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Solid-State Radiation Damage Studies: Measurements and FLUKA Simulation

This presentation discusses the measurements and FLUKA simulations of radiation damage in solid-state detectors. It includes information on various sensor types, their charge collection capabilities, and their response to different levels of radiation exposure. The study also compares the damage caused by ionizing radiation and neutron irradiation. The results provide valuable insights for the development of durable and reliable detectors for particle physics experiments.

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Solid-State Radiation Damage Studies: Measurements and FLUKA Simulation

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  1. Solid-State Radiation Damage Studies: Measurements and FLUKA Simulation FCAL Hardware Meeting November 15, 2017 Bruce Schumm UC Santa Cruz Institute for Particle Physics

  2. 2 X0 pre-radiator; introduces a little divergence in shower Sensor sample Not shown: 4 X0 “post radiator” and 8 X0 “backstop”

  3. Silicon Diode Sensors • n-bulk (N) and p-bulk (P) • Both float-zone (F) and Magnetic Czochralski (M) for each of N,P • 300-400 m thick bulk • Various manufacturers • Heaviest doses for pad (not strip) sensors 3

  4. PF Type Charge Collection for 270 Mrad @600 V, ~20% charge collection loss (60C annealing) “T506 Standard” Sensor (BeamCal performance estimates based on this result 270 Mrad = 1 “T506” of exposure PF Si Diode Sensor 4

  5. PF Type Charge Collection for 570 Mrad Currents roughly x2 more than for 270 Mrad 570 Mrad Exposure PF Si Diode Sensor 5

  6. NF Type Charge Collection for 300 Mrad @600 V, ~40% charge collection loss (58C annealing) 1-hour annealing steps 300 Mrad Exposure NF Si Diode Sensor 6

  7. NC Type Charge Collection for 300 Mrad Breakdown (probably not fundamental) limited VB @600 V, charge collection loss likely less than 30% 300 Mrad Exposure NC Si Diode Sensor Annealing vs. time (at ~250 C) rather than vs. temperature

  8. N-Type LumiCal Prototype Fragment After annealing, charge collection at 600V likely well above 50% after 300 Mrad exposure Sensor via Sasha Borisov, Tel Aviv 300 Mrad Exposure “LumiCal” N-Type Diode Sensor 8

  9. Silicon Diode Currents • Appear to be similar from one technology to the other • Appear to scale roughly linearly with dose • Not affected by high-temp annealing • These are expected • Thus, focus on one sensor: the 270 Mrad exposure of sensor WSI-P4 (PF-type) 9

  10. PF Type I vs. Temperature; 270 Mrad 270 Mrad Exposure Current doubling for event ~70 C (expected) Detector area is about 0.025 cm2 10

  11. Radiation Exposure Unit For comparisons between sensors and sensor technologies, for both charge collection and (for Si) current/power draw Define exposure in “T506” units. One “T506” equals • 270 Mradof ionizing (e+- induced) energy loss • 2.7x1011 “RAND” (see below) of neutron-induced non-ionizing energy loss (NIEL) 11

  12. Comparison to Neutron Irradiation Results Based on results from numerous neutron-irradiation studies, Lindstrom et al. NIMA 466(2),308 [2001] provide a damage proportionality factor  that relates neutron fluence to current density at T = -100 C. Using FLUKA to estimate the T506 neutron fluence (see below), and the expected temperature dependence for a 2.50 C extrapolation, we converted this to an expectation for the T506 current density • Numbers agree within a few % (better than they should!) • Supports (but doesn’t prove) the notion that T506 leakage current is due primarily to non-ionizing energy loss (NIEL) from neutrons 12

  13. Gallium Arsenide Sensor provided by Georgy Shelkov, JINR Sn-doped Liquid-Encapsulated Czochralski fabrication 300 m thick 13

  14. GaAs Charge Collection for 21 Mrad Significant charge collection loss 21 Mrad Exposure (0.08 “T506”) GaAs Sensor 14

  15. GaAs Pre- and Post-Irradiation Current Draw For VB = 600 V; post-irradiation after 75oC anneal 21 Mrad Exposure (0.08 T506) GaAs Sensor 15

  16. Industrial Sapphire Sensor provided by Sergej Schuwalow Fabricated by Crystal GmbH, Berlin Layered Al-Pt-Au contact structure Current low (< 10 nA) after irradiation 16

