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New Small Wheel Background
Charles Young (SLAC)
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NEW JD GEOMETRY
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Geometry Description
• Based on engineering plans from Marco et al– Thinner Disk compared with Runs 1 / 2 – Outside of Hub is not tapered
• Cutouts in cladding to accommodate chamber supports
– “Mismatch” between Disk and Hub cladding• Inner radius of Disk cladding is circular • Outer radius of Hub and cladding is polygon
– Larger gap between Disk and endcap calorimeter with three rings
– “L-shaped” polyboron shielding on Hub as in Run 2• Stainless steel bushing not yet implemented • Some engineering details ignored, as in all such
background simulations
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Side View of Disk and Hub
5-cm front plate
4-cm back plate
polygon on outside
cylinder on outside
tapered cylinder on inside
beam line
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Side View Including Disk Cladding
4-cm polyboron cladding on Disk
1-cm lead cladding on Disk
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Side View Including Hub Cladding
5-cm polyboron cladding.Note cutouts for NSW supports.3-cm thick lead cladding (not shown here) has similar cutouts.
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End View of Disk and Hub Cladding
Hub polyboron cladding
Hub lead cladding
Hub and its cladding have polygonal outer circumference
Inner radii of lead and polyboron cladding on Disk
Note radial gap between polyboron pieces
Note radial gap between lead pieces
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Side View of L-Shaped Cladding
“L-shaped” cladding
5-cm polyboron cladding on Hub.Disk and its cladding not shown
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Side View of First Ring
Innermost ring between JD and endcap calorimeter, made of steel
Disks
beam line
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Close-Up Side View of First Ring
Innermost ring between JD and endcap calorimeter
Note gap between ring and disks. Ring is mounted on JD and spring-loaded so it touches endcap calorimeter
Disks
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Side View Including Part of 2nd Ring
Disks
Innermost ring between JD and endcap calorimeter
Second ring between JD and endcap calorimeter attached to Disk
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Side View of 1st and 2nd Rings
Second ring made up of three materials: steel, polyboron and lead
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Side View of All Three RingsNote gap between 3rd ring and JD is larger than gap for 1st ring
3rd ring: polyboron + lead
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SIMULATION RESULTS
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Simulation Conditions
• Three detector geometries– 2012 geometry– Run 2 geometry– NSW geometry, as outlined earlier
• Otherwise identical assumptions: – √s = 14 TeV– s(pp) = 70 mb– Normalized to luminosity = 1034 cm-2 sec-1 – TGC sensitivities
2012 & Run 2 results from ATL-COM-MUON-2014-027.2012 corresponds to “I1” in Note.
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2012 Geometry
Red: Photon hitsBlue: Neutron hitGreen: Charged particle hits except e+/e-
Yellow: e+/e- hits
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Run 2 Geometry
Red: Photon hitsBlue: Neutron hitGreen: Charged particle hits except e+/e-
Yellow: e+/e- hits
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NSW Geometry
Red: Photon hitsBlue: Neutron hitGreen: Charged particle hits except e+/e-
Yellow: e+/e- hits
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Summary of Changes & Explanation
• 2012 to Run 2– Reduction by ~2x– Thinner beam pipe– Additional shielding around JD and JT
• Run 2 to NSW – Increase by ~2x, i.e. rates similar to 2012– Reduced JD shielding
Changes here refer to those
due to geometry changes
only.