1. Special Focus Workshop “Towards 10 ps single soft photon detectors” 2013 IEEE NSS/MIC/RTSD Seoul Sunday Oct 27, 2013

2. 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!

4. Photo Diode Avalanche Photo Diode APD Single Photon Avalanche DiodeSPAD GeigerMode Avalanche PhotodiodeGM-APD Digital Photo Counters The Silicon PhotoMultiplier: SiPM

5. 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……?

6. 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 Use a MicroChannelPlate MCP? Quantum Limited Imaging Detectors, RIT 2009, John Vallerga, jvv@ssl.berkeley.edu

7. The transmission dynode: ultra thin (20 - 100 nm) layers diamond SiNitride (Si 3 N 4 ) Si doped (SiRichNitride, SRN) CsI doped SiO 2 In vacuum: no gaseous detector……….. - ultra fast (single electron) detector: σ = 10 ps - E-force much larger than Lorenz force: operates in B-field - radiation hard - low mass

8. In vacuum: no gaseous detector……….. Classical Photo Cathode: Quantum Efficiency (QE) ~ 40 % at max Can this be largely improved?

9. Towards we ain’t there yet 10 ps not 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!

10. At the end:

11. 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 ps detectors Contrarily, Cherenkov radiation becomes more important’ ‘There is no fundamental limit for the QE of photo cathodes’