1. Production Readiness Review of L0/L1 sensors for DØ Run IIb R. Demina, August, 2003 Irradiation studies of L1 sensors for DØ 2b Regina Demina University of Rochester

2. Production Readiness Review of L0/L1 sensors for DØ Run IIb R. Demina, August, 2003 Outline  Radiation environment and silicon sensor specs  Results on prototypes  Conclusions

3. Production Readiness Review of L0/L1 sensors for DØ Run IIb R. Demina, August, 2003 Requirements for silicon sensors  Main challenge for silicon sensors - radiation  Depletion voltage (  )  Leakage current (  )  noise  Doses comparable to LHC – use their R&D  NB: Uncertainty in  estimate– conservative approach: 1.5 safety margin 10 years of CMS at inner radius

4. Production Readiness Review of L0/L1 sensors for DØ Run IIb R. Demina, August, 2003 Depletion voltage  fb  Spec L0, L1 V break >700 V T=-10 o C with warm up periods: 4 months 1 st year, 1month each next year Specification on breakdown voltage derived based on depletion voltage evolution Spec L2-5 V break >350 V Hamburg model

5. Production Readiness Review of L0/L1 sensors for DØ Run IIb R. Demina, August, 2003 Signal to noise ratio In present design: S/N> 10 T<-10 o C for L0 S/N> 18 T<-5 o C for L1 Important to test I leak after irradiation on prototype sensors and on test structures during production Total I leak  in L0 sensor Corresponds to s/n>10 Noise contributions: Capacitive load: 450+43C(pF) Al strip resistance + analogue cables (L0) Shot noise I leak =I 0 +  Ad (  =3E-17A/cm) Thermal noise in R bias

6. Production Readiness Review of L0/L1 sensors for DØ Run IIb R. Demina, August, 2003 Irradiation studies at KSU  More details in T. Bolton’s talk  10 MeV p, sweep the beam using electrostatic deflector  Anneal at 60 o C for 80 min, then keep cold  Measure I at 1 o C, extrapolate to 20 o C Single sided low  sensors with guard band structure produced by HPK

7. Production Readiness Review of L0/L1 sensors for DØ Run IIb R. Demina, August, 2003 Leakage current  Raw currents measured at T=1 o C  Vbreak>700V (spec) =~19fb -1 at r=1.8 cm

8. Production Readiness Review of L0/L1 sensors for DØ Run IIb R. Demina, August, 2003 I leak vs T  Measure at 1 o C, extrapolate to 20 o C  Verify temperature dependence

9. Production Readiness Review of L0/L1 sensors for DØ Run IIb R. Demina, August, 2003 I leak vs   I=  p  p  p =11.6  10 -17 A / cm for 10 MeV p  Hardness of 10MeV protons vs 1 MeV neutrons  =  (10MeVp) /  (1 MeVn)=11.6/4.56=2.54 (compared to3.87 * )  G.P Summers et al., IEEE Trans Nucl. Sci NS-40,6(1993)1372 D. Bechevet et al. NIM A 479(2002)487 At 10 MeV p Montreal N.B.  =3.0e-17A/cm for 1 MeV n, if use  =3.87 Extrapolated to @-10 o C I leak =140  A in L0 S/n>10

10. Production Readiness Review of L0/L1 sensors for DØ Run IIb R. Demina, August, 2003 Depletion voltage vs flux  Use 1/c 2 vs V to determine V depl – 30- 50% uncertainty

11. Production Readiness Review of L0/L1 sensors for DØ Run IIb R. Demina, August, 2003 V depl vs  full size sensors Parameter: Cgcgc gaga kaka E aa gygy kyky E ay N c0  ef f  0 Value: 1.13E-13 cm -2 1.9E-2 cm -1 1.81E-2 cm -2 2.4E13 s -1 1.09 eV 6.6E-2 cm -1 1.5E15 s -1 1.325 eV 1 - Use Hamburg model with stable damage, short and long term annealing terms Flux in protons/cm 2  main effect on C (scales with 1/  )

12. Production Readiness Review of L0/L1 sensors for DØ Run IIb R. Demina, August, 2003 Other properties after irradiation  Cint: 3 pF(before)  6 pF (after 9.35E13 = 19 fb -1 ): N C =1680e(before)  1815 (after) S/n>9 No change in R poly after irradiation

13. Production Readiness Review of L0/L1 sensors for DØ Run IIb R. Demina, August, 2003 Conclusions  Single sided low  sensor technology with guard band structure is used for the inner layers  L1 sensors produced by HPK were tested up to 9.35E13 10 MeV p/cm 2  Hardness factor was found to be 2.54 instead of theoretically predicted 3.87, but in agreement with a study by Rose collaboration  Using this number and 1.5 safety factor we estimate 9.35E13 10 MeV p/cm 2 to be equivalent to 19 fb -1 at r=1.8 cm (L0)  After this dose u No break down was observed up to 1000 V u Sensors deplete at 350-400 V in agreement with the hamburg model  Based on the observed increase in leakage current we expect I leak =140  A for L0 sensors at operating T of –10 o C  s/n=~10 u C int increased from 3 to 6 pF, which will lead to increase in C noise from 1680e  1815e u S/n is expected to be above 9 for L0 after 20 fb -1  We believe that these sensors will perform adequately after 20 fb -1

14. Production Readiness Review of L0/L1 sensors for DØ Run IIb R. Demina, August, 2003 Back up slides do not print

15. Production Readiness Review of L0/L1 sensors for DØ Run IIb R. Demina, August, 2003 Luminosity profile for damage estimate

16. Production Readiness Review of L0/L1 sensors for DØ Run IIb R. Demina, August, 2003 Fluence estimations for Run IIb  based on CDF silicon leakage current measurements in Run Ia+b  observed radial dependence ~1/r 1.7  measured CDF silicon sensor leakage currents are scaled to DØ sensor geometries and temperatures to give shot noise contributions of leakage currents  for depletion voltage calculations, a 1 MeV equivalent neutron fluence is assumed: u  1Mev n =2.19·10 13 r[cm] -1.7 [cm -2 /fb-1] (Matthew et al., CDF notes 3408 & 3937)  safety factor 1.5 applied

17. Production Readiness Review of L0/L1 sensors for DØ Run IIb R. Demina, August, 2003 Performance extrapolations for Run IIb  S/N extrapolations assume u noise in front end of SVX4: 450+43*C(pF) u total silicon strip capacitance: 1.4pF/cm u L0 analog cable assumed (and measured): 0.4pF/cm u noise due to series resistance of metal traces in silicon ~210e-700e depending on module length u noise due to finite value of bias resistor: ~250e u shot noise due to increased leakage currents: s ~1100e for L0 after 15fb -1 if T=-5C s ~1000e for L2 (20cm long module) after 15fb -1 if T=0C

18. Production Readiness Review of L0/L1 sensors for DØ Run IIb R. Demina, August, 2003 V depl vs   Test diods