1. Microscope Performance at elevated dark rates Richard Jones University of Connecticut collaboration GlueX collaboration meeting, Newport News, Feb. 2-4, 2011

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

3. GlueX collaboration meeting, Newport News, Feb. 2-4, 2011 3 the microscope readout  spectrum coverage 70% - 75% in 0.1% steps  energy resolution 0.5% (60 MeV) r.m.s.  rate capability 500 MHz per GeV  tagging ratio optimum goal 70% rates at 2.2  A on a 10 -4 radiator (10 8  /s) Design requirements

4. GlueX collaboration meeting, Newport News, Feb. 2-4, 2011 4 the microscope readout Design parameters  square scintillating fibers  size 2 x 2 x 20 mm 3  clear light guide fibers along electron direction  aligned along electron direction for reduced background sensitivity silicon photomultipliersSiPMs)  readout with silicon photomultipliers (SiPMs) focal plane electron trajectory SiPM sensors scintillating fibers clear light fibers

5. GlueX collaboration meeting, Newport News, Feb. 2-4, 2011 5 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 180 mrem/h without shielding180 mrem/h 30 mrem/h with shielding 30 mrem/h when operating the beam at full intensity of 10 8  /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 chosen to assess Si device effects

6. GlueX collaboration meeting, Newport News, Feb. 2-4, 2011 6 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 8 / 100 rem  slope is factor 8 / 100 rem  some evidence that the slope is decreasing with dose 6 MHz initial dark rate: 6 MHz 72 MHz final dark rate: 72 MHz

7. GlueX collaboration meeting, Newport News, Feb. 2-4, 2011 7 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. 2x10 10 /cm 2 of 1 MeV neutron-equivalent flux  use Hall A conversion factor 830 rem  total dose: 830 rem x 67  expected DR increase: x 67 x 33  observed DR increase: x 33  results are consistent if one allows for nonlinear increase 1 rem → 2.4 × 10 7 n eq /cm 2

8. GlueX collaboration meeting, Newport News, Feb. 2-4, 2011 8 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.

9. GlueX collaboration meeting, Newport News, Feb. 2-4, 2011 9 tagger hall projections  10 year lifetime of readout electronics  10 7 seconds of beam per year  always running at full intensity  projected dark rate increase total beam time: 28,000 h neutron dose: 5,000 rem (unshielded) 900 rem (shielded) linear from [2]: 400 (unshielded) linear from [3]:200 (unshielded) 35 (shielded)

10. GlueX collaboration meeting, Newport News, Feb. 2-4, 2011 10 Monte Carlo model of a SiPM single pixel behavior: gain = C pixel (V b -V BD ) recovery is exponential recovery time constant “recovery time” = 3  r = time for pixel to reach 95% of full gain t V VbVb V BD rr gain  r = R quench (C pixel +C quench )

11. GlueX collaboration meeting, Newport News, Feb. 2-4, 2011 11 Monte Carlo model of a SiPM expected pulse height distribution energy deposition in scintillatornumber of pixels @ 15% PDE

12. GlueX collaboration meeting, Newport News, Feb. 2-4, 2011 12 simulation questions 1.Can the performance goals be achieved with SiPM readout, under initial dark rate conditions? 2.What is the performance like at elevated dark rate? parameterdesign goal single-channel pulse rate 4 MHz electron detection efficiency 95 % electron hit time resolution200 ps Hint Hint: there is a scale set for dark rate by the rate x 10 9 Hz

13. GlueX collaboration meeting, Newport News, Feb. 2-4, 2011 13 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

14. GlueX collaboration meeting, Newport News, Feb. 2-4, 2011 14 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

15. GlueX collaboration meeting, Newport News, Feb. 2-4, 2011 15 pulse height distributions first results:first results: signal pulse heights at 4 MHz and 10 7 Hz dark rate news:news: the CPTA (Photonique) device is saturating (  r = 1  s) Hamamatsu device is okhence the after-pulsing !Hamamatsu device is ok (  r = 15 ns) – hence the after-pulsing ! Hamamatsu 3x3mm 2 MPPC CPTA 2x2mm 2 SSPM

16. GlueX collaboration meeting, Newport News, Feb. 2-4, 2011 16 pulse height distributions first results:first results: signal pulse heights at 4 MHz and 10 7 Hz dark rate news:news: the CPTA (Photonique) device is saturating (  r = 1  s) Hamamatsu device is okhence the after-pulsing !Hamamatsu device is ok (  r = 15 ns) – hence the after-pulsing ! Hamamatsu 3x3mm 2 MPPC CPTA 2x2mm 2 SSPM

17. GlueX collaboration meeting, Newport News, Feb. 2-4, 2011 17 time resolution study time walk correctiontime resolution (RMS) Hamamatsu device at 4 MHz signal, 10 MHz dark rateHamamatsu device at 4 MHz signal, 10 MHz dark rate

18. GlueX collaboration meeting, Newport News, Feb. 2-4, 2011 18 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 10 10 Hzeffects in time resolution start to become noticeable at 10 10 Hz dark rate 10 GHz dark rate 100 GHz

19. GlueX collaboration meeting, Newport News, Feb. 2-4, 2011 19 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 10 10 Hzeffects in efficiency start to become noticeable at 10 10 Hz dark rate 10 GHz dark rate 100 GHz

20. GlueX collaboration meeting, Newport News, Feb. 2-4, 2011 20 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 can satisfy all performance requirements up to dark rates of 10 GHz, which gives a healthy safety factor.Simulation has shown that the Hamamatsu MPPC can satisfy all performance requirements up to dark rates of 10 GHz, which gives a healthy safety factor.

21. GlueX collaboration meeting, Newport News, Feb. 2-4, 2011 21