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Time Resolution Measurements for 8” MCP:Noise Filter and Shape Fitting
Alexander Vostrikov
University of Chicago
January 29, 2013
Fast Timing (PSEC) Group Tuesday Regular Meeting
A. Vostrikov (UChicago) Time Resolution Measurements for 8” MCP January 29, 2013 1 / 12
Introduction
Goal
Improve differential time resolution.
Approaches
High frequency noise filtering.
Pulse shape fitting.
Data
8” MCP April 5, 2012.
Scope data: 10 Gsample/sec (100 psec).External trigger.Two opposite channels of the one stripline.
A. Vostrikov (UChicago) Time Resolution Measurements for 8” MCP January 29, 2013 2 / 12
Motivation for noise filtering
Differential time resolutiondepends on signal-to-noiseratio.
A lot of efforts to reduce thenoise were done at the APStesting facility.
Suggested approach
Cut the noise in frequencydomain during the dataanalysis.
Figure: Differential time resolution asa function of noise-to-signal ratio.8” MCP data collected onApril 5, 2012. [Andrey Elagin]
A. Vostrikov (UChicago) Time Resolution Measurements for 8” MCP January 29, 2013 3 / 12
Motivation for pulse shape fitting
Figure: Time resolution versus thenumber of primary photo-electrons fordifferent timing techniques:single/multiple thresholds, CFD, fitting.[NIM A607: 387–393, 2009]
Figure: The same plot with the abscissaexpanded to cover from 40 to 110photo-electrons and the ordinateexpanded to cover from 1 to 9 psec.[NIM A607: 387–393, 2009]
A. Vostrikov (UChicago) Time Resolution Measurements for 8” MCP January 29, 2013 4 / 12
Time and frequency domains
10 12 14 16 18 20 22 24Time, nsec
−80
−60
−40
−20
0
20
Volt
ag
e, m
V
Original
Filtered@ 800 MHz
Figure: Time domain.
0 1 2 3 4 5Frequency, GHz
−70
−60
−50
−40
−30
−20
−10
0
Fou
rier
Tra
nsf
orm
, d
BFigure: Frequency domain.
Noise filter removes all frequencies in Fourier transformation higherthan frequency cut level.
Here frequency cut level of 800 MHz selected.
A. Vostrikov (UChicago) Time Resolution Measurements for 8” MCP January 29, 2013 5 / 12
Events selection
0 1 2 3 4 5 6Full signal width (nsec)
0
500
1000
1500
2000
2500
3000
3500
4000
4500
Eve
nts / (100 psec)
Channel #1: 14064 events
Figure: Noise filter is OFF.
0 1 2 3 4 5 6Full signal width (nsec)
0
1000
2000
3000
4000
5000
6000
7000
Eve
nts / (100 psec)
Channel #1: 14005 events
Figure: Noise filter is ON.
Full signal width is defined as difference between CFD timing at 10%of falling and rising edges.
Selection cut is 1.3 nsec.
A. Vostrikov (UChicago) Time Resolution Measurements for 8” MCP January 29, 2013 6 / 12
Time resolution: Noise filter effect
0 50 100 150Time difference, psec
0
20
40
60
80
100
120
140
160
Eve
nts / (2 psec)
sigma=11.94 psec2035 events
Figure: Noise filter is OFF.
0 50 100 150Time difference, psec
0
50
100
150
200
250
Eve
nts / (2 psec)
sigma=6.90 psec1988 events
Figure: Noise filter is ON.
Pulses with amplitude between 110 and 130 mV selected.
Time difference distribution is fitted with Gaussian.
Time resolution is σ-parameter of the fit.
A. Vostrikov (UChicago) Time Resolution Measurements for 8” MCP January 29, 2013 7 / 12
Pulse shape fitting
Figure: Noise filter is OFF.
Pulse shape is fitted with Gaussian between two black lines.
A. Vostrikov (UChicago) Time Resolution Measurements for 8” MCP January 29, 2013 8 / 12
Time resolution: Pulse shape fitting effect
0 50 100 150Time difference, psec
0
20
40
60
80
100
120
140
160
Eve
nts / (2 psec)
sigma=11.94 psec2035 events
Figure: Spline. Noise filter is OFF.
0 50 100 150Time difference, psec
0
20
40
60
80
100
120
140
160
180
Eve
nts / (2 psec)
sigma=10.21 psec2035 events
Figure: Gaussian fit. Noise filter is OFF.
Pulses with amplitude between 110 and 130 mV selected.
Parameter t0 of Gaussian fit to the pulse shape is timing for the fitresults.
A. Vostrikov (UChicago) Time Resolution Measurements for 8” MCP January 29, 2013 9 / 12
Time resolution: Pulse shape fitting effect
0 50 100 150Time difference, psec
0
50
100
150
200
250
Eve
nts / (2 psec)
sigma=6.90 psec1988 events
Figure: Spline. Noise filter is ON.
0 50 100 150Time difference, psec
0
50
100
150
200
250
Eve
nts / (2 psec)
sigma=6.86 psec1988 events
Figure: Gaussian fit. Noise filter is ON.
A. Vostrikov (UChicago) Time Resolution Measurements for 8” MCP January 29, 2013 10 / 12
Differential time resolution vs. Pulse amplitude
0 50 100 150 200 250Pulse amplitude, mV
0
5
10
15
20
25
30
35
40
Differe
ntial time reso
lution, pse
c
CFD
Fit
CFD @ 800 MHz
Fit @ 800 MHz
Figure: Differential time resolution as afunction of pulse amplitude.
0 5 10 15 20 25 30Inverse ppulse amplitude, 1/V
0
5
10
15
20
25
30
35
40
Differential time resolution, psec
CFD
Fit
CFD @ 800 MHz
Fit @ 800 MHz
Figure: Differential time resolution as afunction of inverse pulse amplitude.
A. Vostrikov (UChicago) Time Resolution Measurements for 8” MCP January 29, 2013 11 / 12
Time Resolution Measurements for 8” MCP:Noise Filter and Shape Fitting
Alexander Vostrikov
University of Chicago
January 29, 2013
Fast Timing (PSEC) Group Tuesday Regular Meeting
A. Vostrikov (UChicago) Time Resolution Measurements for 8” MCP January 29, 2013 12 / 12
