For the majority of subdetectors, events are merged at the Digi level, so the desired collections of digis must be present in the input and overlay streams, and must be specified with the corresponding InputTags. The major exception to this treatment is the Hcal, where proper overlay for MC production should add data pedestals to simulated hits before the digitization is done.
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The input collections are specified in the cfi.py files that configure the DataMixingModule. These
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The input collections are specified in the cfi.py files that configure the DataMixingModule. These
 are listed in the /python directory, and are given in the files
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 mixOne_X_on_Y_cfi.py files in the DataMixingModule/python directory. The overlay file is also specified here.
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The mixOne_X_on_Y_cfi.py files in the DataMixingModule/python directory also contain some specific flags for running the DataMixingModule and the underlying overlay code in Mixing/Base, which handles
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The mixOne_X_on_Y_cfi.py files in the DataMixingModule/python directory also contain some specific flags for running the DataMixingModule and the underlying overlay code in Mixing/Base, which handles
 all of the event juggling. Comments are included, below.
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 There are two modes for Ecal overlay, and three modes for Hcal. The Ecal overlay can merge Digis by merely adding channels with hits in the input and overlay streams after gain conversion. An appropriate gain is selected for
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the final merged Digi. The Ecal can also add RecHit energies in cells where there is energy in
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the final merged Digi. The Ecal can also add RecHit energies in cells where there is energy in
 both the input and overlay event. For Hcal, the same two Digi or RecHit modes are available. In addition, there is a "production" mode where the digis from the overlay stream are used as
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"pedestal" for the SimHits that are in the input stream. The Digis are converted back to charge using appropriate calibration constants, the charge from the SimHits is added, and then new Digis
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"pedestal" for the SimHits that are in the input stream. The Digis are converted back to charge using appropriate calibration constants, the charge from the SimHits is added, and then new Digis
 are made.
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DataMixingModule Outputs

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As specified in the mixOne_X_on_Y_cfi.py files, the outputs of the DataMixingModule are new Digis
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As specified in the mixOne_X_on_Y_cfi.py files, the outputs of the DataMixingModule are new Digis
 with different producers and labels. One cannot just overwrite the old Digis, unfortunately. Here is a list of the possible produced objects:
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 As can be seen in the cff file, these are from producer 'mix', with process name 'PRODMIX'.
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Further Processing of DataMixingModule Output

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Further Processing of DataMixingModule Output

  As is obvious from the previous section, any new processor that wishes to read the new Digis has to have its input re-directed to look at the DataMixer digis instead of the "standard" inputs.
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 The script DigiRecoExampleMC_STARTUP_cfg.py sets up the Reconstruction. This imports ReconstructionDM_cff.py, where all of the re-direction of inputs is done. In the current version of the release, there is also the file RecoLocalTracker_cff.py which handles some issues with
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the SiStrip reconstruction processing specific to cosmics data. These scripts will be updated as
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the SiStrip reconstruction processing specific to cosmics data. These scripts will be updated as
 proper Reconstruction sequences change.
 
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