1. 26.2.02CMS SLHC workshop, D.J.A. Cockerill (RAL)1 CMS SLHC Workshop The CMS ECAL Detector at SLHC D Cockerill RAL 26.2.2004

2. 26.2.02CMS SLHC workshop, D.J.A. Cockerill (RAL)2 CMS ECAL at SLHC Contents  SLHC  Radiation environment EE, EB, Preshower  Detector performance EE, EB  Conclusions

3. 26.2.02CMS SLHC workshop, D.J.A. Cockerill (RAL)3 SLHC – terms of reference SLHC Integrated dose/fluenceFactor 6.6 wrt ECAL TDR Dose and neutron rates Factor 10 wrt ECAL TDR, for 10 35 cm -2 s -1 CERN-TH/2002-078 Physics Potential for LHC (10 7 s/year) 3 years at 10 34 cm -2 s -1, 100 fb -1 /y, 300 fb -1 3 years at 10 35 cm -2 s -1, 1000 fb -1 /y, 3000 fb -1 Total 3300 fb -1 ECAL TDR, 1997 Radiation levels for 10 years LHC to 5.10 5 pb -1 = 500 fb -1 Maximum luminosity 10 34 cm -2 s -1

4. 26.2.02CMS SLHC workshop, D.J.A. Cockerill (RAL)4 SLHC – upgrades Phase 2 Major hardware changes for 2020 Equip SPS with superconducting magnets New dipoles in LHC arcs E C of M  25 TeV LHC Luminosity and Energy upgrade LHC Project Report 626 Phase 0 No hardware upgrades 1  2.3  3.6 10 34 cm -2 s -1 Phase 1 Hardware upgrades: insertion, injector 3.3  4.6  6  7 10 34 cm -2 s -1 Phase 1 Superbunch, i b 1A, bunch length 300m to avoid electron cloud effects ~ 9. 10 34 cm -2 s -1

5. 26.2.02CMS SLHC workshop, D.J.A. Cockerill (RAL)5 SLHC – radiation load Radiation loads for tests, balance 1) with 2) ? ECAL TDR radiation levels, scaled to 3300 fb -1, used as the reference point in this talk 1) SLHC design study calculations Assumes each fill to nominal luminosity Assumes turnaround time between fills of 1h Caveats: Integrated luminosity drops by ~40% if LHC turnaround 6h Fill to fill variations: a factor ~0.7-0.8 less Early beam aborts, factor 2? on integrated luminosity 2) ECAL TDR radiation calculations A safety factor of 2-3 advised on simulation results A further factor of 2-3 advised for cables and capacitors

6. 26.2.02CMS SLHC workshop, D.J.A. Cockerill (RAL)6 EE at SLHC Repair of SC array would require the dismounting of EE readout electronics on rear of backplate High activation levels, access time limited Qualify SC components for SLHC before EE build Supercrystals and their internal components are inaccessible and cannot be replaced. Components: VPTs, HV pcbs, capacitors, resistors Signal & HV cable, quartz monitoring fibres 5mSv/h Unshielded dose rate 0.2mSv/h  =3  =1.48

7. 26.2.02CMS SLHC workshop, D.J.A. Cockerill (RAL)7 EE Integrated Dose for 3300 fb -1 400 Inner radial limit of active electronics 300 200 100 kGy EE radial distance from beam pipe (mm) Maximum Dose at  = 3 350kGy (35MRad) SCs, VPTs, HV pcbs (capacitors, resistors), HV/LV cables, monitoring fibres Maximum Dose at  = 2.6150kGy (15MRad) Active ECAL readout electronics

8. 26.2.02CMS SLHC workshop, D.J.A. Cockerill (RAL)8 EE Integrated Neutron Fluence for 3300 fb -1 Active electronics behind polyethylene moderator 50 40 30 20 10 Neutrons/cm 2 /10 14 Inner radial limit for active electronics Maximum fluence at  = 3 5.10 15 /cm 2 SCs, VPTs, HV pcbs (capacitors, resistors), HV/LV cables, monitoring fibres Maximum fluence at  = 2.6 5.10 14 /cm 2 Active ECAL readout electronics EE radial distance from beam pipe (mm)

9. 26.2.02CMS SLHC workshop, D.J.A. Cockerill (RAL)9 Supercrystal items, Co 60 Irradiation tests All tests so far OK – no show stoppers, capacitors (unbiased) 9% change To do in 2004: VPTs, faceplates, capacitors and resistors to 500 kGy Brunel University source, 1kGy/h, ~ 21 days

