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Welcome to the mini-review of the Roman Pot mechanics for the ALFA project in ATLAS

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Some points to start with…..Some points to start with….. Discuss and compare two different solutions to of a mechanical

“conflict” problem

Consider both mechanical aspects and LHC vacuum aspects of the two solutions

If possible also try to include financial and realization time aspects of the two solutions.

“Brain storming” meeting that is do not hesitate to interrupt speakers in order to object and ask questions

Remember : A “stupid” question might turn out to be important

But first s a short introduction to the project for the outsiders……

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ATLAS Roman Pots

• Goal: Determine absolute luminosity at IP1 (2-3% precision)

• Measure elastic rate dN/dt in the Coulomb interference region (à la UA4). |t|~0.00065 GeV2 or Θ ~ 3.5 microrad.

RP

IP

RPRP RP

RP RP RP RP

This requires (apart from special beam optics)• to place detectors ~1.5 mm from LHC beam axis• to operate detectors in the secondary vacuum of a Roman

Pot • spatial resolution sx = sy well below 100 micron (goal 30

micron) • no significant inactive edge (< 100 micron)

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Roman Pot locationsRoman Pot locations

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Overlap extrusions brazed on bottom

Top flangePumping hole

Rectangular body out of centerBrazing under test S.Mathot (TS-MME)

The Pot The Pot

First prototype being prepared• Will soon be vacuum tested• Simulation of contribution to the impedance budget ongoing

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The detectors-fiber trackerThe detectors-fiber trackerChoice of technology:• minimum dead space• no sensitivity to EM induction from beam• resolution ~ 30 m

Concept• 2x10 U planes 2x10 V planes• Scintillating fibers 0.5 mm2 squared• 64 fibers per plane• Staggered planes• MAPMT readout

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Complete detector for one Roman Pot i.e. 1460 channels

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8-1 i.e. left side8-1 i.e. left side

+26 mm -33 mm

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1-2 i.e. right side1-2 i.e. right side

-32 mm -3 mm

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+26 mm -33 mm

-32 mm -3 mm

IP

IP

Left

Right

Install a normalstation here

Install slightlymodified station here

Modified stationhere in 2010

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Back up

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