The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011
What is known experimentally about timing determinants
in MCP detectors
Anton Tremsin
University of California at Berkeley / Arradiance, Inc
The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011
Event timing signal pickup
2. Event time measured by the signals from the anode. Both spatial and temporal channels are from the same signal, no need to synchronize.
1. Event time measured by the signal from the MCP output electrode.
Need to synchronize that signal with the spatial data coming on a separate electronics channel. At high rates may be a challenge.
The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011
Event time measured by the signals from the anode: TTS is increased by the presence of the energy distribution in the MCP output electron signal.
Event timing variation across 18 mm tube
The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011
Event timing variation across 18 mm tube
Map of the variation in event arrival time, showing variation in amplifierdelay for the RD20 32 channel chip.18mm sealed tube cross strip detector.
Variation in event arrival time in a horizontal slice of the image above. Across the middlethe variation is less than 500 ps.
O.H.W. Siegmund, et al., AMOS 2010
There is a variation of event time across the field of view in case of the signal pickup from
the MCPout electrode.
The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011
Time jitter for the event time stamp as a function of MCP gain. Showing better performance at higher gain.
Time stamp jitter as a function of MCP gain. See plot on right for details.
O.H.W. Siegmund, et al., AMOS 2010
Event timing variation across 18 mm tube
Event timing is determined by the signal to noise ratio.
The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011
Single photon/electron counting: detector hardware
Active area, 25 mm
A. S. Tremsin, et al., Nucl. Instr. Meth. A 580 (2007) 853.A. S. Tremsin, et al., IEEE TNS 54 (2007) 706.
The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011
Experimental setup
Synchrotron generated photon pulses
~ 70 ps wide, 2 ns apart
2D Imaging +time for each
detected photon
Scattered photons
Thin film samples
A. S. Tremsin, et al., Nucl. Instr. Meth. A 580 (2007) 853.A. S. Tremsin, et al., IEEE TNS 54 (2007) 706.
The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011
Timing resolution: single photoelectron
Elastically scattered photons
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250
300
0 2 4 6 8 10
Time delay (ns)
Co
un
ts
0
1000
2000
3000
4000
5000
6000
7000
8000
0.7 0.8 0.9 1 1.1 1.2 1.3
Time (ns)
Ph
oto
n c
ou
nts
Measured
Gaussian fit55 ps RMS
Timing accuracy 55 ps RMS
A. S. Tremsin, et al., Nucl. Instr. Meth. A 580 (2007) 853.A. S. Tremsin, et al., IEEE TNS 54 (2007) 706.
The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011
Both elastic and inelastic scattering are present
Only elastic scattering
1
10
100
1000
10000
1 2 3 4 5
Time delay (ns)
Co
un
ts
HOPG
Nex synchrotron pulse (very weak)
1
10
100
1000
10000
100000
1 2 3 4 5
Time delay (ns)
Co
un
ts
BN
Nex synchrotron pulse (very weak)
Inelastic X-ray scattering
The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011
Timing resolution vs. MCP gain
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0.8
0.9
1
-0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5
Time (ns)
Ph
oto
n f
lux
(a
rb. u
nit
s)
3200V
3600V
3800V
Photon peak measured by the detector:Gain 7e5 FWHM=283 psGain 2e6 FWHM=200 ps
Gain 3.5e6 FWHM=165 ps (all data taken at this gain)
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1000
2000
3000
4000
5000
6000
7000
8000
0.7 0.8 0.9 1 1.1 1.2 1.3
Time (ns)
Ph
oto
n c
ou
nts
Measured
Gaussian fit55 ps rms,
130 ps FWHM
The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011
Synchrotron bunch diffusion measured with MCP
Bunch population after injection
Diffusion of electrons between the adjacent bunches was optimized with our detection system
Bunch population ~76 min later
W. E. Byrne, et al., Proceedings EPAC’06, Edinburgh, June 2006
The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011
2716
2718
2720
2722
2724
2726
2728
2730
2732
2734
2736
0 5 10 15 20 25 30 35
Y position (mm)
Co
un
ts
In our system the jitter was limited by something else, not by transit of electron signal at the anode.
XY map of events on the anode: correlate event time with the XY position. Correct for transit time at the anode.
