InfrastructureCollimators

Beam line

Shielding - Concrete / Pb

Misc Superstructures - Ferris wheel

Power / Water / Vacuum Hardware

Collimators

• Manufacturing drawings essentially complete

• Out for budgetary quotes

• Material: Recast of existing 29 tons of Pb

• Collimator 1: Single Pb cast / machined structure +- 1mm

• Primary Collimator (2): •

Large wall with square hole: Smaller precision 3 axis alignable collimator: 3” down stream & shadow shielded Material: PbCu or Pb+ 6% Antimony (hardening agent) Tolerance +- 0.15 mm all surfaces w.r.t. center

• Collimator 3: Single large Pb wall cast +- 2mm tolerance

• Plan: Place order this fiscal year

Collimator 1

Collimator 3

Collimator 2 (primary)

Enclosed Region

Region 2 open access

Beamline

• Recycle “G0 instrumentation girder” --> “Qweak instrumentation girder”

• Add additional “Target BPM” inside scattering chamber:

BPM inside the scattering chamber, just upstream of the target that moves / tracks with the target flask.

Locking the DC beam position on this BPM --> the beam will always be centered on the target!

Allows the target to be moved and "drag" the beam with it for straight forward neutral axis studies and beam/target position set.

If the target x/y position “changes / drifts” during cooling, the position calibration changes (motion mechanism slips) and/or beamline

gets “bumped” and alignment is messed up - these are immediately visible by comparison to the target BPM readings with its "twin" that

does not move located just outside the scattering chamber.

The BPM inside the scattering chamber can always be the master reference for the center of the target and is the ideal choice to put the DC position lock on.

Absolute location of beamline BPM’s drops out of any regression analysis.

If we wish to regress on say x/y helicity correlated beam motion it can be done totally in terms of relative units - it need not be absolute position as no arithmetic using absolute surveyed locations is required.

Sensitivity to helicity correlated angle modulation is obtained by using this internal BPM and an external BPM upstream - again no absolute reference is required.

In other words the system is self calibrating and can be used to check the beamline BPM survey for internal constancy.

So we have some redundancy!

Beamline

Shielding - Concrete / Pb

• All collimator “bodies” large enough in radius that line of sight from target to Region III chamber and Quartz requires penetration of all three collimator walls.

• Collimator Base: Concrete - no magnetic material 2 m’s upstream of target and 1 meter below base surface.

• Shielding as close to target as possible Between collimator 1 and scattering chamber - probably Pb (suspect this will reduce Moller background when but into Monte-Carlo)

• Except for access alcoves(s) enclose region between collimators 1 and 2 (primary) with concrete (Al rebar) (suspect this will reduce Moller background when but into Monte-Carlo)

• Leave sides and top fully accessable between collimator 2 (primary) and collimator 3 - for region II chambers

Shielding - Concrete / Pb

• Detector Hut:

Made of “green blocks” for base and back wall & existing concrete beams. New front shield wall:

No Fe rebar (will use Al or ss)Number of stackable piecesMay have some Pb at small radius for photon shieldingNot a precision structure

• Pb Lintels inside QTOR frame

• Pb wedges inside magnet to plug cracks between coils

• Misc shileding around beam pipe at interfaces

Region III Rotator Stand & Ferris Wheel

• Region III Rotator Stand:

Made of recycled G0 forward downstream beamline stand, but ss lower legs.

Recycle all G0’s Pb boxes around 2’ beam pipeConstructed 2 new ss boxes and filled with Pb for region around/upstream of region III rotator - done and stored away.

• G0 Ferris Wheel --> Qweak Detector Support Structure

All Al and ss, rigid and strong - would be expensive to reproduceHas cable trays and HV cables already mounted.Allows Pb shielded 2’ beam pipe to go through center.

• Detectors will be mounted on perimeter - slighted in-front of and at larger radius than Ferris wheel outside diameter - this open access from three sides

• Easy to mount scanner, etc.

Stainless Steel Lower Legs

Al

Cable tray

Fe

Region III

Region 3 Rotator Sub-assemblies

QTOR at MIT / BatesAll coils / Holders Installed