MuCool / Linac Diagnostic Beamline and MTA facility: External Beams Dept. C. Johnstone, + others...
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MuCool / Linac Diagnostic Beamline and MTA facility:
External Beams Dept.C. Johnstone, + othersReview Nov. 30, 2005
Purpose:test the basic techniques and components proposed for muon ionization cooling and
provide accurate measurements of linac beam properties important for future, stable high-intensity running of the downstream accelerators.
Description:The new beamline and facility consists of15 Hz pulsed-magnetic extraction system which diverts an entire Linac macropulse into the new beamline
An ~50 m long beamline which feeds and ends in experiments housed in a 20 x 40 hall; the Mucool Test Area (MTA)Using civil construction and resources that remain from the 400-MeV Linac Upgrade; this project is considerably economical. The experimental hall is shielded and separated from the Linac by 12 of concrete blocks the beamline penetrates through these shield blocks to the hall
The new facility is capable of:Accepting full Linac beam intensity (1.6 x 1013 protons @ 15 Hz) to within the radiological limits imposed by the current state of shielding and radiological controls
MTA facility: Plan View
Low-loss Beam Extraction from LinacExtraction to MTABegins upstream and continues downstream of 400-MeV chopper to contain H- magnetic stripping losses to 10-4 level. Requires 10 movement of Q74 upstream*The entire Linac macropulse is extracted (the length of the macropulse may be varied from 2-50 by the 750-keV chopper.Pulsed extraction magnets:Pulsed extraction magnets: two C magnetsOne 3 magnet upstream and one 7.5 magnet downstream; single power supply for both>1 of clearance/no conflicts with 400-MeV line No 400-MeV vacuum interruption for installation/removalDesign is complete; bids are in; awaiting final division budgets*kicking beam through Q74 causes a large displacement in the 2 Linac beampipe with accompanying high losses.
400 MeV Linac Enclosure~2m Extraction DriftsRamp trajectoriesRamp enclosure wall
H- Extraction RequirementsBeam entering ramp requires ~30 of bend relative to LinacDipole field strengths 7kG to avoid stripping H-, upstream of chopper, ~6kG (Chopper is highly sensitive to electrons and sparking)First component to clear is Q2Controls beam separation to Booster/diagnostic lineCannot be moved; tricky to alignRequires 11 to clear manifolding, 13-15 beam center to center relative to transfer lineNext element to clear is lambertsonDipole (CR) conveniently fits next to transfer line between Q2 and lambertsonIf CR dipoles are used (10 max) another one is required to avoid enclosure corner, 45 total is required for ramp curvature and align beam parallel with the experimental hall enclosure.
Linac modifications: Q74 moves ~10 upstreamQuad to be movedBLD will be removed to make space for quad
Two C magnet: 10, 25 long, 6.2 kG, 3, 7.5 bendsChopperPulsed Extraction System: Two C Magnets
Extracted Beam trajectories
Critical Path: C magnets 76.281(1.9375 m)ssssssssssssssssssssssszz
Tube 2 0.0625 WALL 304 SS 1.5 Beam Tube
16.75 slot(0.4254 m)(17.8 total flange toquad steel)QUADRUPOLE3.005 4.563(0.1159 m) 25.866(0.6570 m) IRONz4.869(0.1126 m) TUBE 304 SS 3.25 0.0625 WALLR1.625(0.04128 )1.949 (0.0495 m)4.618(0.1173 m)X2.125 min (0.0540 m)See example coil and lamination details in text + tables2 schedule to pipe 1.850(0.0470 m)Example coil(0.4096 Cu):Gap: 2.000~1/16 spacing between beam tubes@entrance to magnetBeam tubes in longer magnet
Diagnostic Line Design - New design incorporates10 m straight for transverse emittance measurements of linac beam50 cm low beta waist at center of straightOrder of magnitude change in beam sizeAccess to low beta focus pointDispersion suppression
Inexpensive straight bore through shield blocksSimple, stable match to linac based on linac FODO cells (~90)High (~7m) dispersion point for momentum-spread measurement
Half-width beam size:MW1MW2MW3Experimental HallShield blocks
Layout, plan viewShield blocks
Operational details of Diagnostic TuneMinimum beam stay clear 0.3 (8mm) in upstream 2 chopper mating flange and triplet quadrupoles based on 10 mm-mr linac emitance.Dispersion suppression can be checked and tuned by :varying linac output energy and varying last CR dipole strengthBeam will be steered into hall using trims after the diagnostic straightLow-beta waist can be adjusted and focused onto the second multiwire (just downstream of shield blocks)Using the quad low-beta triplet Critical Devices:Pulsed extraction magnetsBeam stop upstream and downstream of shield blocksOccupancy and radiological controlsBeam stops provide unlimited occupancy in experimental hallPostings, fencing, eberm module will allow us to run at ~1 Hz and full linac intensityPulsed power supply will be hard-wired to 1 Hz.
Low-loss beam tune for MTA runningBeamline can be re-tuned for MTA experiments to achieve the lowest-loss optics. One example is given below with momentum spread included. The peak beam envelope is reduced by 1 cm in the half width (2 cm full width). If a polarity flip of the quadrupole is allowed, even smaller beam envelopes can be achieved.
Power supplies and power requirements
Resource Synopsis: M&S
Beamline ComponentsWith the exception of the C magnet, all beamline components are availablequadrupoles and dipolestrim magnetsdiagnosticsbeam stopsinstrumentation and controls such as an eberm system
Power SuppliesWith the exception of the pulsed power supply, all major supplies and a number of smaller ones are availabledipole suppliesmisc quad and trim supplies
Vacuumion pumps are available (30 liters/min)misc vacuum components
Water55 Linac water is availableTevatron sled available
Resource requests: Summary
PPDC magnetPPD Machine shop:magnet stand fabrication/modify existing standsspool pieces
TDmagnet inspection and testingsmall repairs (hoses)
AD (SWF)C magnet power supply laborInstallation:vacuum, safety, water, power supplies, beamline, controls
Muon FundsC magnet power supply partselectricianscable tray and civil (6 bore through shield blocks)
C magnet specifications:
C magnet specificatons cont
06 Shutdown Tasks - completeQuadrupole moveInstallation of new chopper flanges and gate valveFurther installation can then proceed independent of linac and as time and resources permit
Chopper Modification Drawings
New Chopper Parts: detail
Status of MTA/Linac beamline - summaryLine design complete and components identifiedFinal layouts and full engineering in progressC magnet bids contract awarded to Everson; shipping by Jan, 2007 Q74 move and chopper modifications/gate valve completed 06 shutdown and A0 CR dipoles pulled from Tevatron enclosureFurther installation can now proceed without vacuum interruption/disruption to Linac or BoosterInstallation complete in 07 shutdown