Picosecond Timing Workshop

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Discovering the Future
Sales meeting 2005
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Production sites, US
1. PHOTONIS Key Facts

• Lancaster, PA
• Photomultipliers
• Power Tubes

• Matamoros, Mexico
• Photomultipliers

• Sturbridge, MA
• Microchannel plates
• Channel multipliers
• Fiber optics

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1. PHOTONIS Key Facts
Production sites, Europe

• Brive, France
• Photomultiplier tubes
• Image intensifiers
• Special products
• Streak tubes
• Scientific microchannel plates
• Neutron and gamma detectors
• Electron multipliers
• Multichannel photomultipliers

• Roden, Netherlands
• Image intensifiers
• Hybrid Photo-Diode (HPD)

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Planacon MCP-PMTs

• Two inch square flat PMT with dual MCP
  multiplier.
• Anodes, 2x2, 8x8 and 32 x 32 configurations.
• Improved Open Area Ratio device now available
• Bi-alkali cathode on quartz faceplate.
• Easily tiled, low profile, excellent time
  resolution, excellent uniformity.

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PLANACON Family

• 50mm Square family of MCP based PMTs
• 8500X 4 anode
• 8501X 64 anode
• 8502X 1024 anode
• New improved Active Area Variants available with
  86 active area, 85002/85012/85022
• 64 anode PMT available with integrated
  Anger-logic readout
• Gated High Voltage Power Supply available

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Improved Open Area Ratio Planacon

• Packaging is streamlined to maximize detector
  area relative to device dimensions
• 2.28 sq. vs. 2.50 sq.
• 0.45 vs. 0.65 ht.
• 86 vs. 66 OAR
• 68 gms vs. 128 gms

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MCP-PMT Operation
photon
Faceplate Photocathode
Photoelectron
DV 200V
Dual MCP
DV 2000V
Gain 106
DV 200V
Anode
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MCP-PMT Construction
Indium Seal
Faceplate
Ceramic Insulators
MCP Retainer
Dual MCP
Anode Pins

• Spacing between faceplate and MCP and MCP and
  anode can be varied for different applications
• Anode can be easily modified

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PMT Processing
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Comparison with Conventional PMT
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Comparison with Conventional PMT
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MCP Characteristics

• Standard family uses 25?m pore size / 32 ?m pitch
  / 8 bias angle / 401 LD chevron
• Prototypes have been built with 25?m pore size /
  32 ?m pitch / 8 bias angle / 601 LD chevron
• Long-life glass
• Standard dynamic range glass results in 50 ?A
  strip current ? Maximum average current of 5 ?A
• Move to Extended Dynamic Range glass for 500?A
  strip current ? Maximum average current of 50 ?A
  
• Collection efficiency, including first strike
  multiplication statistics, is 60 for 25µm.

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Single Electron Spectrum

• Good photon counting properties at gains of 0.2
  1 x 106. Currently working on increasing gain by
  2X.
• PeakValley typically gt 21 with uniform
  illumination of faceplate.
• Collection efficiency for single photoelectrons
  65.

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Uniformity

• Cathode uniformity within 10 over full active
  area.
• Anode uniformity 1.51 over the 2 active area
  in analog mode.
• Goal is to obtain 1.21 anode uniformity.
• Decrease at edge of pixels due to cross-talk
• Data provided by Jerry Vavra, SLAC

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Spatial Variations of Detection Efficiency
C. Field, T. Hadig, David W.G.S. Leith, G.
Mazaheri, B. Ratcliff, J. Schwiening, J. Uher,
and J. Vavra
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Timing Limitations

• TTS limited by
• Cathode MCP Gap and Voltage
• Recoil electrons (cause long TT shoulder)
• Transit time (Variations in p.e. velocity)
• Want small gap and high field
• MCP-Anode Gap and Voltage
• Transit time (variations in electron velocity)
• Marginally on recoil electrons (Broadens pulse
  width)
• Want small gap and high field
• Pore-size, LD, and voltage of MCP
• Transit time variation through the pore
  (secondary emission velocity variations)
• Want small pore size, minimum LD and high field

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Recoil Electrons
Faceplate
pe
Recoil Electron
L
MCP

• Scattered electrons can travel a maximum of 2L
  from initial strike
• Produces a TTS shoulder
• Reduces the DQE for direct detection

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85011 430 Drop Faceplate

• Cathode MCP gap is decreased from to 0.85mm
• Photocathode active area is reduced to 47mm from
  50mm

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85011 430 Drop Faceplate
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Effect of Reduced PC-MCP Gap
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32 Anode Timing ResolutionTiming Uniformity

• 85011 430 (0.86mm gap) MCP-PMT shows good
• uniformity over 32 anodes, each anode readout by
  a separate SLAC CFD channel

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Cathode MCP Transit Time

• Increased voltage or decreased gap can
  drastically reduce the transit time, and
  therefore transit time spread

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Amplification in Pore

• Typical secondary yield is 2
• For 401 LD there are typically 10 strikes (210
  103 gain single plate)
• Number of strikes depends on velocity of
  individual secondary electrons

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MCP Transit Time

• Transit time assumes 10 strike in 401 LD with
  1000V applied per plate, Chevron configuration

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Future Directions

• Increase the anode configurations offered
• Improved average anode current (50 100 uA)
• Step faceplate and anode to optimize timing
• MCP input treatment to optimize DQE and reduce
  recoiling effect
• Develop variants optimized for
• Photon counting with high spatial resolution
• Low cross-talk and magnetic field immunity
• Cryogenic Applications
• Ultra-low background
• Develop other geometries as required by specific
  markets and applications