1. 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

2. 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
ATLAS Upgrade Workshop
D. Pallin, Clermont-Fd

3. 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 :
<50 Gy/year sampling1
<11 Gy/year sampling2
<2.5 Gy/year sampling3
ATLAS Upgrade Workshop
D. Pallin, Clermont-Fd

4. 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 (Ultimate scenario)
~12% for 5 years of running at (IR-Upgrade scenario)
~18% for 5 years of running at 1035.
ATLAS Upgrade Workshop
D. Pallin, Clermont-Fd

5. 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

6. 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
 ~ 30% light loss max
ATLAS Upgrade Workshop
D. Pallin, Clermont-Fd

7. TileCal issues/ radiation effects on electronics
From Niel, TID and SEE radiation tests:
All active components tested above required doses (safety factors included) for
OK for
All components survived to doses expected for
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

8. 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
SF=  (MB scenario /MB nominal )

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

10. 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