L.D. Ellsworth

Efficient, high‐spectral‐resolution Bragg crystal x‐ray polarimeter

Utilizing Bragg scattering near 90 degrees , an x-ray polarimeter is described that has high spectral resolution and reasonable efficiency. The latter is achieved by using a position-sensitive proportional counter to discriminate spatially resolved x rays dispersed by the crystal. This instrument has been used to measure the linear polarization of lines from one- and two-electron oxygen ions. For this study, aligned initial states have been populated in oxygen beams by various excitation processes in foil, gas, and thick solid targets. In spite of the small probability for the production and radiative decay of few-electron excited states in the presence of intense background radiation, the instrument resolution and efficiency are sufficient to permit polarization measurements.

Polarization fractions of K X-rays emitted by fast fluorine ions incident in different charge states on helium

Abstract Polarization fractions have been measured for K X-rays emitted by energetic fluorine ions passing through helium gas. A strong monotonic charge state dependence is found, increasing to an observed polarization of ∼ 30% for highly charged ions.