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Long term annealing of neutron irradiated detectors evaluated at LHC operational temperatures

Investigating the impact of extended annealing on heavily irradiated detectors at operational temperatures of the Large Hadron Collider for radiation hardness evaluation. The study explores correlations and compares radiation resistance through various processing steps and evaluations at different institutes.

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Long term annealing of neutron irradiated detectors evaluated at LHC operational temperatures

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  1. Long term annealing of neutron irradiated detectors evaluated at LHC operational temperatures E. Verbitskaya, V. Eremin, I. Ilyashenko Ioffe Physico-Technical Institute of Russian Academy of Sciences St. Petersburg, Russia Z. Li Brookhaven National Laboratory, Upton, NY, USA J. Härkönen Helsinki Institute of Physics, CERN/PH, Geneva, Switzerland Marko Mikuž, Vladimir Cindro Jožef Stefan Institute, Ljubljana Chris Parkes Glasgow University 8 RD50 Collaboration Workshop Prague, June 25-28, 2006

  2. Type of Si Processing Radiation characteristics of heavily irradiated detectors Technotest Goal of the project: Finding correlations and comparison of radiation hardness with respect to: E. Verbitskaya et al., 8 RD50 Workshop, Prague, June 25-28, 2006

  3. Technotest Participants Detector processing: ♦Ioffe Physico-Technical Institute (PTI) + Research Institute of Material Science and Technology (RIMST) ♦ BNL ♦ Helsinki Institute of Physics (HIP) Irradiation: ♦ CERN (protons 24 GeV/c) ♦ Iosef Stefan Institute, Ljubljana (neutrons 1 MeV) Evaluation ♦ Ioffe Physico-Technical Institute ♦ BNL ♦ HIP ♦ Iosef Stefan Institute ♦ Glasgow University E. Verbitskaya et al., 8 RD50 Workshop, Prague, June 25-28, 2006

  4. Status of the work • Experiments carried out: •  detectors processed at three institutions  irradiated by 1 MeV neutrons, Fn = 11010- 51015 cm-2  irradiated by 24 GeV/c protons, Fp = 11014 and 11015 cm-2 1 MeV neutrons: pres. 5 RD50 Workshop, Florence I-V characteristics, TCT signal 24 GeV protons: pres. 7 RD50 Workshop, CERN SCSI in detectors from MCZ Si; Vfd and Neffinin long term annealing Current study in 2006 1 MeV neutrons: studies of annealing (initial stage)  detectors processed from MCZ and FZ n-type Si  annealing at 80°C E. Verbitskaya et al., 8 RD50 Workshop, Prague, June 25-28, 2006

  5. Experimental samples Resistivity, kW·cm n-Si FZ: 4-6 n-Si MCZ: 1 E. Verbitskaya et al., 8 RD50 Workshop, Prague, June 25-28, 2006

  6. Manufacturing procedure E. Verbitskaya et al., 8 RD50 Workshop, Prague, June 25-28, 2006

  7. Experimental annealings: 80C, steps with variable time  TCT using 840 nm laser pulse generation of free carriers, p+ side, n+ side Current pulse response is measured at RT and -15C (ATLAS) All measurements: range of bias voltage 20/50-900 V E. Verbitskaya et al., 8 RD50 Workshop, Prague, June 25-28, 2006

  8. Current pulse response, n-Si, Fn = 51013 cm-2 Before annealing PTI-Cz-c12, n+ side PTI-FZn2-b11, p+ side Before annealing: FZ Si: SCSI (-SC) MCZ Si : no SCSI (all samples) - evaluation of response from n+ side, hole collection V: 10-900 V E. Verbitskaya et al., 8 RD50 Workshop, Prague, June 25-28, 2006

  9. MCZ Si, Fn = 51013 cm-2:different processing RT RT -15 C RT tcoll is smaller at -15C E. Verbitskaya et al., 8 RD50 Workshop, Prague, June 25-28, 2006

  10. Fn = 5 e13 cm-2, tann= 76 min RT RT RT -15C E. Verbitskaya et al., 8 RD50 Workshop, Prague, June 25-28, 2006

  11. Evolution of response under annealing,MCZ Si, Fn = 51013 cm-2, V = 200 V, hole collection RT: detector is fully depleted, +Neff decreases – E becomes more uniform E. Verbitskaya et al., 8 RD50 Workshop, Prague, June 25-28, 2006

