New particle ID detector for Crystal Ball at MAMI-C

1. New particle ID detector for Crystal Ball at MAMI-C Daniel Watts, Daria Sokhan, Claire Tarbert University of Edinburgh John Annand, Douglas Macgregor, Evie Downie, J McGeorge University of Glasgow

2. PID-I • Constraints of MWPC-I • and targets → siting of PMTs • at downstream end • Design specifications • Good separation of • p, p with little overhead • in material before MWPC • and CB detectors

3. MWPC-II & PID-II • MWPC-II redesigned for MAMI-C experiments • PID-II outside MWPC  inbetween the MWPC chambers  → Opted for setup similar to PID-I • ButPMTs at upstream end - TAPS

4. PID-II schematic PID-II schematic • PID-II – removable! • (redesigned MWPC connectors) • rPID-II >rPID-I • Keep same segmentation (24) • tscint = 4mm (PID-I: 2mm) FPID(INNER) = 108.4mm FMWPC = 133mm PMTs 500mm g beam PMT support ring MWPC Chambers MWPC supports CB Tunnel PID-II scintillators Hamamatsu H3164 - 10

5. PID-II test module – light attenuation • 90Sr beta source • Observe position of landau as source moved along scintillator • → light attenuation Active detector region Enhancement near PMT PID-II Test module PID-I Test module Position of landau peak (arb units) Distance from PMT (mm)

6. PID-II GEANT Simulation Pions K+ Energy deposited in PID-II (GeV) Protons Energy deposited in CB (GeV) • Use PID-I simulation parameters – light output, light collection efficiency, QE … • → Reasonable agreement with experimental data • Include increase in PID-II scintillator thickness Flat KE distribution up to 0.7 GeV Isotropic angular distribution No shower shape restrictions

7. PID-II – schedule and status months Delivery of scint. Total construction time ~ 5.2 months Cutting & prep of scint. Lightguide manufacture Element assembly & tests Delivery of PMTs Detector assembly & tests Implementation into MWPC & CB Present status

8. Summary • Manufacture/delivery of PID-II components complete • Module testing completed in ~2 weeks • Completed detector ready in early June

10. Radius mwpc = 66.5cm Liquid hydrogen target

11. PID-II • PID-I support ring router-rinner = 14mm • 4 mm clearance each side to the polarised target. Hydrogen target will have problem – clearance = 0mm! 51,5 65.5

12. PID-II & polarised target

13. PID-II PMTs • Same tubes and bases as for PID-I • BUT use new packaged tube + base assemblies -include magnetic shield • Hamamatsu H3164 - 10

14. Very preliminary decay gammas from nucleon knockout 12C(g,ppp)9Li Eg=400-500 MeV 2.69 MeV Low energy clusters from shaded region Q value

15. Simulatedp+ signals in Crystal Ball ≤ 2 crystals in p+ shower No restriction on shower size m+ decay Highest cluster energy (GeV) Nuclear interaction Incident p+ energy (GeV)

16. Very preliminary decay gammas from nucleon knockout 12C(g,ppp) 2.69 MeV Low energy clusters from shaded region Q value

18. PID-II – schedule and status • rPID-II >rPID-I • Same segmentation (24) • Lscint chosen to give PID Info for all proposed targets • Lscint =50 cm (PID-I 32cm) PID-II Test module PID-I Test module

19. New polarised target design