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Dennis Wright (SLAC) and Aatos Heikkinen (HIP) Interlaken, Switzerland 27th September - 1st October, 2004. Adding Kaons to the Bertini Cascade Model. Outline. Reasons for the extension How the model was extended elementary cross sections number of particle types treated code changes
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Dennis Wright (SLAC) and Aatos Heikkinen (HIP) Interlaken, Switzerland 27th September - 1st October, 2004 Adding Kaons to the Bertini Cascade Model
Outline • Reasons for the extension • How the model was extended • elementary cross sections • number of particle types treated • code changes • Early results • Plans • improvements, further extensions 1
Reasons to Extend the Bertini Cascade • No existing Geant4 hadronic model does a reasonable job handling strange particle interactions at 0 < E < 5 GeV • only LEP model handles kaons at all in this region • Low energy kaons (and other strange particles) are important for BaBar and hadron calorimetry in higher energy experiments • Bertini cascade has been demonstrated to work fairly well for pions and nucleons • Bertini cascade model is relatively easy to extend to strange particles 1
Adding New Cross Sections • Model assumes particles travel through a nucleus and interact with nucleons according the free particle cross sections • Need K+ p, K+ n, K- p, K- n cross sections from 0 to 15 GeV • For subsequent intra-nuclear interactions need everything else: • K0, K0bar, L, S+, S0, S-, X0, X- (W- -ignored) • no resonances • manycrosssectionsavailablefromCERNparticlecatalogs • many others ( K0 p, L n, ... ) require isospin arguments, guesswork • K0 p = K+ n • K0bar n = K- p • up to 7-body final states are important (and have been measured) 1
Code Changes • New classes • G4CascadeKplusNChannel, G4CascadeLambdaPChannel, ... • Contain final state particle types, elementary cross section, multiplicity data from T = 0 – 15 GeV • Add strange particle branches for generation of multiplicity and final states • G4ElementaryParticleCollider • G4NucleiModel • Other classes changed: • G4InuclElementaryParticle • G4CascadeInterface 1
Significant non-changes • Use existing angular distribution parameterizations • Use existing final state momentum partition parameterizations • Use existing pion nuclear potential (hard-sphere 7 MeV deep) • No nucleon-nucleon correlations added for kaons • Strange particle production (by incident pi, n, p) not added • No resonances added 1
Improvements • Find better nuclear potentials for K, L • Should be deeper • Install pi, p, n – induced strange particle production • cross sections exist • If correlations are important, add absorption on quasi-deuterons • Parameterize and use measured angular distributions for finals states induced by kaons • Extend to incident hyperons? 1