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Introduction to VELO Upgrade 7th December 2010 LHCb VELO Upgrade Electronics Meeting 1 LHCb VELO Upgrade electronics meeting 7 th -8 th December 2010 Paula Collins

Introduction to VELO Upgrade

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Introduction to VELO Upgrade. LHCb VELO Upgrade electronics meeting 7 th -8 th December 2010 Paula Collins. Charm samples similar to B factories. LHCb : A great start!. Very clean signals in low and high multiplicity B decay channels. Clear CP violation in raw data!. Electroweak - PowerPoint PPT Presentation

Text of Introduction to VELO Upgrade

Page 1: Introduction to VELO Upgrade

LHCb VELO Upgrade Electronics Meeting


Introduction to VELO Upgrade

7th December 2010

LHCb VELO Upgrade electronics meeting7th-8th December 2010

Paula Collins

Page 2: Introduction to VELO Upgrade

LHCb: A great start!

7th December 2010 2LHCb VELO Upgrade Electronics


Charm samples similar to B factories



an s


ls in







B d






Clear CP violation in raw data!

Page 3: Introduction to VELO Upgrade

LHCb upgrade : The Opportunity

7th December 2010LHCb VELO Upgrade Electronics

Meeting 3

LHCb will be upgraded during 2015/2016 to run at 5-10 times greater luminosity and double the hadronic trigger efficiency

Independent of LHC/SLHC upgrade Accumulate -> 20 x statistics Accumulate 1-2 fb-1 per year for 5 years Can we run at the larger pile-up? We

already did! With machine partially filled (344) bunches, we have been running at upgrade occupancies already

2 5 10 15 20 Luminosity (1032cm-2s-1 )







ts /






10 1032cm-2s-1

20 1032cm-2s-1


2 1032cm-2s-1

LHCb is designed to run at a fraction of the luminosity of theGPDs by tuning down b* / shifting beams

Luminosity 2.1032

Crossings with ≥ 1 interaction 10 MHz Average number of interactions per crossing 1.2 Accumulate 1-2 fb-1 per year for 5 years





Page 4: Introduction to VELO Upgrade

LHCb Upgrade – The MotivationLHCb – Precision Experiment

Bs→J/y f CP violating phase: SM error in 2 fb-1, precision measurement in 50 fb-1

Angular asymmetries in Bo→K*o m+m-.

BS→m+m- very sensitive to SUSY effects: 3s possible around 2 fb-

1, precision measurement in 50 fb-1

Tree level g measurement – 4-5o in 2 fb-1, 1o in 50 fb-1

LHCb – Discovery Experiment

Angular coverage very complementary to ATLAS and CMS

Long VELO allows us to measure long lived particles

Exotic particle searches, non SM Higgs….

7th December 2010LHCb VELO Upgrade Electronics

Meeting 4

Page 5: Introduction to VELO Upgrade

LHCb Upgrade Strategy – stay flexible!We do not know how the physics

case will evolve at the end of 2011But we know that our current triggerhas a bottleneck at 1 MHz

7th December 2010LHCb VELO Upgrade Electronics

Meeting 5

MOVE to a fully software based trigger!• All electronics must be redesigned to

zero-suppress data and transfer events @40MHz to a massive CPU filter farm !

• (For 10 1032cm-2s-1 , we can still use the current L0 hardware trigger with relaxed thresholds to limit event rate to 5MHz)

• Complete replacement of VELO and HPDs.

Page 6: Introduction to VELO Upgrade

Current VELO is doing a great job!Why upgrade?

Experiment has operated up to m=2.6 pretty successfully

VELO itself is showing a superb performance Noiseless operation Excellent resolution Good Pattern Recognition Best impact parameter resolution at LHC


T Ruf,R. McNulty

Page 7: Introduction to VELO Upgrade

Reason 1 : Severe Irradiation Damage


At 7 mm from beam we accumulate370 MRad or 8 x 1015 neq/cm2.



