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12GeV Upgrade - Beam Transport. Existing Arcs and 4m Dipole Preliminary Design and Safety Review. Beam Transport Interface Mike Bevins February 22, 2007. Beam Transport Interface - Outline. Existing C-style dipole interface What’s NOT changing New H-style dipole interface

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existing arcs and 4m dipole preliminary design and safety review

12GeV Upgrade - Beam Transport

Existing Arcs and 4m DipolePreliminary Design and Safety Review

Beam Transport Interface

Mike Bevins

February 22, 2007

beam transport interface outline
Beam Transport Interface - Outline
  • Existing C-style dipole interface
  • What’s NOT changing
  • New H-style dipole interface
  • Alignment plan
  • ARC shifts
  • ARC Vacuum
  • Safety
  • Cost Estimate & Schedule
  • Risk Assessment
existing c style dipole interface
Existing C-style dipole interface

ARC Dipoles

B-line – vertical bending dipole

existing c style dipole support
Existing C-style dipole support

Beam Direction

Typical ARC and hall transport horizontal bending dipole support scheme

Outrigger bolted to magnet core

Tie bar (fastens cap to magnet core)

Alignment cartridge base bolted to stand

Alignment cartridge cap

what s not changing
What’s NOT changing
  • Alignment specs
    • Position to +/-0.5mm in x & y, +/- 1.0mm in z
  • Vacuum specs
    • Beam line partial pressure of hydrogen <10-6 torr
    • Total pressure of all other constituents less than 5x10-7 torr
    • Fabrication, welding, cleaning & handling, and leak checking specs still apply
      • 22631-S-001 Fabrication of Ultra-High Vacuum Equipment
      • 22632-S-001 Cleaning and Handling of U.H.V. Components
      • 22633-S-001 Welding Specification For U.H.V. Components
      • 22634-S-001 Helium Leak Test For U.H.V. Components
      • Note an update and consolidation of our vacuum specs is underway
  • Support stands
  • Dipole chambers

New H-style dipole interface

Prototype H-style dipole

  • H-steel interferes with existing outrigger support
  • H-steel runs directly through the holes tapped into the magnet core used to support the outrigger
  • Prefer not to cut away H-steel to clear existing support



New H-style dipole interface

  • Proposed solution
  • Eliminate outrigger supports
  • Build single cap that spans both cartridge bases
  • Requires NO modification to magnet core
  • Requires NO change to cartridge base support structure
  • Does require 3rd flat on one of the cartridge basses for adjustments normal to the beamline

New H-style dipole interface

Fastener in existing tapped hole

Increased cap thickness to support cartridge post (previously reinforced by outrigger)

Bracket to fasten cap to magnet core

3rd flat req’d on this cartridge base

Cartridge post


Alignment Plan – Existing scheme

  • Existing C-style dipole alignment scheme
  • Alignment fixture indexes on machined flats on each end of the magnet
  • Two bolts are used to fasten the fixture to the magnet (mounting holes tapped into upper machined surface on the magnet core)
  • Problems -
    • Lab alignment group reports that it can be difficult to ensure that the fixture is seated properly against the magnet
    • Scheme only provides two alignment points on each magnet
    • Fixtures would require modification to eliminate interference with new H-steel dipoles

Machined flats

Existing C-style ARC dipole

Prototype H-style dipole

Existing C-style dipole up-beam alignment fixture dipole


Alignment Plan – Existing scheme

Existing C-style ARC dipole


Alignment Plan – New scheme

  • Use threaded retro-reflector nests in old fixture fastening holes
  • Provides four points for alignment
  • Alignment group has done mock-up to confirm line-of-sight with the addition of H-steel
  • Additional testing is planed to check repeatability of the installation of nests and the location of the tapped holes in the magnet core
    • May need to fiducialize each dipole and leave nests in place

Retro-reflector nest

C-style ARC dipole with retro-reflector nests installed


Alignment Plan – New scheme

Mock H-steel

Retro-reflector nest line-of-sight check with mock H-steel (viewed from laser tracker)


Alignment Plan – New scheme

Threaded retro-reflector nest


Alignment Plan

  • Vertical bending B-line dipoles
  • Dipoles are aligned using four tooling ball nests mounted to side of dipole
  • Addition of H-steel does not interfere with existing scheme

