ATLAS at the Super-LHC

• Examples of Expected Physics Gains

• ATLAS Upgrade Requirements

• Proposed UK Programme

• Resource Requirements

• Conclusions

Phil Allport

Representing ATLAS UK

Examples of Expected Physics Gain

Measure coupling of neutralino to Higgs. Determine its higgsino component.

Requires Requires 5 years of SLHC5 years of SLHC Dark Matter?Dark Matter?

××1010

• Physics case for 10× luminosity much better known after first significant high energy data from the LHC• However we can expect: Improved mass reach for discovery by ~500GeV

(50%) with increased luminosity Greatly increased statistical precision on rare or

very high energy processes• Because of statistics and mass reach, SLHC is to a large degree complementary to the ILC − only LHC/SLHC can pair produce particles with mass ≥ 0.5 TeV.

• Precision Standard Model physics with 10 data (sensitive to new physics) • Higgs couplings • Triple and quartic gauge couplings• Strongly coupled vector-boson scattering (if there is no Higgs)• Rare top decays through FCNC

• Extended mass reach for new particles (by ~0.5 to 1 TeV):• Heavy Higgs-bosons, extra gauge bosons, resonances in extra-dimension models, SuperSymmetry particles (if relatively heavy).

• SuperSymmetry (if relatively light, already discovered at LHC)• complete the particle spectrum• access rare decay channels and measure branching ratios• improve precision (e.g. to test against WMAP results)

See Eur. Phys. J. C39(2005)293

Examples of Expected Physics Gain

• Strongly coupled vector-boson scattering (if there is no Higgs)

Examples of Expected Physics Gain

In absence of clear Higgs at LHC, SLHC statistics could be needed to probe the W, Z scattering process which has diverging cross-section in SM without Higgs.It is therefore particularly sensitive to whatever new physics must exist to keep this process finite. Requires Requires several years of SLHCseveral years of SLHC

LHC LHC SLHC SLHC

Even with 300fbEven with 300fb-1-1 many potentially important channels can be statistics limited many potentially important channels can be statistics limited

80 fb-1/yr

SH

UT

DO

WN

600 fb-1/yr

20

0 f

b-1/y

r

3000

300

30

10-20 fb-1/yr

First physics run: O(1fb-1)

SUSY@1TeV

SUSY@3TeV

Z’@6TeV

ADD X-dim@9TeV

Compositeness@40TeV

H(120GeV)

Higgs@200GeV

Examples of Expected Physics Gain

2009 2011 2013 2015 2017 2019

To keep ATLAS running more than 10 years the inner tracker will need to be replaced. (Current tracker designed to survive up to 730 fb-1)

For the luminosity-upgrade the new tracker will have to cope with:• much higher occupancy levels• much higher dose rates

To build a new tracker for 2015, work needs to start now.

Timescales:• R&D until 2009 leading into a full tracker Technical Design Report (TDR) in 2010• Construction phase to start immediately TDR completed and approved.

This proposal deals with the tracker upgrade programme only. It concentrates on a part of the new proposed barrel detector region facing particular challenges, but where the UK has special expertise. The intermediate radius barrels are expected to consist consist of modules arranged in rows with common cooling, power, clocking and cooling.The aim of this proposal is to prototype the smallest unit for these radii (a “super-module”) that can operate independently, testing all subsystems. This may or may not also be a mechanically self-supporting object (a “stave”).

ATLAS Upgrade Requirements

ATLAS

UK leadership on sensors, irradiation studies, module prototyping and production, optoelectronics, data links, final alignment systems, data acquisition and engineering components.

The ATLAS Silicon Central TrackerUK led project: all 4 barrels and 9 disks of EndCap-C assembled in UK

Pixels (50 m 400 m): 3 barrels, 2×3 disks 4.7cm < r < 20cm• Pattern recognition in high occupancy region• Impact parameter resolution (in 3d)Radiation hard technology: n+-in-n Silicon technology, operated at -6°CStrips (80 m 12 cm) (small stereo angle): “SCT” 4 barrels, 2×9 disks • pattern recognition 30cm < r < 51cm• momentum resolutionp-strips in n-type silicon, operated at -7°CTRT 4mm diameter straw drift tubes: barrel + wheels 55cm < r < 105cm• Additional pattern recognition by having many hits (~36)• Standalone electron id. from transition radiation

Current Inner Tracker Layout

r=30cm

0.61%

Mean Occupancy in Innermost Layer of Current SCT

Pixels: 2 m2, ~80M channels

SCT: 60 m2, ~6.3M channels

TRT straws: ~400k channels

ID TDR

WP1: Physics and Layout Studies

Note: numbers based on factor 10 increase in luminosity but still 25 ns bunch crossing. Would be worse for longer (50 ns) bunch crossing time.

