1. page 1 www.photek.co.uk 1 Detector and Electronics R&D for picosecond resolution, single photon detection and imaging J.S. MilnesPhotek Ltd T.M. ConneelyUniversity of Leicester J. Lapington

2. www.photek.co.uk 2 Introduction Application of CERN developed ASICs into Industry Three collaborative projects between –Photek Ltd, manufacturer of vacuum image intensifiers and PMTs –University of Leicester, Space Research Centre Hi-Content & IRPICS; Multi-anode photon detectors CDIR; A high time precision centroiding anode

3. www.photek.co.uk 3 Electronics NINO ASIC –8 or 32 channel differential amplifier/discriminator, using a time over threshold technique –Excellent time resolution of up to ~10 ps RMS jitter on the leading edge –Differential LVDS outputs for common-mode noise rejection –High Dynamic Range at input: 1.25 × 10 5 to 1.25 × 10 7 electrons –Good Match for MCP output

4. www.photek.co.uk 4 Electronics High Performance Time-to-Digital Convertor ASIC (HPTDC) –A programmable TDC –25 ps LSB resolution on 8 channels –100 ps LSB resolution on 32 channels –LVDS inputs to match NINO outputs –Can be configured for TTL input

5. www.photek.co.uk 5 NINO – Time Walk Calibration The NINO uses a time-over-threshold technique to measure the detector signal Pulse output has width proportional to the collected charge This results is a “time walk” of the leading edge due to variation of the signal amplitude This effect must be calibrated to achieve sub 100 ps time resolution As an MCP detector produces a broad range of signal amplitudes, the detector output was used for the calibration procedure

6. www.photek.co.uk 6 Hi-Content Detector - Outline 8×8 anode on a multilayer ceramic 1.5 mm wide square anode pads on a 1.6 mm pitch Two chevron-stack 3.2 µm pore MCPs provide a gain of 10 6 and a fast rise time of 80-90 ps MCP Output is gold coated to improve the count rate linearity 8 NINO chips, with 8 channels each, closely coupled to detector to reduce the capacitance load and hence noise

7. www.photek.co.uk 7 Hi-Content Detector - Results Time correlated single photon counting from the laser illuminated detector The solid line shows the uncorrected data The “time walk” corrected histogram is shown as a dashed line Corrected histogram has 78 ps RMS Subtracting the trigger jitter of 65 ps in quadrature leaves 43 ps for the system and laser Laser pulse is approximately 40 – 45 ps!

8. www.photek.co.uk 8 Hi-Content Detector - Applications The Hi-Content project is aimed at providing a multi-channel PMT for time-resolved spectroscopy in life science applications: –Fluorescence Lifetime Imaging (FLIM) –Forster Resonance Energy Transfer Imaging (FRET) –Fluorescence Correlation Spectroscopy (FCT) These applications require: –High time resolution –High count rate capability –Parallel photon detection

9. www.photek.co.uk 9 IRPICS Detector IRPICS is a follow up to Hi-Content Detector size has increased to a 40 mm diameter Multi-anode density has increased to 32×32 0.83 mm wide square anode pads on a 0.88 mm pitch Modular readout electronics using the HPTDC and a 32 channel version of the NINO have been developed Currently provide 256 readout channels with 100 ps LSB resolution, enough to have a 16×16 multi-anode detector The detector is currently in production at Photek

10. www.photek.co.uk 10 C-DIR Anode Readout - Detector C-DIR : Charge Division Imaging Readout A novel imaging readout for MCP based resistive sea detectors Resistive sea detectors operate by capacitive coupling of the output from the MCP to a readout anode through a ceramic back plate This concept has been proven with Wedge & Strip, Tetra Wedge, Delay Line and Resistive read-out anodes The read-out anode remains outside the vacuum envelope The read-out anode is isolated from the high voltage No vacuum feed-throughs are required

11. www.photek.co.uk 11 C-DIR Anode Readout - Concept The capacitive nature of the resistive sea suggests a new kind of charge sharing readout anode This uses purely capacitive coupling between a discrete array of nodes on the anode Surface mount capacitors are then used to split the collected charge between four readout nodes The x & y co-ordinates of the detected photon(s) can then be reconstructed using a simple imaging algorithm: Q i is the charge collected at each readout node

12. www.photek.co.uk 12 C-DIR Anode Readout - Results A low capacitance load makes it possible to use high speed amplifiers such as the NINO ASIC as the analogue readout electronics The use of fast amplifiers then allows high-rate single photon imaging However this sacrifices resolution due to increased noise The figure shows mask imaging data for the C-DIR prototype, illuminated at single photon levels The mask was a 3×3 grid, with a 50 µm hole surrounded by eight 25 µm holes The 25 µm holes produce a detector response with a 300 µm FWHM, corresponding to a detector resolution of approximately 100×100 pixels (taking one FWHM unit as a pixel)

13. www.photek.co.uk 13 HPTDC Module - Outline We are currently developing an HPTDC module It will be an integral part of all the projects discussed A modular architecture allows for multiple HPTDC cards On-board FPGA for control and data processing USB readout and control Aim to be on the market this year

14. www.photek.co.uk 14 HPTDC Module - Architecture

15. www.photek.co.uk 15 Summary Incorporated CERN ASICs into commercial photon detectors and electronics 2 multi-anode detectors and a novel read-out anode have been developed An HPTDC module will be available soon

16. www.photek.co.uk 16 Thank you for listening Photek Limited 26 Castleham Road, St Leonards on Sea, East Sussex, TN38 9NS, UK T +44 (0)1424 850555 F +44 (0)1424 850051 E sales@photek.co.uk W www.photek.co.uk