[Halld-offline] pythia-geant.map, back to basics

[Mark Ito]

Folks,

I am proposing we go back to the original Eugene Chudakov version of 
pythia-geant.map (revision 3195, attached fyi) as the default in the 
bggen/run directory.

This version allows all particles to be decayed in pythia except for the 
core 32 particles defined by Geant (Gamma=1 through Antiomega+=32). 
These 32 are passed on to Geant. See 
http://wwwasdoc.web.cern.ch/wwwasdoc/geant/node72.html .

Note that this means:

• etas and pi0s are decayed by Geant
• eta prime, rho0, and omega0 are decayed by pythia

Although rho0 and omega0 are mentioned in the file, they are decayed by 
pythia due the minus sign in their "Geant type". They are retained in 
the file as an example of how to pass a resonance onto the output file 
undecayed. My understanding is that they can be dropped completely from 
this file with no effect on the output.

Why do this now? With the new decay chain reporting scheme checked in 
last week, passing to Geant exactly those particles known (by default) 
to Geant should not be a problem, in principle. If while doing a study 
one wants to know, for example, which two photons go with which pi0, 
that information is available in the HDDM now even if the decay happens 
in Geant.

My plan is to check in this change in on the trunk later this week 
unless I hear objections. Sooner if people want.

-- Mark

-- 
Mark M. Ito, Jefferson Lab, (757)269-5295, marki at jlab.org

-------------- next part --------------
! GEANT --> PYTHIA map
! GEANT type= id >0 (regular) - PYTHIA decays are forbidden
!       type=-id  PYTHIA decays are allowed
! GEANT   PYTHIA  Comment 
!  type    KF
  1         22    ! gamma
  2        -11    ! e+
  3         11    ! e-
  4         12    ! neutrino
  5        -13    ! mu+
  6         13    ! mu-
  7        111    ! pi0
  8        211    ! pi+
  9       -211    ! pi-
 10        130    ! K0L
 11        321    ! K+ 
 12       -321    ! K-
 13       2112    ! neutron
 14       2212    ! proton
 15      -2212    ! antiproton
 16        310    ! K0S
 17        221    ! eta
 18       3122    ! Lambda0
 19       3222    ! Sigma+
 20       3212    ! Sigma0
 21       3112    ! Sigma-
 22       3322    ! Xi0
 23       3312    ! Xi-
 24       3334    ! Omega-
 25      -2112    ! antineutron
 26      -3122    ! antiLambda0
 27      -3112    ! antiSigma-
 28      -3212    ! antiSigma0
 29      -3222    ! antiSigma+
 30      -3322    ! antiXi0
 31      -3312    ! antiXi+
 32      -3334    ! antiOmega+
-80        113    ! rho 0
-81        223    ! omega0
-82       2224    ! Delta++