A Particle Time Tagger with Picosecond ResolutionThe Radio Frequency Photomultiplier Tube

A. Margaryan, R. Ajvazyan, S. ZhamkochyanAlikhanyan National Science Laboratory, Yerevan, Armenia

J.R.M. AnnandSchool of Physics and Astronomy, University of Glasgow, Scotland, UK

Measurement of the passage of time is an ancient preoccupation

10000 yr BP5000 yr BP 1300 yr BP

Outline

Principles of operationMeasured and simulated performanceExtension from spherical to spiral scanningSome Applications, Cherenkov ...Outlook

27th June 2013 The Radio Frequency Photomultiplier Tube A.Margaryan/J.R.M. Annand 3

The Radio Frequency Photomultiplier TubePrinciple of Operation

Circular sweep RF deflection of photo electronsConvert time to spatial dependenceFast position sensitive electron detectorMCP Gain ~107

Single photon counting possiblePrototype device resistive anodeFast ~ns output pulse

Operates similar to circularstreak camera.However produces ns outputpulses like standard PMT.

A. Margaryan et al., Nucl. Instr. and Meth. A566,321,2006

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RF Scanning SystemEvacuated Test Tube with Thermionic Cathode

Image of CW electron beamcircle with radius ~20 mm

20 V, 0.5 → 1 GHzScan radius 1 mm/V (0.1 rad/W1/2)

Ele

ctro

n G

un

Ele

ctro

de

Pho

spho

r S

cree

nActual structure of RF deflectors for 500 MHz operation

Deflection of the electron by the circular polarised magnetic field generatedby the RF caviry

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1 GHz RFPMT Output Pulses Resistive AnodeCircularly scanned 2.5 keV electrons incident on

Baspik, 25-10y, Chevron MCP array

Recorded by TDS3054B, 500 MHz, 5 GS/s

Direct from RFPMT anode After amplifier

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Simulation of Transit Time Spread (Simion-8: charged particle trajectories in EM fields)

HV = 2.5 kV

HV = 5.0 kV

HV = 10 kV

TTS (ps) to cross-over at D1TTS (ps) to MCP electron detector

HV: K-to-E1HV: Cathode to Electrode

Simulation does not considertime dispersion of Cherenokov photons

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Pixelated Anode:Read “Time” directly

Amp. Discr. Encoder Memory

Pixelated Anode

Macro Time: RF cycle number

Micro Time: pixel number

Time = N/RF

+ i /2

RF

No TDC necessary

Position of hit on anode directly related to hit time1st tubes use charge division from resistive anode to obtain Pixelated anode... record time directly1 GHz, 20mm radius →8ps/mmRecord short flash with high precisionOr record the time dependence of an extended signalGets more complicated if signal covers more than 1 RF cycleExtend micro time range by “spiral” scan

i

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Spiral Scanning with 2 RF Deflectors

Gun

Accelerating Electrode

Lens

RF1: 1

RF2: 2 = 1.1

1

Scr

een Apply 2 RF fields, of slightly different

frequency“Beat” in superposed response modulates radius of scanned circle

Period of Spiral

Pixelated anode necessary

Spiral scan: Y.D. Chernousov et.al. NIM-A451,2000,541

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Spiral Scan Images: Phosphor Screen

750 MHz Only 825 MHz Only 750 & 825 MHz Combined

Possibilities for Pixelated Anode?Need large fast deviceMPPC Multiple pixel APDOff-the-shelf devices havecommon readoutrelatively small areaPulse length relatively longbut sharp rise timeCustom detectors available?

Test with 20 mm scint. foil + S10362 MPPC

S103621 mm2

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Potential RFPMT ApplicationsNuclear Physics:

Cherenkov DetectorHigh precision time of flight measurementsMomentum measurement, Particle IDProposed use JLab (e.g. PR12-10-001 experiment)

Medical Imaging: Positron Emission Tomography (PET)Array Cherenkov detectors of back-to-back 'sTime of flight of back-to-back's coordinatealong line of flight of 's (10 ps gives ~2.5 mm)

Gravitational Red ShiftFrequency shift of identical clocksplaced at different gravitational potential

(1 + )U/c2

= 0 if relativity holdsH ~ 400m, U/c2 ~ 4.4 x 10-14

Determine upper limit on 7 x 10-6

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Cherenkov Simulation

Ingredients1 GeV/c Radiator parametersquartz:= 1.47number detected photo electronsquartz + bialkalai: N

PE = 155/cm

Timing precision of RFPMT= 5ps

Single-photon time distribution

Mean-time distribution

L = 25 mm

L = 10mm PMT

2 GeV/c, L=25 mm

Quartz

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Particle Separation by Propagation Time

1.5 GeV/c

2.0 GeV/c

3.0 GeV/c

Propagation Time (ps)

Propagation Time (ps)

Propagation Time (ps)

Quartz RadiatorL = 1000 mmPerpendicular incidenceTime resolution RFPMT 15 psMC calculation for 5000 and 5000 at each incident momentumTrack Cherenkov photons to RFPMT

Idealised calculation L = 1000 mm, 2 GeV/c

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Possible Application LHC

M.G. Albrow et al., arXiv:0806.0302v2 [hep-ex]

GAS-TOFCherenkov

Substitute RFPMT ?

Measure forward protonsproduced in collisions at ATLAS& CMS. Times T

1 & T

2

Synchronise RF for RFPMTwith LHC beam bucketsDetect p by left/right GAS-TOFBackground rejection frominteraction point from T

1 - T

2

Calibration from independentvertex measurement

420 m flight path

In principle RFPMT can besynchronised with the acceleratorRF system:Mainz 2.5 GHzJLab 0.5 GHz (to each hall)

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Summary & Outlook

Extensive testing with thermionic electron sourceRF deflector works efficientlyachieves ~0.1 rad/W1/2, (1mm/V)

Circular scanning working at 1 GHzSpiral scanning working with 750, 825 MHzSimulations predict small transit time spreads possible< 1ps point cathode, around 5ps extended cathodePotential applications in hadron physics identified(as well as many other fields)A prototype RFPMT has been designed at Photek Ltd.Need additional funding to start small-scale productionand quantitative testing of timing precisionDevelopment continues at Yerevan

Thanks for your attention