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

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

Time Of internally Reflected Cherenkov E N Cowie - TORCH - TIPP 2014 The basics of the TORCH design 3 05 June 2014 TORCH aims to achieve ps timing over large areas. Utilises Cherenkov light for fast signal production. Focussing optics along edges couple light to photodetectors. 5m 6m

TORCH in LHCb E N Cowie - TORCH - TIPP 2014 pp 10 – 300 mrad LHCb showing potential locations for TORCH [1] 4 05 June 2014 See: The RICH detector of the LHCb experiment Antonis Papanestis Session 2a) Experiments and Upgrades

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

Focussing E N Cowie - TORCH - TIPP 2014 Schematic of focussing optics 6 05 June 2014 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.

Photon Detection E N Cowie - TORCH - TIPP 2014 Required granularity of the final TORCH MCP June 2014 Development of MCP-PMTs underway. Final device requires: 1.Stable gain performance up to least 5C/cm 2. 2.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 mm pitch with 53x53mm 2 active area.

Photon Detection E N Cowie - TORCH - TIPP 2014 Required granularity of the final TORCH MCP June 2014 Three phases of development by Photek: 1.Long lifetime ALD coated single channel. Currently under study. 2.High granularity devices. Pixel size and pitch matching final device. 3.Full prototype. Full size and pitch, high granularity, long lifetime.

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

MCP-PMT Simulation E N Cowie - TORCH - TIPP 2014 Simulated uncertainty on position using charge-sharing as a function of gain and electronics threshold June 2014 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, Photek LTD. Electronics Threshold (fC)

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

Timing E N Cowie - TORCH - TIPP 2014 σ opt = 55ps Simulated optics timing distribution June 2014 Timing smear divided into three categories: 1.Contributions arising from the PMT. 2.Contributions arising from the optics.

Timing E N Cowie - TORCH - TIPP June 2014 Timing smear divided into three categories: 1.Contributions arising from the optics. 2.Contributions arising from the PMT. 3.Contributions arising from the Electronics. NINO leading edge jitter [3]. HPTDC timing resolution [4].

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

E N Cowie - TORCH - TIPP 2014 Fused Silica MCP-PMTs Test-Beam June 2014 Focussing Surface Radiator plate measuring 350x120x10 mm 3 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.

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 June 2014

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

References [1] The LHCb Collaboration, “Letter of Intent for the LHCb Upgrade”, CERN-LHCC , 29 March 2011 (v2). [2] T. M. Conneely, J. S. Milnes, J. Howorth, Nuclear Instruments and Methods in Physics Research A 732 (2013) [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, [5] R Gao et al, 2014 JINST 9 C E N Cowie - TORCH - TIPP June 2014

Extra Slides E N Cowie - TORCH - TIPP June 2014

Start Time E N Cowie - TORCH - TIPP Example from PV of same eventAfter removing outliers 05 June 2014

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

Effects of Modular Design E N Cowie - TORCH - TIPP June 2014 Module considered Without dispersion or reflection off lower edge Including dispersion and reflection off lower edge

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

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

Photon Detection E N Cowie - TORCH - TIPP 2014 Example of MCP internal layout June 2014 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.