MARS: a status report

We are building a momentum achromat recoil spectrometer (MARS) for use with the new K500 superconducting cyclotron at Texas A and M University. MARS uses a unique optical design utilizing two dispersive planes to combine a momemtum achromat with a recoil mass spectrometer. This configuration makes MARS applicable to a broad range of nuclear reaction studies utilizing inverse kinematics. It also leads to a system that is well matched to the range of secondary particle energies that will be produced in reactions with K500 beam. MARS will have a typical mass resolution of δM/M≅1/300, with an energy acceptance of ±9% ΔE/E and a geometric solid angle of up to 9 msr. A beam swinger system will alow reaction products in the angular range 0deg to 30deg to be studied. MARS will be used to study both the excited states and decay properties of very proton- and neutron-rich nuclei. MARS will also be used to provide a reaction mechanism filter to assist investigations of the dynamics of heavy ion collisions and to produce secondary radioactive beams for reaction and spectroscopic studies of particular interest for nuclear astrophysics. We briefly describe the design of MARS, give a status report on its construction and an overview of the scientific program planned for it. (orig.)