1. Performance of the PANDA Barrel DIRC Prototype 1 GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt 2 Goethe-Universität Frankfurt Marko Zühlsdorf 1,2 for the PANDA Cherenkov Group

2. Marko Zühlsdorf Facility for Antiproton and Ion Research 11/12/2014IEEE 2014 NSS/MIC HESR SIS 100/300 SIS18 RESR/CR 30 GeV Protons 70 MeV p-Linac p Target 10 7 p/s @ 3 GeV Collecting Accumulating Precooling Accelerating Cooling 100m PANDA 2 Darmstadt, Germany

3. Marko Zühlsdorf AntiProton ANnihilation at DArmstadt 12 m Hadron physics experiment at FAIR Wide range of fields (e.g. charm physics, exotics, hypernuclear physics, …) Cooled antiprotons up to 15 GeV/c on a fixed target Almost 4π coverage target Hadronic PID in the center part covered by two DIRC detectors PANDA Barrel DIRC for polar angle range 22° - 140° Pion/kaon separation up to 3.5 GeV/c DIRC counter used successfully at BaBar 11/12/2014IEEE 2014 NSS/MIC3 p

4. Marko Zühlsdorf 11/12/2014IEEE 2014 NSS/MIC Detection of Internally Reflected Cerenkov Light Condition for Cherenkov radiation: 4

5. Marko Zühlsdorf 11/12/2014IEEE 2014 NSS/MIC PANDA Barrel DIRC radiator readout electronics Design Options Radiator, focusing optics, expansion volume,... focusing optics 5 expansion volume

6. Marko Zühlsdorf Baseline design working solution for PANDA Alternative designs to improve performance and reduce cost Radiator One wide plate instead of 5 narrow bars per segment Fewer pieces to be polished Less strict requirements for optical and mechanical quality of side surfaces Potential significant cost reduction but PID capability not proven Expansion volume (camera) One synthetic fused silica prism per segment instead of oil tank Better optical properties Smaller detection surface Fewer photon sensors needed Less readout channels PID capability not proven DIRC Design Options 11/12/2014IEEE 2014 NSS/MIC 30 cm 6

7. Marko Zühlsdorf Photon Sensors 11/12/2014IEEE 2014 NSS/MIC7

8. Marko Zühlsdorf DIRC Optics 11/12/2014IEEE 2014 NSS/MIC8 125 cm 30 cm

9. Marko Zühlsdorf Geometrical Reconstruction 11/12/2014IEEE 2014 NSS/MIC radiator detection plane 9 20° track polar angle 140° 10 mrad 30 track azimuth angle Geometrical reconstruction uses location of bar and pixel to determine photon vector in the radiator. Works well for narrow bars but fails for wide plates Width of radiator not negligible anymore 5 narrow bars, unfocused (MC Simulation) 3 wider bars, unfocused inspired by BaBar DIRC

10. Marko Zühlsdorf Probability density functions (pdf) can be generated with ~100k Monte Carlo tracks with same parameters and saved in histograms. Probability Density Functions 11/12/2014IEEE 2014 NSS/MIC 22° polar angle p = 3.5 GeV/c π K In 3 dimensions (x, y, t) hit patterns show differences between particle species πKπK 10 PMT map, with 5 x 3 sensors, 64 pixels each x y normalized PDF for a specific pixel π sample K sample Inspired by Belle II TOP MC Simulation Likelihood ratio testlnL K -lnL P

11. Marko Zühlsdorf Prototype Tests 11/12/2014IEEE 2014 NSS/MIC11 Prototypes tested in 2008, 2009, 2011, 2012, 2014 2012 Prototype with narrow bars CERN PS mixed hadron beam 1 – 10 GeV/c Determined photon yield and single photon Cherenkov angle resolution for different bars and focusing optics over wide angular range. First tests with plate prototype Beam dataSimulation 2012 setup

12. Marko Zühlsdorf 2012 Prototype Test 11/12/2014IEEE 2014 NSS/MIC12 Simulation Beam data σ = 13 mrad

13. Marko Zühlsdorf 2014 Prototype Test 11/12/2014IEEE 2014 NSS/MIC13 122.5 cm Pion beam 1.7 GeV/c Prototype Beam time at GSI; 5 weeks in summer 2014 2014 prototype is similar to a module of the final detector 5 x 3 Planacon MCP-PMT 960 pixels (in total >1200 readout channels) Wide plate w/ and w/o focusing lens Narrow bar with different lenses Simulation has just started

14. Marko Zühlsdorf Preliminary Results 11/12/2014IEEE 2014 NSS/MIC14 Narrow Bar Data New 3-component lens with better focusing and no air gap to reduce photon loss No comparison with simulation yet but data shows typical folded ring structure Beam data, 125 deg: SiO 2 NLAK

15. Marko Zühlsdorf Preliminary Results 11/12/2014IEEE 2014 NSS/MIC15 Wide Plate Simulation: Geant 4 Radiator plate Cylindrical lens 120° polar angle 1.7 GeV/c pions pixelated: true locations:

16. Marko Zühlsdorf Preliminary Results 11/12/2014IEEE 2014 NSS/MIC16 Wide Plate Data: First glimpse on occupancies with raw cuts on timing and event multiplicity Simulation predicts ~20 hits/track Simulation: Beam data:

17. Marko Zühlsdorf Summary and Outlook Summary The Barrel DIRC is a key component of the PANDA particle identification system. Baseline design with narrow bars and high-refractive lens meets PANDA PID goals. Cost optimization identified two design alternatives (wide plate, solid fused silica camera), to be validated with simulation and prototype tests. A first look at the 2014 prototype data shows promising results for radiator plate. Outlook Improve simulation to better match beam data Validate plate reconstruction approach Measure PID performance in mixed hadron beam at CERN in summer 2015 Decision on a design for PANDA Barrel DIRC TDR in early 2016 11/12/2014IEEE 2014 NSS/MIC17

18. Marko Zühlsdorf Summary and Outlook Summary The Barrel DIRC is a key component of the PANDA particle identification system. Baseline design with narrow bars and high-refractive lens meets PANDA PID goals. Cost optimization identified two design alternatives (wide plate, solid fused silica camera), to be validated with simulation and prototype tests. A first look at the 2014 prototype data shows promising results for radiator plate. Outlook Improve simulation to better match beam data Validate plate reconstruction approach Measure PID performance in mixed hadron beam at CERN in summer 2015 Decision on a design for PANDA Barrel DIRC TDR in early 2016 11/12/2014IEEE 2014 NSS/MIC18 Thank you! t x PD plate top view Y. Arita, March 9, 2013, QFPU Final International Forum Belle II TOP