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TORCH – a Cherenkov based Time-of-Flight Detector

TORCH – a Cherenkov based Time-of-Flight Detector. Euan N. Cowie on behalf of the TORCH collaboration. Outline. TORCH Design and Principles. Suitability for use in LHCb . MCP Requirements. Results and simulation work. Electronics. Test-Beam plans and Preparation.

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TORCH – a Cherenkov based Time-of-Flight Detector

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  1. TORCH – a Cherenkov based Time-of-Flight Detector Euan N. Cowie on behalf of the TORCH collaboration E N Cowie - TORCH - TIPP 2014

  2. Outline • TORCHDesign and Principles. • Suitability for use in LHCb. • MCP Requirements. • Results and simulation work. • Electronics. • Test-Beam plans and Preparation. E N Cowie - TORCH - TIPP 2014

  3. Time Of internally Reflected Cherenkov 5m • TORCH aims to achieve 10-15ps timing over large areas. • Utilises Cherenkov light for fast signal production. • Focussing optics along edges couple light to photodetectors. 6m The basics of the TORCH design E N Cowie - TORCH - TIPP 2014

  4. See: The RICH detector of the LHCbexperiment AntonisPapanestis Session 2a) Experiments and Upgrades TORCH in LHCb 10 – 300 mrad p p LHCb showing potential locations for TORCH [1] E N Cowie - TORCH - TIPP 2014

  5. Motivation • TORCH will be used in conjunction with RICH 1 & 2. • Covers momentum region up to 10GeV/c. • Pion-Kaontime-of-flight difference ~35ps over 9.5m. • 3-σ separation 10-15 ps. • ~30 photons detected per track gives requirement of 70ps per photon. π-K ToF difference as a function of particle momentum E N Cowie - TORCH - TIPP 2014

  6. Focussing • Converts photon propagation angle into position on focal plane. • Photodetector is split into 128 pixels, with resolution ~1mrad. • Accounts for uncertainty in photon emission position through plate. • Covers angles from 0.45rad to 0.85rad. Schematic of focussing optics E N Cowie - TORCH - TIPP 2014

  7. Photon Detection • Development of MCP-PMTs underway. • Final device requires: • Stable gain performance up to least 5C/cm2. • Granularity equivalent to 8x128 pixels. • Proposed device has 64x64 pixels. • Nearest neighbour charge sharing in fine granularity direction. • Pixels ganged together in coarse granularity direction. • 60 mm pitch with 53x53mm2 active area. Required granularity of the final TORCH MCP. E N Cowie - TORCH - TIPP 2014

  8. Photon Detection • Three phases of development by Photek: • Long lifetime ALD coated single channel. • Currently under study. • High granularity devices. • Pixel size and pitch matching final device. • Full prototype. • Full size and pitch, high granularity, long lifetime. Required granularity of the final TORCH MCP. E N Cowie - TORCH - TIPP 2014

  9. MCP-PMT Lifetime Coated (improved) MCP-PMT Uncoated MCP-PMT TORCH Minimum Requirement Photocathode response as a function of collected charge [2]. E N Cowie - TORCH - TIPP 2014

  10. MCP-PMT Simulation • Extra granularity achieved with charge sharing. • Uncertainty in reconstructed position depends on gain and electronics threshold. • For more information see poster: Simulation studies of a novel, charge sharing, multi-anode MCP detector.Thomas Conneely & James Milnes, PhotekLTD. Electronics Threshold (fC) Gain ( electrons) E N Cowie - TORCH - TIPP 2014 Simulated uncertainty on position using charge-sharing as a function of gain and electronics threshold.

  11. Timing Timing smear divided into three categories: Contributions arising from the PMT. σpmt = 23ps Phase 1 MCP-PMT timing distribution. E N Cowie - TORCH - TIPP 2014

  12. Timing σopt = 55ps Timing smear divided into three categories: Contributions arising from the PMT. Contributions arising from the optics. Simulated optics timing distribution. E N Cowie - TORCH - TIPP 2014

  13. Timing Timing smear divided into three categories: Contributions arising from the optics. Contributions arising from the PMT. Contributions arising from the Electronics. NINO leading edge jitter [3]. HPTDC timing resolution [4]. E N Cowie - TORCH - TIPP 2014

  14. Electronics HPTDC Nino8 • Initial tests of Nino8 and HPTDC show intrinsic resolution of 40ps [5]. • R&D into electronics using 32 Channel NINO chips with HPTDC underway. Nino32 E N Cowie - TORCH - TIPP 2014

  15. Test-Beam Fused Silica • Radiator plate measuring 350x120x10 mm3 joined to a focussing block. • Read out by two MCP-PMTs on the focal plane. • Aiming for December deployment at T9 beam on the PS at CERN. MCP-PMTs Focussing Surface E N Cowie - TORCH - TIPP 2014

  16. Future Work • Phase 1 MCP-PMTs continue to be tested. • Phase 2 MCP-PMTs delivered this year. • Phase 3 to follow next year. • A prototype module will be developed to prove the full concept. • Proposal will be submitted to LHCb upon successful completion of R&D phase. E N Cowie - TORCH - TIPP 2014

  17. Fin Thanks for listening! E N Cowie - TORCH - TIPP 2014

  18. References [1] The LHCb Collaboration, “Letter of Intent for the LHCb Upgrade”, CERN-LHCC-2011-001, 29 March 2011 (v2). [2] T. M. Conneely, J. S. Milnes, J. Howorth, Nuclear Instruments and Methods in Physics Research A732 (2013) 388-391. [3] M. Despeisse et al.IEEE TRANSACTIONS ON NUCLEAR SCIENCE, VOL. 58, NO. 1, FEBRUARY 2011 [4] J. Christiansen, “High Performance Time to Digital Converter”, CERN/EP-MIC, 2002. [5] R Gao et al, 2014 JINST9C02025. E N Cowie - TORCH - TIPP 2014

  19. Extra Slides E N Cowie - TORCH - TIPP 2014

  20. Start Time Example from PV of same event After removing outliers ps E N Cowie - TORCH - TIPP 2014

  21. Modular Design A modular design for TORCH E N Cowie - TORCH - TIPP 2014

  22. Effects of Modular Design Without dispersion or reflection off lower edge Including dispersion and reflection off lower edge Moduleconsidered E N Cowie - TORCH - TIPP 2014

  23. Dispersion n Wavelength (nm) Wavelength dependence of refractive indexes Photon production spectrum E N Cowie - TORCH - TIPP 2014

  24. Performance Correct ID Correct ID Mis-ID Mis-ID Kaon ID performance Pion ID performance E N Cowie - TORCH - TIPP 2014

  25. Photon Detection • Photodetectors required to have precise single photoelectron time resolution and long lifetime • MCP-PMTs chosen for lower intrinsic transit-time spread. • Atomic Layer Deposition coating will be used to increase lifetime. Example of MCP internal layout E N Cowie - TORCH - TIPP 2014

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