microscope performance at elevated dark rates richard jones university of connecticut collaboration...

Microscope PerformanceMicroscope Performance

at elevated dark ratesat elevated dark rates

Richard JonesUniversity of Connecticut

GlueX collaborationcollaboration meeting, Newport News, Feb. 2-4, 2011

GlueX collaboration meeting, Newport News, Feb. 2-4, 20112

Outline the microscope readout

effects of neutron radiation

Monte Carlo model

simulation of a pulse train

time resolution

detection efficiency

results vs. dark rate

lifetime projections


the microscope readout

spectrum coverage70% - 75% in 0.1% steps

energy resolution0.5% (60 MeV) r.m.s.

rate capability500 MHz per GeV

tagging ratiooptimum goal 70%

rates at 2.2 A on a 10-4 radiator (108 /s)Design requirementsDesign requirements


the microscope readout

Design parametersDesign parameters square scintillating fibers

size 2 x 2 x 20 mm3

clear light guide fibers

aligned along electron along electron directiondirection for reduced background sensitivity

readout with silicon silicon photomultipliersphotomultipliers (SiPMs)SiPMs)

focal plane

electron trajectory

SiPM sensors

scintillating fibers

clear light fibers



Neutron rates estimated using tagger hall simulation [1].

Experiments show the main effect of radiation damage on SiPM’s is to increase the dark rate [2,3].

in the region of the microscope readout

without shielding 180 mrem/h180 mrem/h

with shielding 30 mrem/h30 mrem/h

when operating the beam at full intensity of 108 /s on the GlueX target

[1] A. Somov, “Neutron Background Estimates in the Tagger Hall”, gluex-doc-1646, 2010.

[2] Y. Qiang, “SiPM Radiation Hardness Test”, report available at http://www.jlab.org/Hall-D/software/wiki/index.php/SiPM Radiation Hardness Test

[3] Y. Musienko, D. Renker, Z. Charifoulline, K. Deiters, S. Reucroft, and J. Swain, “Study of Radiation Damage Induced by 82 MeV Protons on Multi-pixel Geiger-Mode Avalanche Photodiodes”, Nucl. Instr. Meth. A610 (2009) 87-92.

units chosento assess Sidevice effects



Measurements made at Jlab in Hall A

[2] Y. Qiang, “SiPM Radiation Hardness Test”, report available at http://www.jlab.org/Hall-D/software/wiki/index.php/SiPM Radiation Hardness Test

total dose after 33 h = 153 rem

Hamamatsu 3mm MPPC

rise is roughly linear

remains after recovery period

slope is factor 8 / 100 rem8 / 100 rem

some evidence that the slope is decreasing with dose

initial dark rate: 6 MHz6 MHzfinal dark rate: 72 MHz72 MHz



Measurements with 82 MeV protons at PSI


2x1010/cm2 of 1 MeV neutron-equivalent flux

use Hall A conversion factor

total dose: 830 rem830 rem

expected DR increase: x 67x 67

observed DR increase: x 33x 33

results are consistent if one allows for nonlinear increase

1 rem → 2.4 × 107 neq/cm2



Measurements with 82 MeV protons at PSI



tagger hall projections

10 year lifetime of readout electronics 107 seconds of beam per year always running at full intensity

projected dark rate increase

total beam time: 28,000 hneutron dose: 5,000 rem (unshielded)

900 rem (shielded)

linear from [2]: 400 (unshielded)linear from [3]: 200 (unshielded)

35 (shielded)


Monte Carlo model of a SiPM

single pixel behavior:single pixel behavior:

• gain = Cpixel(Vb-VBD)

• recovery is exponential

• recovery time constant

• “recovery time” = 3r = time for pixel to reach 95% of full gain

t

VVb

VBD r

gain

r = Rquench (Cpixel+Cquench)


Monte Carlo model of a SiPM

expected pulse height distributionexpected pulse height distribution

energy deposition in scintillator number of pixels @ 15% PDE


simulation questions

1.1. Can the performance goals be achieved with Can the performance goals be achieved with SiPM readout, under initial dark rate conditions?SiPM readout, under initial dark rate conditions?

2.2. What is the performance like at elevated dark rate?What is the performance like at elevated dark rate?

parameter design goalsingle-channel pulse rate 4 MHzelectron detection efficiency 95 %electron hit time resolution 200 ps

HintHint: there is a scale set for dark rate by the rate x <pulse height>

109 Hz


simulation of a single pulse

pulse model includes SiPM, preamp, and 40’ cable pulse shape was validated in bench tests with 2x2 CPTA device points are from model, curve is an empirical fit to the points


simulation of a pulse train

• pulse train simulated by summing pulses from individual pixels• includes scintillator decay time, pixel recovery, cross-talk, …

after-pulses

Hamamatsu S10931-25P MPPC at 4 MHz signal and 10 GHz dark rate


pulse height distributions

• first results:first results: signal pulse heights at 4 MHz and 107 Hz dark rate• news:news: the CPTA (Photonique) device is saturating (r = 1 s)• Hamamatsu device is okHamamatsu device is ok (r = 15 ns) – hence the after-pulsing !hence the after-pulsing !

Hamamatsu 3x3mm2 MPPC CPTA 2x2mm2 SSPM


time resolution study

time walk correction time resolution (RMS)

• Hamamatsu device at 4 MHz signal, 10 MHz dark rateHamamatsu device at 4 MHz signal, 10 MHz dark rate


time resolution study

• Hamamatsu device at 4 MHz signal, elevated dark ratesHamamatsu device at 4 MHz signal, elevated dark rates• effects in time resolution start to become noticeable at effects in time resolution start to become noticeable at 10101010 Hz Hz

dark rate 10 GHzdark rate 10 GHz dark rate 100 GHzdark rate 100 GHz


efficiency study

• Hamamatsu device at 4 MHz signal, elevated dark ratesHamamatsu device at 4 MHz signal, elevated dark rates• effects in efficiency start to become noticeable at 10effects in efficiency start to become noticeable at 101010 Hz Hz

dark rate 10 GHzdark rate 10 GHz dark rate 100 GHzdark rate 100 GHz


conclusions

• CPTA (Photonique) device is ruled out based on insufficient high-rate capability (slow pixel recovery)

• Hamamatsu 3x3mm device (14,400 pixels) meets all of the requirements for the microscope readout.

• Estimates for dark rate in a microscope readout based on the MPPC S10931-025P are in the range 0.8 – 1.6 GHz after 10 years of expected operation.

• Simulation has shown that the Hamamatsu MPPC Simulation has shown that the Hamamatsu MPPC can satisfy all performance requirements up to dark can satisfy all performance requirements up to dark rates of 10 GHz, which gives a healthy safety factor.rates of 10 GHz, which gives a healthy safety factor.

microscope performance at elevated dark rates richard jones university of connecticut collaboration...

Documents

newport news

sipm radiation hardness

study of radiation damage

gluex target

mev protons

rem slope

si device effects slide

rem total dose