Vertical bending B-line dipole


West Arc


East Arc



ARC Shifts

To accommodate changes in the spreaders & recombiners the beam path length must be adjusted by shifting several arcs

  • Shifts are pure z-shifts
  • Current optics design calls for small shifts that are likely well within the remaining adjustment in the alignment cartridges (nominally +/-1cm)
    • Remaining adjustment will be field checked later this year
    • Preliminary designs have been developed to accommodate shifts ~1cm if required

Bracket slotted along the axis and normal to dipole

Tie bar & shim can be replaced with bracket slotted along the axis and normal to dipole

ARC Shift – Design for ~1cm shift

  • Goal : Shift arc dipoles and quad girders in machine z ~1cm without altering the support stand, dipole, or quad girder
    • Dipole shift solution

Up-beam dipole support

Down-beam dipole support


ARC Shift – Design for ~1cm shift

  • Quad Girders
    • Mounting very similar to dipoles
      • Alignment cartridge caps fastened to girder with two bolts and pinned using button feature on the cap

Threaded holes


Typical cartridge cap

Typical arc girder interface


ARC Shift – Design for ~1cm shift

  • Solution for quad girders
  • Replace existing 4”x4” caps with a two piece 5”x5” design that incorporates the shift
  • The inner disk eccentrically revolves the upper girder mounting features on the outer body around the fixed cartridge base
  • Outer body of the cap can be used in every arc that requires a shift
  • The inner disk would be arc shift specific
  • Design would NOT limit the nominal range of adjustment
  • Depending on the final magnitude of the shifts and the number of arcs requiring a shift it may be simpler and more cost effective to have multiple one piece offset cap designs


Outer body

Inner disk

Cartridge base


ARC Vacuum

  • The gas load will increase over the present 6GeV design as a result of:
  • Increased thermal outgassing
    • Dipoles running hotter heating the chamber walls
    • Synchrotron radiation heating near dipoles
  • Increased photon stimulated desorption from synchrotron radiation
  • Rough calculations indicate that initially local pressures will be higher than present condition
  • Initial consultation with CASA indicates that this will be acceptable
  • A more detailed vacuum study is underway and will be presented as part of the Preliminary Design and Safety Review of ARC 10 and Hall D layout in April of this year
  • Ion pumps & valves are planned to be refurbished as part of the normal CEBAF maintenance

Safety Considerations

  • Personnel training
    • Jlab & sub-contractor
  • Radiation
    • Designated areas for containment and radiation survey of materials that will be removed from the tunnel
  • Storage
    • Vacuum drift tubes & bellows, hardware, misc. supports
  • Material handling
  • Hot work
  • Electrical Hazards
  • Details to be presented as part of the Installation Plan and Estimate Review to be held in May of this year

Cost Estimate & Schedule

Existing parts getting replaced (cartridge bases, caps, etc…) will likely be used elsewhere in the machine!

  • Detail design to be completed late in FY08
  • Fabrication and delivery to support installation activities in FY12

Risk Assessment

  • Technical - Low
  • Supports -similar designs exist and are already proven
    • A prototype of the H-style dipole double cap is planed to check installation onto alignment posts
  • Vacuum - rough calculations suggest no changes required
    • Detailed study underway
  • Alignment - proof of concept complete
  • Procurement Schedule - Low
  • No long-lead items identified
  • Cost – Low
  • Significant portion of cost is based on engineering estimates
    • Plan to refine with vendor quotes
  • Uncertainty in remaining adjustment in cartridges to accommodate arc shifts
    • Plan to confirm with field check
  • Plan and estimate to support/align modified dipoles complete
    • Plans are in place to confirm present assumptions
    • Alignment and installation personnel involved in designs
  • Risks are low
  • Safety considerations are similar to existing ones sans scale
  • Detailed vacuum calculations are underway – preliminary studies indicate no change required
conclusion and reminder of charge
Conclusion and Reminder of Charge

Thanks to the review panel and all participants!

George Biallas (Chair), CASA Representative, Bob May, Chris Curtis

  • We appreciate comments for the reviewers and all in attendance
  • Preliminary design reviews shall address the readiness of the design to be taken to final/detailed design
    • Technical
    • Safety
    • Cost
    • Risk
  • The preliminary design review should generate a list of follow-on items to help the designers/engineers in their jobs
    • What needs to be addressed or considered prior to the CD2 Reviews?
    • What needs to be addressed or considered during the detail design next fall?
  • Questions?