What is known experimentally about timing determinants in MCP detectors

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


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.


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



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.


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 is determined by the signal to noise ratio.


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.


Experimental setup

Synchrotron generated photon pulses

~ 70 ps wide, 2 ns apart

2D Imaging +time for each

detected photon

Scattered photons

Thin film samples



Timing resolution: single photoelectron

Elastically scattered photons

0

50

100

150

200

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



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


Timing resolution vs. MCP gain

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

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)

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,

130 ps FWHM


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


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

0

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


MCP output pulse with a 50 anode

Peter Wurz and Lukas Gubler, Rev. Sci. Instrum. 67 (5), 1996

25 um pores

10 um pores


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


Pulse widths from the MCP vs. pore diameter






E. Schyns, Clermont-Ferrand, January 2010











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.

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0 50 100 150 200 250 300 350 400

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


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

-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

-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



Self triggered timing resolution

-0.6

-0.4

-0.2

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



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)

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What is known experimentally about timing determinants in MCP detectors

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