Single-Particle Simulations (HOWTO)

How to generate easily a simulated PISA DST with single-particle events.
4 fool-proof steps:

This page is not fully up-to-date. Take a look here for the most recent developments:
Single-Particle Embedding in EMCal (HOWTO)

1. PISA environment: Make sure that the standard PISA environment is well defined for your account. This should be the case if you have followed C. Maguire's instructions which basically say:
   • Copy the two shell scripts .phnx_alias and .phnx_cshell from /afs/rhic/phenix/PHENIX_LIB/PRO/boot/ to your $HOME directory and adapt them.
   • Modify your .cshrc file on your $HOME directory to include the lines:
   
   if($?PHNX_ARCH)then
   source $HOME/.phnx_alias
   else
   source $HOME/.phnx_cshell
   endif
2. Generation of an OSCAR-type PISA input file (via EXODUS):.
• Run (a slightly modified version of) R. Averbeck's exodus_generate code to generate your favourite single-particle spectra. This code (which is part of the EXODUS package) permits you to easily select the type of test-particle (as well as its distribution in pT, y and phi and the number of simulated events) and outputs an OSCAR-compliant file to be ''digested'' by PISA.
• If you want to try that, simply copy the files $AFSHOME/../enterria/exodus/exodus_generate, $AFSHOME/../enterria/exodus/defined_particles.txt and $AFSHOME/../enterria/exodus/seeds.txt on to your working directory and run it (./exodus_generate).
3. Generation of a ROOT-type PISA hit file::
• Install on your directory your favourite PISA version control files (e.g. the PISA files for normal/retracted arms, no / 2D / 3D magnetic-field ...). To do that, again just follow C. Maguire's instructions
. For example, if you want to use PISA for "Full 3D magnetic field, normal arms (run00d)" conditions simply source /afs/rhic/phenix/software/simulation/run00d/pisaDLinker.csh on your working directory. This will install all the files which PISA needs to perform the simulation (*).
• Run PISA (./pisa), enter the 3 usual carriage-returns and once you have your PISA prompt, simply type:

PISA> text_file to select the OSCAR-compliant file (which has to be called, or soft-linked to, oscar.input)
PISA> ptrig 5000 (or any other number of events you want to simulate ...)
PISA> ...
PISA> exit (this is important, because otherwise your file won't be closed ...)
• After this, PISA will output a PISAEvent.root hit file.
4. Generation of a ROOT-type PISA DST file:
• Install the macros for PISA-to-DST production (camTaskRun.C, camTaskIni.C, and camTaskPar.C). To do that, source the perl script which installs for you the version of the official camTask*.C macros compatible with your selected PISA version (e.g., for the aforementioned PISA version you should do: source /afs/rhic/phenix/software/simulation/run00c/taskCLinker.csh).
• You are now ready to run camTaskRun.C:

root -b
root [0] .x camTaskRun.C(5000,1,1,1,"PISAEvent.root","PISA_DST.root");
root [] ...
root [] .q

Once this is done you are ready to use your final simulated PISA_DST.root file for any analysis you may want to carry out ... (the most typical one: embedding your single particle simulated spectrum into real events for particle efficiency calculations ...). HERE you can find a short script which performs the 4 aforementioned steps (plus the running of the EMCAL real+simul DST merging macro ...).

(*) According to Ralf Averbeck, in the current PISA version in the repository the vertex coordinates of the single particles as they are generated by EXODUS are not taken into account by the PISA simulation. This will be soon corrected.


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