5Radius (cm)

Dose after 100 fb-1

n eqc


x 1





7 mm

Recent RD50 studies have shown that silicon irradiated at these levels still delivers a signal of ~ 8ke- / MIP

Efficient heat removal mandatory to avoid thermal runaway!Diamond cooling substrate candidate solutionElectronics must be of sufficiently low noise to cope with reduced signal

Distance from silicon tip to thermal connection too great

Page 8: Introduction to VELO Upgrade

Reason 0

Electronics has to digitise, zero suppress and transmit event data at 40 MHz

By pixel standards the occupancy of the VELO is miniscule, but the data rate is HUGE

1 chip has to transmit 10-20 Gbit / second Our current granularity, occupancies = ok but FE electronics and DAQ are



It’s the trigger,stupid

Page 9: Introduction to VELO Upgrade

All Change for the VELO? No! Can reuse

Vacuum vessel Motion system – as much

as possible LV and HV systems CO2 cooling plant

What’s new Module Cooling interface RF foil Readout infrastructure

7th December 2010LHCb VELO Upgrade Electronics

Meeting 9

This object and the challenge of readingIt out is the subject of thenext few days discussion

Page 10: Introduction to VELO Upgrade

Timepix VELOPix Why we Timepix (and Timepix2)

The square pixel (55um x 55um) gives equal spatial precision in both directions, removing the need for a double sided modules and saving a factor 2 in material.

IBM 130 nm CMS process the extremely low occupancy (< 2 ppm) environment is ideally

suited to the time-over-threshold conversion, as the efficiency will not suffer from the relatively large (1us) dead time.

It has great radiation hardness potential and very small periphery

It is a very economic way (power&space) to obtain >6 bit digitization




Comparator threshold


ToT = TE - LE


ToT = f(Q)

Conversion by time-over-threshold

1. replace ‘shutter’ based acquisition/readout scheme by continuous, dead-timeless operation.2. sustained readout of pixels with maximal average particle flux = 5 particles/cm2/253. power consumption must stay within1-2 W4. pixel functionality:

• reduce TOT count range and resolution : 4 to 6 bit scheme is sufficient. • reduce rise time to reduce time-walk effects.• add bunch identification to hit.

What we need to change

Page 11: Introduction to VELO Upgrade

Challenge of the foil

For the upgrade foil design will be critical CFRP composite option

Low density, space qualified, possibility of reinforcement with carbon nanotubes, single integrated unit

Metal alloy option Focus on fabrication technique : possibility of machining using 5-

axis milling machine Fabrication work in collaboration with CMA (composite Mirror

Applications) Challenges include

Uniformity of thickness and stiffness Vacuum tightness Must be compatible with ultra high vacuum and dynamic

beam effects i.e. NEG coating RF shielding capabilities Irradiation resistance Incorporate compound curvatures of L shape option


Foil construction one of the major achievements of current VELO 8 year R&D project at Nikhef to manufacture leak tight 03 mm AlMg3 foil

of correct dimensions

LHCb Velo Upgrade Electronics Meeting

Page 12: Introduction to VELO Upgrade

Sensor R&D Planar silicon

Things are looking up for charge collection, especially for thin sensors R&D focussing on guard rings Irradiation of planar silicon + Medipix3 planned


Diamond Exciting option for removing thermal

runaway headache Very radiation hard Double act: sensor and thermal path

3d sensors Super radiation hard Many Medipix/Timepix assemblies


Page 13: Introduction to VELO Upgrade

Strip Option In case the material budget/power

consumption of the pixel option falls beyond specifications or time limits, a backup strip option is being prototyped.

Key points: Optimisation of strip capacitance to

bring down noise Cooling simplified Possible move to “spider web” –

simplified pattern recognition Increase in number of strips and better

layout – expected occupancy at upgrade will be 0.5%

IP resolution superior to pixels New chip needed (synergy with IT)




Page 14: Introduction to VELO Upgrade

Infrastructure Critical for Upgrade R&D

Laser test stand already used extensively for timepix characterisation

Vacuum chamber construction underway Module0 prototypes to be produced and irradiated

in coming months Testbeam capability

Timepix based telescope constructed and operated for LHCb upgrade in collaboration with Medipix group

Has already produced fantastic results and is a key tool Will be discussed in this meeting


Page 15: Introduction to VELO Upgrade


Current machine schedule fluctuating Regular 4 month shutdowns anticipated Possible VELO related inverventions ~ 4 months Longer shutdowns for LHC related interventions

Triplet replacement, Linac4 etc. GPD upgrades staged, with larger interventions to

synchronise with machine – preferably after 200 fb-1

LHCb upgrade installation – 2016/2017 Module production to start in 2013


Page 16: Introduction to VELO Upgrade


Module Prototyping milestones

Up to mid 2011 Demonstrator staves and

modulesin three types Mechnical type

With CVD diamond Or another cooling solution

Electronics type With metallisation on dimaond With flex

Cooling connection demonstrator Suitable pipe and attachments Different gluing options,

number of pieces of silicon etc.

