TileCal issues and Combined Performance Workshop on ATLAS Upgrades for High Luminosity Feb. 14th 2005 D. PALLIN LPC Clermont-FD TileCal issues and Combined Performance

TileCal issues / main limitations Main identified Tilecal limitations to operate at SLHC increase of radiation levels increase of pile-up possible LHC operation with bunch spacing less than 25ns Start investigations on radiation & ageing effects on the sensor (detector) radiation effects on the electronics pile-up effects on jet energy resolution ATL-TILECAL-2005-002 ATLAS Upgrade Workshop D. Pallin, Clermont-Fd 14-02-2005

TileCal issues/ radiations in the Tilecal Radiations levels on fibres & tiles (1034): Re-estimation of 96TDR radiations levels using last radiation maps total dose for all scenarios ~ scaling from 1034 At 1034 : <50 Gy/year sampling1 <11 Gy/year sampling2 <2.5 Gy/year sampling3 ATLAS Upgrade Workshop D. Pallin, Clermont-Fd 14-02-2005

TileCal issues/ radiation effects tiles+fibres Impact on light loss (tiles+fibres) R=0,834exp(-D/43)+0.166exp(-D/1,35) with D in kGy The maximum anticipated light loss (in sampling 1) is ~3% for 5 years of running at 1034 (Nominal scenario) ~7% for 5 years of running at 2.3 1034 (Ultimate scenario) ~12% for 5 years of running at 4.6 1034 (IR-Upgrade scenario) ~18% for 5 years of running at 1035. ATLAS Upgrade Workshop D. Pallin, Clermont-Fd 14-02-2005

TileCal issues/ ageing on tiles+fibres Ageing (tiles+fibres) Tilecal TDR Analyses going on to measure or to give more refined limits on Ageing Test bench at LIP (radiations & ageing) Analysis of regularly tested Tilecal modules <1% per year ATLAS Upgrade Workshop D. Pallin, Clermont-Fd 14-02-2005

TileCal issues/ light budget Impact on Tilecal performances-energy measurement 20 pe/GeV enough to achieve the required Tilecal energy resolution 40 pe/GeV needed to detect the muon signal in each samples Mean light yield on produced modules ~ 65pe/GeV ‘Light loss budget’ 65-40=25 pe/GeV. => 40% decrease still acceptable Uniformisation of the light loss in each samples tiles are calibrated using Cs system PMT’s HV can handle calibration variation of a factor 2 Calculations leads to a E decrease by ~3-5% for a light yield deterioration of 50%  Decrease of (Tilecal) energy measurement due to . . light yield degradation could be fully recovered  Marginal effect on (Tilecal) Energy resolution  2y @1033+ 5y @1034+ 5y @1035 ~ 30% light loss max ATLAS Upgrade Workshop D. Pallin, Clermont-Fd 14-02-2005

TileCal issues/ radiation effects on electronics From Niel, TID and SEE radiation tests: All active components tested above required doses (safety factors included) for 10y @1034 OK for 5 y @2.3 1034 All components survived to doses expected for 5y @1035 BUT without enough safety margin left conservative safety factors: better knowledge at LHC start Additional radiation tests needed to reach required factors especially on Mother board ,digitizer, interface, ELMB, LVPS Hopefully same electronics could be kept. If not (radiation levels underestimated) partial upgrade? Redesign ? ATLAS Upgrade Workshop D. Pallin, Clermont-Fd 14-02-2005

Combined performances Pile-up The spread of the deposited energy by MB evts scales as  (MB per BX) Difficult to anticipate the size after shaping/filtering (see options in Larg talks) but LARG pile up effet larger than in Tilecal Effect on the jet energy resolution could be reduce also at reconstruction level (jet defined in a smaller R cone, ET cuts on cells). BUT MAJOR impact on energy resolution when MB  fast evaluation of the deterioration of the jet energy resolution in function of pile up and jet energy Use standard jet energy parametrisation : From 96TDR, 99TDR : (R=0.4, no dig. filt., had. scale) PU(larg)~9 GeV, PU(Tilecal)~2 GeV => c2 ; c1 = elec noise ~ 3 GeV ; a=62,4%, b=1.7% ATLAS Upgrade Workshop D. Pallin, Clermont-Fd 14-02-2005 SF=  (MB scenario /MB nominal )

Combined performances nominal IR upgd., B ATLAS Upgrade Workshop D. Pallin, Clermont-Fd 14-02-2005

D. Pallin, Clermont-Fd 14-02-2005 Summary Tilecal detector: Radiations will not affect to much the tile+fiber system, NO impact on the Tilecal Performances on Energy measurement and resolution Tilecal Electronics: Hopefully same electronics could be kept. A possible strategy: Wait for first measurements of radiation levels at LHC start. Perform Radiation tests up to safety required levels. If radiation levels underestimated or electronics fail at higher doses investigate for new electronics: partial upgrade? Redesign ? Combined Performances needs more detailled simulation to evaluate pile up contribution to jet energy ATLAS Upgrade Workshop D. Pallin, Clermont-Fd 14-02-2005