  12. Evolution of response under annealing 200 V Dependence of vdr vs. E and T Pulse width: depends on vdr(T) Difference: Low E: e – 30%, h – 50% High E: e, h – 10% E. Verbitskaya et al., 8 RD50 Workshop, Prague, June 25-28, 2006

  13. Q vs. V and tsh , MCZ n-Si, Fn = 51013 cm-2 tsh = 10 ns Total charge, RT tsh – shaping time E. Verbitskaya et al., 8 RD50 Workshop, Prague, June 25-28, 2006

  14. Q vs. V and tsh , MCZ n-Si, Fn = 51013 cm-2 E. Verbitskaya et al., 8 RD50 Workshop, Prague, June 25-28, 2006

  15. Current pulse response, MCZ n-Si, Fn = 51014 cm-2 Different processing p+ side, electron collection Before annealing V: 50-900 V RT RT Double Peak shape with different H1/H2 RT -15 C E. Verbitskaya et al., 8 RD50 Workshop, Prague, June 25-28, 2006 SCSI for all detectors, at RT and -15 C

  16. Fn = 5 e14 cm-2, tann= 156 min, RT H1/H2 ratio in DP is different: E(x) is different Practical aspect: tcoll is sensitive to technology E. Verbitskaya et al., 8 RD50 Workshop, Prague, June 25-28, 2006

  17. Fn = 5e14 cm-2, tann= 156 min, -15C At -15C: Pronounced DP with H1/H2>1 even at 900 V - reduction of E at n+ side E. Verbitskaya et al., 8 RD50 Workshop, Prague, June 25-28, 2006

  18. Evolution of response under annealingMCZ Si, Fn = 51014 cm-2 V = 500 V, RT Electron collection E(x) changes from full depletion to partial depletion at RT and -15C E. Verbitskaya et al., 8 RD50 Workshop, Prague, June 25-28, 2006

  19. Evolution of response under annealing,MCZ Si, Fn = 51014 cm-2, V = 500 V • is the same at RT and –15C • = 6 ns - lowest value! E. Verbitskaya et al., 8 RD50 Workshop, Prague, June 25-28, 2006

  20. Q vs. V under annealingMCZ n-Si, Fn = 51014 cm-2 Single peak  Double peak  E. Verbitskaya et al., 8 RD50 Workshop, Prague, June 25-28, 2006

  21. Q vs. V and tsh at RT and –15C Visible CCE reduction at tsh = 10 ns  Reduction is less at –15C(vdr) E. Verbitskaya et al., 8 RD50 Workshop, Prague, June 25-28, 2006

  22. Different processing, Q vs. V at RT Difference in H1/H2 E. Verbitskaya et al., 8 RD50 Workshop, Prague, June 25-28, 2006

  23. Vfd and Neff evaluated from pulse responseinitial annealing stage Vfd E. Verbitskaya et al., 8 RD50 Workshop, Prague, June 25-28, 2006

  24. Neff evaluated from pulse response Effective macroscopic parameters: As-irradiated MCZ Si detectors: Annealing 160 min: 5e13 cm-2: sensitive to processing reduces sensitivity 5e14 cm-2: no sensitivity E. Verbitskaya et al., 8 RD50 Workshop, Prague, June 25-28, 2006

  25. n+ p+ E2 E1 Eb Wb W2 W1 Reconstruction of E(x) from DP response Fn = 5e14 cm-2 p+ Electric field gradient dE/dx and Neff in the region adjacent to p+ contact are different and sensitive to detector processing  difference in balance of DDs and DAs induced by radiation E. Verbitskaya et al., 8 RD50 Workshop, Prague, June 25-28, 2006

  26. E(x) reconstruction HIP-Cz-66 PTI-Cz-d11 E. Verbitskaya et al., 8 RD50 Workshop, Prague, June 25-28, 2006

  27. Conclusions Detectors from n-type MCZ silicon irradiated by 1MeV neutrons Fn = 51013 cm-2 • Space Charge (+) • Insignificant difference of pulse response before and after annealing  Fn = 51014 cm-2 • Space Charge (-) • DP current pulse shape dominates • H1/H2 is affected by technologyand changes under annealing • Annealing reduces difference in effective macroscopic parameters Protons, Fp = 11015 cm-2: influence of technology is still observed! RT  –15C: • trapping lifetime is the same • reduction of E at n+ side • higher drift velocity, reduction of current and dissipated power E. Verbitskaya et al., 8 RD50 Workshop, Prague, June 25-28, 2006

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