1. STFC RAL EE at SLHC CERN 15/04/08 R M Brown - RAL 1 EE at SLHC What do we expect at SLHC? EE Layout VPT vulnerability to radiation - Faceplate darkening - Photocathode ageing HV Filter card Active electronics Other EE components Induced activity Summary

2. STFC RAL EE at SLHC CERN 15/04/08 R M Brown - RAL 2 What do we expect at SLHC? Koutchouk IoP Liverpool Jun 2007 Instantaneous luminosity (cm -2 s -1 ) Year SLHCLHC L ~ 440 fb -1 L ~ 3040 fb -1 Total L ~ 3500 fb -1 (10 7 s/year, 50% efficiency) (cf ECAL TDR: L ~ 500 fb -1 ) ~ x7

3. STFC RAL EE at SLHC CERN 15/04/08 R M Brown - RAL 3 Dose versus in EE (LHC)

4. STFC RAL EE at SLHC CERN 15/04/08 R M Brown - RAL 4 Neutron fluence (>100keV) in EE

5. STFC RAL EE at SLHC CERN 15/04/08 R M Brown - RAL 5 Fluence and Dose for 500 fb -1 Neutron + charged hadron fluence (cm -2 ) for E>100 keV 500 fb -1 Absorbed dose (Gy) Immediately behind crystals 500 fb -1

6. STFC RAL EE at SLHC CERN 15/04/08 R M Brown - RAL 6 Layout of EE elements

7. STFC RAL EE at SLHC CERN 15/04/08 R M Brown - RAL 7 Faceplate exposures to n and Neutron fluence is 7x10 14 n/cm 2 (Reactor) Accompanying -dose ~100 kGy Relative loss at 425 nm = 25% For comparison, expected exposures at LHC (500 pb -1 ) at = 3 are: 7x10 14 n/cm 2 and 50 kGy (nm) Induced absorption Induced absorption vs wavelength for 1mm thick sample of US-49C exposed to 20kGy ( 60 Co) ( = 2.6 at LHC) Light loss (PWO) ~ 9%

8. STFC RAL EE at SLHC CERN 15/04/08 R M Brown - RAL 8 Extrapolation to SLHC exposures US-49A US-49C X VPT anode response Transmission loss for PWO light under 60 Co irradiation A faceplate of US-49A glass has been irradiated up to 1250 kGy - The damage tends to saturate and the ratio: ( T/T 0 ) 450 (350 kGy) 1.7 x ( T/T 0 ) 450 (50 kGy) For US-49C: loss of PWO light < 20% for 350 kGy ( = 3.0 at SLHC) A US-49A faceplate was exposed to 10 16 n/cm 2 with an accompanying dose of 1600 250 kGy Unfolding the neutron damage using extrapolated 60 Co data (and ignoring s from induced activity in the glass): T/T 0 (neutron) < 15% for < 3.0 at SLHC ( T/T 0 (neutron) < 30% for US-49C at SLHC????)

9. STFC RAL EE at SLHC CERN 15/04/08 R M Brown - RAL 9 Photocathode lifetime VPT Photocurrent (nA) 2.98.0 2.5 2.00.6 1.60.1 Photocathode current for L =10 34 cm -2 s -1 I K (0) = 200 nA 30 days at I K (0) = 200 nA ~ 650 fb -1 at = 2.9 ~ 2000 fb -1 at = 2.5

10. STFC RAL EE at SLHC CERN 15/04/08 R M Brown - RAL 10 HV Filter Card components ( ) ComponentValue Capacitor1 nF Capacitor470 pF Resistor 22 M Resistor 10 M Resistor 10 M Resistor 10 M 0.0 0.4 0.8 1.2 1.6 10 1 10 3 10 5 10 7 Capacitance (pF) Frequency (Hz) 0.0 0.4 0.8 1.2 1.6 10 1 10 3 10 5 10 7 Capacitance (pF) Frequency (Hz) Before irradiationAfter 135 kGy HV Filter card components irradiated to 135 kGy ( 60 Co) (~ SLHC at = 2.6) - Small change in capacitor values (slight improvement in leakage current) - Negligible change in resistor values

