CMS SLHC Workshop

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

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

3. SLHC – terms of reference CERN-TH/2002-078 Physics Potential for LHC (107 s/year) 3 years at 1034 cm-2 s-1, 100 fb-1 /y, 300 fb-1 3 years at 1035 cm-2 s-1, 1000 fb-1 /y, 3000 fb-1 Total 3300 fb-1 SLHC Integrated dose/fluence Factor 6.6 wrt ECAL TDR Dose and neutron rates Factor 10 wrt ECAL TDR, for 1035 cm-2 s-1 ECAL TDR , 1997 Radiation levels for 10 years LHC to 5.105 pb-1 = 500 fb-1 Maximum luminosity 1034 cm-2 s-1 CMS SLHC workshop, D.J.A. Cockerill (RAL)

4. SLHC – upgrades LHC Luminosity and Energy upgrade LHC Project Report 626 Phase 0 No hardware upgrades 1  2.3  3.6 1034 cm-2 s-1 Phase 1 Hardware upgrades: insertion, injector 3.3  4.6  67 1034 cm-2 s-1 Phase 2 Major hardware changes for 2020 Equip SPS with superconducting magnets New dipoles in LHC arcs E C of M25 TeV Phase 1 Superbunch, ib 1A, bunch length 300m to avoid electron cloud effects ~ 9. 1034 cm-2 s-1 CMS SLHC workshop, D.J.A. Cockerill (RAL)

5. SLHC – radiation load 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: <Luminosity> a factor ~0.7-0.8 lessEarly beam aborts, factor 2? on integrated luminosity 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 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 CMS SLHC workshop, D.J.A. Cockerill (RAL)

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

7. EE Integrated Dose for 3300 fb-1 400 Maximum Dose at  = 3 350kGy (35MRad) SCs, VPTs, HV pcbs (capacitors, resistors), HV/LV cables, monitoring fibres Maximum Dose at  = 2.6 150kGy (15MRad) Active ECAL readout electronics kGy 300 200 Inner radial limit of active electronics 100 EE radial distance from beam pipe (mm) CMS SLHC workshop, D.J.A. Cockerill (RAL)

8. Inner radial limit foractive electronics 50 40 Neutrons/cm2/1014 30 Active electronics behind polyethylene moderator 20 10 EE Integrated Neutron Fluence for 3300 fb-1 Maximum fluence at  = 3 5.1015/cm2 SCs, VPTs, HV pcbs (capacitors, resistors), HV/LV cables, monitoring fibres Maximum fluence at  = 2.6 5.1014 /cm2 Active ECAL readout electronics EE radial distance from beam pipe (mm) CMS SLHC workshop, D.J.A. Cockerill (RAL)

9. Supercrystal items, Co60 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 CMS 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 50.1014 cm-2 Tests carried out at Minnesota, 252Cf source, 2.14 MeV neutronsNeutron rate 107 cm-2 s-1  rate at  = 3 at 1034cm-2 s-1 Noise induced in VPT from local activation ~ 3200e- 10000e-at 1035Compton electrons, from s s, enter VPT faceplateLight, from electrons above Cerenkov threshold, yield VPT photo-electrons CMS SLHC workshop, D.J.A. Cockerill (RAL)

11. EE induced activation ECAL TDR Induced activation at  = 3 ~0.25 mSv/h <L> = 0.5.1033 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 limit 5mSv SLHC at 1035 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!) CMS SLHC workshop, D.J.A. Cockerill (RAL)

12. EE Readout for 3300 fb-1 Unshielded access time 25 hours Set of 100 readout channels Inner radial limit r = 50cm,  = 2.6 LV regulators to 5.1014 /cm2 Beam Active readout electronics PE moderator to reduce neutron fluence 1 hour Access constraints severe at inner radiiRequire robust LV regulators on EE from outset CMS SLHC workshop, D.J.A. Cockerill (RAL)

13. EB at SLHC for 3300 fb-1 Dose 2kGy Neutrons 7.1013 cm-2 APD certificationAll screened to 5kGy (some have received 10kGy) – most OK (some have significant change in breakdown voltage - rejectedmost change by only ~1V, vs. 40V breakdown margin)Other tests2001, Karlsruhe, 48 APDs, 20kGy, 2.1013 n/cm2 – all OKMinnesota, >1000 APDs, 1-2. 1013 n/cm2 – all OK = 1.48 at APDsDose 5kGy Neutrons 1.3.1014 cm-2 Need a programme of APD neutron tests to ~2.1014 n/cm2 and annealing tests at 18oC CMS SLHC workshop, D.J.A. Cockerill (RAL)

14. Beam Preshower at SLHC for 3300 fb-1 Preshower 1.65 < || < 2.6Silicon sensors at –5oC Neutrons from EEProtected by 4cm of moderator.Further 4cm, upstream, gives 8cm of protection for TrackerSilicon at = 2.6Neutrons 1.3.1015 cm-2Dose 700kGy (70MRad) EE Dismounting from inner coneActivation at  = 2.8 ~3mSv/h  1.7 hours for annual dose (EE dominated?) Need simulation for isolated Preshower, to determine repair accessibility. CMS SLHC workshop, D.J.A. Cockerill (RAL)

15. Preshower at SLHC for 3300 fb-1 Silicon sensors to = 2.6 1.3.1015 n/cm2, 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 ElectronicsExpect big trouble with ST LV regulators0.25m chips (front end, ADC, control system etc) “should” survivebut no guarantees or tests to SLHC levels PACE 0.25m chip – not tested under irradiation yet(PACE DMILL was tested to 6x1014 n/cm2, 100 kGy, and was ok) CMS SLHC workshop, D.J.A. Cockerill (RAL)

16. LY lossdistribution for 677 xtals 20 30 40 % LY loss ECAL Crystal Performance Crystal LY loss from Co60 dose rate studies At SLHC, =3, at shower max Dose rate = 10 x 15 = 150Gy/h Data rate, Cantonal Irradiation240 Gy/h, 2hRepresentative 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 CMS SLHC workshop, D.J.A. Cockerill (RAL)

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

18. Crystal light yield at LHC StartupLowHighSLHC1033 2.1033 1034 1035 100 Light Yield % 80 60 40 0 <  < 3.0 At SLHC, see significant changes in crystal LY<LY> drops by ~25% EB, 30% EE. CMS SLHC workshop, D.J.A. Cockerill (RAL)

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

20. EE performance at SLHC Resultant noise 250 (700 with activation) MeV ET per channel-excluding pileup contributions & other electronics issuesCharged hadron effects on xtal LY need to be taken into account CMS 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 issuesCharged hadron effects on xtal LY need to be taken into account CMS 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 ET 250 MeV or greater (excl. pileup) EB APD studies to ~2.1014 n/cm2 needed Detector Noise/channel 190 MeV or greater (excl. pileup) Preshower Replacement of inner silicon likely to be needed – very difficult CMS SLHC workshop, D.J.A. Cockerill (RAL)

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

25. SLHC – running time ~45% less Lint if turnaround is 6h and not 1h CMS SLHC workshop, D.J.A. Cockerill (RAL)