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Notes on PYTHIA8 tuning using PROFESSOR in ATLAS


  • Documentation: (
  • To run in any other directory than /example: export PYTHIA8DATA=/home/dkar/atlas/tuning/pythia_with_old_hepmc/pythia8145/xmldoc
  • export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$PWD/../local/lib
  • To compile: make main32 HEPMCLOCATION=$PWD/../local
  • To run: ./main32.exe main32.cmnd test.out (or my.hepmc to pipe output through Rivet)


Pythia8 most writes output in the HepMC GenEvent output format, which can be read into Atlas using ReadEventFromFile in GenAnalysisTools:

 from AthenaCommon.AlgSequence import AlgSequence
 topSequence = AlgSequence()

 from ReadEventFromFile.ReadEventFromFileConf import ReadHepMc
 read = ReadHepMc()
 read.File = "filename.hepmc2g"
 topSequence += read

 theApp.EvtMax = 500




  • Documentation (
  • Latest version 2.06.03 did not work with PYTHIA 8.145, switched to 2.05.01
  • Download and install: (./configure --prefix=$PWD/../local/ --with-momentum=GEV --with-length=MM; make; make install; use HEPMCLOCATION=$PWD/../local OR mkdir build install, work in build, ../HepMC-2.05.01/configure -prefix=$PWD/../hepmc/install -with-momentum=GEV -with-length=MM and then make; make install; reconfigure PYTHIA with ./configure --with-hepmc=$PWD/hepmc/hepmc/install --with-hepmcversion=2.05.01; (re)make. )


  • Documentation (
  • Download and Install (./configure --prefix=$PWD/../local/; make; make install; Use bin/lhapdf-getdata to put PDFsets in share/lhapdf/PDFsets/)
  • Link: export LHAPATH=$PWD/..local/share/lhapdf/PDFsets
g++ -O2 -ansi -pedantic -W -Wall -Wshadow -fbounds-check -Wno-shadow -I../include -I/home/dkar/atlas/tuning/pythia_with_old_hepmc/pythia8145/runpythia/../local/include \ -o ../bin/main32.exe \
        -L../lib/archive -lpythia8 \
        -lhepmcinterface \
        -L/home/dkar/atlas/tuning/pythia_with_old_hepmc/pythia8145/runpythia/../local/lib -lHepMC \
        -L/home/dkar/atlas/tuning/pythia_with_old_hepmc/pythia8145/runpythia/../local/lib -lLHAPDF

g++ -O2 -ansi -pedantic -W -Wall -Wshadow -fbounds-check -Wno-shadow -I../include -I $HOME/tuning/pythia8145/examples/../local/include -o ../bin/main32.exe -L../lib/archive -lpythia8 -lhepmcinterface -L $HOME/tuning/pythia8145/examples/../local/lib -lHepMC -L $HOME/tuning/pythia8145/examples/../local/lib -lLHAPDF

./configure --with-hepmc=$PWD/../local/ --with-hepmcversion=2.05.01 --with-lhapdf=$PWD/../local/lib/

"Official" ATLAS Stuff

  • Get: svn co svn+ssh://
  • Rivet: need Rivet***.so and *.aida files to include an internal analysis and link: export RIVET_ANALYSIS_PATH=$PWD

Tuning Workflow

  1. Setup the directory structure. Create mc/XXX directories. [NOT NEEDED]. Script:

  1. Decide which parameters to tune.
    • Start off by MPI tune.
    • By prof-scanparams -> prepares used_params files. They should reside in mc/XXX/.
    • Use: prof-scanparams -i $PWD/../mc -o $PWD/../mc -N 100 mpi_params. (created MC/XXX dirs too)/ prof-sampleparams -o $PWD/../ -N 5 mpi_params

  1. Decide which analysis/datasets to tune to.
    • For MPI tune (and to avoid jet slices, for now), use ATLAS 900 and 7000 MB and UE (track and cluster), CDF 1.8 and 1.96 MB. (8 in total).
    • Only needs to generate soft QCD.
    • For each mc/XXX, there will be different directories corresponding to cmE.

  1. Generate MC samples.
    • Input run_params_cmE (from run directory) and used_params (from /mc/XXX/)
    • The scripts to run will be, where cmE will determine which run_params_cmE file and Rivet analysis is included.
    • Arguments to the run script: begin-run-no (000) end-run-no (099)
    • Should result in mc/XXX/cmE/Rivet.aida for each cmE.
    • Merge by: (change end-run-no to argument)
    • Extend 1 param: previous number of runs x Delta(p)_ext/Delta(p)_prev
  2. Weights file with weights assigned to different analysis.
    • Use Pythia6 MPI tuning file?
    • :X:Y denotes X-axis range where to tune to. For different weights on different ranges, multiple lines corresponding to the same histogram.
    • Copy reference data from /afs/, store them in "ref" directory.
    • To extract all analysis: sed -n 's/AidaPath/&/p' filename >
    • To add weight "1.0" to all: sed "s/$/ 1.0/g" filename >

