CBETA Fractional Arc Test

Magnet and Beam Pipe Layout

The magnet and beam pipe layout for the fractional arc test splitter line and first FFAG girder is defined on the following drawings: The dipoles shown for the common magnets (S1.BEN01 and S1.BEN08) are BNL ERL magnets that will be used for the fracational arc test. These will later be replaced by new magnets designed for the final CBETA machine.

The following magnets are included the splitter line 1 section:
  • 2 common dipole magnets (S1.BEN01 and S1.BEN08)
  • 6 additional dipole magnets (S1.BEN02 to S1.BEN06)
  • 8 quadrupole magnets (S1.QUA01 to S1.QUA08
  • 4 vertical correctors (V_CORR_01 to V_CORR_04)
The first FFAG girder includes 9 BNL assembled Halbach permanent magnets, including BDH which is half the lenght of the others. The 8 full-length Halbach magnets include either horizontal or vertical corrector coils surrounding each.


The Instrumentation planned to be installed for the fractional arc test consists of the following:
  • Beam Position Monitors (BPMs)
    • 6 in splitter line S1, using V301 electronics
    • 4 in the first FFAG girder, using V301 electronics
      • EPICS IOC Names: IFABPM01 ... IFABPM04
  • Beam Arrival Monitors (BAMs)
    • 2 in splitter line S1, using V301 electronics connected to the 1st and last button assemblies
  • View Screens
    • 1 at the end of the MLC
    • 2 in splitter line S1
      • Type A (ref. 7208-601-Rear-Beam-Viewer 030918.pdf, sheet 1)
      • Insert vertically
      • Includes tungsten beam stop
      • At OUT position, the bottom of the beam-stop will be 12.5mm above the middle plane of the beampipe
      • At the IN position, the BeO disk will be vertically centered in the beampipe
      • An operator needs to insert a gauge block (between the bellows) to set the 29-mm diameter tungsten at the center of the beampipe.
    • 1 at the end of splitter line S1 (entrance into the FA girder)
    • 2 in the first FFAG girder
      • Type B (ref. 7208-601-Rear-Beam-Viewer 030918.pdf, sheet 12)
      • No beam stop
      • At the IN position, the BeO disk will be centered at 42 MeV beam
      • A short flanged extension has to be added to the viewer driving mechanism to prevent interfere with the magnets and the associated hoses and wires
    • 1 after the first FFAG girder
      • 7208-302-021618.pdf
      • Stationary viewer with a 2” diameter BeO disk, offset horizontally (inside of the ring) for the 42 MeV beam
    • Drawings
  • Beam Loss Monitors (BPMs)
    • A few BLM options will be tested during the fractional arc test. BLMs are not considered essential druing the fractional arc test since the beam current will be very low during this stage of beam tests.
The specific locations for the instrumentation are shown on the following drawing:
  • (instrumentation drawing to be provided here)

Power Supplies

(Details regarding power supplies to be added here)

Status of Fractional Arc Test Assembly

Magnet delivery from Elytt

Friday March 2, 2018

The following magnets are planned to be shipped on Friday March 2, 2018:
  • 3 dipole magnets
  • 2 quadrupole magnets
  • 4 vertical corrector magnets
Update provided by Elytt on March 2, 2018: Elytt-status-03-March-2018.pdf

Main Linac Cryomodule (MLC)

Friday March 2, 2018

Six Solid State Amplifiers (SSAs) are in the process of being installed and expect to be ready to begin testing next week.

Circulators not yet received.

-- RobMichnoff - 02 Mar 2018
Topic revision: r3 - 10 Mar 2018, RobMichnoff
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