Impact of SLHC on the operation and Performances of ATLAS Tile Cal

1. Impact of SLHC on the operation and Performances of ATLAS Tile Cal • Critical TileCal issues • Radiation level • Events pile up • Timing • Impact on performances • Jet Energy LinearityResolution T. Del Prete, WG per SLHC

2. ATLAS Central Calorimeters Tile hadron calorimeter EBC LB EBA T. Del Prete, WG per SLHC

3. Sample 3 Sample 2 Sample 1 A section of EB cylinder with most exposed components Fingers w/ LVPS In some sectors we have scintillators instead of C10 E3 & E4 (cryo scintillators) sit between cryostats E1 & E2 (gap scintillators) sit on endplate Most of active elements are Inside the iron adsorber T. Del Prete, WG per SLHC

4. Neutron flux (Khz/cm2) @1034 T. Del Prete, WG per SLHC

5. n, g doses @1034 cm-2s-1 Tile hadron calorimeter T. Del Prete, WG per SLHC

6. LHC Upgrade scenarios Issues: Radiation damage Pileups of MB events Bunch spacing and trigger Timing T. Del Prete, WG per SLHC

7. Plan to implement upgrades in severalphases: • phase 0: stretch machine to its limits (no hardware modifications to LHC) • phase 1: increase luminosity by one order of magnitude (modification of the interaction regions) • phase 2: modify the arcs as well (upgrade cryogenics, beam dump, collimation, …) • higher Ös not considered... • This is obtained by: • Increase I, shorter b, double the bunch number, shorten bunch spacing, Super-SPS (1 TeV) ... • Let me concentrate in two scenarios: L= 1034 - 1035 cm-2s-1 T. Del Prete, WG per SLHC

8. Impact of radiation on Light budget Ligth loss because or radiation (g + n) was discussed in 96TDR and new tests are starting. A fair parametrization of the ratio of light budget after irradiation is: (D in Kgray) Maximum expected light loss (in sample 1) for 5 years: ~3% running at 1034 (Nominal scenario) ~7% running at 2.3 1034 (Ultimate scenario) ~12% running at 4.6 1034 (IR-Upgrade scenario) ~18% running at 1035. (Natural fibers/scintillators ageing is about 1%/year) T. Del Prete, WG per SLHC

9. Impact on TileCal Energy measurement • Limitations due to Light Budget (Photo statistics) • 20 pe/GeVminimum LB for the design energy resolution • 40 pe/GeVneeded to detect the muon signal • NOW LB ~ 65pe/GeV • We may survive with a LB loss up to about 40% • Another issue: • Uniformity of response: • All TileCal cells are individually calibrated (to the em. scale) by a Cs calibration system • The PMT HV system can handle a variation of Gain up to x2 • We do not expect problems from cell calibration T. Del Prete, WG per SLHC

10. Conclusion on Rad-ageing • The decrease of LB due to Radiation can be partially recovered • In a reasonable scenario where LHC luminosity increases from 1033 to 1035: • Ldt = 2y @1033+ 5y @1034+ 5y @1035 • The impact of decreased LB on Energy measurement should be modest (3-5%) T. Del Prete, WG per SLHC

11. Overall performances • We are much more concerned on the effect of pileup of MB events on the Jet Energy Reconstruction. The number of pileup events is proportional to L and little can be done to reduce the effect: • Filter/Shape the detector signal (Larg) should reduce this noise (by how much?) • Reduce DR where a Jet is defined and apply a hard cut to Ecell(which effect on linearity?) • The undesired PU events can be seen as a noise whose variance is proportional to the number of PU. This adds (in variance) to electronic noise: T. Del Prete, WG per SLHC

12. Jet Resolution in different scenarios T. Del Prete, WG per SLHC

13. Some conclusions on EJ resolution • Jet resolution becomes worse, increasing the number of PU events • s/E ≈ 10% @1034 ≈ 30% @ 1035for Ejet= 100 GeV • We have to understand the impact on: • Trigger issues • Missing Energy resolution • Physics T. Del Prete, WG per SLHC

14. Radiation effects on Electronics All components have been tested (TID,NIEL, SEE...) above the rad doses (including safety factors) for 10Y @ 1034 OK for 5Y @ L=2.3 1034 they should survive 5Y @ L = 1035 but no NO safety margin. Some components: Mother Boards, Digitisers, Interface, ELMB, LVPS are more rad-fragile and need further tests. We hope to keep some electronics. If not: partial upgrade, redesign… T. Del Prete, WG per SLHC

15. SLHC bunch spacing • In some LHS upgrades the bunch crossing rate is different from 40.08 MHz. • This will have large impact on ReadOut logic of TileCal (but not only). • TileCal signal shape must be syncronous with Bunch Clock for: • Flag the correct time of each data fragment over the whole ATLAS • Perform the optimal filter at the RODs (TileCal) • The TTC logic, TDAQ and locally all our logic is strictly bound to the 40.08Mhz structure of BC. • Any change of this basic frequency will have deep consequences also on the detectors. • We will not discuss any further this scenario. T. Del Prete, WG per SLHC

16. BC BCR L1A BC BCR L1A TTC TTC Principio del readout Set Phase of clk wrt pulses ReadOutDriver 16 Digitizer 40.08 MH Digitizer • L1ID • BCID 8 ½ wedges 48 pmt each 6 PMT Opt. Filt. Event Fragment • Qi • Ti • GoFi • .••• To LVL2 Tile wedge BCID, LV1ID T. Del Prete, WG per SLHC

17. (Tentative) Conclusions • The Detector (Sci./Fibre) will NOT suffer important damage from radiation • We will not rebuild TileCal! • Some, more exposed, parts will have to be replaced • The F/E electronics will suffer more. Before any action: • Measure radiation effects at LHC startup • If necessary decide which items need upgrade/redesign • If SLHC needs increase BC rate, all the F/E logic has probably to be redesigned. This will be a major problem. • The combined performances in terms of Jet energy measurements need more simulation. Issues are: • Linearity • Resolution in Jet Energy and ETMiss T. Del Prete, WG per SLHC