11. STFC RAL EE at SLHC CERN 15/04/08 R M Brown - RAL 11 HV Filter Card components (n) HV Filter card components irradiated to 10 15 n/cm 2 (spallation spectrum at ISIS) ( > 3.0 at LHC, ~ 2.0 at SLHC ) (While biased at 1 kV) (Components similar but not identical to final selection) - Small change in capacitor values (slight improvement in leakage current) - Negligible change in resistor values - No breakdown up to 2 kV Resistors Capacitors

12. STFC RAL EE at SLHC CERN 15/04/08 R M Brown - RAL 12 Active electronics MGPA tested to 50 kGy (~1/3 worst SLHC) (10 keV X-rays at ~10 kGy/h) 3% reduction in gain (pulse shape unchanged) APV25 exposed to 2x10 14 /cm 2 (300/MeV/c) 15% reduction in gain Optical link components (Tracker version) tested to 1.5 MGy ( 60 Co) and ~5x10 15 n/cm 2 (18 MeV) (~10x SLHC for EE) – loss in fibres small – TX (LLD ASIC + laser diodes) OK – Optical cables OK – Optical connectors appear OK – QR codes OK – PCB and connector embrittlement n – Lasers die at 2-3 10 15 n/cm 2 Barrel Trigger Tower irradiated with p (63 MeV) to 1.5x10 13 p/cm 2 (20 kGy at 1.7 Gy/s) (Dose ~worst LHC, Hadron fluence ~1/3 worst LHC) Tower still working at end of exposure Will LV Regulators survive 5x10 14 n/cm 2 ? 100 200 300 400 kGy Inner limit of active electronics 3.02.6 2.01.6 Absorbed dose for 3500 fb -1 20060010001400 Radial distance from beam (mm) 5.0 4.0 3.0 2.0 1.0 Hadron fluence at ADCs z = 3520 mm Active electronics behind polyethylene moderator 10 15 /cm 2 Neutron fluence for 3500 fb -1

13. STFC RAL EE at SLHC CERN 15/04/08 R M Brown - RAL 13 Radiation tests of other components

14. STFC RAL EE at SLHC CERN 15/04/08 R M Brown - RAL 14 EE Activation 0100200300400 z(cm) 0 100 150 50 r(cm) Estimated dose rate in Sv/h after 60 d at L = 5x10 33 cm -2 s -1 and 1 d cooling. (CMS closed) After 4 months cooiling the dose rates are ~2.5x lower 150 54 24 Occupational dose limits: - 1 mSv/wk - 15 mSv/yr Assume induced activity levels at SLHC ~10xLHC Time to Annual limit at = 3 is ~10 h LHC (ECAL TDR)

15. STFC RAL EE at SLHC CERN 15/04/08 R M Brown - RAL 15 Summary Passive components: – including HV filter card – OK Active electronics: - Optical links - OK - MGPA gain -15% at = 2.6? - Trigger towers not tested to full EE fluence at LHC!! VPTs: - Faceplate darkening -30% - Photocathode ageing -40% Combined loss 60%? Crystals: - Ask Francesca!

16. STFC RAL EE at SLHC CERN 15/04/08 R M Brown - RAL 16 Endcap upgrade for SLHC? At VPTs: Dose( =2.2) / Dose( =3.0) ~1/10 (neutron fluence ~1/3) ~25% (18/71) Supercrystals are at >2.2 Replace for SLHC? Unfortunately, complete rows of supercrystals must be dismounted to replace inner units – remote handling! VPTs with Ce-glass windows – very rad-hard But photocathode ageing depends on integrated charge - NB LYSO has a high light yield and would accelerate this effect.