LHC

1
D. Lissauer Brookhaven National
Laboratory Presentation to HEPAP Future
Facilities Subcommittee
U.S. Participation in LHC Upgrade

• LHC Upgrade Schedule and Options
• Physics Motivation
• Detector Upgrades
• Machine Upgrade Options
• Conclusions
• Questions/Answers

2
LHC Schedule Upgrade Options

• LHC Schedule
• First Beams April 2007
• Physics Run July 2007
• LHC Upgrade Options
• Luminosity upgrade SLHC L 1035 cm-2 s-1
• --extends LHC mass reach by 20-30
• --modest changes to machine
• --very challenging for experiment
• --time scale 2014
• Energy Doubled LHC - EDLHC ?s 25 TeV L
  1034-1035 cm-2 s-1
• --extends LHC mass reach by 1.5-2 for
  L1034-1035
• --requires new machine (e.g. 15 T magnets )
• --very expensive option
• --time scale gt 2020

3
Physics Potential of SLHC

• integrated luminosities
  Detector Performance at SLHC
• LHC 100 fb-1/year L ? 2 x 1034
  needs to be similar to LHC.
  
• SLHC 1000 fb-1/year L 1035

• Higgs physics
• rare decay modes
• Higgs self-couplings
• Higgs couplings to fermions and bosons
• Supersymmetry
• Heavy Higgs bosons of the MSSM
• Mass reach up to 3 TeV
• New Gauge Bosons
• Strongly-coupled vector boson system
• WLZL g WLZL WLWL g WLWL , ZLZL
• Extra Dimensions
• Quark substructure
• Electroweak Physics
• production of multiple gauge bosons (nV .ge. 3)
• triple and quartic gauge boson couplings

4
Strongly Coupled Vector Boson System
If no Higgs, expect strong VLVL scattering
(resonant or non-resonant) at

• Difficult at LHC
• At SLHC
• degradation of fwd jet tag and central jet veto
  due to pile-up
• BUT factor 10 in statistics ? 5-8? excess in
  WL WL scattering
• ? other low-rate channels accessible

5
Indicative Physics Reach
Units are TeV (except WLWL reach) Integrated
luminosities correspond to 1 year of running at
nominal luminosity for 1 experiment
PROCESS LHC SLHC
EDLHC 14 TeV 14 TeV 28 TeV
100 fb-1 1000 fb-1
100 fb-1 Squarks 2.5
3 4 WLWL
2? 4? 4.5? Z
5 6
8 Extra-dim (?2) 9 12
15 q
6.5 7.5 9.5 ?
compositeness 30 40
40
6
Detectors General Considerations
7
ATLAS
8
CMS
9
Inner Tracking

• The inner tracker will need to be re-built using
  higher granularity detectors in a harder
  radiation environment in order to preserve the
  current pattern recognition, momentum resolution,
  b-tagging capability.
• a Radiation increase by 10.
• a To keep Occupancy constant granularity has to
  increase by a factor 10.
• Small Radius Region Vertex detector (r lt 20cm)
• aim for a pixels size factor 5-8 smaller than
  today
• (50x400 mm2 g 50 x 50 mm2) g benefit
  b-tagging, t-tagging
• RD
• Pixels Sensor Technologies
• Super rad-hard electronics to achieve small
  pixel sizes.

10
Inner Tracking

• Intermediate Radius 20ltrlt60 cm
• Aim for cell sizes 10 times smaller than
  conventional Si strip
• detectors.
• benefit momentum-resolution and pattern
  recognition
• RD
• Lower cost/channel compared to present Si strip
  detectors
• Si macro-pixels of an area 1mm2 pads or
  shorter strips ?
• Single sided two dimensional readout (new
  concepts)
• Large Radius 60ltr
• Large area Si detectors.
• Could use present day radiation resistant
  strip technology,
• or new single sided technology
• RD
• Similar to intermediate radius less demanding
  except for cost.

11
Inner Tracking
Engineering/Integration Aim at a factor of 10
more channels but with less material. This means
that the System aspects have to be integrated and
understood from the start. RD new light
weight materials for stable structures, Power
Multiplexing of readout cooling,
alignment installation and maintenance
aspects Activation 250 mSv/h implications for
access and maintenance Timescale Need 8-10
years from launch of RD 4-6 years of
RD and prototyping , 4 years to build,
12
Calorimeter
Increased Luminosity will increase the
contribution of the pile up to the noise by a
factor of 3. Increased radiation will imply
moderate changes to the detectors mostly in the
forward direction. RD Endcap find an
alternative to plastic scintillator (CMS) Long
term irradiation effects on crystals.
(CMS) Readout electronics some will need to
be upgraded for increased radiation level.
E.g ATLAS Front end board should be redesigned
either by making components more radiation
resistant,and/or use analog optical links to
bring the signals out.
13
Muon System

• Current ATLAS/CMS Muon systems have a safety
  factor of 3-5 with respect to background
  estimations.
• Background has strong geometric dependence
• Detectors that now function at high-h at LHC will
  function at low-h in SLHC
• Radio-activation at high h, of shielding,
  supports and nearby detectors
• may limit maintenance access
• Strategy
• Balance robust detectors vs. shielding and
  reduced high-h acceptance
• RD
• Study limits of current detectors possible
  use of CSCs at lower h.
• At high-h - higher rates higher granularity
  CSCs, GEMs?