Early 2012 12 chip module with

Timepix II and protoype sensor Mechanical, thermal,

outgassing, metrology testing

Irradiation tests Late 2012

12 chip module with final components Full characterisation

Page 17: Introduction to VELO Upgrade


Other milestones

Chip available in 2012 Implying not only electronics design effort but also

prototyping and qualification in testbeam Sensor technology decision on same timescale

Module cooling structure decision mid 2011 Module geometry should already be final Optical/Copper signal chain decision this meeting Mechanical structure finalised end 2011

Page 18: Introduction to VELO Upgrade


Production tasks Production is almost on us and

must be well prepared Wafer probing Sensor testing Bump bonding Dicing, thinning, metallisation Flip chip assembly, inspection Bare module probing Module assembly – mechanical, wire bonding Assembled module testing Optical interface tests Supporting DAQ, cooling systems Databases Irrradiation tests Metrology Transport jigs QA plan ….

Are there institutes to take on these tasks?

Page 19: Introduction to VELO Upgrade

Strawman Layout

Simulation softwareElectronics R&DInfrastructureFoil R&DStrip Option

CO2 vs LN2 cooling choice

Link TechnologyPlanar Silicon option

Module Cooling Structureand hybridisation options

Chip Readout and

Link Integration


Module 0 construction


(arrows are indicative)

Diamond sensor option3d sensor option

Goes to TTReplacementneeded

Organisation in 2010,As presented on VELO Upgradeweb page

Page 20: Introduction to VELO Upgrade

Strawman Layout

Simulation softwareElectronics R&DInfrastructureFoil R&DStrip Option

CO2 vs LN2 cooling choice

Link TechnologyPlanar Silicon option

Module Cooling Structureand hybridisation options

Diamond sensor option3d sensor option

Marco Gersabeck

Steve Blusk

Val O’Shea and Tony Smith

Dave Bailey

Gianluigi Casse

Marina Artuso

Chris Parkes

Tomasz Skwarnicki

Ken Wyllie

Richard Plackett

Ray Mountain

Abraham Gallas

Page 21: Introduction to VELO Upgrade

Organisation at time of LOI submission: VELO Upgrade Institutes:

USC Nikhef Glasgow CERN + Lausanne Syracuse Liverpool Warwick Manchester Bristol Erlangen + New from now: Oxford

7th December 2010LHCb VELO Upgrade Electronics

Meeting 21

Changes Needed: Module 0 convenor More focus needed on

cooling options +…

Page 22: Introduction to VELO Upgrade

Rough cost estimates

Velo is constructed with ~ 25 stations Each station has 2 modules, each module contains 2 hybrids of 6

chips on one piece of ~ 12 cm square silicon + one piece 12 cm square optical grade diamond

About 1000 data links for the whole VELO and 50 Tell40s LV and HV power supplies to be reused Vacuum tank to be reused New cooling system, foils, and bases Tell40 and long distance cables not included R&D, manpower, quality control, in-house assembly costs, testbeam

verifications, system integration etc. etc. All not included System integration material costs could likely mount up to 0.5-1

MChf (based on experience of current VELO)

Page 23: Introduction to VELO Upgrade

New Material Costs (minimum)

item Pieces/surface areaSilicon (n in p, oxy) 100 300 kCHF

Diamond (for cooling plane)

1200 cm^2 120 kCHF

Flex production 100 300 kCHF

Chips (130 nm) 600 800 + 200 kCHF

Flip-chip assembly 1200 cm^2 200 kCHFTSV’s N/A for baseline Total module cost 1200 cm^2 1920 kCHF (cf 600 kCHF

current VELO)Foil 1000 kCHF

Other mechanics 600 kCHF

High speed cables and interconnects

500 kCHF

Other Electronics Components

300 kCHF

Total VELO cost 4320 kCHF