10. 26.2.02CMS SLHC workshop, D.J.A. Cockerill (RAL)10 Supercrystal items, Neutron Irradiation tests All neutron irradiation tests so far OK – no show stoppers 1 capacitor, measured under irradiation, long cables, -17% To do: VPTs, faceplates, capacitors and resistors to 50.10 14 cm -2 Tests carried out at Minnesota, 252 Cf source, 2.14 MeV neutrons Neutron rate 10 7 cm -2 s -1  rate at  = 3 at 10 34 cm -2 s -1 Noise induced in VPT from local activation ~ 3200e -  10000e - at 10 35 Compton electrons, from  s  s, enter VPT faceplate Light, from electrons above Cerenkov threshold, yield VPT photo-electrons

11. 26.2.02CMS SLHC workshop, D.J.A. Cockerill (RAL)11 EE induced activation ECAL TDR Induced activation at  = 3 ~0.25 mSv/h = 0.5.10 33 cm -2 s -1, cooling time 1 day A further drop by ~0.7 after some weeks Dose regulations/advice Dose limit 1mSv/week Annual dose limit5mSv SLHC at 10 35 cm -2 s -1  factor 20 on ECAL TDR Time to Annual dose  = 3.0 5mSv/h 1 hour  = 2.6 2mSv/h 2.5 hours  = 2.0 0.4mSv/h 12 hours  = 1.48 0.2mSv/h 25 hours ↪ for dismounting EE from HE. Done at outer radius. Repairs on EE: need shielding, remote handling (if indeed repairs actually permitted!)

12. 26.2.02CMS SLHC workshop, D.J.A. Cockerill (RAL)12 EE Readout for 3300 fb -1 Set of 100 readout channels Inner radial limit r = 50cm,  = 2.6 LV regulators to 5.10 14 /cm 2 PE moderator to reduce neutron fluence Active readout electronics Access constraints severe at inner radii Require robust LV regulators on EE from outset Beam 1 hour Unshielded access time 25 hours

13. 26.2.02CMS SLHC workshop, D.J.A. Cockerill (RAL)13 EB at SLHC for 3300 fb -1 APD certification All screened to 5kGy (some have received 10kGy) – most OK (some have significant change in breakdown voltage - rejected most change by only ~1V, vs. 40V breakdown margin) Other tests 2001, Karlsruhe, 48 APDs, 20kGy, 2.10 13 n/cm 2 – all OK Minnesota, >1000 APDs, 1-2. 10 13 n/cm 2 – all OK Need a programme of APD neutron tests to ~2.10 14 n/cm 2 and annealing tests at 18 o C Dose 2kGy Neutrons 7.10 13 cm -2  = 1.48 at APDs Dose 5kGy Neutrons 1.3.10 14 cm -2

14. 26.2.02CMS SLHC workshop, D.J.A. Cockerill (RAL)14 Preshower at SLHC for 3300 fb -1 Preshower 1.65 < |  | < 2.6 Silicon sensors at –5 o C Neutrons from EE Protected by 4cm of moderator. Further 4cm, upstream, gives 8cm of protection for Tracker Silicon at  = 2.6 Neutrons 1.3.10 15 cm -2 Dose 700kGy (70MRad) Beam EE Dismounting from inner cone Activation at  = 2.8 ~3mSv/h  1.7 hours for annual dose (EE dominated?) Need simulation for isolated Preshower, to determine repair accessibility.

15. 26.2.02CMS SLHC workshop, D.J.A. Cockerill (RAL)15 Preshower at SLHC for 3300 fb -1 Silicon sensors to  = 2.6 1.3.10 15 n/cm 2, 700kGy (70MRad) Increased leakage current Increased voltage required to full depletion, <500V for TDR levels Leakage current compensation tested to 6xTDR ( ~SLHC) If depletion voltages of 1000V needed, likely that even best sensors will break down Will be at limit of HV supply components Complete replacement of inner sensors on a fairly regular basis Electronics Expect big trouble with ST LV regulators 0.25  m chips (front end, ADC, control system etc) “should” survive but no guarantees or tests to SLHC levels PACE 0.25  m chip – not tested under irradiation yet (PACE DMILL was tested to 6x10 14 n/cm 2, 100 kGy, and was ok)

16. 26.2.02CMS SLHC workshop, D.J.A. Cockerill (RAL)16 ECAL Crystal Performance 20 30 40% LY loss LY loss distribution for 677 xtals Crystal LY loss from Co 60 dose rate studies At SLHC,  =3, at shower max Dose rate = 10 x 15 = 150Gy/h Data rate, Cantonal Irradiation 240 Gy/h, 2h Representative of SLHC worst case Densely ionising hadron shower effects not included LY loss calculated from measured induced absorption Assume all colour centres activated – gives worst case

