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

Abstract

New operation mode, "separated flow mode", has been developed for in-flight proton decay experiments with the SHARAQ spectrometer. In the separated flow mode, the protons and the heavy-ion products are separated and measured in coincidence at two different focal planes of SHARAQ. The ion-optical properties of the new mode were studied by using a proton beam at $246~{\rm MeV}$, and the momentum vector was properly reconstructed from the parameters measured in the focal plane of SHARAQ. In the experiment with the $({}^{16}{\rm O},{}^{16}{\rm F})$ reaction at a beam energy of $247~{\rm MeV/u}$, the outgoing ${}^{15}{\rm O}+p$ produced by the decay of ${}^{16}{\rm F}$ were measured in coincidence with SHARAQ. High energy resolutions of $100~{\rm keV}$ (FWHM) and $\sim 2~{\rm MeV}$ were achieved for the relative energy of $535~{\rm keV}$, and the ${}^{16}{\rm F}$ energy of $3940~{\rm MeV}$, respectively.