Optical design of the TOFI (time-of-flight isochronous) spectrometer for mass measurements of exotic nuclei

The design of a novel recoil time-of-flight isochronous spectrometer for systematic mass measurements of nuclei which lie far from the valley of β-stability is described. Using a four identical cell approach, optical aberrations of the spectrometer are minimized resulting in a calculated flight-time mass resolving power of m/Δm=2000. With the spectrometer designed for a solid angle acceptance of Ω=2.8 msr and a momentum over charge acceptance of (Δp/ze)/(p/ze)=+-2%, use of the high intensity proton beam at LAMPF will facilitate good statistics experiments yielding new direct mass measurements with uncertainties of 30 keV to 1 MeV (depending on production rates) for nuclei with A<70. (orig.)