17. 26.2.02CMS SLHC workshop, D.J.A. Cockerill (RAL)17 ECAL LY during LHC fills - SLHC  =0  =2.5 Crystal light yield LHC luminosity fill by fill Colour centre creation dependent on dose rate Dose rate changes during fill and with eta More changes in EB! EE saturates to constant level

18. 26.2.02CMS SLHC workshop, D.J.A. Cockerill (RAL)18 Crystal light yield at LHC Startup Low High SLHC 10 33 2.10 33 10 34 10 35 100 40 80 Light Yield % 60 0 <  < 3.0 At SLHC, see significant changes in crystal LY drops by ~25% EB, 30% EE.

19. 26.2.02CMS SLHC workshop, D.J.A. Cockerill (RAL)19 Crystal LY changes at SLHC RMS LY changes during fills Barrel LY changes ~3% through the period of a fill Endcap LY changes ~1% (crystals saturated) LY monitoring – main challenge in EB 10% 5% 0% Eta 3.0 1.5 0

20. 26.2.02CMS SLHC workshop, D.J.A. Cockerill (RAL)20 EE performance at SLHC Initial performance 50 MeV E T, preamp noise 3500e - Activation noise, SLHC  = 2.5, 10000e -  140 MeV E T per channel Losses Xtal LY loss 0.7  0.2 Induced abs data VPT faceplate 0.8  ? Guess, 10% to 20kGy VPT Q.E. (burn-in study) 0.4  ?60% loss, 6 days at I k = 1  A  18y at 10 34 at  = 2.5 VPT gain1.0No change observed Reduced HV0.9Working margin Resultant factor0.2 (Hadron damage to xtals, another factor 0.5?) Resultant noise 250 (700 with activation) MeV E T per channel - excluding pileup contributions & other electronics issues Charged hadron effects on xtal LY need to be taken into account

21. 26.2.02CMS SLHC workshop, D.J.A. Cockerill (RAL)21 EB Performance at SLHC EB noise likely to be ~190 MeV per channel - excluding pileup contributions & other electronics issues Charged hadron effects on xtal LY need to be taken into account Leakage Current/xtal Noise equivComment APD current (TDR) 20  A 60MeVWith annealing, single sampling? APD current (SLHC) 130  A 150MeV As  (leakage current) Annealing not included Add EB preamp noise140MeV50MeV in quadrature Losses Crystal factor0.75190MeVLY loss in crystals APD - Xtal glue?Measured to 5kGy? APD Q.E., Gain?Reduce gain, leakage?

22. 26.2.02CMS SLHC workshop, D.J.A. Cockerill (RAL)22 ECAL at SLHC - Conclusions EE Repairs very difficult if not impossible, activation Qualify all components to SLHC levels before EE build VPT and component irradiation tests in 2004 to 350kGy Induced activity noise could be important limitation Charged hadron effects on Xtal LY, tests to be completed Detector Noise/channel E T 250 MeV or greater (excl. pileup) EB APD studies to ~2.10 14 n/cm 2 needed Detector Noise/channel 190 MeV or greater (excl. pileup) Preshower Replacement of inner silicon likely to be needed – very difficult

23. 26.2.02CMS SLHC workshop, D.J.A. Cockerill (RAL)23 Backup slides

24. 26.2.02CMS SLHC workshop, D.J.A. Cockerill (RAL)24 Simulation of crystal behaviour at LHC Simulation of crystal LY loss Colour centre creation and recovery  LHC luminosity according to beam lifetime during fill  Fill of 20h, turnaround 4h (old regime)  Relative fill to fill variations, 0.2  1.0  Dose rate calculated at 1cm steps along each xtal  Colour centres and LY loss calculated for each cm along xtal  Crystal data from GIF for creation and annealing time constants  LY loss along full crystal iterated in 1h intervals  LY losses calculated for 0<  <3.0

25. 26.2.02CMS SLHC workshop, D.J.A. Cockerill (RAL)25 SLHC – running time ~45% less L int if turnaround is 6h and not 1h Fill lifetimeTurnaround (h)T run (h)L int fb -1 /y 15h, L 0 =10 34 15122 15h, L 0 =10 34 61278 6.5h, L 0 =4.5.10 34 13524 6.5h, L 0 =4.5.10 34 66286