Pixels:Very short -strips:Short (3cm) -strips (stereo?):Long (12 cm) -strips (stereo layers):

r=5cm, 8cm, 12cmr=24cmr=32cm, 46cm, 60cmr=75cm, 95cm

z=±40cmz=±40cm/100cmz=±100cmz=±100cm

All Silicon Tracker Proposal

WP 1: Physics and Layout Studies

Including disks this leads to:

Pixels: 2 m2, ~150,000,000 channels

Very short strips: 1.2/3m2, ~2.4/6,000,000 channels

Short (3cm) strips: 60 m2, ~25,000,000 channels

Long strips: 120 m2, ~13,000,000 channels

Occupancy vs radius (25 ns)

• Understanding radiation background issues at SLHC crucial for successful design and operation of inner tracker.

Quarter slice through ATLAS inner tracker Region, with 5cm moderator lining calorimeters. Fluences obtained using FLUKA2006, assuming an integrated luminosity of 3000fb-1.

WP2: Radiation Background Benchmarking and Simulations at the SLHC

→ Radiation degrades performance of detector and readout systems

→ High levels of activation will require careful consideration for access and maintenance.

• UK played leading role at LHC and has unique expertise in this area.

• Programme proposed for SLHC, led by UK, divided into two main areas:

1) Radiation background simulations.

2) Benchmarking of the Monte Carlo simulation codes with LHC data.

1) Radiation simulations 2) Benchmarking • New moderator design and predictions

for inner tracker.• Moderator reduces neutron energy

making them less damaging to silicon.

• Beamline activation studies. • Access and maintenance to inner

tracker impossible with current beamline. New design needed.

• Machine interface studies.• Increased integration between

machine and experiment inevitable. For example machine magnets are being proposed near tracker.

Programme

• Radiation monitor installation and analysis of data.• Collaboration with several institutes

established (Ljubljana, Arizona, Prague).

• Different monitoring technologies being installed in and around ATLAS experiment.

• Measurements of fluences (pion, neutron, 1Mev-eq. etc.) and doses.

• Minimum-bias measurements for benchmarking of event generators (eg Pythia).

WP2: Radiation Background Benchmarking and Simulations at the SLHC

Programme reviewed and endorsed by ATLAS Upgrade Steering Group.Seek support to take on a leadership role in this programme.

Super-Module/Stave Concept

WP4: FE Electronics and Interconnects

WP3: Sensor Research and Development

WP5: Optoelectronics Readout System

WP6: Power Distribution Schemes

WP7: Engineering WP8: Data Acquisition and Off-detector Readout

Current Barrel Module

WP3: Sensor Research and Development

For LHC doses:

• Main failure mode is when full depletion voltage grows beyond breakdown voltage. Undepleted region low field → poor charge collection.

For the SLHC doses (r=27cm: 1015neq/cm2=1.8×1015p/cm2):

• Will not be able to operate (conventional) silicon fully depleted (VDEP >> 1000V) However, p-type silicon with n-strips (collecting electrons) can work as the undepleted region is semi-insulating after heavy irradiation.

• Trapping is dominant radiation effect on sensor performance.

Optimize for charge collection efficiency CCE not for VDEP

• High currents threaten stable operation (thermal runaway)

Require robust cooling to reduce currents and remove heat

Pulse height distribution of a miniature n+-in-p detectors with 106Ru β-source, after exposure at the CERN-PS to 7.5×1015p cm-2 with LHC speed electronics.

p-type 1cm detectorafter 7.5×1015p cm-2

(2MGy)

7000e-

10,000e

5000e

This technology is promising for replacement silicon, but need full-size commercially manufactured sensors

ATLAS UK lead the programme which has developed detectors able to withstand > 4 times the expected 27cm radius dose at SLHC

The target for SLHC micro-strips is survival to ~1.8 ×1015p/cm2 (1015neq/cm2) with S/N > 10.

