1. Hall B and GEANT4 Mark Ito Jefferson Lab GEANT4 Tutorial May 22, 2006

2. Mark Ito, Jefferson Lab, GEANT4 Tutorial2 Hall B currently houses the CLAS detector. CLAS will be modified and upgraded to CLAS12 which will be the only large acceptance, multi-purpose detector for fixed target high energy electron scattering experiments. CLAS12 will operate with an upgraded luminosity of 10 35 cm -2 s -1, an order of magnitude increase over CLAS. With these capabilities, CLAS12 will support a broad experimental program in fundamental nuclear physics Hall B Overview

3. May 22, 2006Mark Ito, Jefferson Lab, GEANT4 Tutorial3 Present-day CLAS

4. May 22, 2006Mark Ito, Jefferson Lab, GEANT4 Tutorial4 Drift chambers argon/CO 2 gas, 35,000 cells Electromagnetic calorimeters Lead/scintillator, 1296 PMTs Torus magnet 6 superconducting coils Gas Cherenkov counters C 4 F 10 Gas, 216 PMTs Time-of-flight counters plastic scintillators, 684 PMTs Large angle calorimeters Lead/scintillator, 512 PMTs Operating luminosity 10 34 cm -2 s -1 C EBAF L arge A cceptance S pectrometer (CLAS)

5. May 22, 2006Mark Ito, Jefferson Lab, GEANT4 Tutorial5 Requirements for Hall B Upgrade Requirements: Need high statistics capabilities for exclusive processes – High operating luminosity of 10 35 cm -2 s -1  – Particle ID to higher momenta (e - /  ,  p    –  –  More complete detection of hadronic final state Complement CLAS detection system with new Central Detector for – Tracking and magnetic analysis – Particle identification Upgrade the CLAS forward detection system – Add high threshold Cherenkov detector p  ~ 5 GeV/c – Improve time-of-flight resolution to 60 – 80 ps – Increase calorimeter granularity for    separation Reduce DC occupancies to reach higher luminosities – Reduce DC cell sizes (decrease solid angle and sensitive time) – Improve magnetic shielding for Møller electrons.. Solution:

6. May 22, 2006Mark Ito, Jefferson Lab, GEANT4 Tutorial6 Hall B Instrumentation to Meet Experimental Requirements Preshower Calorimeter Forward Cherenkov (LTCC) Forward Drift Chambers Inner Cherenkov (HTCC) Superconducting Torus Magnet Central Detector CLAS12 Forward Calorimeter Forward Time-of-Flight Detectors

7. May 22, 2006Mark Ito, Jefferson Lab, GEANT4 Tutorial7 CLAS12 Forward Detector Single Sector (exploded view)

8. May 22, 2006Mark Ito, Jefferson Lab, GEANT4 Tutorial8 CLAS12 – Central Detector 1m Flux return Superconducting solenoid coil (B max = 5T) TOF light-guide Central TOF Silicon Vertex Tracker

9. HDDS / AGDD / XML Hierarchical description Human readable Modular description Browsing tools Powerful parsing tools Open for GEANT3, GEANT4, GEANT5 Joint effort with Hall-D

10. Simple example 01 <box name="SITE" X_Y_Z="1200. 1200. 1200." material="Air" comment="master volume for description" /> <tubs name="TUBE" Rio_Z="0. 500. 400." material="Iron" comment="Test tube"/> <box name="TBOX" X_Y_Z="800. 800. 200." material="Lead" comment="Test box"/>

11. Simple example 02 <box name="SITE" X_Y_Z="1200. 1200. 1200." material="Air" comment="master volume for description" /> <tubs name="TUBE" Rio_Z="0. 500. 400." material="Iron" comment="Test tube"/> <box name="TBOX" X_Y_Z="800. 800. 200." material="Lead" comment="Test box"/> <tubs name="HOLE" Rio_Z="0. 100. 200." material="Air" comment="Hole in box" />

12. May 22, 2006Mark Ito, Jefferson Lab, GEANT4 Tutorial12 Summary ● CLAS12 will use GEANT4 as its primary simulation tool ● Hall B has adopted Hall D's XML scheme to do geometry definition on the fly ● Further cooperation envisioned ● Acknowledgments: – Richard Jones, UConn: HDDS – Joern Langheinrich, South Carolina: HDDS2GEANT4