Separated flow operation of the SHARAQ spectrometer for in-flight proton-decay experiments

A new “separated flow” operating mode has been developed for in-flight proton-decay experiments using the SHARAQ spectrometer. In this mode, the protons and heavy-ion products are separated and measured in coincidence at two different focal planes of the SHARAQ. The ion-optical properties of the new mode were studied using a proton beam at 246 MeV, and the momentum vector was reconstructed from the parameters measured in the focal plane of the SHARAQ. In the experiment with the (16O, 16F) reaction at a beam energy of 247 MeV/u, the outgoing 15O+p produced by the decay of 16F were measured in coincidence with the SHARAQ. High energy resolutions of 100 keV (FWHM) and ∼2 MeV were achieved for a relative energy of 535 keV and a 16F kinetic energy of 3940 MeV, respectively. The mode allows a new form of missing-mass spectroscopy using a reaction probe with a particle-decay channel.