Updates to Geant 4 hadronic physics in 8

Updates to Geant 4 hadronic physics in 8. 1 LCG Simulation Validation Meeting 21 -June-2006 Gunter Folger 1/19/2022 1

Contents n Bug fixes n Physics modeling improvements n Review of hadron elastic scattering n Changes to Physics Lists n stopping particles n Elastic scattering 1/19/2022 2

Bug fixes Checking energy-momentum conservation revealed several problems n LE parameterized model – main problems fixed, few other ongoing n Mostly seen with strange hyperons, anti-protons, antineutrons n QGSC – fixed problem in interface class n Particles were added twice when a particle with strangeness was present n QGS – ongoing n Violation of energy up to about 3 Ge. V, rate ~ 10 -3, depending on energy of primary 1/19/2022 3

Fixes in LEP models n Classes corrected n G 4 Reaction. Dynamics n G 4 Nucleus n G 4 Inelastic. Interaction Dennis Wright, 11 May 2006 1/19/2022 4

Improvements n Neutron HPElastic models: added method Do. Not. Suspend() n Hadron elastic scattering ( M. Kossov) n General review of hadron elastic scattering started end 2005, reported at previous meetings n p-H n n-H, relevant for plastic scintillators n p, n – D, t, He, and then up n ( see presentations of M. Kossov in April and May 2006) 1/19/2022 7

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Elastic n New G 4 UHadron. Elastic. Process n Isotope composition taken in account n Proton/neutron on hydrogen uses elastic cross section systematics by M. Kossov n Existing cross sections otherwise n Recoil ion produced above a threshold for ion kinetic energy (default T>100 Ke. V) n n 1/19/2022 When no recoil, create local energy deposit Thus neutrons now have local energy deposit ! 10

Elastic (cont. ) n New G 4 Hadron. Elastic n Combine 3 models to sample momentum transfer t n n Energy and momentum is balanced n 1/19/2022 QElastic (M. Kossov) for proton/neutron on Hydrogen S-wave model for very low projectile momenta (p<20 Me. V/c) G 4 LElastic (old) for the rest Energy is conservation achieved by local energy deposit when no recoil ion is produced 11

Physics Lists n Introduce Chips modeling for stopping particles in all physics lists based on QGS and FTF. n See M. Kossov, Validation meeting 23 -March 2005 n Replaces capture processes for µ-, pi-, and Kn Replaces annihilation at rest for anti-proton and anti-neutron n Updated elastic scattering in all physics lists based on QGS and FTF. 1/19/2022 12

Physics Lists n Updated QGSP_EMV n better CPU performance for slightly less accurate physics n In Geant 4 8. 0 this variant uses EM physics close to Geant 4 7. 1 n In Geant 4 8. 1, use available options in standard EM for multiple scattering to achieve improved performance n Lists using Bertini cascade for pions now also use Bertini cascade for Kaons, K+, K-, K 0 L, and K 0 S. n List including Binary cascade now handle inelastic interaction of ions using Binary Light Ion Cascade. 1/19/2022 13

Summary n Several fixes improving energy conservation of physics models n Improvements made available n n Improved stopping activated in QGS/FTF Physics Lists Improved elastic scattering n for neutron/proton in Hydrogen, n for low momenta n conserving Energy and momentum n Small revisions to other physics lists n Full detail will be in release notes n Draft: http: //cern. ch/~gunter/relnotes-81 -hadronic. html 1/19/2022 14