Test Beam Simulation

1. Test Beam Simulation • Recent activities • General activities • Old runs checks (v8 BTRelease) • BT tuple and histograms • LDF file generation • Pipeline reconfiguration (PS&SPS) • Coordinates check in G4Generator • v9 Gleam based simulations • ACD recon in progress • PS activities • New configurable geometry (thanks Benoit and Stefan) • More in progress (Luca and Nicola M.) --> this week? • Positron annihilation runs • Electron runs (1 and 10 GeV), different angles and positions • Some Photons & Proton runs • SPS activities • First runs! • Geometry and Beam description (thanks Benoit and Stefan) • Electron at 10 and 280 GeV • Team Work (Tom, Stefan, Leon, Richard, Franz) • https://confluence.slac.stanford.edu/display/BeamTest/Monte+Carlo+Production+Log

2. Old PS setup Dumper Passive Material CU volume Tagger Beam Si Magnet

3. New PS setup

4. New SPS setup

5. Geometry

6. Improvements & Requests • Particles score @ reporting plane – hadron runs! • Bug fixing • CU container volume in XML – in progress • CU position & orientation • New Pipeline runs • Alternative Physics Lists – in progress • BeamtestTuple fill • Documentation update • SPS simulations • CU dummy CAL • Dumper position change – to be done • PS setup change – in progress • Ancillary detectors Simulation and Digi/Recon • More positions and angles? – more to come • Fill confluence!

7. Test Beam Simulations • We need feedback from users! • CCB group needed

8. G4 validation • One of the main goals of Test Beam • Special studies (e.g. positron annihilations) • General studies • Multiple Scattering at different energies • EM shower properties in CAL & bottom TKR • Hadronic showers? • TKR Clusters & Delta rays production • Needs • Description of Beam (first few days) • Geometry validation (BeamTest and CU) • Statistical significant variables …

9. Simulation Overview • Goal of simulation is to produce “raw data”, representing the response of the LAT to a given event, which can be fed to the reconstruction • Logically breaks into four steps: • Event generation – “source particle” • Simulation of LAT response to the generated event • Digitization: the conversion of simulated LAT response to “raw data” • Simulation of Trigger Tracy at DC2 kickoff

10. LAT GeometrySimulation and Reconstruction • Main Point: • Most detailed LAT geometry to date including all features • From active devices • To surrounding support structures • Including electronics, wrapping, … • etc. • Large number of updates to geometry • Primarily CAL and ACD • Still working on improvements for DC-3: • e.g. Curved ACD tiles • One other important point: • The reconstruction, through the propagator, uses the same geometry as the simulation • Geometry for CU? Tracy at DC2 kickoff

11. Incident Gamma Incident Gamma Incident Gamma Conversion Point Conversion Point Conversion Point Propagation of primarye+ and e- through LAT Propagation of primarye+ and e- through LAT Production and Trackingof Secondaries McPositionHits in Active Siliconof Tracker McPositionHits in Active Siliconof Tracker McIntegratngHitsproduced in theCalorimeter Crystals Overview of Geant4 Simulation • Geant4 determines the evolution of the event • G4 given “source” which is propagated through the LAT • G4 output to TDS: • McParticles – particles produced during trackinig • McPositionHits – positions and energy deposited in Silicon and ACD • McIntegratingHits – energy deposited in “sub-cubes” of CsI crystals • Passed on to Digitization stage • For TB we use G4 v8.0.p01 • “Vanilla” G4 for everything… • So far we use v3.2 multiple scattering Tracy at DC2 kickoff

12. Photon processes: Photoelectric, Compton Scattering and Pair Production Cross Section, Angular and Energy Distribution Charged particles processes Ionisation Landau and Bethe Bloch Range, Straggling, Stopping Power Multiple Scattering Angular distribution, Energy Dependence Bremsstrahlung Cross Section, Angular and Energy Distribution Delta Ray production Energy distribution, Multiplicity Positron Annihilation EM shower development Muon-nucleus interactions Neutron interactions HE hadron-nucleus interactions Nucleus-nucleus elastic scattering Hadronic showers in CsI Some to check and add e.g. synchrotron GLAST G4 physics

13. Requirements: EM processes • Tracking region: small scale • individual processes: pair conversion, bremsstrahlung white: incoming photon black: electron, positron green: W orange: hit Si wafers red: strip energy Note: other gamms not shown Toby at G4 2003 workshop

14. Multiple scattering • MCS in the W layer determines the angular resolution! • Discover problem at MCS in version 5.* • Back to MCS v3.2 on the basis of experimental data W white: incoming photon green: W boundaries Orange: Si boundaries Si Toby at G4 2003 workshop

15. Calorimeter: large scale • Basic shower properties for leakage correction blue boxes: CsI segments black: electrons and positons red: light repsonse not much lost on this one! Toby at G4 2003 workshop

16. Requirements: Hadronic Processes • proton-nucleus cross sections, multiplicities • Same for He, C, N, O, etc. (components of cosmic rays) • E loss for min-I heavy nuclei (used to calibrate calorimeter) Toby at G4 2003 workshop