0000000000121993
AUTHOR
H. Knab
Precision Spectroscopy on Trapped Radioactive Ions: Ground-State Hyperfine Splittings of 133 Ba + and 131 Ba +
The ground-state hyperfine splitting of radioactive Ba+ isotopes of mass 133 and 131, confined in a r.f. quadrupole trap, has been measured by laser-microwave double resonances. The results are Δν(133) = 9 925 453 554.59(10) Hz and Δν(131) = 9 107 913 698.97 (50) Hz. The experiment, including measurements of systematic shifts, was performed on quantities of about 1012 isotopes, produced by nuclear reactions and collected at the ISOLDE facility at CERN. The precision is comparable to equivalent measurements on stable isotopes and demonstrates the high-sensitivity of the stored-ion technique. The experiment can be regarded as a first step to a systematic precision study of hyperfine anomalies…
On the possible determination of hyperfine anomalies by trapped ion spectroscopy
Abstract Laser-microwave double-resonance techniques in radiofrequency (rf) traps and Penning traps represent a powerful tool to determine hyperfine structure splittings as well as nuclear g factors to high precision. While hyperfine structure constants have been determined in a number of cases below the 10 −10 level of precision, electronic g factors have been measured to 10 −7 and there are good prospects of obtaining similar accuracy for g l . Moreover sensitive techniques have been developed for injection of ions from outside the trap. This opens the possibility to determine hyperfine anomalies at least to the 1% level of precision for chains of unstable isotopes.
Hyperfine structure andg-factor measurements in ion traps
We report about measurements on ground-state hyperfine splitting constants of stable Eu+ isotopes in radio frequency ion traps and experiments on the electronicg-factor of Ba+ in a Penning trap. From the precision of both measurements, which ranges between 3·10−6 and 5·10−7, we conclude that precise determination of the differential Bohr-Weisskopf effect in chains of isotopes will be possible in the near future.
Experimental ground stateg J-factor of Ba+ in a Penning ion trap
We observed the Zeeman-splitting of the 6S1/2 – 6P1/2 resonance transition of Ba+-ions (493.4 nm) in a 6T magnetic field. The ions were stored in a Penning quadrupole trap. We polarized the ground state by optical pumping and in a microwave-optical double resonance experiment we measured the ground state Zeeman-splitting. From the resonance frequency and the cyclotron frequency of electrons stored in the same trap we derived theg-factor of the 6S1/2 state. The result isgJ(6S1/2)=2.002 490 6(11), in reasonable agreement with recent calculations.
Ground- and excited stateg-factors of Ba+
We observed the Zeeman-splitting of the 6S 1/2-6P 1/2 resonance transition of Ba+ ions (493.4 nm) in a 6 T magnetic field. The ions were stored in a Penning quadrupole trap. From the splitting and the simultaneously measured cyclotron frequency of stored electrons we derived theg-factors of the 6S 1/2 and 6P 1/2 states. The results areg(6S 1/2)=2.00267(20) andg(6P 1/2)=0.66634(22).
Experimental lifetime of the metastable 5D 3/2 state in Ba+
A discrepancy exists between theoretical and experimental lifetimes of the metastable 5D3/2 state in Ba+. In order to redertermine that lifetime, we probe the population of the metastable 5D3/2 state of a Ba+ ion cloud stored in a Paul ion trap in the presence of He buffer gas as the function of time delay after pulsed laser excitation of this state. The measured decay rates at different buffer gas pressures are extrapolated to zero pressure and we obtain a radiative decay time of 48.0±5.9 s. This is not in agreement with theoretical predictions of about 80 s, but reduces the discrepancy from a previously reportet experimental value of 17.5 s. If the possibility of finestructure mixing to a…