Speaker
Brigitte Roussiere
(Institut de Physique Nucléaire)
Description
Laser spectroscopy gives access to fundamental properties of the ground and rather
long-lived isomeric states such as the change in the mean square charge radius (
) and the nuclear moments. Measurements on tellurium isotopes (Z = 52) can provide
reliable information on the shape of nuclei, structure of states, and effects of
dynamics. Indeed from A = 115 to 133, all the odd-A Te isotopes exhibit an isomeric
state and the measurement of the isomeric shift gives us a direct indication of the
influence of the neutron-core coupling on the nuclear deformation. Moreover the
determination of the magnetic moments yields information on the structure of the
states. In particular the measurements on the neutron-rich tellurium isotopes allow
us to study the variation of the kink at N = 82 approaching the proton magic number
Z = 50.
ISOLDE offers the opportunity for studying the tellurium isotope series over a wide
mass range, from the nuclei located near the N = 66 neutron mid-shell to the neutron-
rich ones beyond the neutron shell closure at N = 82. In this contribution we will
present the laser spectroscopy experiment performed on the neutron-rich tellurium
isotopes and the results obtained up to now. The neutron-rich Te isotopes have been
produced by the 238U fission induced by 1 GeV protons in a uranium carbide target
associated with a hot plasma ion source. The laser spectroscopy measurements have
been performed on the 127-136Te ground states and on the 123,125,127,129,131,133Te
isomeric states using the COMPLIS (COllaboration for Measurements using a Pulsed
Laser Ion Source) setup that allows resonance ionization spectroscopy (RIS) on laser-
desorbed atoms. To avoid direct and disturbing ionization of the isobars by the non-
resonant step, a three step process had to be used to ionize selectively the
tellurium isotopes: 214.35, 591.6 and 1064 nm. Spectroscopic information (isotope
shift and hyperfine structure) has been obtained by scanning the first excitation
step (the 5p4 3P2 5p3 6s 3S1 optical transition at 214.35 nm) of the RIS process.
The analysis of the data is still in progress. However the values obtained for
the even-even isotopes show that the kink at N = 82 remains in Te, i. e. in an
isotopic series with a proton number very close to the magic number Z = 50.
Author
Brigitte Roussiere
(Institut de Physique Nucléaire)
