LHC detector upgradesSteinar STAPNES1 Physics motivation for increased luminosity Some examples of the physics potential Machine Upgrade Detector interface

LHC detector upgrades Steinar STAPNES 1

Physics motivation for increased luminosity Some examples of the physics potential

Machine Upgrade Detector interface issues and timescales

LHC detector changes ID changes, charges in the forward area, radiation

effects, what can be kept

Ongoing activities and organisation Conclusions

LHC Detector Upgrades Overview


Physics motivation Fairly detailed studies made

Now also at: Eur. Phys. J, C 39, 293-333 (2005)

Detector performance, pile-upincluded All results are preliminary

Assumption : L dt = 1000 fb-1 per experiment per year of running

• Standard Model: multiple Gauge Bosons, top rare decays, …Standard Model: multiple Gauge Bosons, top rare decays, …• Higgs : rare decays, couplings, self-couplings, heavy Higgs MSSM, …Higgs : rare decays, couplings, self-couplings, heavy Higgs MSSM, …• Beyond SM: strong EWSB, SUSY, Z’, compositeness, ….Beyond SM: strong EWSB, SUSY, Z’, compositeness, ….

More details hereMore details here


Physics motivation Main scenario used

LHC SLHC

s 14 TeV 14 TeVL 1034 1035

Bunch spacing t 25 ns 12.5 ns *

pp (inelastic) ~ 80 mb ~ 80 mbN. interactions/x-ing ~ 20 ~ 100(N=L pp t) dNch/d per x-ing ~ 150 ~ 750<ET> charg. particles ~ 450 MeV ~ 450 MeV

Tracker occupancy 1 5/10Pile-up noise in calo 1 ~3Dose central region 1 10

104 Gy/year R=25 cm


Physics motivation Expected detector performance


Physics motivation Examples MSSM Higgs sector : h, H, A, H

In the green region only SM-like h observable at LHC (300 fb-1/exp), unless A, H, H SUSY particles LHC can miss part of MSSM Higgs sector

For mA < 600 GeV, the LC can demonstrate indirectly (i.e. through precision measurements of h properties) SUSY-type Higgs sector at 95%C.L.--> this region is ~ fully covered at SLHC

Red and blue lines: SLHC extensions for 3000 fb-1/exp.Regions where 1 heavy Higgs can be discovered at 5 or excluded at 95% C.L. at SLHC

mh < 130 GeVmA mH mH


Physics motivation Examples





Triple Gauge Bosons W W, Z

Probe non-Abelian structure of SU (2) and sensitive to New Physics

, k from W l Z , kZ , g1

Z from W Z l ll l =e, 1034

l = 1035 (to be conservative ..)

-couplings increase as ~ s constrained by tot, high-pT tailsk-couplings : softer energy dependence constrained mainly by angular distributions

Z

kZ

Z

14 TeV 100 fb-1 28 TeV 100 fb-1 14 TeV 1000 fb-1 28 TeV 1000 fb-1

95% C.L. constraints for 1 experiment from fits to tot, pT

, pT

Z

- SLHC sensitivity at the level of SM radiative corrections- only high-pT muons and photons used (assuming trackers not replaced)






Physics motivation Summary


Physics motivation Some conclusions of these studies

Significantly increased physics reach in practically all typical LHC physics channels.

It is not clear today (need LHC first results and operation experience in all areas – for machine and detectors – to make more qualified statements) if these improvements are absolutely crucial for new physics, or rather if they represent (gradually) better measurements and better exploitation of the LHC energy domain.

However, in either case upgrading the LHC seems very attractive and an obvious next step to plan for.

Physics summary:

The luminosity will increase as function of time at LHC, we will need to upgrade the detectors to take advantage of this.

Some parts of the detector systems might have performance problems or operational problems, and will therefore require interventions and improvements faster than foreseen today.

We have an impressive expertise about the construction and we know today how we would like to improve the detectors - and we will soon have some human resources available to study practical improvements.

The pragmatic view:


LHC upgrade Machine/detector interface

The most relevant parameters for the detectors from previous talk (Ruggiero):

BCO interval: 25ns, 15ns, 12.5ns, 10ns (or 75ns) Forward area/beampipe : Would like to move the closest machine element

towards the IP Timescales : see previous talk – assume 2014±2 years

Increased radiation levels (and resulting activation) : Need to improve shielding, moderators, access procedures, and safety in general – important constraint for any change considered

Driven by this plot, but alsoby lifetime of IR quads 700 fb-1


LHC detector changes The critical areas

To take advantage of a luminosity increase the detector performance of ATLAS and CMS have to be kept – i.e tracking, b-tagging, vertexing, energy and momentum measurements

The detector changes have to be ”reasonable”, one cannot replace the entire detectors for reasons of cost and time.