14
Level-1 Trigger/DAQ

• Increased LHC Luminosity up to SLHC means trigger
  and DAQ needs to evolve in time.
• Reduced Bunch crossing to 12.5 n-sec will have an
  impact on the Level 1 trigger architecture.
• RD
• Study Required modifications to LVL1 trigger and
  detector front end
• electronics.
• Data transfer for processing at 80 MHz sampling.
• Synchronization (TTC, etc) becomes an issue for
  short bunch crossing
• period.
• How to handle bandwidth (rate ? size) is an
  issue both for readout and
• for event building.

15
LHC Upgrade Options

• SLHC Luminosity upgrade to 1035
• -- increase bunch intensity to beambeam limit
  ? L 2.5 x 1034
• -- halve bunch spacing to 12.5 ns (electron
  cloud limitation?)
• --Reduce ? to ??0.25 m (from 0.5 m)
• --Increase crossing angle.
• --Reduce bunch length. (new RF)
• --Super Bunch option being investigated.

moderate hardware changes time scale ? 2014

• EDLHC ? s upgrade to 25 TeV
• -- ultimate LHC dipole field B 9 T ? ?s
  15 TeV
• ? any energy upgrade requires new machine
  Injector
• -- present magnet technology up to B 10.5 T
• small prototype at LBL with B 14.5 T
• -- magnets with B17 T may be reasonable
  target for operation
• in gt2020 provided intense R D
• on new superconductors (e.g.
  Nb3Sn)

major hardware changes time scale ? 2020
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U.S. Role in Machine RD

• LHC RD by the U.S. Labs will focus on increasing
  the luminosity.
• Understand the limitations of the current machine
  configuration, particularly the IRs, and
  develop proposed modifications.
• Low b insertion sections (separation dipoles,
  triplet quads)
• Develop high-field Nb3Sn magnets for new low b
  insertion b 15-20 cm seems possible.
• Next Generation Machine Instrumentation and
  feedback systems.
• Other luminosity upgrade RD to be addressed by
  CERN, e.g.
• r.f. upgrades for halving bunch length or
  handling superbunches
• collaborate with U.S. labs on RD on luminosity
  upgrade magnets
• RD for EDLHC adequately covered by U.S. base
  program.
• High-field Nb3Sn dipole RD and BNL, FNAL and
  LBNL addresses either EDLHC or VLHC.

17
Conclusions

• Physics reach of LHC can be extended
  significantly by increasing the Luminosity by a
  factor of 10 or by doubling the energy of the
  machine.
• Luminosity upgrade can be achieved by 2014
• Detectors must preserve (the expected LHC)
  performance to realize the physics potential.
• RD for both machine and detectors upgrades
  needs to start soon. (Note that many present
  ATLAS/CMS detectors started RD in 87) Assuming
  sufficient funds, this is covered by the
  LHC Research Program.
• US Machine RD projects are well suited to the
  capabilities at
• the three national labs. (FNAL, BNL LBNL)

18
Conclusions

• Tracking system upgrade is the most challenging.
  The system
• will need to be almost completely rebuilt.
  Significant RD is
• needed covering the full spectra from generic
  new materials
• to system integration.
• Calorimeters and Muon systems should be able to
  perform well with moderate upgrades.This will
  involve mostly increasing the radiation hardness
  of the readout electronics.
• Trigger,DAQ will be upgraded benefiting from
  commercial developments.
• Strong US involvements in the SLHC will ensure
  significant U.S. presence at the physics frontier
  for the coming decades.

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Questions from the Committee

• What is the estimated cost of the tracking
  upgrade, given the greatly increased channel
  count associated with the Luminosity upgrade?
• 2. Can you give more information on the scope
  and cost of the Nb3Sn magnet RD for the
  luminosity upgrade? More generally , what would
  be the scope of the U.S. part of the accelerator
  upgrade?
• 3. What is the scope and cost of the U.S. part of
  the detector upgrades?

20
Tracking Cost estimate

• The estimate is very preliminary and is based on
  the following assumptions The active components
  of the tracker are all Si. The inner radius has
  upgraded Si Pixel detectors, followed by Si Strip
  detectors, in the outer radius we use single
  sided 2-D Si detectors.
• The estimate was done by scaling the cost of the
  ATLAS Si detector as well as information from
  CMS, and the CDF/D0 upgrade cost.
• In scaling the costs we had to make assumptions
  on how the main cost drivers will scale with the
  number of channels, the area and the expected
  time evolution.
• The RD and final design will have to be driven
  by optimizing the cost to performance of the
  overall system.

