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
GlueX collaboration meeting, Newport News, Feb. 2-4, 20113
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
GlueX collaboration meeting, Newport News, Feb. 2-4, 20114
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
GlueX collaboration meeting, Newport News, Feb. 2-4, 20115
effects of neutron radiation
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
GlueX collaboration meeting, Newport News, Feb. 2-4, 20116
effects of neutron radiation
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
GlueX collaboration meeting, Newport News, Feb. 2-4, 20117
effects of neutron radiation
Measurements with 82 MeV protons at PSI
[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.
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
GlueX collaboration meeting, Newport News, Feb. 2-4, 20118
effects of neutron radiation
Measurements with 82 MeV protons at PSI
[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.
GlueX collaboration meeting, Newport News, Feb. 2-4, 20119
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)
GlueX collaboration meeting, Newport News, Feb. 2-4, 201110
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)
GlueX collaboration meeting, Newport News, Feb. 2-4, 201111
Monte Carlo model of a SiPM
expected pulse height distributionexpected pulse height distribution
energy deposition in scintillator number of pixels @ 15% PDE
GlueX collaboration meeting, Newport News, Feb. 2-4, 201112
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
GlueX collaboration meeting, Newport News, Feb. 2-4, 201113
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
GlueX collaboration meeting, Newport News, Feb. 2-4, 201114
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
GlueX collaboration meeting, Newport News, Feb. 2-4, 201115
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
GlueX collaboration meeting, Newport News, Feb. 2-4, 201116
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
GlueX collaboration meeting, Newport News, Feb. 2-4, 201117
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
GlueX collaboration meeting, Newport News, Feb. 2-4, 201118
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
GlueX collaboration meeting, Newport News, Feb. 2-4, 201119
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
GlueX collaboration meeting, Newport News, Feb. 2-4, 201120
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.
GlueX collaboration meeting, Newport News, Feb. 2-4, 201121