0000000000076408
AUTHOR
D. E. Evans
First on-line laser spectroscopy of radioisotopes of a refractory element
The first fully on-line isotope shift measurement of a radioactive refractory element is reported. Collinear laser-induced fluorescence measurements were made on the radioactive isotopes ${}^{170,172,173,174}\mathrm{Hf}$ produced with a flux of $2--3\ifmmode\times\else\texttimes\fi{}{10}^{3}$ ions per second from an ion-guide fed isotope separator. The method may be applied to all elements and isomers with lifetimes as short as 1 ms. The systematics of the new charge radii measurements are well reproduced by theory, with the maximum deformation in the chain occurring significantly below the midshell.
On-line laser spectroscopy of refractory radioisotopes at the JYFL IGISOL facility
A major objective of the laser-IGISOL program has been realized with the first ever on-line observation of collinear laser induced fluorescence from an ion of a refractory element. The measurements demonstrate that the IGISOL can be operated in a mode that produces ion beams of good emittance with reasonable extraction efficiency. The technique has been used to study the neutron-deficient Hf isotopes.
First collinear laser spectroscopy measurements of radioisotopes from an IGISOL ion source
Abstract The standard Doppler-free technique of collinear laser spectroscopy has been successfully applied to radioisotopes from the ion-guide isotope separator (IGISOL) at the University of Jyvaskyla. The laser resonance fluorescence signals for the 140,142,144 Ba radioisotopes show that the ion beam energy spread is less than 6 eV, allowing the laser technique to have both high resolution and a sensitivity comparable with the best obtained at conventional facilities.
Nuclear moments and charge radii of the171Hf ground state and isomer
The magnetic moment, quadrupole moment and mean-square charge radial changes, relative to 172Hf, have been measured for the 171Hf ground state and the ½-[521] isomeric state, using on-line laser spectroscopy. The magnetic moments of the isomer and ground states are found to be + 0.526(16)µn and -0.674(12)µn, respectively. The spectroscopic quadrupole moment of the ground state is found to be +3.463(27) b. No change in mean-square charge radius is observed between the ground state and isomeric state. The observation of an inversion in the odd-even staggering at 171Hf is consistent with the suggested deformation trends.
First measurement of radioisotopes by collinear laser spectroscopy at an ion-guide separator
The first successful application of an ion-guide separator (IGISOL) for collinear laser spectroscopy of radioisotopes has achieved an efficiency comparable with the best obtained with catcher-ionizer facilities. The ion beam energy spread was determined to be less than 6 eV, allowing laser fluorescence resonance signals for the Ba-140,Ba-142,Ba-144 radioisotopes to be detected with high resolution and sensitivity. Applications of this technique to measuring nuclear properties of refractory elements and short lived isomers promises to be particularly advantageous.
A thirty second isomer in Hf
An isomer has been detected in Hf-171 with a half-life of T-1/2 = 29.5(9) s. The state was populated in the Yb-170(alpha,3n)Hf-171m reaction at a beam energy of E-alpha = 50 MeV in an on-line ion guide isotope separator. The isomeric Hf-17lm(+) beam was extracted from the ion guide, mass-analysed and implanted in the surface of a microchannel-plate. The half-life of the collected activity was measured from the decay of the microchannel-plate count rate. We associate the isomer with the first excited slate in Hf-171 with spin 1/2(-) at an excitation energy of 22(2) keV.