1. The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011 What is known experimentally about timing determinants in MCP detectors Anton Tremsin University of California at Berkeley / Arradiance, Inc

2. The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011 Event timing signal pickup 2. Event time measured by the signals from the anode. Both spatial and temporal channels are from the same signal, no need to synchronize. 1. Event time measured by the signal from the MCP output electrode. Need to synchronize that signal with the spatial data coming on a separate electronics channel. At high rates may be a challenge.

3. The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011 Event time measured by the signals from the anode: TTS is increased by the presence of the energy distribution in the MCP output electron signal. Event timing variation across 18 mm tube

4. The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011 Event timing variation across 18 mm tube Map of the variation in event arrival time, showing variation in amplifier delay for the RD20 32 channel chip. 18mm sealed tube cross strip detector. Variation in event arrival time in a horizontal slice of the image above. Across the middle the variation is less than 500 ps. O.H.W. Siegmund, et al., AMOS 2010 There is a variation of event time across the field of view in case of the signal pickup from the MCP out electrode.

5. The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011 Time jitter for the event time stamp as a function of MCP gain. Showing better performance at higher gain. Time stamp jitter as a function of MCP gain. See plot on right for details. O.H.W. Siegmund, et al., AMOS 2010 Event timing variation across 18 mm tube Event timing is determined by the signal to noise ratio.

6. The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011 Single photon/electron counting: detector hardware Active area, 25 mm  A. S. Tremsin, et al., Nucl. Instr. Meth. A 580 (2007) 853. A. S. Tremsin, et al., IEEE TNS 54 (2007) 706.

7. The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011 Experimental setup Synchrotron generated photon pulses ~ 70 ps wide, 2 ns apart 2D Imaging + time for each detected photon Scattered photons Thin film samples A. S. Tremsin, et al., Nucl. Instr. Meth. A 580 (2007) 853. A. S. Tremsin, et al., IEEE TNS 54 (2007) 706.

8. The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011 Timing resolution: single photoelectron Elastically scattered photonsTiming accuracy 55 ps RMS A. S. Tremsin, et al., Nucl. Instr. Meth. A 580 (2007) 853. A. S. Tremsin, et al., IEEE TNS 54 (2007) 706.

9. The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011 Both elastic and inelastic scattering are present Only elastic scattering Inelastic X-ray scattering

10. The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011 Timing resolution vs. MCP gain Photon peak measured by the detector: Gain 7e5 FWHM=283 ps Gain 2e6 FWHM=200 ps Gain 3.5e6 FWHM=165 ps (all data taken at this gain)

11. The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011 Synchrotron bunch diffusion measured with MCP Bunch population after injection Diffusion of electrons between the adjacent bunches was optimized with our detection system Bunch population ~76 min later W. E. Byrne, et al., Proceedings EPAC’06, Edinburgh, June 2006

12. The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011 In our system the jitter was limited by something else, not by transit of electron signal at the anode. XY map of events on the anode: correlate event time with the XY position. Correct for transit time at the anode. Event timing correction: XY→T corrected

13. The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011 MCP output pulse with a 50  anode Peter Wurz and Lukas Gubler, Rev. Sci. Instrum. 67 (5), 1996 25 um pores 10 um pores

14. The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011 Signal pick up from the MCP or from the anode a)Measured by taking the pickup signal from the back of MCP plate which is preamplified and processed by the TAC B&H SPC-130. b)Average of the time sum in the delay line one direction as measured on the delay line signals by the eight-channel TDC (Roentdek TDC8HP). 40 mm active diameter MCPs mounted in a Chevron configuration. 5  m pore MCP, L/D=60:1, 12° bias MgO coating for optimum electron detection. Arno Vredenborg, Wim G. Roeterdink, and Maurice H. M. Janssen, Review of Scientific Instruments 79, 063108 2008

15. The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011 Pulse widths from the MCP vs. pore diameter

16. The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011 Pulse widths from the MCP vs. pore diameter

17. The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011 Pulse widths from the MCP vs. pore diameter

18. The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011 E. Schyns, Clermont-Ferrand, January 2010

19. The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011 E. Schyns, Clermont-Ferrand, January 2010

20. The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011 E. Schyns, Clermont-Ferrand, January 2010

21. The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011

26. Detector walks: what can be learned from XS detector Each strip has preamplifiers and 50 MHz ADC. Digital waveform is processed. Same effects are present as in LAPPD detector, but at longer time scales. A. S. Tremsin, et al., IEEE Trans. Nucl. Sci. 56 (2009) 1148

27. The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011 Event timing calculation through CFD A. S. Tremsin, et al., IEEE Trans. Nucl. Sci. 56 (2009) 1148

28. The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011 Self triggered timing resolution Pulse generator produced pulses amplified by the RD20 readout board. Digital peak detection A. S. Tremsin, et al., IEEE Trans. Nucl. Sci. 56 (2009) 1148

29. The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011 Large panel detector questions The smallest pore size for 8” MCPs (20 um or 10 um) Gap between the MCPs – poor Pulse Height Distribution - is one MCP configuration possible? Distance to photocathode to be minimized (J. Va’vra results) Charge footprint to be spread over ~4 mm – timing of the pulse is broadened Walk effects – both temporal and spatial (with event gain) Gain required for detector operation (signal to noise defined by the front end electronics and anode)