0000000000793619
AUTHOR
Rubén López-coto
Observation of the hyperfine transition in lithium-like bismuthBi20980+: Towards a test of QED in strong magnetic fields
We performed a laser spectroscopic determination of the $2s$ hyperfine splitting (HFS) of Li-like ${}^{209}{\text{Bi}}^{80+}$ and repeated the measurement of the $1s$ HFS of H-like ${}^{209}{\text{Bi}}^{82+}$. Both ion species were subsequently stored in the Experimental Storage Ring at the GSI Helmholtzzentrum f\"ur Schwerionenforschung Darmstadt and cooled with an electron cooler at a velocity of $\ensuremath{\approx}0.71\phantom{\rule{0.16em}{0ex}}c$. Pulsed laser excitation of the $M1$ hyperfine transition was performed in anticollinear and collinear geometry for ${\text{Bi}}^{82+}$ and ${\text{Bi}}^{80+}$, respectively, and observed by fluorescence detection. We obtain $\ensuremath{\De…
Laser spectroscopy measurement of the 2s-hyperfine splitting in lithium-like bismuth
We have recently reported on the first direct measurement of the $2s$ hyperfine transition in lithium-like bismuth (209Bi80+) at the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany. Combined with a new measurement of the $1s$ hyperfine splitting (HFS) in hydrogen-like (209Bi82+) the so-called specific difference ${\rm{\Delta }}^{\prime} E=-61.37(36)$ meV could be determined and was found to be in good agreement with its prediction from strong-field bound-state quantum electrodynamics. Here we report on additional investigations performed to estimate systematic uncertainties of these results and on details of the experimental setup. We show that the dominating uncertainty a…
Detection system for forward emitted photons at the Experimental Storage Ring at GSI
A single photon counting system has been developed for efficient detection of forward emitted fluorescence photons at the Experimental Storage Ring (ESR) at GSI. The system employs a movable parabolic mirror with a central slit that can be positioned around the ion beam and a selected low noise photomultiplier for detection of the collected photons. Compared to the previously used system of mirror segments installed inside the ESR the collection efficiency for forward-emitted photons is improved by more than a factor of 5. No adverse effects on the stored ion beam have been observed during operation besides a small drop in the ion current of about 5% during movement of the mirror into the b…