Proton polarizing system with Ar-ion laser for p⇒-RI scattering experiments

A proton polarizing system for use in scattering experiments with radioactive isotope beams is described. Protons in a naphthalene crystal doped with pentacene are polarized in a magnetic field of 0.3 T at 100 K by transferring a large population difference among the photo-excited triplet states of pentacene to the hydrogen nuclei. An Ar-ion laser, which demands minimal maintenance during scattering experiments, is employed to excite the pentacene molecules. A proton polarization of 37% is obtained.