Laser FT updated (final?) proposal

Sowjanya, Kendall November 7, 2017

DUNE Calibration TF meeting

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Counter Proposal• To get around the problem of only 3 ports along the outer APAs, leverage on the

instrumentation ports that are outside the Field cage

• This gives crossing tracks but probably lasers L1, L2, L3 & L4 are constrained in space/angle

• Can only shine through the FC gaps (MicroBooNE experience?)

• Structure of the FC (3D drawing to understand geometry considerations)

• In the orange dotted boxes drift region, full field map cannot be extracted.

NORTH

SOUTH

WEST

EAST

All ports “multipurpose”

ports

• Light blue: inside FC; Dark blue: outside FC; Green: Cryogenic port (could swap or use, to be determined)

• All ports on top of the TPC • Outside ports are 404mm from FT centerline to outside wall of FC (along

support feedthrough line). Field shaping elements another ~70mm away. 3

Current Feedthrough Proposal (for calibration) APA

APA

APA

CPA

CPA

L1

L2

L3

L4

NORTH

SOUTH

WEST

EAST

404 mm

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• This may be our final proposal. Do we see any deal breakers or outstanding issues with it?

• Next steps: build a strong case to understand the limitations of this system and if more is needed.

Spacing details for outer ports - Jack Fowler

Limited positions due to maintaining symmetry with other systems (closest to mid-drift achievable)

Same North-South distance on the East side as well

We need to decide North-South distance of these ports NOWouter portsinner ports

• Two options for Laser:

• Shine laser through FC gaps vs through FC opening (applies to all ports including the ports outside the FC)

• Whatever decision we make should work reasonably well in both cases. Do we have such a case?

• For the ports outside the FC, things are tricky

• Laser head sits on the side of the FC at 404 mm away from FC

• What are our angular limitations, when shining through gaps vs a FC opening at 404 mm distance from the FC? (need drawings)

• What is the desirable North-South distance for these ports? (near mid-drift) vs being closer to APA?

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Laser port concerns/considerations

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Opaqueness of FC: From Bo

FC tubeFC tube

In reality this point sits 404 mm away from the outer wall of the FC

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• This may be our final proposal. Do we see any deal breakers or outstanding issues with it?

• Next steps: build a strong case to understand the limitations of this system and if more is needed.

Summary

BACK UP

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• This may be our final proposal. Do we see any deal breakers or outstanding issues with it?

• Next steps: build a strong case to understand the limitations of this system and if more is needed.

Spacing details for outer ports - Jack Fowler

Limited positions due to maintaining symmetry with other systems (closest to mid-drift achievable)

Same North-South distance on the East side as well

We need to decide North-South distance of these ports NOW

Laser Feedthroughs • Bo gave a really nice talk on Drift field distortions due to CPA/FC imperfections:

https://indico.fnal.gov/event/15245/

• Broken resistor case was the most potentially worrisome. We will know a resistor is failed but not where. Unlikely to be able to wait for a cosmic to go through the correct position, need laser or similar system to identify and confirm failure.

• Diagnosing this requires crossing tracks at least on the EAST/WEST sides.

• For the central FT column, need more studies — no conclusion reached. Will address in the coming weeks.

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Not asking this column

Ports circled in yellow not

possible

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Laser Feedthroughs — A constraint

Along the outer APAs only 3 ports are possible because of space constraints