Ion-Optical Tuning of the Large Acceptance Spectrometer for Improved Angular Resolution and Acceptance
Abstract
The trade-off between angular resolution and acceptance in scattering-angle measurements with a magnetic spectrometer is quantitatively evaluated for the Large Acceptance Spectrometer (LAS). The dependence on the multipole magnet field strength is investigated. Third-order transfer matrices were calculated with GICOSY, and particle transport was simulated with MOCADI. The vertical angular resolution is defined as the standard deviation between reconstructed and true angles, while the acceptance is determined from the transport efficiency within an elliptical gate in target angle space. The resolution improves with increasing field strength, reaching mrad at +20\%, consistent with mrad. In contrast, stronger fields reduce the vertical acceptance and solid angle. These results demonstrate a trade-off between resolution and acceptance. Enhanced vertical focusing shifts the focal condition away from the nominal focal plane, enabling high-precision reconstruction.
Keywords
Cite
@article{arxiv.2605.08127,
title = {Ion-Optical Tuning of the Large Acceptance Spectrometer for Improved Angular Resolution and Acceptance},
author = {Taichi Miyagawa and Junki Tanaka and Shinsuke Ota and Masanori Dozono and Nobuyuki Kobayashi and Lakmin Wickremasinghe and Fumiya Furukawa and Daichi Ishii and Sho Nishioka and Kota Takahashi and Erika Ukai},
journal= {arXiv preprint arXiv:2605.08127},
year = {2026}
}