21
Tracking Cost estimate

• Mechanics The mechanics does not scale with the
  number of channels.
• One has to keep the services and the total
  weight to a minimum.
• The cost estimate assumes there is added
  complexity due to light weight
• Si Detectors Scale with the detector area and
  only marginally with the granularity.
• The optimization of the number of layers and
  exact location has not been finalized. The total
  amount of Si will be factor of 5-10 greater
  than the present ATLAS detector.
• Possible cost reduction
• Si detectors Cost is driven to a large extent
  by the size of the wafers and industry is
  moving toward larger wafers.
• Minimize the the amount of Si by using
  advances in detector technology. For example
  single sided 2D readout can be used in the
  medium and larger radii where the segmentation
  needs are dominated by tracking accuracy rather
  than occupancy.

22
Tracking Cost estimate

• On detector read out electronics
• The readout electronics cost is driven by the
  number of channels.
• Take advantage of the reduction in the feature
  size of the electronics. (ATLAS design used
  ATMEL/DMILL rad hard technology that has a
  conservative feature size of 1.2 Micron in the
  Strips. CMS and ATLAS pixels are using sub micron
  technology of 0.25 micron)
• Present industry standard is 0.18 moving
  toward 0.13 microns. We expect that by the time
  we go into production the standard feature size
  will be as low as 0.08 microns. Allowing for a
  substantial reduction in the power and space
  needed for the electronics and allowing for finer
  granularity without an increase in power and
  space needed.
• The reduction in power has important
  implication also on the cooling and services that
  will be needed.

23
Tracking Cost estimate

• Module integration
• Module integration costs include costs of
  Hybrids and the components assembly.
• In the case of the Pixel detectors the cost of
  bump bonding Si is a significant part of the
  module integration.
• Significant cost reductions are possible
  assuming one of the integrated developments
  matures in time. They integrate the readout and
  the active detector on the same wafer
  eliminating the need for individual bonds.
• Cables Data Links
• Assumed a higher level of multiplexing compared
  to the present solutions. In particular the
  amount of power cables that need to be reduced
  for physics (reduced mass), space and cost
  reasons.
• Power Supplies
• Power supplies will need to be optimized and
  serve a larger number of modules. This has
  implication on coherent noise and very detailed
  system integration will be needed to achieve
  this.

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Tracking Cost estimate

• Cooling (Additional) The needed cooling capacity
  will scale with the number of channels, but we
  have taken advantage of the lower power
  requirements of the lower feature size
  electronics. A large part of the external cooling
  can be reused.
• Off detector electronics (Read out Drivers) We
  have to take advantage of advances and reduction
  in the cost of electronics. We assume that a
  factor of 10 more data 10 years from now will
  cost factor of 1.5 more than present cost.
• The Tracker cost for one detector thus estimated
  to be between
• 150-180 M. (assuming the full detector is built
  in the US)
• These numbers are only given as a rough
  estimate. We are not ready for an engineering
  estimate, which will have to be done after RD
  has progressed and better optimization done.

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U.S. Machine RD

• See note from Jim Strait

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Scope and cost of U.S. involvement.

• Scope
• The U.S. has 20 of the Physicists on both
  experiments and contributes close to 20 toward
  the construction of ATLAS CMS.
• In the RD phase of the LHC program the U.S.
  contributions have been more significant. The
  U.S. participation in electronics development and
  production is significantly higher than 20 .
• We expect this to hold true also in the SLHC
  era.
• We note that the Upgrade will take place while
  the LHC will be fully operational and a large
  maintenance and operations effort will be in
  place.
• The maintenance and operation will be
  concentrated at CERN. In principle this
  responsibility will be shared equally between all
  collaborators.
• The division of responsibility for the upgrade
  has not been finalized. We assume the U.S. Share
  will be the same as during the construction of
  the experiments. (20).
• There is a good possibility that the U.S. will
  trade off some of the MO responsibility for
  additional responsibility in the Upgrade.
• .

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U.S. cost for SLHC experiments.

• Cost
• The total cost estimate of the upgrade is hard to
  predict.
• We expect the main cost to be in the tracking
  upgrade.
• The exact scope of the upgrade for the different
  systems is not clear and will be somewhat
  different in the two experiments.
• The split between the different systems and what
  upgrade will be done will have to be a result of
  optimization based on actual LHC experience.
• One can only make a straw man upgrade model
  for the detector upgrade.
• This cost does not include RD that we expect to
  be covered from the ongoing LHC Research Program.
  
• We expect that the experiments share will be more
  than 2/3 and the rest for the accelerator.