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Special Focus Workshop “Towards 10 ps single soft photon detectors” 2013 IEEE NSS/MIC/RTSD Seoul Sunday Oct 27, 2013. A very successful soft photon detector: the Photomultiplier (1934). ‘good’ quantum efficiency rather fast low noise @ high gain: very sensitive
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Special Focus Workshop “Towards 10 ps single soft photon detectors” 2013 IEEE NSS/MIC/RTSD Seoul Sunday Oct 27, 2013
A very successful soft photon detector: the Photomultiplier (1934) • ‘good’ quantum efficiency • rather fast • low noise @ high gain: very sensitive • little dark current, no bias current • radiation hard • quite linear • voluminous & heavy • no position resolution • expensive • quite radioactive • can’t stand B fields Amplification by multiplication: low noise!
Photo Diode Avalanche Photo Diode APD Single Photon Avalanche Diode SPAD GeigerMode Avalanche Photodiode GM-APD Digital Photo Counters The Silicon PhotoMultiplier: SiPM
Si-PMs are now in the focus: Efficiency: potentially 100 % but: pixelizing reduces efficiency (borders) Flat, thin, light, cheap Capable to stand strong B-field Noise, afterpulsing, recovery time Best possible time resolution……?
Use a MicroChannelPlate MCP? MCP (in vacuum) John Vallerga: TimePix + MCPs We do not know how to make MEMS made MCPs. Problems: aspect ratio of holes, ion back flow, acceptance Quantum Limited Imaging Detectors, RIT 2009, John Vallerga, jvv@ssl.berkeley.edu
The transmission dynode: ultra thin (20 - 100 nm) layers diamond SiNitride (Si3N4) Si doped (SiRichNitride, SRN) CsI doped SiO2 • ultra fast (single electron) detector: σ = 10 ps • E-force much larger than Lorenz force: operates in B-field • radiation hard • low mass In vacuum: no gaseous detector………..
Classical Photo Cathode: Quantum Efficiency (QE) ~ 40 % at max Can this be largely improved? In vacuum: no gaseous detector………..
Towards we ain’t there yet 10 psnot quite an arbitrary goal single the ultimate sensitivity soft ~ 1 eV: there are other photons (like 511 keV) photon a very fundamental particle detectors that is where we are here for Have a good exchange of information!
Provoking speakers: • Paul Lecoq • Gary Varner • John Smedley • bringing forward ‘aggressive’ thesis’ like: • ‘with Si-PMs 10 ps time resolution may be feasible, • but at the cost of a lot of noise’ • ‘Scintillators are too slow for applications in 10 psdetectors • Contrarily, Cherenkov radiation becomes more important’ • ‘There is no fundamental limit for the QE of photo cathodes’