  17. Sapphire Charge Collection for 300 Mrad Low pre-irradiation charge-collection and significant charge loss after irradiation Sensors via Sergej Schuwalow, DESY Zeuthen 500 m thick Al2O3 300 Mrad Exposure (1.1 “T506”) 17

  18. Silicon Carbide Sensor provided by Bohumir Zatko, Bratislava Schottky-barrier contacts mounted on 4H-SiC structure Epitaxial (active) layer thickness 70 m 18

  19. SiC Charge Collection for 77 Mrad 4H SiC Sensor 98C anneal 77 Mrad Exposure (0.29 “T506”) Charge collection mostly above 50% 19

  20. BeamCal Neutrons from FLUKA Many thanks to Ben Smithers, UCSC undergraduate 20

  21. BeamCal Simulation in FLUKA(Ben Smithers, SCIPP) • BeamCal absorbs about 10 TeV per crossing, resulting in electromagnetic doses as high as 100 Mrad/year • Associated neutrons can damage sensors and generate backgrounds in the central detector • GEANT not adequate for simulation of neutron field  implement FLUKA simulation • Design parameters from detailed baseline description (DBD) • Primaries sourced from single Guinea Pig simulation of e+- pairs associated with one bunch crossing

  22. FLUKA Simulation: 270 Mrad T506 Baseline • 51 C of 13.3 GeV SLAC ESA electrons onto target • Raster over 1 cm2 area • Realistic mix of e± and neutrons (Giant Dipole Resonance) Project: Assuming this baseline damage is due entirely to neutron dose, use FLUKA to estimate damage effects throughout BeamCal 22

  23. T506 Neutron Fluence from FLUKA Mean number of neutrons per cm2 per 13.3 GeV primary 23

  24. T506 Neutron Dose (Step 1/3) 24

  25. T506 Neutron Dose (Step 2/3): NIEL Scaling 25

  26. NIEL in Silicon N(E) 26

  27. T506 Neutron Energy Spectrum (FLUKA) • In range where N(E) is slowly varying • Note that N(E) is for Si only; caveat (small?) for drawing assumptions about GaAs, Sapphire, SiC Peaks around Ecrit for Tungsten 27

  28. T506 Neutron Dose (Step 3/3) “T506 Unit” of Neutron Dose 28

  29. FLUKA Scoring Planes for BeamCal (Layers 12 and 30) A B C 29

  30. Layer 12 Fluence Profile (Position B) • Much less ballistic than T506 • Rand/Rad ratio much ;arger Layer 12 Position B 30

  31. Layer 12 Neutron NIEL for one Snowmass Year (107 s), T506 Units Recall: T506 about 3 years’ dose of electromagnetic radiation 31

  32. Layer 30 Neutron NIEL for one Snowmass Year (107 s), T506 Units Recall: T506 about 3 years’ dose of electromagnetic radiation 32

  33. Estimated Si Sensor Power Draw by Layer after a Snowmass Year, at -100 C • Integral for -100 C would be ~80 W • Integral for -300 C would be ~10 W 33

  34. Summary • Four different sensor technologies studied • Much CC loss at 300 Mrad, Si does OK though. • Si develops significant leakage current, consistent with prior observations for neutron-induced damage; no such comparison for CCE or for the other sensor technologies • Neutron field simulated via FLUKA and benchmarked with T506 • If radiation damage is neutron-dominated, somewhat larger and much more widespread than if EM-induced damage • Results are preliminary: Awaiting confirmation! 34

  35. Backup 35

  36. Layer 2 Detector - Fluence E+&E- Neutrons

  37. Layer 4 Detector - Fluence E+&E- Neutrons

  38. Layer 6 Detector - Fluence E+&E- Neutrons

  39. Layer 8 Detector - Fluence E+&E- Neutrons

  40. Layer 10 Detector - Fluence E+&E- Neutrons

  41. Layer 12 Detector - Fluence Neutrons

  42. Layer 14 Detector - Fluence Neutrons

  43. Layer 16 Detector - Fluence Neutrons

  44. Layer 12 Fluence Profile Position A Layer 12 Position A 44

  45. Layer 12 Fluence Profile Position C Layer 12 Position C 45

  46. Layer 30 Fluence Profile Position A Layer 30 Position A 46

  47. Layer 30 Fluence Profile Position B Layer 30 Position B 47

  48. Layer 30 Fluence Profile Position C Layer 30 Position C 48

  49. Energy Deposition vs. Angle • In MeV/cm3 per beam crossing • From GUINEA Pig incoherent pairs But recall caveat! 49

  50. T506 Neutron Fluence (Reminder) 50

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