Dispersion-matched spectrometer in the low-energy branch of the Super-FRS for high-resolution measurements with large-emittance relativistic fragment beams

Abstract Precision measurements with an incident ion beam characterized by a large phase space represent a great challenge for in-flight rare-isotope facilities. Projectile fragments and fission products separated in flight have an inevitable large angular and momentum spread due to their stochastic creation processes and the atomic interactions in the production target, degrader and detector materials. A solution is to use dedicated ion-optical spectrometers with a high-resolution which can be obtained by circumventing the influence of the inherent large transverse and longitudinal emittance of the fragment beams. We demonstrate the method by coupling the different ion-optical sections of the magnetic in-flight separator Super-FRS in the Low-Energy Branch and show that the required high resolution can be achieved via dispersion-matched modes.