October 2001General Tracker Meeting IEKP - Universität Karlsruhe (TH) 1 Results on proton irradiation tests in Karlsruhe F. Hartmann IEKP - Universität Karlsruhe (TH) p do Bulk & Surface Damage  Strip parameters after irrad. V FD for (300µm) and 500  m sensors after 10 years LHC Expected power for 500  m sensors after 10 years LHC Outlook

October 2001General Tracker Meeting IEKP - Universität Karlsruhe (TH) 2 Irradiation Facility Compact Cyclotron at Forschungszentrum Karlsruhe 34 MeV protons 1000 nA Beam spot: 2cm O T < -10°C Area: 20x40cm 2 Duration: 100cm 2 in 15min (1 sensor, 5e13p/cm 2 )

October 2001General Tracker Meeting IEKP - Universität Karlsruhe (TH) 3 Cold Box Dry N 2 atmosphere at –10°C. Flexible box to hold sensors, teststructures and/or modules! Laser focus Simple power lines Temp. monitor

October 2001General Tracker Meeting IEKP - Universität Karlsruhe (TH) 4 Simulate LHC bias conditions with respect to surface damage! LHC  During proton irrad.: Diode acts as a current source due to the p ionising effect  SOLVE: 1V potential by applying V bias = 1V, But AC must also be on GND! Current source

October 2001General Tracker Meeting IEKP - Universität Karlsruhe (TH) 5 How to Realize? Simulate LHC bias conditions with respect to surface damage! Conductive rubber  V bias = 1V during irrad

October 2001General Tracker Meeting IEKP - Universität Karlsruhe (TH) 6 Sensors before/after Irradiation

October 2001General Tracker Meeting IEKP - Universität Karlsruhe (TH) 7 Fluences in the Tracker ~1.5e14 n/cm 2 for 320  m ~0.5e14 n/cm 2 for 500  m Upper limits: U FD <500V P(-10°C)<400mW

October 2001General Tracker Meeting IEKP - Universität Karlsruhe (TH) 8 Irradiation Scheme 2 fluences chosen : Inner Tracker: 1.8e14 p/cm 2 (~3e14 n/cm 2 ): – expected for low resisitivity silicon (300µm) * 1.8 ≈ 18y LHC Outer Tracker: 0.5e14 p/cm 2 (~8e13 n/cm 2 ): – expected for high resistivity silicon (500  m) *1.5 ≈ 15y LHC Material (6“, 500µm thick):  1 sensor W6b from Hamamatsu  1 sensor OB2 from ST Microelectronics  6 teststructures from Hamamatsu Biasing: 1V, 12V, 100V, non Notice: Inner Tracker fluence on Outer Tracker (500µm) sensors instead of 300µm, PRO: 1. resistivity almost right 2. No 320µm sensors present, 3. HPK will in future deliver inner 300µm sensors CON:  unusual high V FD

October 2001General Tracker Meeting IEKP - Universität Karlsruhe (TH) 9 Fluence Measurement 1.) Measurement by Ni-foil activation behind sensors: Calibration at 26 MeV Scaling with cross section to higher energies Fluence in [p/cm2] Hardness factor  (E) scales to neutron equivalent 2.) I leak measurement: Temperature scaling to 20°C I(20°C)=I(T)*R(T); R(T)=(293K/T) 2 ·e (-E/k(1/293K-1/T)) ; E=1.4eV I/V=  *   (T=20°C)=4e-17 A/cm Fluence in [n(1MeV)/cm 2 ]

October 2001General Tracker Meeting IEKP - Universität Karlsruhe (TH) 10 Karlsruhe probing equipment Bias stencil/template Measurements take ~ hours Changing of sensor ~ 5 min Environment: –10°C, RH~1%

October 2001General Tracker Meeting IEKP - Universität Karlsruhe (TH) 11 IV-Curve before/after Irrad.

October 2001General Tracker Meeting IEKP - Universität Karlsruhe (TH) 12 Power Consumption 60  A/cm 3 => I leak (-10°C)=270  A (W6b) => P(500V, -10°C)=135mW/sensor Actual designed cooling power 400mW for each module (at least). P ~ U FD I ~ d 2 d ~d 3

October 2001General Tracker Meeting IEKP - Universität Karlsruhe (TH) 13 CV-Curve before/after Irrad. U FD ~ d 2 => U FD (320  m) = 410V ST and HPK sensors are stable up to V bias =1000V after irradiation! Even strip tests were done at V bias = 1000V!

