Physics and detector considerations for SHLC

1. Physics and detector considerations for SHLC P. Lecoq

2. Key questions for ECAL at SLHC • How physics requirements will evolve from LHC to SLHC? • By how much will the ECAL degrade at SLHC? Try to quantify the impact on the physics potential • Can we survive with patches to the present detector or do we need more drastic upgrades?

3. Physics requirements • ECAL at LHC has been optimized for the H→ ggchannel • Best emenergyresolution in the 10-100GeV range • Vertex identification fromtracker information • Granularitydefined by angularprecision and LHC pile-upconsiderations • At SLHC physicsislikely to me more « jet-oriented » • Self coupling of EW gauge bosons • WW and WZ scattering • Sparticule spectroscopy, … • How well can perform the original ECAL design for this physics? • Is granularity good enough? • Can pile-up be manageable? • Is the present ECAL design compatible with a reasonable performance of the whole Tracker/ECAL/HCAL chain?

4. ECAL performance degradation at SLHC • Expected to concernmostly the forwardregion • Preshowermay not survive the hightrackdensity and neutron fluence • EE willsufferratherstrong radiation damage • Crystal induced absorption • Consequences of a large LY loss on position and energy resolution • Significant effect on FNUF if damage larger than 1m-1 • Permanent or semi-permanent damage (stars) • Defect clustering • Damage/rate effect on VPTs • Effect of increased neutron fluence on detector electronics

5. Scintillation is not affected • Light transport is affected through the formation of optical absorption bands • LY loss • Variation in FNUF • Damage saturates • Rejection criteria: 1.5m-1 • Damage recovers • Dynamic saturation in LHC conditions at about 0.1-0.5m-1 going up to 0.8-1.2m-1 at SLHC LHC irradiation saturation model (dominated by em damage) Batch 4 Batch 5 Batch 6 BTCP From S. Baccaro CMS-Week-June05 35 Gy/h

6. LY & FNUF versus g irradiation % LY Loss Non-uniformity increase (%/X0) Conclusion: ECAL will degrade under g irradiation at SLHC but effect probably acceptable

7. Effect of FNUF degradation on energy resolution

8. p and p irradiations suggest a permanent and cumulative damage • Compatible with star formation (heavy fission fragments recoil) • Scintillation is not affected • Batarin et al. NIM A540 (2005)131 • High Rayleigh scattering behavior • Similar irradiations with non fissionable materials (CeF3) seem to confirm this hypothesis SLHC non saturation model (dominated by hadron damage) From M.Huhtinen, F. Nessi and al., NIMA545 (2005), p63 and F. Nessi et al., NIMA587 (2008), p266

9. Tests were made with 1014pcm-2 corresponding to about 1year SLHC@ 1035cm-2s-1 at h = 3 and 10 years at h = 2 • But dose was injected in 10hours instead of 1:10 years (factor 103:104) • Tolerable damage ( 2m-1) for 1013pcm-2 injected in 10 hours • Difficult to explain by simple optical considerations that Rayleigh scattering alone can produce 10m-1 induced absorption in a finite and close environment with high light confinement (high refractive index) • Several effects can mimic a Rayleigh scattering behavior ( Frenkel Knock-on Oxygen) and be very dose rate dependent • On top of stars is there a possible additional dose rate effect? • If yes what is the proportion of the real cumulative damage effect at SLHC conditions? SLHC non saturation model Follow-up

10. Study optical influence of star produced scatters on the crystal light collection (tests and simulation)- Ongoing work at CERN • Study of the hadron cumulative effects but at lower dose rates • Is there a dose rate threshold effect? • Difficult tests to be discussed and organized within the ECAL communty • Test independantly the behavior of ECAL with heavily damaged crystals • Test of a EE supercrystals damaged at g saturation (about 1.5 to 2m-1) and severely damaged by p planned in the H4 test beam in Autumn 2009 Crystal damage studies Proposed action list

11. Can we survive with patches to the present system or do we need a more drastic redesign? • Requires better understanding of the physics requirements • Requires an assesment of the ECAL damage at SLHC conditions • catastrophic or semi-catastrophic scenario? • Consider technology improvements • More resistant PWO • Crystal fibers Forward ECAL at SLHC?

12. New PWO (Mo-La) developped for PANDA are a factor 2.5 more resistant (to g) than CMS-PWO and have a factor 2 higher LY • Could be considered to replace most exposed EE supercrystals More resistant PWO PANDA Technical Proposal PANDA CMS

13. Can we use the Preshower space (about 15cm) to develop a calorimeter layer with: • ultra-high granularity providing imaging capability • Cerenkov and scintillation dual readout capability providing em fraction determination • Excellent timing properties from the Cerenkov signal • If yes what is the ideal place for this layer in the whole TK-ECAL-HCAL chain Heavy Scintillating and Cerenkov fibers

14. The micro-pulling-down technology allows to grow up to 2m long scintillating and Cerenkov fibers of the same material (density 7) Heavy Scintillating and Cerenkov fibers Ø 2mm 30cm Ce doped LuAG Sintillator undoped LuAG Cerenkov

15. Preliminary results

16. Physics requirements need to be better understood for the integrated chain: TK-ECAL-HCAL • Preshower may not survive SLHC • More tests are needed for EE to understand if a degraded working mode with « minor » upgrade is acceptable or if a more drastic upgrade is required Conclusions