Pulsed magnetic field method for measuring polarization of radioactive beams

A new method has been developed for measuring the magnitude of nuclear spin polarization of a secondary, radioactive beam by making a pulsed magnetic field measurement that does not require advance knowledge of the nuclide's magnetic moment. Using a standard β NMR apparatus, a magnetic double ratio is determined from the counting rates in 0 deg. and 180 deg. β detectors for magnetic field on and off conditions. This ratio provides direct information on the induced spin polarization of a radioactive beam. A demonstration of the method was performed using spin polarized 12B nuclei produced by fragmentation of an 80 MeV/nucleon 18O beam in a Nb target