A large acceptance spectrometer for reaccelerated radioactive beams at the proposed facility for rare isotope beams (FRIB) in the USA

A large acceptance ray-tracing spectrometer is being designed in order to fully exploit the research opportunities that will be offered by reaccelerated radioactive beams in the energy range 6–15 MeV/nucleon from the proposed facility for rare isotope beams (FRIB) in the USA. The preliminary design of the spectrometer has been benefitted by several similar instruments in Europe (e.g. VAMOS, PRISMA, MAGNEX). The design is of QQD type (quadrupole–quadrupole–dipole) with two large-bore quadrupoles and a large-gap 70° bending magnet offering an angular acceptance around 50 msr and a momentum acceptance of 10%. The maximum magnetic rigidity is 2.5 T-m, providing a range appropriate for the most neutron-rich products expected from binary reactions with reaccelerated radioactive beams. The spectrometer will play an important role in nuclear structure and reaction studies, combined with gamma-ray and particle detector arrays around the target.