STORI’24：Design optimization of the isochronous mode in the HIAF-SRing

Abstract The challenge of mass or equivalently the binding energy of the exotic nuclei is up to the limits of nuclear existence which are characterized by tiny production cross-sections and short half-lives. The isochronous mode of the Spectrometer Ring at the High Intensity heavy-ion Accelerator Facility project in China (HIAF-SRing) offers the capacity for such measurements. However, many factors limit the revolution time resolution of the isochronous mode of the large acceptance HIAF-SRing. Nonlinear field errors as well as fringe fields of the wide aperture dipoles and quadrupoles strongly excite the higher order aberrations which negatively affect the revolution time resolution. Moreover, the transverse emittance of the beam is inversely proportional to the revolution time resolution. Their influence is investigated here and a possible correction scheme with sextupole magnets and octupole magnets is shown. With higher order corrections, a mass resolution of R(FWHM) = 1×106 corresponding to a relative revolution time of σ(T)=T ∼ 4:9×10−7 is provided by the isochronous setting γt = 1:43 of the SRing with a momentum acceptance of ±0:2%.