GEANT4 simulations for the Lund R 3 B prototype Douglas Di Julio Lund University, Lund, Sweden

Outline TSL proton tests GEANT4 proton simulations Preliminary GEANT4  -ray simulations

Experimental tests at TSL 180 MeV Protons 1 mm thick 60x60 mm 2 SSSDs Prototype Beam profile 180 MeV protons Two-1mm thick SSSDs –Beam positioning and electronic collimator Goal: measure resolution of the crystals and to test gain corrected summing Calibration: Cu Collimator Beam spot ~40 mm 2

Energy Resolution Resolution measured with the Lund R3B calorimeter Compilation of energy resolution data

Gain Corrected Summing At 180 MeV: –21% events lost to inelastic processes –32% recovered from add back –47% deposit full energy in single crystal At 300 MeV, no events deposit full energy, however 60% can be recovered by gain correct summing GEANT4 simulations

Gain Corrected Summing Gain corrected summing with central, above and below crystals M=1 events centered around proton incident energy M>1 events contained in structure shifted to lower energies

GEANT4 Simulations Material: CsI and Mylar for foils Vacuum gap between crystals 10x mm 15x42 10x10

Gain Corrected Summing Binary Cascade model used Resolution: R = 5.15E 1/2 Simulated Sum Spectrum

Gain Corrected Summing

E dep in crystal E dep in wrap Sum Detector resolution switched off

Gain Corrected Summing Reducing the foil thickness can reduce the effect Counteracts energy resolution presented earlier How does the reduced foil thickness effect light collection? M=2 events

Preliminary  -ray simulations Resolution measured with CsI/APD Elements, relation used in simulation For  -ray simulations: Low energy package – Photoelectric, conversion, Rayleigh, and Compton Scattering Low energy package for e- Multiple scattering, ionisation, Bremsstrahlung, and annihilation (for e+) Uniform irradiation of the full central crystal face

Preliminary  -ray simulations 1 MeV Sum Spectrum 15 crystals 6.1 MeV Sum Spectrum 15 crystals

Future work Compare simulation results with in-beam tests at the Lund Nuclear Microprobe Light collection properties –Light cross talk between crystals