October 2001General Tracker Meeting IEKP - Universität Karlsruhe (TH) 14 Hamburg Model U FD (N eff )~d 2 Beneficial annealing gaga  a (20°C) Stable Damage gcgc c Reverse Annealing gYgY  Y (20°C) PhD Thesis M. Moll: g a =(1.81  0.14)e-2 cm -1  a (20°C) =55h g c =(1.49  0.04)e-2 cm -1 c=(10.9  0.8)e-2 cm -1 /N eff g Y =(5.16  0.09)e-2 cm -1  Y (20°C)=475d

October 2001General Tracker Meeting IEKP - Universität Karlsruhe (TH) 15 Developement of U FD Data is fully compatible with the „Hamburg model“ fit!  Predictions for different annealing scenarios possible!

October 2001General Tracker Meeting IEKP - Universität Karlsruhe (TH) 16 Full depletion as function of annealing time and fluence Fluence given at once, then annealing.

October 2001General Tracker Meeting IEKP - Universität Karlsruhe (TH) 17 Annealing scenario: 14 days at RT each year Iterative calculation of full depletion voltage

October 2001General Tracker Meeting IEKP - Universität Karlsruhe (TH) 18 Depletion voltages for diode minisensor and full sensor  Future: diode measurements as reference!

October 2001General Tracker Meeting IEKP - Universität Karlsruhe (TH) 19 Strip Leakage Current As expected: Increase in leakage current!

October 2001General Tracker Meeting IEKP - Universität Karlsruhe (TH) 20 Bias Resistance Measurement: Apply U=2V Measure I Calculate R=U/I Correction: Measure I leak (high after irrad) Correct R c =U/(U/R+I leak ) No change in bias resistances !

October 2001General Tracker Meeting IEKP - Universität Karlsruhe (TH) 21 Coupling Capacitance No change in coupling capacitances !

October 2001General Tracker Meeting IEKP - Universität Karlsruhe (TH) 22 Interstrip capacitance of HPK full sensor (1 neighbour) 100 fF =3.2 pF 20 fF Wedgeshaped sensor: Longer strips on the sides, but less neighbours!  structure

October 2001General Tracker Meeting IEKP - Universität Karlsruhe (TH) 23 Interstrip Capacitance No change in interstrip capacitance before/after 1MHz. Homogeneous interstrip distribution before/after irrad.

October 2001General Tracker Meeting IEKP - Universität Karlsruhe (TH) 24 Future CMS dedicated teststand at the Cyclotron Scan area: 20 x 50 [cm] Scan speed: 1.25x 2.5 [cm/s] Maximum load: 20kg (New dedicated beamline)

October 2001General Tracker Meeting IEKP - Universität Karlsruhe (TH) 25 Future: irradiation of a full module TEC outer, TEC inner,TOB,TIB Longterm with high voltage, current, power Test of S/N, CCE, (pedestal,noise,shape) Test of components: sensor, electronics, mechanics. First IEKP TEC module

October 2001General Tracker Meeting IEKP - Universität Karlsruhe (TH) 26 ☻ Conclusion ☺ ☻ 1.Both: ST and HPK comply with the specification of irradiation hardness ☺ 2.Data fits „Hamburg model“ well and shows a decent behavior after 10 years of LHC operation ☻ 3.No changes in the strip parameters observed ☺ 4.Future dedicated teststand promise easy access to the cyclotron ☻ 5.Further plans: 300µm sensors and full modules will be irradiated!

October 2001General Tracker Meeting IEKP - Universität Karlsruhe (TH) 27 NEW: Ingot pre-qualification (june 2001) All measurements on diode and minisensor  Save large sensors as spares!  INGOT: IV & CV on diode  To determine V depletion, fluence estimation and  -factor.  PROCESS: Cint, Rint, leakage current, R poly vs. V bias upto V depletion + 50V (for ~10 strips) Hamamatsu proposed to produce a couple of additional sensors out of each new ingot for irradiation pre-qualification  Special procedure in addition to the standard task.