One would like to keep as much as possible of the existing large items (calorimeters, muon systems, magnets, cooling, gas, cables, pipes, support structures, movement systems, cryogenic systems, etc).

Based on the physics considerations and machine constraints - what to upgrade:

The Inner Detectors will need to be replaced (expected lifetime of 10 years at 1034 – due to sensor damage and damage of electronics elements).

Changes will be needed in the forward area (in order to move machine elements closer to the detectors). These changes affects shielding and beampipe, and might also conflict with existing calorimeters or magnets.

CMS in particular believe that for keeping an efficient muon trigger ID tracking information should be used at level one.

Radiation and activation levels increase, and ageing and space-charge effects of calorimeters and muon chambers need to be studies in more detail, the goal is clearly to change as little as possible

Depending on the chosen BCO frequency - the impact on the existing electronics can change significantly.

Trigger and DAQ need to be upgraded (due to lifetime of many parts this will probably happen earlier for parts of the system – and higher luminosity can be anticipated in these changes)

So the most clear modifications needed are:


LHC detector changes Radiation levels at SLHC


LHC detector changes ID changes

In the current ATLAS/CMS trackers a factor ten luminosity increase would imply that the detectors die within months, and/or become useless due to increased occupancy creating problems for the tracking, and/or going beyond the acceptable readout rates.

This applies to both PIXEL and Strip systems in ATLAS and CMS. The TRT in ATLAS will have an occupancy which approaches 100% and cannot be used.

An other way of saying this is that the current technologies, with important new developments could work at a factor 3 higher radius.

So we are looking at a full silicon tracker (the best current example is CMS)

TRT endcap A+B TRT endcap CTRT barrel

SCT barrel SCT endcap

Pixels


ID layout and granularity SLHC ID layout example

• 3 Pixel Layers

14,32,48 Sectors

5,12,18 R Location

• 4 Short strip layers

22,32,40,48 Sectors

27,38,49,60 R Location

• 2 Long Strip layers

32,40 Sectors

75,95 R Location

• Moderator


With existing ATLAS tracker

Track reconstruction efficiency inside high-pT jets (from 400 GeV Higgs decays) for different luminosities L=0, 1034, 5×1034, 1035

Rate of fake tracks

Clearly not good enough but it does not fall over …

LHC detector upgrade Pattern recognition at SLHC


10,000e

5000e

Sensors: main issues are : Reverse currents rise. Trapping increases. Bulk type inverts to effectively p-type – depletion voltage increase.

Consider to use p type bulk material to operate more effectively under-depleted, collection electrons (less trapping)

For example: A conservative target for SLHC short strips would be survival of ~2 ×1015 cm-2 1MeV neutron equivalent, with S/N > 10

For PIXEL area more difficult, replaceable or 3D type (see RD50 studies for 1016 cm-2 1MeV neutron equivalent sensors)

Both CMS and ATLAS have very good experience with sensor production and quality in current experiments

For the innermost layer(s) special measures or replaceable system need to be considered – most significant R&D area

LHC detector upgrade Elements of new IDs ?

Cost comparison for fixed volume

-

5.00

10.00

15.00

20.00

25.00

30.00

10,000 50,000 100,000 200,000 500,000

Volume required

$/c

hip

025

013 unscaled

013 1/2

013 1/4

013 1/8

(65 $/chip)

Electronics in DSM work well, parts already tested to 100 MRad (and more but not powered), ie 0.13um or 0.09um processes can do the job (CMOS or SiGe) - and costs are quite reasonable

The lowest layers need special attention – even more true for sensors (make replaceable?)

Yield/costs; ATLAS PIXEL chip has around 80% yield, production costs promising (but prototyping costs large – one iteration assumed in plot on the left)

Important R&D area: Very significant improvements in power distribution (serial powering or rad hard DC/DC) needed


LHC detector upgrade ID production clusters and timescales

CMS assembly with identical systems at 7 sites to produce ~15K modules.

Aim to complete 15000 modules in 2 years

Nevertheless; to complete the R&D, build pre-series, complete the module production and integrate, all ready by 2014 is challenging

Costs will similar (or likely significantly larger) than the current trackers (these are 80-90 MCHF)

Example of robotics & large scale organizational approach:


LHC detector changes Activation and move of TAS/QUAD

Moving the last element closer to the IP clashes with shielding/toroids and CALO elements (impact depending on radial size of machine elements in question and their position)

Activation levels already critical, would help to increase Be part of beam-pipe, generally any machine element in this region likely to increase backgrounds

Generally speaking, a careful common optimisation of the forward regions of the detectors is needed wrt: Shielding/activation, Opening scenario, Beam-pipe changes, Magnetic fields

Maintenance operations must be designed for maximum of 5 mSv/year total dose (safety factor).


