Spin-polarized hydrogen maser

Abstract

Maser action on the hydrogen hyperfine transition has been achieved at a temperature of 0.3 K in a liquid-helium-lined resonator. Polarized atoms are provided by magnetic ejection from a low-temperature discharge in a high magnetic field. The maser demonstrates the feasibility of a proposed low-temperature frequency standard. Operation of the atomic hydrogen source represents an essential step toward magnetic trapping of hydrogen at very low temperatures. Operated continuously, the source provides 5×${10}^{12}$ atoms/sec to the maser. In a 1 sec single pulse it can provide up to 2×${10}^{13}$ polarized atoms.