Roma 17 Ottobre 2005

T. Del Prete, WG per SLHC

Impact of SLHC on the operation andPerformances of ATLAS Tile Cal

•Critical TileCal issues

•Radiation level

•Events pile up

•Timing

•Impact on performances

•Jet Energy LinearityResolution

Roma 17 Ottobre 2005

T. Del Prete, WG per SLHC

ATLAS Central Calorimeters

Tile hadron calorimeter

LBEBA

EBC

Roma 17 Ottobre 2005

T. Del Prete, WG per SLHC

A section of EB cylinder with most exposed components

Fingers w/ LVPS

E3 & E4 (cryo scintillators) sit between cryostats

E1 & E2 (gap scintillators) sit on endplate

In some sectors we have scintillators instead of C10

Sample 3

Sample 2

Sample 1

Most of active elements areInside the iron adsorber

Roma 17 Ottobre 2005

T. Del Prete, WG per SLHC

Neutron flux (Khz/cm2) @1034

Roma 17 Ottobre 2005

T. Del Prete, WG per SLHC

n, doses @1034 cm-2s-1

Tile hadron calorimeter

Roma 17 Ottobre 2005

T. Del Prete, WG per SLHC

LHC Upgrade scenarios

Issues: Radiation damage Pileups of MB events Bunch spacing and trigger Timing

Roma 17 Ottobre 2005

T. Del Prete, WG per SLHC

Plan to implement upgrades in several phases:

•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 s not considered...

This is obtained by:Increase I, shorter , double the bunch number, shorten bunch spacing, Super-SPS (1 TeV) ...

Let me concentrate in two scenarios: L= 1034 - 1035 cm-

2s-1

Roma 17 Ottobre 2005

T. Del Prete, WG per SLHC

Impact of radiation on Light budget

Ligth loss because or radiation (+ n) was discussed in 96TDR and new tests are starting. A fair parametrization of the ratio of light budget after irradiation is:

35.1/43/ 166.0834.0 DD eeR (D in Kgray)

~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.

Maximum expected light loss (in sample 1) for 5 years:

(Natural fibers/scintillators ageing is about 1%/year)

Roma 17 Ottobre 2005

T. Del Prete, WG per SLHC

Impact on TileCal Energy measurement

Limitations due to Light Budget (Photo statistics)

•20 pe/GeV minimum LB for the design energy resolution•40 pe/GeV needed 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

Roma 17 Ottobre 2005

T. Del Prete, WG per SLHC

•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%)

Conclusion on Rad-ageing

30% LBLB

Roma 17 Ottobre 2005

T. Del Prete, WG per SLHC

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 R 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:

PUsfsfcccbEc

Ea

EE 22

121 )(

Roma 17 Ottobre 2005

T. Del Prete, WG per SLHC

Jet Resolution in different scenarios

Roma 17 Ottobre 2005

T. Del Prete, WG per SLHC

Some conclusions on EJ resolution

Jet resolution becomes worse, increasing the number of PU events

/E ≈ 10% @1034 ≈ 30% @ 1035 for Ejet = 100 GeV

We have to understand the impact on:

•Trigger issues

•Missing Energy resolution

•Physics

Roma 17 Ottobre 2005

T. Del Prete, WG per SLHC

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…

Roma 17 Ottobre 2005

T. Del Prete, WG per SLHC

SLHC bunch spacingIn 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.

Roma 17 Ottobre 2005

T. Del Prete, WG per SLHC

TTCBCBCRL1A

Digitizer

ReadOutDriver

•Qi

•Ti

•GoFi

.•••

8 ½ wedges48 pmt each

Principio del readout

40.08 MH

Set Phase of clk wrt pulses

Opt. Filt.

Tile wedge

6 PMT

• L1ID• BCID

To LVL2

TTCBCBCRL1A Event Fragment

BCID, LV1ID

16 Digitizer

Roma 17 Ottobre 2005

T. Del Prete, WG per SLHC

(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