1. 14-11-2005SLHC Working Group - Nadia Pastrone1 CMS ECAL Detector at SLHC SLHC high radiation environment  consequences on ECAL Bunch crossing period: 12.5, 25, 75 ns  implications on FE 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 Max luminosity 10 34 cm -2 s -1 Radiation levels for 10 years LHC to 510 5 pb -1 = 500 fb -1  2 10 13 n/cm 2 &  dose 3-5 kGy SLHC (10 35 cm -2 s -1 ) Integrated dose/fluence6.6 (ECAL TDR) Dose and neutron rates 10 (ECAL TDR)

2. 14-11-2005SLHC Working Group - Nadia Pastrone2 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 with turnaround time 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

3. 14-11-2005SLHC Working Group - Nadia Pastrone3 ECAL Endcap: 1.48 < |  | < 3.0, 25 X 0 14648 PbWO 4 crystals Barrel: |  |<1.48, 25.8 X 0 61200 PbWO 4 crystals Preshower (Pb/Si) 3 X 0 OFF DETECTOR  Data integrity checks Event formatting Bandwidth to DAQ: Maximum 528 Mb / s Average 200 Mb / s Data Reduction: Selective readout Zero suppression  Suppression factor ~20

4. 14-11-2005SLHC Working Group - Nadia Pastrone4 A D Pipeline 256 words Event Buffer LV1, delay ~3  s, max. rate 100 kHz Data Merge 250 words/ second Trigger primitives generation 800 Mbps 1 word/25ns 800 Mbps 6.3  s / event Clock&control CCU / LVDS_Mux 8 fibers, redundant 40Mbps 40MHz 1 25 Trigger primitives: Tower energy Bunch crossing ID Fine grain bit 1 25 12345   FE readout

5. 14-11-2005SLHC Working Group - Nadia Pastrone5 Front End Board C.Collard, “CMS ECAL Front-End boards: the XFEST project” Requirements: trigger primitive generation data readout on L1 trigger OK clock & control optical link interfaces based on FENIX ASIC with 4 operating modes triple redundancy against SEU 5 Strip sum Fenix (pipeline buffer for data) 1 Trigger Fenix (trigger primitives) 1 Data Fenix (event formatting) Slow control LVR (read voltages and currents) Slow control VFE (read APD I leak and capsule temperature sensor)

6. 14-11-2005SLHC Working Group - Nadia Pastrone6 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 = 150 Gy/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

7. 14-11-2005SLHC Working Group - Nadia Pastrone7 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

8. 14-11-2005SLHC Working Group - Nadia Pastrone8 Crystal light yield at LHC Startup Low High SLHC 10 33 2.10 33 10 34 10 35 Light Yield % 0 <  < 3.0 100 40 80 60 At SLHC significant changes in crystal LY: drops by ~25% EB, 30% EE.

9. 14-11-2005SLHC Working Group - Nadia Pastrone9 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%  3.0 1.5 0

10. 14-11-2005SLHC Working Group - Nadia Pastrone10 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

11. 14-11-2005SLHC Working Group - Nadia Pastrone11 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

12. 14-11-2005SLHC Working Group - Nadia Pastrone12 EE Integrated Neutron Fluence @ 3300 fb -1 Active electronics behind polyethylene moderator 50 40 30 20 10 Neutrons/cm 2 /10 1 4 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)

13. 14-11-2005SLHC Working Group - Nadia Pastrone13 Supercrystal items, Co 60 Irradiation tests All tests so far OK – no show stoppers, capacitors (unbiased) 9% change To do : VPTs, faceplates, capacitors and resistors to 500 kGy Brunel University source, 1kGy/h, ~ 21 days

14. 14-11-2005SLHC Working Group - Nadia Pastrone14 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

15. 14-11-2005SLHC Working Group - Nadia Pastrone15 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!)

16. 14-11-2005SLHC Working Group - Nadia Pastrone16 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

17. 14-11-2005SLHC Working Group - Nadia Pastrone17 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 48 APDs, 20kGy, 2.10 13 n/cm 2 – all OK >1000 APDs, 1-2. 10 13 n/cm 2 – all OK Dose 2kGy Neutrons 7.10 13 cm -2  = 1.48 at APDs Dose 5kGy Neutrons 1.3.10 14 cm -2 Need programme of APD neutron tests to ~2.10 14 n/cm 2 & annealing tests at 18 o C

18. 14-11-2005SLHC Working Group - Nadia Pastrone18 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 4 cm, upstream, gives 8 cm of protection for Tracker Silicon at  = 2.6 Neutrons 1.3.10 15 cm -2 Dose 700 kGy (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.

19. 14-11-2005SLHC Working Group - Nadia Pastrone19 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)

20. 14-11-2005SLHC Working Group - Nadia Pastrone20 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. 14-11-2005SLHC Working Group - Nadia Pastrone21 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. 14-11-2005SLHC Working Group - Nadia Pastrone22 ECAL at SLHC - Conclusions ENDCAPS Repairs very difficult if not impossible, activation Qualify all components to SLHC levels before EE build Need VPT and component irradiation tests to 350 kGy 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) BARREL APD studies to ~210 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