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[ALICE3] TRK update: New radii for the simplified-realistic OT paving - #16009
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Detailed specifications of the geomtry: https://cernbox.cern.ch/s/HKhKYWesvNdnJZB Module FPC: the flex now extends 2.1 mm beyond the chips on each long side for wire bonding (was 1 mm), so the FPC is 54.4 mm wide (was 52.2 mm). The margin is an OT constant, constants::OT::fpc::wireBondMargin, and the FPC width is derived from it; the ML module edge is unchanged. Paving: L9 and L10 follow the mechanical CAD radii, 620 and 820 mm, with 42 and 56 staves per ring (21 and 28 per quarter barrel). L8 is at 442 mm with 30 staves per ring (15 per quarter barrel), the smallest radius at which 30 staves still give about 1 mm of active overlap for tracks from the interaction point. The border-to-border neighbour overlap is 8.4-9.0 mm in the stave plane. The stave count of the realistic OT layer is now taken from the configuration and must be even; the count derived from the radius is kept as the fallback for nStaves = 0. The builder warns when the resulting active neighbour overlap is below rowActiveOverlap. The OT outer shell moves from 82.0 to 83.0 cm inner radius, since the flipped outermost layer at 820 mm reaches 826 mm. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
bulukutlu
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fcolamar,
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njacazio
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October 26, 2026 12:25
njacazio
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Oct 26, 2026
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Detailed specifications of the geometry: https://cernbox.cern.ch/s/HKhKYWesvNdnJZB
Module FPC: the flex now extends 2.1 mm beyond the chips on each long side for wire bonding (was 1 mm), so the FPC is 54.4 mm wide (was 52.2 mm). The margin is an OT constant, constants::OT::fpc::wireBondMargin, and the FPC width is derived from it; the ML module edge is unchanged.
Paving: L9 and L10 follow the mechanical CAD radii, 620 and 820 mm, with 42 and 56 staves per ring (21 and 28 per quarter barrel). L8 is at 442 mm with 30 staves per ring (15 per quarter barrel), the smallest radius at which 30 staves still give about 1 mm of active overlap for tracks from the interaction point. The border-to-border neighbour overlap is 8.4-9.0 mm in the stave plane.
The stave count of the realistic OT layer is now taken from the configuration and must be even; the count derived from the radius is kept as the fallback for nStaves = 0. The builder warns when the resulting active neighbour overlap is below rowActiveOverlap.
The OT outer shell moves from 82.0 to 83.0 cm inner radius, since the flipped outermost layer at 820 mm reaches 826 mm. From the mechanics WG this was confirmed to be within specifications with the outer TOF interface.