Event timing correction: XY→Tcorrected
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5
10
15
20
25
30
35
0 5 10 15 20 25 30 35
X (mm)
Y (
mm
)
2690
2700
2710
2720
2730
2740
2750
0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0
X or Y position (mm)
Co
un
ts
The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011
MCP output pulse with a 50 anode
Peter Wurz and Lukas Gubler, Rev. Sci. Instrum. 67 (5), 1996
25 um pores
10 um pores
The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011
Signal pick up from the MCP or from the anode
a) Measured by taking the pickup signal from the back of MCP plate which is preamplified and processed by the TAC B&H SPC-130.
b) Average of the time sum in the delay line one direction as measured on the delay line signals by the eight-channel TDC (Roentdek TDC8HP).
40 mm active diameter MCPs mounted in a Chevron configuration.
5 m pore MCP, L/D=60:1, 12° bias
MgO coating for optimum electron detection.
Arno Vredenborg, Wim G. Roeterdink, and Maurice H. M. Janssen, Review of Scientific Instruments 79, 063108 2008
The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011
Pulse widths from the MCP vs. pore diameter
The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011
Pulse widths from the MCP vs. pore diameter
The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011
Pulse widths from the MCP vs. pore diameter
The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011
E. Schyns, Clermont-Ferrand, January 2010
The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011
E. Schyns, Clermont-Ferrand, January 2010
The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011
E. Schyns, Clermont-Ferrand, January 2010
The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011
The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011
The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011
The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011
The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011
The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011
Detector walks: what can be learned from XS detectorEach strip has preamplifiers and 50 MHz ADC.
Digital waveform is processed.
Same effects are present as in LAPPD detector, but at longer time scales.
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Time (ns)
Ap
lifi
ed s
ign
al (
V)
7.80E+04
1.41E+05
2.00E+05
2.66E+05
3.30E+06
A. S. Tremsin, et al., IEEE Trans. Nucl. Sci. 56 (2009) 1148
The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011
Event timing calculation through CFD
-0.2
-0.15
-0.1
-0.05
0
0.05
0.1
0.15
0.2
0 0.05 0.1 0.15 0.2 0.25 0.3
Time (s)
Measu
red
Sig
nal
(V) Initial pulse
-0.2
-0.15
-0.1
-0.05
0
0.05
0.1
0.15
0.2
0 0.05 0.1 0.15 0.2 0.25 0.3
Time (s)
Measu
red
Sig
nal
(V)
Initial pulse
Delayed
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-0.15
-0.1
-0.05
0
0.05
0.1
0.15
0.2
0 0.05 0.1 0.15 0.2 0.25 0.3
Time (s)
Measu
red
Sig
nal
(V)
Initial pulse
Delayed
CFD
-0.2
-0.15
-0.1
-0.05
0
0.05
0.1
0.15
0.2
0 0.05 0.1 0.15 0.2 0.25 0.3
Time (s)
Measu
red
Sig
nal
(V)
Initial pulse
Delayed
CFD
A. S. Tremsin, et al., IEEE Trans. Nucl. Sci. 56 (2009) 1148
The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011
Self triggered timing resolution
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0
0.2
0.4
0.6
0 1 2 3 4
Time (s)
Vo
lta
ge
(V
)
1.0us
1.5us
Pulse generator produced pulses amplified by the RD20 readout board. Digital
peak detection
0
50
100150
200
250
300350
400
450
997 998 999 1000 1001 1002 1003
Measured time between peaks (ns)
Cou
nts
3.5E+04
7.0E+04
1.0E+05
1.4E+05
1 s between
0
50
100150
200
250
300350
400
450
1497 1498 1499 1500 1501 1502 1503
Measured time between peaks (ns)
Cou
nts
3.5E+04
7.0E+04
1.0E+05
1.4E+05
1.5 s between peaks
A. S. Tremsin, et al., IEEE Trans. Nucl. Sci. 56 (2009) 1148
The Factors that Limit Time Resolution in Photodetectors, Workshop, University of Chicago, 28-29 April 2011
Large panel detector questions
•The smallest pore size for 8” MCPs (20 um or 10 um)
•Gap between the MCPs – poor Pulse Height Distribution - is one MCP configuration possible?
•Distance to photocathode to be minimized (J. Va’vra results)
•Charge footprint to be spread over ~4 mm – timing of the pulse is broadened
•Walk effects – both temporal and spatial (with event gain)
•Gain required for detector operation (signal to noise defined by the front end electronics and anode)