Polarization-Dependent Disappearance of a Resonance Signal -- Indication for Optical Pumping in a Storage Ring?

Abstract

We report on laser spectroscopic measurements on Li${}^{+}$ ions in the experimental storage ring ESR at the GSI Helmholtz Centre for Heavy Ion Research. Driving the $2s{}^3{S}_1(F=\frac{3}{2})\leftrightarrow 2p{}^3{P}_2(F=\frac{5}{2})\leftrightarrow 2s{}^3{S}_1(F=\frac{5}{2})$ $\Lambda$-transition in ${}^7$Li${}^{+}$ with two superimposed laser beams it was found that the use of circularly polarized light leads to a disappearance of the resonance structure in the fluorescence signal. This can be explained by optical pumping into a dark state of polarized ions. We present a detailed theoretical analysis of this process that supports the interpretation of optical pumping and demonstrates that the polarization induced by the laser light must then be at least partially maintained during the round trip of the ions in the storage ring. Such polarized ion beams in storage rings will provide opportunities for new experiments, especially on parity violation.

14 pages, 8 figures, new version with small adjustments, closest to final publication in PRAB

References in corpus (2)

• Measurement of the ${\beta }^{+}$ and orbital electron-capture decay rates in fully-ionized, hydrogen-like, and helium-like ${}^{140}$Pr ions
• Test of Time Dilation Using Stored Li+ Ions as Clocks at Relativistic Speed

Cited by in corpus (4)

• Expanding Nuclear Physics Horizons with the Gamma Factory
• Towards an electrostatic storage ring for fundamental physics measurements
• Evolution of the ionic polarization in multiple sequential ionization: general equations and an illustrative example
• A Setup to Study Atomic State Population Dynamics and Optical Polarization at CRYRING@ESR