GEANT4 simulations for the Lund R3B 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 mm2 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 mm2

Energy Resolution

Resolution measured with the LundR3B 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

10x30

130 mm

15x4

210x10

Gain Corrected Summing

• Binary Cascade model used

• Resolution: R = 5.15E1/2

Simulated Sum Spectrum

Gain Corrected Summing

Edep in crystal Edep in wrap

Sum

Detector resolutionswitched 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/APDElements, 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 simulations1 MeVSum Spectrum15 crystals

6.1 MeVSum Spectrum15 crystals

Future work

• Compare simulation results with in-beam tests at the Lund Nuclear Microprobe

• Light collection properties– Light cross talk between crystals