10–15 Aug 2025
SAFE Credit Union Convention Center
America/Los_Angeles timezone

An extended Froissart-Stora formula for changing crossing speed

TUP009
12 Aug 2025, 16:00
2h
SAFE Credit Union Convention Center

SAFE Credit Union Convention Center

1401 K St, Sacramento, CA 95814
Poster Presentation MC1 - Colliders and other Particle and Nuclear Physics Accelerators TUP: Tuesday Poster Session

Speaker

Eiad Hamwi (Cornell University)

Description

When the closed-orbit spin tune is ramped linearly through an isolated spin-orbit resonance, the asymptotic polarization loss is well-approximated by the Froissart-Stora formula. However, it is often observed in accelerator simulations that the crossing speed, defined as the slope of the amplitude-dependent spin tune with respect to the machine azimuth, changes at the moment of resonance crossing. For example, the behavior of the amplitude-dependent spin tune in the vicinity of a higher-order spin-orbit resonance can often be reasonably approximated by such a piecewise-linear function. In this paper, we derive an extension to the Froissart-Stora formula which describes the asymptotic polarization loss in the case of changing crossing speed. We then demonstrate that this formula provides a good estimate of the polarization lost when crossing a higher-order spin-orbit resonance in both a toy model and simulations of RHIC.

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Author

Joseph Devlin (Cornell University (CLASSE))

Co-authors

Desmond Barber (Deutsches Elektronen-Synchrotron DESY) Georg Hoffstaetter (Cornell University (CLASSE))

Presentation materials

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