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

2. 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

3. 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)

4. 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

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

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

7. 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

8. 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

9. GEANT4 Simulations Material: CsI and Mylar for foils
Vacuum gap between crystals
10x30
130 mm
15x42
10x10

10. 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+)

11. Gain Corrected Summing
Proton simulations
Resolution:
Sum Spectrum

12. Gain Corrected Summing

13. Edep in crystal
Edep in wrap
Sum

14. 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

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

16. -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

17. 6.1 MeV gamma Preliminary results Average multiplicity ~2 crystals
~30% of the events under the full
energy peak after gain corrected
summing

18. 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.

19. Thank you for
your attention