The Lund R3B prototype: In-beam proton tests and simulations Douglas Di Julio Lund University, Lund, Sweden

Outline CALIFA and the Lund R3B prototype Experimental tests at TSL with 180 MeV protons Geant4 proton simulations and comparison with experiment Preliminary -ray simulations and beam tests at the Lund Nuclear Microprobe Future work

The Lund R3B Prototype CALIFA: Surrounds target at R3B experiment Measure energy of protons (up to 300 MeV) and - rays (up to 15 MeV) Lund Prototype: 15 CsI(Tl) crystals 65 microns reflecting foil Light output uniformity adjusted to better than 0.6% for individual crystals Photodiodes for readout (for TSL tests) Figure taken from: H. Alvarez-Pol et al., Nucl. Instr and Meth. in Phys. Res. B 266 (2008) 4616-4620.

Experimental tests at TSL 180 MeV protons Two-1mm thick SSSDs Beam positioning and electronic collimator Goal: measure resolution of the crystals and to test gain corrected summing Beam profile 180 MeV Protons 1 mm thick 60x60 mm2 SSSDs Prototype Beam spot ~40 mm2

Calibration with 25 mm thick Cu collimator w/ diameter=8 mm Residual energy ~92.7 MeV No calibration

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 10x30 130 mm 15x42 10x10

Physics list For proton simulations For -ray simulations: Binary and Bertini cascade models tested 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+)

Gain Corrected Summing Proton simulations Resolution: Sum Spectrum

Gain Corrected Summing

Edep in crystal Edep in wrap Sum

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

-ray experimental tests Lund nuclear microprobe facility: low energy protons 19F(p,α)16O 6.1 MeV -ray Test APD readout and cooling

-ray simulations 6.1 MeV Preliminary results ~4% of the events lie under the full energy peak of the center crystal Some energy deposited in surrounding crystals

6.1 MeV gamma Preliminary results Average multiplicity ~2 crystals ~30% of the events under the full energy peak after gain corrected summing

Future Work -ray tests at the Lund Nuclear Microprobe Light collection in single crystals Effect of thinner foils on light crosstalk Results from proton tests and simulations published in recent article: D.D.DiJulio et al., “Proton in-beam tests of the Lund R3B calorimeter prototype”, in press. NIM A available online.

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