(Requirements quoted in 1MeV neutron equivalent dose, by convention, but actual irradiation is mostly charged hadrons at low radii)

UK designed, irradiated and measured

Full-size LHCb sensors prototyped by UK on p-type

Miniature micro-strip detector now neutron irradiated by UK

~3×1015neq/cm2 =5.5×1015p/cm2

Prototyping on p-type now by many international groups

protons

neutronirradiated

WP3: Sensor Research and Development

WP4: FE Electronics and Interconnects

• Final design specifications of ABC-next SLHC 0.25μm CMOS microchip

• Procurement and evaluation of ABC-next

Sensor (WP3), optoelectronics (WP5), powering (WP6), super-module prototyping (WP7) and read-out (WP8) studies all rely on an many hundreds of ASICS for UK R&D

• Prepare design for 3cm kapton hybrid and fabricate

• Evaluate first modules

• Identify candidate MCM-D process

• Carry out thermo-mechanical tests to see if MCM-D can be integrated with detector

• Fabricate MCM-D hybrid on silicon for 3cm option

• Make transition to shorter strips

Diode stripRouting layer

ASIC

sensor

Die-attach/flip chip

1) Sensor wafer

2) Add dielectric and open vias

3)Add metal layersand pattern

4) Dice sensor

5) Flip-chip ASICs

6)Wirebondto hybrid

… or make this also part of MCM-D

WP5: Optoelectronics Readout System

Radiation tolerance determination of current readout components• Step index multi-mode and graded index fibres,

• ATLAS lasers, p-i-n diodes for commercial packaging

• other COTS (custom off-the-shelf)

• future custom-made devices (if necessary).

Develop and test connecting link infrastructure for suitability in the SLHC environment in close collaboration with other work-packages.Deliver suitable optoelectronic components for the UK ‘super-module’ prototype for the on and off detector parts.Test for SEU (single event upset) and long-term reliability of candidate high-speed optical readout systems.

WP5: Optoelectronics Readout System

Step index multi-mode fibre irradiation up to 100 Mrad

• 1.33% performance loss/m – very good

• Graded index fibre radiation tests needed

Threshold shift of VCSEL lasers

• All VCSEL alive after annealing• Promising result BUT failures

developed after long term operation• Long term reliability needs to be

investigated with more tests.0

0.5

1

1.5

2

2.5

3

0 1 2 3 4 5 6 7 8 9 10

Fluence 10^15 [n(1 MeV)/cm2]

T

hre

sho

ld [

mA

]

SLHCPreliminary

LHC

Fluence 1015 [n (1MeV)/cm2]0 1 3 52 4 6 7 8 9 10

0.5

1.5

2.5

ΔT

h

[mA

]

20

WP6: Power Distribution Schemes

• Solution of power distribution problem is key for Tracker Upgrade

• RAL was awarded a £50K (incl. effort) seed-corn grant for serial powering. R&D is very well within schedule. Grant runs out in summer 2007

• Grant allowed us to obtain lead in powering distribution R&D in ATLAS

• Understanding of serial powering has greatly increased and results are well received at conferences (LECC 2005, Hiroshima 2006, IEEE NSS 2006)

• Must now increase pace of R&D and make transition from generic studies to engineering of SLHC prototypes

• Power distribution is closely intertwined with ASIC and hybrid design; supermodule electrical and mechanical design; etc. Power distribution should be ahead of these in order avoid additional iterations

• Requested effort for powering distribution R&D is escalated from actual seed-corn expenditure, is well-known, and modest in comparison.

21

• Noise performance and grounding and shielding issues for large structures• Power consumption of regulators• Operation of serial powering systems with many modules (20)• Alternative sensor bias voltage schemes

• ABC-Next operation voltages and power variation• Regulator specifications and design

• AC-coupling schematics• Low voltage buffer design• Need for DC-balanced protocol

• Risk of single-point failure analysis• Over-current protection schemes• Communication with regulators• Slow control information on module currents

WP6: Power Distribution SchemesIssues

SP interface

board

SP Test with Current ATLAS modules

22

Serial powering and parallel power bus with DC-DC conversion

Note: Parallel powering without DC-DC conversion is problematic due to low power efficiency and large IR drops

M1 M2 M3

M1 M2 M3

M1 M2 M3

IP

Parallel powering with DC-DC conversion

SP

Analog and digital voltage

Constant current for both analog and digital power

+ local regulators

WP6: Power Distribution SchemesAlternatives

WP7: EngineeringEngineering issues pose some of the greatest challenges

Limited time to build much larger and more

demanding system

Final detector array will have to occupy same volume as current tracker and use same services routing

Sensor dimensions, hybrid design/technology substrate (with integrated cooling?) data links, connectors, supports etc …all to be defined

The UK is uniquely placed to implement the lessons from the current SCT in any future build

