Update on Physical Parameters that influence Timing Jean-Francois Genat LPNHE Paris LAPPD...

Update on Physical Parameters that influence Timing

Jean-Francois GenatLPNHE Paris

LAPPD Electronics & Integration ReviewJuly 9th 2012, Chicago

Micro-Channel Plates Timing ResolutionTiming resolutions (Transit Time Spread) in the 10-100 ps range

- MCP parameters impacting transit time: Rise-time First strike, Pore Tilt angle, Pore size (diameter, length) Bias voltages (gaps transit times)

- MCP parameters impacting noise and rise-time Photo-cathode noise (mainly impulse noise) Secondary emitter noise Gain fluctuations

- MCP environment Anode T-line bandwidthMagnetic field

- Electronics parametersAnalog bandwidthSample rateElectronics gain (if any)

Electronics noiseSignal integrity (system noise)

Jean-Francois Genat, LAPPD Electronics & Integration Godparents Review, Chicago, July 9 th 2012

MCP steady noise (measured with a digital oscilloscope)

Baseline noise: 700 mV rms

Single Photo-ElectronIs 8 mV

S/N ~10


Timing spreads estimation (rising edge sampling)

Main contributors Detector:

Transit Time Noisedetector

Rise time Gain

Waveform Sampling Electronics:

Noiseelec

Sample rate Analog bandwidth


With SN=10, ts=100ps (10GS/s), abw = 700 MHz, s = 22ps

MCP Timing Resolution(measured vs predicted)

Predicted using rising edge sampling is 22ps

at 10GS/s and 700 MHz analog bandwidth (see above)

Measured on a 8’’ x 8’’ by Andrey Elagin, Razib Obaid, Sasha Vostrikov, and Matt Wetstein early July:https://psec.uchicago.edu/blogs/lappd/wp-content/uploads/2012/06/7-3-12.pdf

Measured 38ps rms for most of the pulses

Note: Some pulses (with broad rising edges and more signal on the neighboring strips) have an rms around 100 picoseconds

Suspect signal to noise... Or other conditions (sampling rate, analog bandwidth)


https://psec.uchicago.edu/blogs/lappd/wp-content/uploads/2012/06/7-3-12.pdf

Conclusion

- Some discrepancy between calculations and measurements

38 ps measured vs 22 ps predicted, but results are on the same order as commercial 2’’ x 2’’ MCPs on a 16 times larger area !

Check floor level

Thanks…Jean-Francois Genat, LAPPD Electronics & Integration Godparents Review, Chicago, July 9 th 2012

Backup slides


MCPs signal development

Short Transit Time: -Thin photo-cathode gap, - High electric field - Thin MCP: small pore size (L/d = 40) < 5mm, l < 200 mm - First strike: cathode on MCP , funnel shaped pore entance

Fast pulse: - Thin anode gap, - High electric field

10-5 mm Hg vacuum rigidity is 1kV/100mm

MCP signal rising edge: qE = ma l = 1mm, E=100V/mm, tr=250ps

Jean-Francois Genat, LAPPD Electronic Review, Chicago, May 20 th 2011

MCP Device Simulations by Lionel De Sa Photo-cathode gap

9

Full device simulations:Valentin IvanovZeke Insepov

(20-30ps total measured)


No repulsion between electronsFactor of 2 = 10ps

TTS contributions

- First gap- First amplification stage- Second amplification stage- Anode gap


Update on Physical Parameters that influence Timing Jean-Francois Genat LPNHE Paris LAPPD...

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