Structures hyperfines du spectre d'étincelle, moment magnétique et quadrupolaire de l'isotope 229 du thorium

Abstract

L'étude à haute résolution du spectre d'étincelle de l'isotope 229 du thorium, dans le domaine infra-rouge situé entre 1 et 3 μ, a été effectuée par spectrométrie de Fourier. La détermination des fonctions d'onde des configurations paires (ds2, d2 s, d3) et impaires (fd2, fds, fs2), a permis de calculer les constantes hyperfines des électrons a7s, a6d, b6d, a5f et b 5f relatives à ces deux groupes de configurations, les données expérimentales étant les valeurs des constantes hyperfines A et B de vingt niveaux que nous avons pu atteindre. On en déduit la valeur du moment magnétique trouvé égal à μ229 = (+ 0,45 ± 0,04) μ N, ainsi que l'ordre de grandeur du moment quadrupolaire (Q229 = + 4,3 barns à 20 % près)

Nuclear radii of thorium isotopes from laser spectroscopy of stored ions

“…The droplet model line [28] was arbitrarily drawn through the 232Th point since our experiment does not give absolute values of <r2>. Thus, the essence (10) a From [19] for comparison of our results is the slope of the <r 2> curve. Obviously our experimental curve appears to be steeper than predicted by the spherical droplet model.…”

“…In the past, measurements of the optical isotope shift and the hyperfine splitting for a few thorium isotopes have been performed, using discharge lamps and Fourier transform spectrometers or grating spectrographs. With these methods, the isotope shifts between 23~ and 232Th [14][15][16] and between 229Th and 2a2Th [17], as well as the hyperfine splittings for 229Th [18,19] have been determined for several optical transitions. From the analysis of the 23~ isotope shift data, the change of the mean square charge radius between these two isotopes had been evaluated [20,21].…”

Wigner Crystals ofTh229for Optical Excitation of the Nuclear Isomer

“…Our value for Q may be compared with the previous value of 4.3 eb ± 20% measured in Th + [19]. The most recent and precise published measurement of the 229 Th isomer energy is 7.6(5) eV [4].…”

Constraining the Evolution of the Fundamental Constants with a Solid-State Optical Frequency Reference Based on theTh229Nucleus

“…The electric field gradient at the nucleus depends sensitively on the structure of the host crystal, and the effect of this term must be considered on a case-by-case basis. Further complicating a reliable estimate of the effect is that only the ground state quadrupole moment of 229 Th is known (4.3 barns [24]). Nevertheless, an estimate for the size of the effect can be obtained by considering only the ground state shift.…”