A "spin filter" for selecting metastable hydrogen, deuterium, or tritium atoms with a given nuclear spin magnetic quantum number ($m_I$) has been built and tested. With the device installed in the Los Alamos "Lamb-shift" polarized-ion source, we have obtained a deuterium negative-ion beam with ∼ 55% spin-state purity for $m_I=1, 0, or -1\mathrm{}$. An improved magnetic field homogeneity in the apparatus is expected to increase the purity to ∼ 75%.

• Received 15 April 1968

DOI:https://doi.org/10.1103/PhysRevLett.20.1180