Determine the residual attributable to densely recorded partran output

Determine how much of the HELIX–TraceWin multiparticle residual would remain when compared against a densely recorded TraceWin partran output that resolves the beam waist rather than interpolating between diagnostic planes.

Background

The paper compares HELIX multiparticle tracking with archived TraceWin partran exports. In the leading drift of the MEBT+HWR line, the TraceWin export is sampled only at diagnostic planes and linearly interpolates between them, producing a chord across the beam waist. This creates large apparent local discrepancies that may reflect output sampling rather than physical disagreement between the codes.

The authors explicitly state that the archived exports cannot determine how much of the discrepancy would survive a more densely recorded partran run. Resolving this would separate genuine code-to-code differences from artifacts of the reference-output sampling cadence.

References

We did not find a rigorous explanation for the discrepancy between the scatter in measured emittances and the low values of the assigned errors and speculate that it can be related to incomplete characterization of the beam waist in the vertical plane of QS #1 or horizontal plane of QS #2.

— Reconstruction of Beam Transverse Parameters in the Fermilab Side-Coupled Linac Using a Normalized Coordinate Framework  (2609.20136 - Chen et al., 17 Sep 2026) in Section “Simple Quadrupole Scan,” page 2

How much of the residual would survive a densely recorded partran run is not something the archived exports can settle.

— HELIX: a hybrid envelope-multiparticle linac code with differentiable space-charge optimization  (2609.04421 - Pathak, 3 Sep 2026) in Section 7.5, “Comparison with TraceWin on PIP-II lattices”