SLHC Tracker LayoutThe UTOPIAn Perspective

Charles Young (SLAC)

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SLHC Parameters

• Peak luminosity ~ 1035 cm-2 sec-1

• Average luminosity 4 x 1034 cm-2 sec-1

• Instantaneous rate important for detector layout and design purposes:– Number of events per bunch crossing– Bunch spacing

• 25 or 50 nsec

– Detector integration time• One BC (at 25 nsec separation)

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Four SLHC Scenarios

• Frank Zimmermann: four scenarios during February 2009 ATLAS Upgrade Week. – http://indico.cern.ch/conferenceDisplay.py?

confId=45460#2009-02-27

• Early Separation (ES)

• Full Crab Crossing (FCC)

• Large Piwinski Angle (LPA)

• Low Emittance (LE) Large Emittance (LE)

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Luminosity Evolution

averageluminosity

From

FZ

’s t

alk

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# Events per Crossing

From

FZ

’s t

alk

Max = 400

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With Luminosity Leveling

Min = 75

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What is UTOPIA?

• A very bad acronym for Upgrade Taskforce On Possible Innerdetector Layout

• Members– Leonardo Rossi (Genova - chair)– Andrea Catinaccio (CERN)– Allan Clark (Geneva)– Nigel Hessey (NIKHEF)– Nikos Konstantinidis (UC London)– Andi Salzburger (CERN- DESY)– Teddy Todorov (Annecy)– Jeff Tseng (Oxford)– Norbert Wermes (Bonn)– Charlie Young (SLAC)

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Mandate

• The mandate is to define a baseline layout for the central tracker in view of the Letter of Intent ATLAS will write for the SLHC.

• As the physics focus of SLHC is not defined yet, we require that the new layout has at 1035cm-2s-1 the same performance as the present detector is expected to have at 1034cm-2s-1.

• We should also take into proper consideration the need to build & commission such a detector in a relatively short time (~ 5 years).

• The new layout should be optimized for the inner tracker, including pixel, short strip and long strip, and barrel plus endcap simultaneously.

• The Task Force is expected to reach a result by October and then hand over the information to the LoI editors.

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UTOPIA Meetings

• Meeting every 3 weeks– Six meetings so far– http://indico.cern.ch/categoryDisplay.py?

categId=1389

• Some agenda items– Encourage comparison/validation of tools– Suggest layout with material estimates– Power estimate cooling– Other considerations and wild ideas

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Current “A Basic Layout”

• See presentation by Nigel Hessey (http://indico.cern.ch/conferenceDisplay.py?confId=61990)

• 4 pixel layers, 3 short strip layers and 2 long strip layers

• “Fixed length” barrel

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Power Estimates

• See presentations by Norbert Wermes (http://indico.cern.ch/conferenceDisplay.py?confId=59516) and Alan Clark (http://indico.cern.ch/conferenceDisplay.py?confId=61990)

• Consider contributions from:– Front end power dissipation (digital + analog)– Losses in local cabling– Leakage current x depletion voltage (depends on

radiation dose)

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Primary Vertex Density

Nominal LHC

ES FCC LE LPA

Peak Luminosity

1034 cm-2 sec-

1

1.0 15.5 15.5 16.3 10.7

(luminous) cm 4.5 3.7 3.7 1.6 5.3

Nevent 19 75 75 75 150

/ Nevent m 2368 493 493 213 353

Density ratio =1.0 4.8 4.8 11 6.7

Nevent 19 294 294 309 403

/ Nevent m 2368 126 126 52 132

Density ratio =1.0 19 19 46 18

~20 times higher

Num

bers

fro

m FZ

’s

talk

SLHC/Upgrade ~ 100 m

lum

inosi

ty

levelin

g

Wit

hout

levelin

g

LHC/ATLAS

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z Resolution

• Modified longitudinal impact parameter, zo x sin(), resolution as a function of for pions.

ATLAS detector paper Figure 10.10

100 m

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Desired Resolution

• LHC/ATLAS: FOM ~ 2368 / 100 ~ 24.

• SLHC/Upgrade: FOM ~ 100 / z-res.

• Similar FOM implies z-res ~ 5 m. – Probably impossible.

• FOM ~ 3 or z-res ~ 30 m can be useful and not obviously impossible.

Careful studies needed to confirm (or refute) this hand waving!

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Level-1 Track Trigger

• See presentation by Nikos Konstantinidis (http://indico.cern.ch/conferenceDisplay.py?confId=59516)

• Doublet(s) – direct impact on layout

• Regional readout – no direct impact

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Computing Impact

• Pattern recognition and reconstruction time driven by combinatorics.

• Can a layout make a (large) impact?

• Possibilities:– Layer doublets– More pixel layers

• What are the costs (in $ as well as physics performance)?

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Summary from UTOPIA

• Come up with a basic layout by October

• Targeted for Letter of Intent

• Upgrade Simulation group doing the hard work!