LHC detector changes Initial measurements/background levels

An early key measurement at LHC is a verification of the radiation and activation levels (in all parts):

Will impact the lifetime of our hardware

Determines the access restrictions, at LHC and SLHC

To calibrate our fluence models

To verify (or falsify) our detector material modeling of “active” materials

Will determine margins for luminosity increases in the muon region

Will determine margins for a number of items sitting in the cavern, COTS, regulation elements, etc.

…. and probably more

So only after these measurements are made we can make real judgments about where and when we will hit critical limits for increased luminosity

See example of simulation of neutron background – used now to optimise shielding and moderators, and beampipe layout (neutrons in kHz/cm2)


LHC detector changes BCO frequency changes

The ID electronics can be redesigned to any new BCO (10,12.5,15, 25 or 75 ns)

Changing the bunch crossing time from 25 ns to 12.5 ns can be done for calorimeters and muon chambers, however not all signal filtering can be optimised for 12.5 ns and BC ID might not be possible at trigger level for all trigger types

Nevertheless, 12.5 ns probably largely ok, BC ID (partly) possible, but S/N not fully optimised in all cases

It will be question of costs/performance to determine what to change …

Changing to 10 or 15 ns would require changes in electronics HW and intervention at FE crate level (on detector)

These consequences only partly understood but they imply a very significant amount of work and costs

Trigger/DAQ will need to be changed (but many parts are already clocked faster than 40 MHz) and in particular lvl 1 parts need to be (partly) rebuilt

75 ns generally ok instrumentally but pile-up will degrade performance


Tracker input to L1 trigger

Proposed boundary conditions Rebuild L1 processors Maintain 100kHz limit for L1 trigger Increase latency to 6.4µs

ECAL digital pipeline holds 256 @ 40MHz Assume clock speed is 80MHz

or some acceptable f agreed with machine

Muon L1 Trigger rate at L = 1034 cm-2s-1

Note limited rejection power (slope) without tracker information

LHC detector changes Tracking trigger at lvl 1 (CMS study)


Current activities R&D ongoing and organisation

Several groups around the world work on electronics, sensors, powering and simulation studies for SLHC, mostly groups close to completing their construction tasks (a few examples have been shown).

Many groups request guidance and organisation for hardware R&D projects (and establish resources). RD50 is a very active in the area of sensor R&D, most of it is very relevant for SLHC.

Work ongoing:

In ATLAS: Steering Group established, two workshops in Feb and July 2005.o Plan to organise R&D with Steering Group and Project Office as part of technical coordination to ensure

coherence. In CMS: Three workshops on SLHC; Feb 2004, July 2004, July 2005.

o To assist in the R&D project definition, already agreed CMS peer-review scheme. Main lines identified: Tracker & Trigger Microelectronics and Power Optoelectronics & data architectures

o Aim to merge at early stage into system(s) ATLAS and CMS are also discussing collaborative efforts when appropriate.

Organisation inside the experiments:

Encourage guided R&D fitting into plans and schedules for upgrades Make sure there are clear guidelines for what R&D projects should be supported (by the experiments) Make sure the human resources and experitise existing in the detector communities are kept active in the

work to optimise the detectors in the future, for changes, upgrades and adaptations

Overall and common view:


LHC detector upgrade Conclusions

Physics case strong for increased luminosity – our understanding will obviously develop as the initial LHC operation get underway

Detectors will need to develop with luminosity (and maybe for other more pragmatic reasons – performance, lifetimes, etc)

New ID (fully or partly) needed for substantial higher luminosity Keep in mind that both experiments foresee to change innermost PIXEL layer(s) anyway

after some years, and this is a significant intermediate milestone Technology seems feasible but several R&D efforts needed to prove it and to optimise

Both experiments want to minimize other changes, both to calorimeter and muon electronics, and large infrastructural items

BCO frequency for SLHC need to be agreed Need early operation experience and background rates at LHC in particular to see if the

current muon systems are ok Need good radiation level and activation studies, and together with the machine, to

optimise the forward region close to (and including) the beampipe Changes needed to DAQ/trigger - some of these can probably be partly anticipated in

natural upgrades over the coming years, a tracking trigger at L1 is being considered Costs significant – rough estimates at 30-50% of current detectors


LHC detector upgrade Conclusions

ATLAS and CMS already have significant activities related to detector upgrade for SLHC, and are establishing internal organisations to direct, encourage, optimise and collaborate in the developments ….

HOWEVER – our main focus is to get started with LHC, probably the by far most important next step for all of us!

THE END

Many thanks to my ATLAS, CMS and LHC machine colleagues for information, comments and corrections

Documents

LHC detector upgradesSteinar STAPNES1 Physics motivation for increased luminosity Some examples of the physics potential Machine Upgrade Detector interface