For R&D, we propose to concentrate on thermal management, low mass tapes (LMTs) and connectors• The radiation effects will require the silicon sensors to run 15OC cooler than at present

Need optimised module design and lower temperature coolant

• The powering, communications and read-out will require radically different solutions

Attention to LMTs and connectors needed now to achive reliability and drive large-scale production

We intend in this, and previous work-packages to ensure (with international colleagues) that all elements are in place to allow design and manufacture of a super-module prototype before the TDR is required, and to prove mass production, affordable construction of the entire tracker is feasible

It is to this end, that we are proposing a programme of prototyping of mechanical and thermal structures along with electrical prototyping and testing

WP7: Engineering

Thermal Management

Challenges for the SLHC: • more modules / more power dissipation

• may need to keep silicon temperature at -25°C.• strong constraint on thermal separation hybrid and sensor

Proposals for study:• sensors on high thermal conductivity spine/base (TPG,CC, other)• Use two-phase cooling again. Limited number of coolants available

• C3F8 (current system)• CO2 (high cooling capacity with very thin pipes)

-23.0°C

12.5°C

-20

-10

0

10

SCT experience C3F8 evaporative cooling system

• constant temperature throughout cooling lines

• high cooling capacity (limited flow)

Also

• successful thermal separation hybrid and sensors.

A key part of the request is to employ a senior project engineer, able ot play a pivotal role in the ATLAS Upgrade Project Office at CERN

The UK project engineer will:

•ensure that the UK effort is coherent

•coordinate the distributed UK engineering effort

•ensure UK engineering effort is efficient and focussed

•work with colleagues in the ATLAS Project Office, to fully optimise the upgrade tracker design

The outputs of all the previous work-packages and WP8 are needed if the goal of a prototype super-module/stave is to be realised by 2010 and the experience and appropriate infrastructure is to be developed to make subsequent pre-production and finally production units

WP7: Engineering

WP8: DAQ and Off-detector Readout

• UK groups are responsible for current ATLAS SCT DAQ and major parts of off-detector electronics• SLHC requires re-design for data-rate, volume, new ASICs, new

datalinks • All existing ATLAS UK expertise gathered together in this work

package• Two necessary paths:

1. Developments from existing (all UK) SCT lab DAQ and readout electronics• To provide vital, timely, support for other SLHC R&D activities

• Needed now in order to:• Test features of new ABC-Next ASIC (WP4)• Read out sensors with existing and new ASICs (WP3)• Read out modules during early stages of super-module

programme • Developments must be underway in 2007 and completed in 2008

WP8: DAQ and Off-detector Readout

2. R&D towards longer-term readout solutions• Needed from 2007 in order to:

• Provide input to design features of ASICs (WP4), optical protocols (WP5), powering scheme protocols (WP6)

• Produce a prototype DAQ chain capable of reading out 400-ASIC super-module at end 2009• Super-module cannot be tested electrically without

this development• Test-bed for scalability studies of DAQ

• Will start by studying potential of generic PC-based components for use in this application

• If found inadequate, return to custom VME-based solutions

ATLAS Tracker Upgrade Summary

Likely date for SLHC luminosity upgrade to 1035 cm-2s-1 is around 2015.Preparations for required inner tracker replacement already urgent.

Simulation: urgently needed to define layout and operation constraints Sensor technology: solutions may exist but urgently require commercial prototyping Front-end electronics: deep sub-micron rad-hard technologies neededInterconnect Technologies: integrated with ASIC design and required granularityOptoelectronics: very radiation hard and much higher bandwidthPowering: individual power to each hybrid/sensor not an optionEngineering: issues may be the biggest challenge:• require integrated design of module/stave with full services incorporated • need to work on cooling, electrical power distribution and optical read-outDAQ: programme not possible at each stage without read-out

Limited time to build large tracker requiring many innovative technologies

The European strategy for particle physics

http://council-strategygroup.web.cern.ch/council-strategygroup/

“The LHC will be the energy frontier machine for theforeseeable future, maintaining European leadership in the

field; the highest priority is to fully exploit the physics potentialof the LHC, resources for completion of the initial programme

have to be secured such that machine and experiments can operateoptimally at their design performance. A subsequent majorluminosity upgrade (SLHC), motivated by physics results

and operation experience, will be enabled by focussed R&D;to this end, R&D for machine and detectors has to be vigorously

pursued now and centrally organized towards a luminosityupgrade by around 2015.”

Back-up Slides