Photodetection
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N. Dinu, T. Gys, C. Joram, S. Korpar, Y. Musienko, V. Puill, D. RenkerEDIT 2011 1
Photodetection Principles, Performance and Limitations
Nicoleta Dinu (LAL Orsay)Thierry Gys (CERN)Christian Joram (CERN)Samo Korpar (JSI Ljubljana)Yuri Musienko (Northwestern U, USA) Veronique Puill (LAL, Orsay)Dieter Renker (TU Munich)
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Photodetection
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N. Dinu, T. Gys, C. Joram, S. Korpar, Y. Musienko, V. Puill, D. RenkerEDIT 2011 2
OUTLINE
• Basics
• Requirements on photodetectors
• Photosensitive materials
• ‘Family tree’ of photodetectors
• Detector types
• Applications
Photodetection
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N. Dinu, T. Gys, C. Joram, S. Korpar, Y. Musienko, V. Puill, D. RenkerEDIT 2011 3
Basics
1. Photoelectric effect2. Solids, liquids, gaseous materials3. Internal vs. external photoeffect, electron affinity4. Photodetection as a multi-step process5. The human eye as a photodetector
Photodetection
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N. Dinu, T. Gys, C. Joram, S. Korpar, Y. Musienko, V. Puill, D. RenkerEDIT 2011 4
Formatting guidelines for preparing slides
Use Calibri as default fontDefault color: white (avoid text in red, difficult to read for many people)Main title: 24 ptsNormal text: 16 ptsReferences: 10 pts
Photodetection
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N. Dinu, T. Gys, C. Joram, S. Korpar, Y. Musienko, V. Puill, D. RenkerEDIT 2011 5
Photodetection
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N. Dinu, T. Gys, C. Joram, S. Korpar, Y. Musienko, V. Puill, D. RenkerEDIT 2011 6
Energy loss eVth in (thin) ohmic contact
Hybrid Photon Detectors (HPD’s) – Basic Principles
• Combination of vacuum photon detectors and solid-state technology;
• Input: collection lens, (active) optical window, photo-cathode;
• Gain: achieved in one step by energy dissipation of keV pe’s in solid-state detector anode; this results in low gain fluctuations;
• Output: direct electronic signal;• Encapsulation in the tube implies:• compatibility with high vacuum
technology (low outgassing, high T° bake-out cycles);
• internal (for speed and fine segmentation) or external connectivity to read-out electronics;
• heat dissipation issues;
DV
(C.A. Johansen et al., NIM A 326 (1993) 295-298)
Optical input window
n+
n
p+
- ++ -+
-
Photon
Photoelectron
Typical stopping range 3-5mm
Photodetection
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N. Dinu, T. Gys, C. Joram, S. Korpar, Y. Musienko, V. Puill, D. RenkerEDIT 2011 7
• Photo-emission from photo-cathode;• Photo-electron acceleration to DV 10-
20kV;• Energy dissipation through ionization and
phonons (WSi=3.6eV to generate 1 e-h pair in Si) with low fluctuations (Fano factorF 0.12 in Si);
• Gain M:
• Intrinsic gain fluctuations sM :
dominated by electronics• Example: DV = 20kV
M 5000 and sM 25• suited for single photon detection with
high resolution;
SiWVthVeM )( D
(C.P. Datema et al., NIM A 387 (1997) 100-103)
Background from electron back-scattering
at Si surface
MFM s
1 pe
2 pe 3 pe
4 pe
6 pe
7 pe
5 pe
Energy resolution of HPD’s - Basic Properties
Photodetection
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N. Dinu, T. Gys, C. Joram, S. Korpar, Y. Musienko, V. Puill, D. RenkerEDIT 2011 8
(http://cmsinfo.cern.ch/Welcome.html/CMSdetectorInfo/CMShcal.html)
(P. Cushman et al., NIM A 504 (2003) 502)
Possible cross-talks
(http://cmsinfo.cern.ch/Welcome.html/CMSdetectorInfo/CMShcal.html)
Multi-pixel proximity-focussed HPD – CMS HCAL
• B=4T proximity-focussing with 3.35mm gap and HV=10kV;
• Minimize cross-talks:– pe back-scattering: align with B;– capacitive: Al layer coating;– internal light reflections: a-Si:H AR
coating optimized @ l = 520nm (WLS fibres);
• Results in linear response over a large dynamic range from minimum ionizing particles (muons) up to 3 TeV hadron showers;
Photodetection
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N. Dinu, T. Gys, C. Joram, S. Korpar, Y. Musienko, V. Puill, D. RenkerEDIT 2011 11
Object illuminance: 0.1lx
EBCCDproximity-focussed
Commercial 2/3” CCD
Hamamatsu N7640EB-CCD
(Hamamatsu)
Electron-bombarded CCD (EBCCD)
extra slide
not shown
Photodetection
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N. Dinu, T. Gys, C. Joram, S. Korpar, Y. Musienko, V. Puill, D. RenkerEDIT 2011 13
• Industry-LHCb development:• LHCb-dedicated pixel array sensor bump-
bonded to binary electronic chip (in close collaboration with ALICE-ITS), specially-developed high T° bump-bonding;
• Flip-chip assembly encapsulated inside vacuum tube using full-custom ceramic carrier;
(M. Moritz et al., IEEE TNS Vol. 51,No. 3, June 2004, 1060-1066)
50mm
Pixel-HPD anode
72mm
(K. Wyllie et al., NIMA 530 (2004) 82-86)
Pixel-HPD’s for LHCb RICHes
(M. Campbell et al., IEEE TNS Vol. 53,No. 4, August 2006, 2296-2302)
Photodetection
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N. Dinu, T. Gys, C. Joram, S. Korpar, Y. Musienko, V. Puill, D. RenkerEDIT 2011 14
RICH2 H X-section
Upper RICH1 HPD plane
Pixel-HPD’s for LHCb RICHes
• Single photon sensitivity over 200nm-600nm (aerogel response and scattering, and chromatic dispersion in gases)
• Detection area of 3.3m2 (500 HPD’s) with active area fraction of ~65% and position resolution 2.5mm (optimum of pixel vs chromatic vs emission point errors)
• Fast response for LHC bunch-crossing rate of 40MHz with good signal-to-noise ratio
• Radiation tolerant (3krad per year)
LHCb data(preliminary)
K ring in RICH1
Photodetection
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N. Dinu, T. Gys, C. Joram, S. Korpar, Y. Musienko, V. Puill, D. RenkerEDIT 2011 16
• Non-exhaustive list:• www.photonis.com: “Photomultiplier tubes, principles and applications”;• www.hamamatsu.com;• www.photek.com;• A.H. Sommer, ”Photoemissive materials”, J. Wiley & Sons (1968);• H. Bruining, “Physics and Applications of Secondary Electron Emission”, Pergamon Press
(1954); • I. P. Csorba, “Image Tubes”, Sams (1985);• Proceedings of the triennial NDIP (New Developments in Photo-detection) Conference (1996-
2008), published in NIMA;
Literature
Photodetection
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N. Dinu, T. Gys, C. Joram, S. Korpar, Y. Musienko, V. Puill, D. RenkerEDIT 2011 17
Applications
1. Readout of scintillators / fibres with PMT/MAPMT. 2. Readout of RICH detectors with HPD. 3. Readout of RICH detector with gas based detectors4. Readout of inorganic crystals with APD. Example: CMS ECAL.5. Readout of scintillators with G-APD. 6. Ultrafast timing for TOF with MCP-PMT
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