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Preliminary PSI SEU Studies

Preliminary PSI SEU Studies. Study SEU effects by measuring the BER of the link in p /p beams at PSI. Measure the SEU rate as a function of current in PIN diode <I(PIN)> SEU rate decreases with increasing <I(PIN)>  SEU occurs in PIN diode.

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Preliminary PSI SEU Studies

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  1. Preliminary PSI SEU Studies • Study SEU effects by measuring the BER of the link in p/p beams at PSI. • Measure the SEU rate as a function of current in PIN diode <I(PIN)> • SEU rate decreases with increasing <I(PIN)>  SEU occurs in PIN diode. • SEU occurs when energy above DORIC threshold is deposited in active region of PIN diode. PSI SEU Studies

  2. PSI Beams Used p (p) contamination in p(p) beam <~10% PSI SEU Studies

  3. Flux Measurements • Flux measured with rate in counter with 2mm diameter scintillator attached directly with optical grease to small Hamamtsu PM. Flux corrected for deadtime due to discriminator pulse width (100ns). • Flux checked for one run by Al foil activation analysis. Measure 24Na activity with Ge(Li) counter. Agreed to within 10 %. • At low beam intensity we checked rate in small counter with rate in large counter, Consistent with measured beam profile. PSI SEU Studies

  4. PSI SEU Studies

  5. SEU Analysis(1) • For <I(PIN)> above 30 mA there is no measurable BER with beam off. •  BER above this value is due to SEU effects. • BER decreases with <I(PIN)>  SEU occur in analogue part of system. Sensitive volume of PIN (350 mm diameter, 15 mm thick) >> sensitive volume of transistors. dominant SEU is due to energy above threshold being deposited in sensitive volume of PIN. • For the same beam type/momentum the SEU rate scales with luminosity. PSI SEU Studies

  6. SEU Analysis(2) • There is no value of <I(PIN)> in the range explored for which the SEU rate is zero.  must accept a finite SEU rate in our TTC system. • To compare different beam particle/momentum/flux(F) define a SEU cross section as sSEU=BER/F • sSEU correlates with sTOTAL • Shape of sSEU versus <I(PIN)> similar for different beam momenta/particle type. PSI SEU Studies

  7. PSI SEU Studies

  8. SEU Analysis(3) • Large sSEU at 300 MeV/c correlates with total cross sections. Other ratios do not scale with sTOTAL • Need detailed SEU calculations (Huitenen) to understand results.. PSI SEU Studies

  9. ATLAS Implications(1) • Can use this data to predict BER for ATLAS operation at any flux. Convolute sSEU with spectrum • Model #1: pessimistic. Take sSEU from momentum with largest value of sSEU (300 MeV/c). • Model #2: guess. Take average from p at 3 different momenta. • Model# 3: Realistic. Requires detailed simulation (Huitenen) to give prediction of sSEU with momentum. PSI SEU Studies

  10. SCT Implications. • Minimum value of <I(PIN)>=75 mA • Pessimistic model gives • sSEU =3 10-16 cm-2 • SCT maximum flux (barrel layer 3) • F= 2 106 cm-2 s-1 • Predict (worst case + pessimistic model) • SEU = 6 10-10 s-1 PSI SEU Studies

  11. SEU and Energy Deposition • Use simple model for DORIC to relate <I(PIN)> to minimum energy deposition in PIN to trigger DORIC • Emin minimum energy to tirgger DORIC (MeV) • IPIN mean PIN current • Ih hysterisis current in DORIC • Eeh energy required to create eh pair in Si (3.6 eV) • e electron charge • w0 1/RC time constant of DORIC i/p (109 s-1) PSI SEU Studies

  12. PSI SEU Studies

  13. Conclusions • SEU rates measured at high fluxes. • Significant SEU rates expected in ATLAS • BER < 10-9 can be maintained for SCT. BER expected ~ few 10-10 . Acceptable provided frequent soft resets are issued (~ 1 Hz). • BER > 10-9 expected for Pixel detector. Needs study to assess significance of this result (Pixel detector has more robust data format for L1 triggers). • Requires calculations from Huitenen to make accurate predictions for ATLAS environment. PSI SEU Studies

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