  1. Look at how runs envelop the data.
    • prof-envelopes --mcdir mc --datadir ref -o envelopes1 --weights w
    • make-plots envelopes2/envelopes/*.dat --pdf
    • ./ -s envelopes/envelopes/ pdf envelopes.html
    • For just one run comparson: compare-histos Rivet.aida; make-plots --pdf *.dat; then makegallery. [maximal all-in-one way: rivet-mkhtml mc1.aida:"MC1 label" mc2.aida"MC2 label"]

  1. Create a runcombs-file which contains combination of MC runs to be used.
    • By prof--runcombs. (prof-runcombs --mcdir mc -c 0:1)

  1. Parameterise the generator response. By prof-interpolate, results in folder ipols that contains a generator parameterisation file.
    • prof-interpolate --mcdir mc --datadir ref --obsfile w2 --runsfile runcombs.dat (-o ipol)
    • Interpolation set written to ref/ipol

  1. Finally tune. Using prof-tune, stored in results/.
    • prof-sensitivities --datadir ref --ipoldir ipol --runsfile runcombs.dat --obsfile w2 --plotmode extrenal -o sensitivity_plots
    • prof-tune --datadir . --weights w4 --ipoldir ref/ipol --runs runcombs.dat (stored in tunes)
    • Show the sensitivity of observables to the parameters varied: --datadir . --oudir splots --observables weights1
    • Show how well the generator runs "enclose" data: prof-envelopes --mcdir mc --refdir ref -o envelopes --weights weights
    • Show scatter plot for each tuning parameter.

  1. Get a way to compare to jetX data, run jetslices and merge. [HS: n Pythia6 we used the following CKIN(3) cuts for the QCD runs: 0, 10, 20, 50, 100, 150]

Note: if you source the local/ script, you will get the Genser versions of AGILe (1.2.2), Rivet (1.5.0), and Professor (1.2.1) in your environment. If you additionally source the local/ file, you will change the Rivet version to the ATLAS tuning build of Rivet 1.4.0.

So analyses which want to keep using Rivet 1.4.0 for now can keep sourcing For everyone else, and particularly if you are starting something new, please only source the script and use Rivet 1.5.0 from Genser. At some point -- when the Py8 runs are done! -- we'll completely remove the local builds.


  • source /afs/ OR source /afs/
  • voms-proxy-init -rfc
  • gsissh
  • qsub [resource requirements] script [script parameter]
  • If you have many jobs using the same script and you want to parallelize them, you can make an array job out of it with the switch: -t from-to:step

Tuning Settings

  • MPI Tune parameters: (/afs/ tune_11_mpi/parameter.ranges)

MultipleInteractions:pT0Ref (0.5 -10, 2.15)
MultipleInteractions:ecmPow (0-5, 0.24)
MultipleInteractions:pTmin (0.1 -10, 0.2)

For :bProfile = 2
MultipleInteractions::coreRadius (0.1-1-, 0.4)
MultipleInteractions:coreFraction (0 -1, 0.5)

For bProfile=3
MultipleInteractions:expPow (0.1 -10, 1)

  • PYTHIA8 Run settings:

The main32 example is very useful for running Rivet. It reads a runcard and writes HepMC events.

PDF:pSet = 8
MultipleInteractions:bProfile = 3 _(double gaussian=2)_
MultipleInteractions:alphaSvalue = SigmaProcess:alphaSvalue
SpaceShower:rapidityOrder = on

! 1) Settings that will be used in a main program.
Main:numberOfEvents = 3000000 ! number of events to generate
Main:timesToShow = 1000 ! show how far along run is this many times
Main:timesAllowErrors = 30 ! abort run after this many flawed events
Main:showChangedSettings = on ! print changed flags/modes/parameters
#Main:showAllSettings = on ! print all flags/modes/parameters
Main:showChangedParticleData = on ! print changed particle and decay data
#Main:showAllParticleData = on ! print all particle and decay data

! 2) Beam parameter settings. Values below agree with default ones.
Beams:idA = 2212 ! first beam, p = 2212, pbar = -2212
Beams:idB = 2212 ! second beam, p = 2212, pbar = -2212
Beams:eCM = 200 ! CM energy of collision

! 3) Pick processes and kinematics cuts
SoftQCD:minBias on

Tune Parameters:


> source
> source /afs/
> source /afs/


> prof-runcombs -c 0:1 --mcdir /afs/ -o runcombs_0_1.dat

>prof-interpolate --mcdir /afs/ --runs runcombs_0_1.dat -o test --ipol cubic --weights /afs/

>prof-tune --runs runcombs_0_1.dat --ipoldir test/ipol --ipol cubic --weights /afs/ -o test --refdir /afs/


Use v1.2.1. how to pass parameters?

> source /afs/

-- DeepakKar - 25-Feb-2011

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Topic revision: r23 - 2011-04-25 - DeepakKar
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