1. Photo-detection EDIT EDIT 2011Single photon counting measurements with an HPD – T. GysSlide 1 Single photon counting measurements with a hybrid photon detector Thierry Gys - CERN/PH-DT EDIT 2011 School CERN 31 January - 10 February 2011

2. Photo-detection EDIT EDIT 2011Single photon counting measurements with an HPD – T. GysSlide 2 Overview Measurement, analysis and discussion of single photoelectron spectra recorded with a hybrid photon detector illuminated by a picosecond pulsed laser diode source

3. Photo-detection EDIT EDIT 2011Single photon counting measurements with an HPD – T. GysSlide 3 Experimental setup: sketch Shaper amplifier PC Charge preamplifier HPD LD driver Gate Multimode optical fibre Light-tight box Lens Dual timer Buffer amplifier LD head HV supply Source meter (Si bias) MCB Synch HV control and monitoring Preamplifier out Shaper out DAC/ADC interface

4. Photo-detection EDIT EDIT 2011Single photon counting measurements with an HPD – T. GysSlide 4 Experimental setup: photograph 1 Shaper amplifier PC LD driver Light-tight box Dual timer Buffer amplifier LD head Source meter (Si bias) HV supply Charge preamplifier and buffer amplifier supplies

5. Photo-detection EDIT EDIT 2011Single photon counting measurements with an HPD – T. GysSlide 5 Experimental setup: photograph 2 Light-tight box Buffer amplifier HPD Multimode optical fibre Lens Charge preamplifier HV cable

6. Photo-detection EDIT EDIT 2011Single photon counting measurements with an HPD – T. GysSlide 6 Introduction – Switching on Introduction –Discussion of measurement protocol and key parameters (Poisson average, electronics noise, dark counts, etc.) –HPD and setup description and operation – safety aspects Switching on –Signal generation and processing Photo-electron energy dissipation – HPD gain Pre-amplification - electronics noise Amplification and shaping – digitization –Diode reverse bias leakage current – depletion - full depletion – electronics noise – capacitive load over-depletion – photoelectron stopping range – charge carrier collection efficiency –High voltage ramp-up diode ohmic contact – photoelectron stopping range – dead layer – HPD gain nominal operating point

7. Photo-detection EDIT EDIT 2011Single photon counting measurements with an HPD – T. GysSlide 7 (Short) measurements Measurements of spectra with various (low/high) LD light intensities Measurements of spectra at non-optimal diode bias (under depletion) and high voltage (smaller peak separation – dead layer) Typical photo-electron spectrum Linear scale Logarithmic scale

8. Photo-detection EDIT EDIT 2011Single photon counting measurements with an HPD – T. GysSlide 8 Analysis and discussion Measurements statistics Estimate Poisson average  from P  (0), correlate with spectrum average Discuss contribution of photo-electron energy dissipation in Silicon – dead layer – Fano factor – small intrinsic gain fluctuations Discuss contribution of photo-electron back-scattering (irreducible continuum – combinatorics - spectrum fit models) Discuss contributions of electronics noise (leakage current/ capacitive load) - link to solid-state detectors and readout electronics

9. Photo-detection EDIT EDIT 2011Single photon counting measurements with an HPD – T. GysSlide 9 Technical references and literature Technical references –HPD data sheets –Charge preamplifier/buffer amplifier/shaper data sheets and manual –MCB data sheets and manual Pre-requisite literature –Pioneering work on photon counting with HPDs –Vacuum photon detectors (image intensifiers) and solid-state detectors –Back-scattering effects Theoretical and experimental work Proposed models of photoelectron spectra