A First Summary of

1
A First Summary of Boundary Conditions for the
Upgrade of LHC Insertions

• Main points from LIUWG meetings
• Project LHC Upgrade Phase I
• WP and WP holders
• Management and Communication
• Perspectives

2
LHC Upgrade-Phase I

• Goal of Phase I upgrade
• Enable focusing of the beams to b0.25 m in IP1
  and IP5, and reliable operation of the LHC at 2
  1034 cm-2s-1 on the horizon of the physics run in
  2013.
• Scope of Phase I upgrade
• Upgrade of ATLAS and CMS experimental insertions.
  The interfaces between the LHC and the
  experiments remain unchanged at ? 19 m.
• Replace the present triplets with wide aperture
  quadrupoles based on the LHC dipole cables
  (Nb-Ti) cooled at 1.9 K.
• Upgrade the D1 separation dipole, TAS and other
  beam-line equipment so as to be compatible with
  the inner triplet aperture.
• The cooling capacity of the cryogenic system and
  other main infrastructure elements remain
  unchanged.
• Modifications of other insertion magnets (e.g.
  D2-Q4) and introduction of other equipment in the
  insertions to the extent of available resources.

3
Participants and Milestones

• Several departments are involved in the Phase
  I project
• AT Department low-beta quadrupoles and
  correctors, D1 separation dipoles, magnet
  testing, magnet protection and cold powering,
  vacuum equipment, QRL modifications.
• AB Department optics and performance, power
  converters, instrumentation, TAS and other
  beam-line absorbers,
• TS Department cryostat support and alignment
  equipment, interfaces with the experiments,
  installation, design effort,
• Milestones
• Conceptual Design Report mid 2008
• Technical Design Report mid 2009
• Model quadrupole end 2009
• Pre-series quadrupole 2010
• String test 2012
• Installation shutdown 2013

4
Summary of the Boundary Conditions (1)

• Cold vacuum (V. Baglin)
• Vacuum stability remains a driving issue
  irrespective of larger aperture ? BS (continue
  to be) required.
• Mechanical stability of the BS during quench (
  r5), BS thickness ? 2mm
• Possibility of cooling the BS at 40-60 K level.
• Concerns gas load (BS transparency) and average
  gas density (background).
• Optics and aperture requirements (S. Fartoukh, R.
  de Maria)
• Most promising solutions symmetric and
  low-beta-max triplets.
• D1 dipole must match the aperture of the triplet.
• The apertures of the matching section (D2-Q4, Q5)
  limit the reach of the triplet. Modifications of
  the BS and magnet position may be needed.
• Cryostats and interconnections (V. Parma)
• Access and transport to IP1/5 require that the OD
  and length of the vacuum vessels of the new
  triplets are similar to the LHC main dipole.
• Re-use of the main components and assembly
  procedure for cryostating sets a limit to the
  cold mass OD of 570 mm (MB).
• Estimated min interconnect length ? 1.3 m
  (magnetic length).

5
Summary of the Boundary Conditions (2)

• Triplet aperture and collimation issues (R.
  Assmann)
• The main concern is the collimation inefficiency
  in IR7.
• Larger triplet aperture opens the possibility of
  opening the jaws and reducing the collimator
  impedance. However, the inefficiency of
  collimation increases.
• Reduction of b drives aberrations, which may
  corrupt the collimation hierarchy.
• Background! Long optimization of TCT with
  experiments.
• Cryogenic limitations and heat extraction (L.
  Tavian, D. Tommasini)
• The present estimate of ultimate e-cloud loads at
  4.5-20 K level higher than the capacity of the
  plants. New ultimate conditions compatible with
  available plant capacity to be defined (after
  commissioning).
• RF in IP4 requires 4 kW at 4.5-20K level of the
  23 kW available. Triplet in 5L will have less
  cooling capacity than the others.
• Replacement of triplets in IP1/5 requires at
  present warm-up of 4 sectors.
• Recent studies of coil insulation demonstrated a
  large potential (gt5) of increasing the power
  extracted from the coil.

6
Summary of the Boundary Conditions (3)

• Options for D1 resistive magnets (M. Karppinen)
• Several possibilities of increasing the gap and
  field of the D1 resistive magnets are considered.
  The most appropriate seems to be to build new
  magnets, optimized to the existing converters and
  cooling plant (located on the surface).
• Issue to be discussed again in the next meeting.
• Powering and protection (F. Bordry, K-H. Mess)
• Quench protection must be considered from the
  beginning as an integral part of the string
  design. Due to considerably higher stored energy,
  the magnets should be decoupled and energy
  extraction included.
• All electronics equipment (including DFBX)
  located outside the tunnel. Severe space
  constraints around IP1 and IP5.
• The favoured powering scheme consists of one 13
  kA PC, 600 A bipolar PC for each magnet, circuit
  branch protection with warm thyristors, cryo-link
  (LTS or HTS), DFBX (or its compact variant based
  on HTS link).
• Several very useful practical reminders (e.g.
  asymmetric voltage taps allowing polarity checks,
  use thin wires different colours!, avoid
  omegas for QH, T-sensor in liquid He, helical
  loops instead of lyras ).

7
Summary of the Boundary Conditions (4)

• 8. Energy deposition (E. Wildner, F. Cerruti, M.
  Mauri)
• The baseline parameters of the triplet, including
  the cold bore and beam screen (6 mm total),
  result in a modified longitudinal distribution of
  losses in the triplet the critical area is the
  Q1-Q2 region.
• The protection of the Q2 and Q3 magnets is
  ensured with the baseline cold bore and beam
  screen. Additional absorber in Q1 can effectively
  reduce the peaks in the Q1-Q2 region.
• The total debris power is 380 W (scales linearly
  with luminosity and length of the triplet).
  Linear average power is 10 W/m (localized peaks
  up to 30 W/m). BS/absorber catches 10-30 of the
  total (3 W/m).
• The TAS protects the front face of Q1. The total
  expected power (300 W) requires a cooling system.
  Backlash to the experiment seem acceptable.

8
Project LHC Upgrade Phase I Work packages

Work packages
Tasks
Work units (deliverables)
9
Project LHC Upgrade Phase I Project Team

10
Management and Communication

• LIUWG (http//liuwg.web.cern.ch/liuwg/)
• Formed in Sept 2007. Includes specialists form
  various groups mandated to develop the conceptual
  and technical designs of the new insertions.
• In 2007, the WG made a review of boundary
  conditions for the optics and each major hardware
  system.
• With the Project in place, extended to all WP
  holders.
• Scheduled to meet every 2-4 weeks.
• Project team
• Coordinates on a continuous basis the coherence
  of requirements and work advance across WP. Meets
  once a week.
• Informs group hierarchy of the advance, resource
  needs and detailed planning.
• Identifies relevant priorities and prepares LIUWG
  meetings.

11
Perspectives

• The first round of discussions has clarified a
  certain number of issues
• Minimize energy dumped at 1.9 K (reduce stored
  energy engineer the BS as an absorber, if
  possible at 40-60 K include energy extraction
  decouple magnet protection).
• Move delicate equipment into shielded areas.
• Important issues for immediate future
• Understand the limits of the collar structure.
• Define the optimal cable usage.
• Advance with the thermal design (cable insulation
  and definition of the heat exchanger).
• Understand the implications (costs) of modifying
  the MS (magnets and other equipment).
• Find a common understanding with the Collimation
  Project- Phase II of the parameters that
  influence the choice of quadrupole aperture.
• Draft budget estimate (PM) for 2008-12 in
  preparation.