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Introduction/Prerequisites

This page shows how to generate, simulate (using AltfastII), and reconstruct events. It assumes you have installed and set up release 14. If not, see Gustaaf's tutorial for setting up a release at Nevis: RunningAnalysis or for setting up a release at BNL: RunningAnalysisAtBNL. You can also set up a release on lxplus at cern by following cern's computing workbook. It may be a good idea to go through the workbook anyway, however, if you intend to do a lot of production, you will not be able to do it on lxplus because of disc space issues. Also, the workbook production runs through the full chain which takes an order of magnitude longer to get through than using AtlfastII.

Generation

After your release has been installed and setup, you will need to create a place where you can do your production. For example, mine is ~/workarea/14.2.10/production. Once created, cd to that directory.

The event generation job transform is csc_evgen_trf.py. The main difference (from what I can tell) between a job options file and a job transform file is that the transform accepts arguments (for example for the number of events, so that you don't have to physically change the contents of the file as with job options). You will also need a job options file which specifies the pythia cards for your event. An example job options file can be copied from ~durbanie/workarea/14.2.10/production/WprWZenuqq.jobOptions.py. This job options file contains W' events decaying to a W and a Z. The W then decays to an electron and its neutrino, and the Z hadronically.

The part where you specify your decay begins after the line Pythia.PythiaCommand = [. Everything after this switches on the W' production, specifies its mass, forces a decay to WZ, and then specifies what the W and Z decay to (see comments in the file). For example to make the W decay hadronically, first turn off the leptonic decay by switching the line "pydat3 mdme 206 1 1" to "pydat3 mdme 206 1 0". Then turn on the hadronic modes (for example, changing "pydat3 mdme 190 1 0" to "pydat3 mdme 190 1 1" will turn on the W-]d-bar u mode). In short, the last number in each line specifies if the process is on (1) or off (0).

Once you have the job options file, simply enter the following line, specifying your own parameters:

csc_evgen_trf.py -t [runNumber] [firstEvent] [maxEvents] [randomSeed] [jobConfig] [outputEvgenFile] [histogramFile] [ntupleFile] [inputGeneratorFile]

As an example:

csc_evgen_trf.py -t 8999 0 100 54298752 WprWZenuqq.jobOptions.py WprWZenuqq.evgen.pool.root NONE NONE

This generates 100 W'->WZ->enuqq events and stores them in the file WprWZenuqq.evgen.pool.root. This should go rather quickly (around 5 min for 100 events).

Simulation

The next step is simulation/digitization using Atlfast II. The transform file used here is csc_simul_trf.py. This takes an input evgen file and first simulates what each particle does to the detector, and outputs a file containing a record of where each particle traversed the detector as well as how much energy was deposited in that detector component. The user can save this record as a root file (called a HITS file) if he or she chooses.

This transform also digitizes events, i.e. simulates the digital output of the detector in response to each event. The result is called an RDO file which stands for Raw Data Object. This is in principle similar to real data that one would expect to get out of the detector. To run simulation, enter this line at the command line:

csc_simul_trf.py [options] [inputevgenfile] [outputhitsfile] [outputrdofile] [maxevents] [skipevents][randomseed] [geometryversion] [physicslist] [jobconfig] [dbrelease]

For example:

csc_simul_trf.py WprWZenuqq.evgen.pool.root WprWZenuqq.HITS.root WprWZenuqq.RDO.root 100 0 12 "ATLAS-GEO-01-01-00" 1 2 QGSP_EMV jobConfig.FastIDKiller.py

Note that this can take a while to complete (~2 hours for 100 events)

Reconstruction

To be completed soon.

-- DustinUrbaniec - 08 Aug 2008

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Topic revision: r1 - 2008-08-08 - DustinUrbaniec
 
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