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…e flanges This fixes air instead of vacuum inside the A-side beam pipe. - RB24/3 built the vacuum mother voRB243CuTubeM but placed the bare copper tube, so its 2 x 298 cm bore was cave air. - The valve placed RB24ValveFl instead of its vacuum mother RB24ValveFlI, leaving 2 x 1.5 cm of air. - Both now place the mother. The Run 4 pipe gets the same RB24/3 fix. - The mothers keep the outer shape of the parts they replace, so no new overlaps appear. - The visibility call now hides voRB243CuTubeM instead of voRB24CuTubeM. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
This fixes air instead of vacuum in the bore of the VMABC pumping modules at z = 8.7 m and 18.8 m. - The module is an assembly of hollow parts with no vacuum volume, so its 28 cm bore was cave air. - A vacuum tube at the inner radius of the transition tube and RF contact now fills it, from one end to the other. - It is placed beside the two copies in caveRB24 only. In the barrel copy the aluSideA pipe runs through the bore. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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Material along the A-side pipe (r stretched): air inside the pipe in red, before and after each commit.
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Clearly a bug. Thanks for correcting. |
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During the integration of VecGeom navigation, it was found that parts of the A-side beam pipe are filled with air
instead of vacuum, which is likely an error. The RB24/3 section builds the vacuum mother of its copper tube but
places the bare tube, and the valve does the same with its flanges, so their bores belong to the surrounding cave
air. The pumping modules (VMABC) at z = 8.7 m and 18.8 m have no vacuum volume at all. In total about 6.5 m of air
lie on the beam axis at z = 4–19 m, about 2 % of a radiation length. This dates back to the port of the pipe from
AliRoot.
This PR fixes this. The vacuum mothers are now placed, and the bore of the two pumping modules is filled with a
vacuum tube. The air on the axis drops from 654.5 cm to 2 cm, without new overlaps. Note that hit counts and energy
deposits in all detectors stay unchanged within 2σ in 500 paired Pythia8 pp events, with TGeo and with VecGeom
navigation.
Material along the A-side pipe (r stretched): air inside the pipe in red, before and after each commit.
Assisted by Claude Code.