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G4 simulation: status and validation strategy

G4 simulation: status and validation strategy. Goals Contributors Status Needed plots Future tasks. EMC clusters. HER. LER. Luminosity. Beam-beam. Goals of the simulation. Tool for remediating interactions of beam related backgrounds

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G4 simulation: status and validation strategy

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  1. G4 simulation: status and validation strategy Goals Contributors Status Needed plots Future tasks MDI meeting

  2. EMC clusters HER LER Luminosity Beam-beam Goals of the simulation • Tool for remediating interactions of beam related backgrounds • Degraded electrons from beam-gas interactions (Coulomb, Bremstrahlung) • Debris from Bhabha scattering (gamma-nuclear, electro-nuclear) In BaBar detector components • DCH, EMC most vulnerable (from B. Peterson plenary, Feb. 2004) • Prediction of backgrounds in 2005/6 IP upgrade relative to current levels • Changes to B1, Q1 fields to ameliorate parasitic losses, reduce by* MDI meeting

  3. G4-based simulation of PEP beam backgrounds • What has been added to the G4 simulation: • improved interaction physics models: • Bertini cascade model (hadronics) • “high precision” package for neutrons (thermalization, capture) • Bhabha generators: • bbbrem (forward beam Bremsstrahlung) • bhlumi (small angle radiative) • Geometry: • detailed model of vacuum chambers and magnets through Q5 • neutron counters • Magnetic fields: • B1, Q1, Q2, Q4, Q5 main fields • correctors • solenoid fringe field outside measurement grid • Analysis packages: • BgsUser: MC truth, TURTLE, GHits (G4) - ntp666 • PepBkgMon: Trigger, digis ntp300 MDI meeting

  4. Contributors • Coordination of G4-based simulation: - W. Lockman • Machine lattice & apertures (TURTLE): - T. Fieguth, R. Barlow • bhabha generators (bbbrem, bhlumi): - N. Blount, WL • PEP beam line geometry: - M. Bondioli, G. Calderini, WL • PEP beam line magnetic field model: - G. Bower, WL • hadronics: - D. Wright • Analysis ntuples: - WL • Validation: optics and apertures: - WL, GRB, TF, GC • SVT analysis: - Brian Petersen • DCH analysis: - M. Cristinziani • DRC analysis: - D. Aston, GRB, J. Va’vra • EMC analysis: - C. Edgar • neutron physics: - GRB MDI meeting

  5. Status • Generators: • bbbrem: validated, deployed (WL) • bhlumi: validated, deployed (NB) • Nuclear interaction modeling: • e/g nuclear processes added • HP package deployed • neutron fission and capture added • Bertini cascade model validated and deployed • neutron thermalization, capture, n-alpha processes being validated (GRB) • n+p -> Dg (in DRC water tank) • 10B5 + n -> 7Li3 + 4He2 (in neutron counters) MDI meeting

  6. Status • Vacuum chamber geometry: • detailed models of Q2 septa • important source of backgrounds • LER complete through Q5 • HER complete through Q4 • validated visually • against CAD model and drawings • vrml fly-through • x-ray cross section plots • G4 vs. TURTLE LER vacuum chamber hit comparison • combined check of optics and apertures • minor aperture differences between G4 and TURTLE at front face of forward Q2 septum MDI meeting

  7. slope: 40mm/mr dx(z=-789 cm) O(1) TRANSPORT: 36 mm/mr dx’(z=+771 cm) (radians) Status • Magnets and fields: • B1, Q1, Q2, Q4, Q5, correctors, solenoid field+fringe • validated against: • magbends (repaired a sign error in SKEW QUAD SK1 rotation) • TURTLE (beam ellipse study) • Transport (launch angle study) MDI meeting

  8. Status • Analysis ntuple: • common framework for single-beam and luminosity related background studies by subsystems experts with access to • Monte Carlo information: • Truth • TURTLE • GHit • Trigger and raw data information • Samples: • Data • Monte Carlo • forward beam Bremsstrahlung (bbbrem) • radiative Bhabha (bhlumi) • LER coulomb and Bremsstrahlung scattered TURTLE rays • Subsystems: please analyze • see planning document MDI meeting

  9. Needed plots/data samples • Single beam: • LER, HER single beam vacuum chamber dose rates from TURTLE simulation • HER rays for G4 studies • subsystem occupancy plots • Colliding beam: • Bhabha vacuum chamber dose rates (E*s) from TURTLE simulation with updated apertures • subsystem occupancy plots MDI meeting

  10. Extra slides MDI meeting

  11. Future Monte Carlo tasks • TURTLE rays: • corresponding to PEP-II upgrade lattice • Geometry: • Add missing SVT material outside the tracking volume • flat cables • matching cards • improve model of B1/Q1 synchrotron masks • Add Q5 HER forward and backward vacuum chambers • replace cloned parts of the vacuum chamber • Follow updates to real vacuum chamber: • forward Q2 septum • Q4/Q5 HER • Add IFR shielding wall • Magnetic fields: • inside permanent magnet Samarium cobalt MDI meeting

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