Extra Energy in Inelastic Hadronic Interactions in GHEISHA / GEANT4 David Bailey University of Toronto Intend to look hadronic interactions in FCAL, … But first checked basic characteristics of hadronic interactions in MC ATLAS GEANT4 - 6 November 2000 Extra Energy in GHEISHA - David Bailey

Extra Energy in GHEISHA - David Bailey Basic Parameters GEANT 4.2.0 ref 2 PhysicsList copied from example N02 GEANT 3.21 Particles generated at centre of huge uniform cubes side half-length = 105 km material either Liquid Hydrogen or Iron “Total Energy” is the sum of step energy losses neutrino energies ATLAS GEANT4 - 6 November 2000 Extra Energy in GHEISHA - David Bailey

Extra Energy in GHEISHA - David Bailey 100 GeV/c2 + in Iron ATLAS GEANT4 - 6 November 2000 Extra Energy in GHEISHA - David Bailey

Total Energy for 100 GeV/c2 + in hydrogen ATLAS GEANT4 - 6 November 2000 Extra Energy in GHEISHA - David Bailey

Total Energy for 1 GeV/c2 neutrons in hydrogen ATLAS GEANT4 - 6 November 2000 Extra Energy in GHEISHA - David Bailey

Sample GEANT4 1 GeV/c2 proton in Hydrogen event printout ATLAS GEANT4 - 6 November 2000 Extra Energy in GHEISHA - David Bailey

Kinetic Energies of some GEANT4 interactions proton 985 MeV 0 MeV proton (438 MeV) pi0 (456 MeV) neutron (248 MeV) pi+ (503 MeV) ∆Q=936MeV neutron 543 MeV proton 0 MeV proton (389 MeV) pi0 (297 MeV) neutron (543 MeV) ∆Q=821MeV ATLAS GEANT4 - 6 November 2000 Extra Energy in GHEISHA - David Bailey

Extra Energy in GHEISHA - David Bailey Gheisha Fortran Gheisha seems to calculate the target particle mass by counting the number of outgoing baryons. SUBROUTINE TWOCLU(IPPP,NFL,AVERN) / SUBROUTINE GENXPT(IPPP,NFL,AVERN) C *** GENERATION OF X- AND PT- VALUES FOR ALL PRODUCED PARTICLES *** C *** NVE 01-AUG-1988 CERN GENEVA *** … C** LORENTZ TRANSFORMATION IN LAB SYSTEM C** 27 TARG=0. DO 36 I=1,NT IF(PV(5,I).GT.0.5) TARG=TARG+1. CALL LOR(I,MX2,I) 36 CONTINUE C*DCB --> David Bailey modification to prevent counting C*DCB incoming baryon as a target particle if (amas.gt.0.5) targ=targ-1. ATLAS GEANT4 - 6 November 2000 Extra Energy in GHEISHA - David Bailey

1 GeV/c2 neutron in hydrogen, Total Energy ATLAS GEANT4 - 6 November 2000 Extra Energy in GHEISHA - David Bailey

Total Energy of 100 GeV/c2 pi+ in Iron ATLAS GEANT4 - 6 November 2000 Extra Energy in GHEISHA - David Bailey

Extra Energy in GHEISHA - David Bailey GEANT 4 has similar code same place as fix to previous energy non-conservation bug // $Id: G4HEInelastic.cc,v 1.5 2000/07/09 09:48:35 hpw Exp $ … // Lorentz transformation in lab system targ = 0; for( i=0; i < vecLen; i++ ) { if( pv[i].getType() == baryonType )targ++; if(verboseLevel > 1) pv[i].Print(i); pv[i].Lor( pv[i], pvmx[1] ); } if ( targ <1) targ = 1; (Twice) but my first attempt (yesterday) to “fix” it failed, and I noticed something else … ATLAS GEANT4 - 6 November 2000 Extra Energy in GHEISHA - David Bailey

Total Energy for 1 GeV/c2 antineutrons in hydrogen ATLAS GEANT4 - 6 November 2000 Extra Energy in GHEISHA - David Bailey

Extra Energy in GHEISHA - David Bailey Summary GHEISHA inelastic hadronic interactions have some “peculiarities”. These are old enough that they must be considered GEANT3 “features”. GEANT4 accurately reproduces these “features”. Do we want these “features” in GEANT4? ATLAS GEANT4 - 6 November 2000 Extra Energy in GHEISHA - David Bailey