Palladlum : a study of nuclear deformation of a refractory element Laser specctroscopy at the IGISOL (Jyvaskla, Finland) and S3-LEB (GANIL, France)

Overview & Synopsis

In this work, laser spectroscopy measurements on the Pd isotopic chain usingdifferent techniques are presented. Thanks to the chemically insensitive IGISOLion-guide production method, it has been possible to reduce the existing gap inoptical spectroscopy data below Z=50, created by the refractory character of theseelements. A study of the deformation of palladium nuclei in the mass region 98 ≤A ≤ 118 is performed comparing the results of two collinear laser spectroscopymeasurements with state-of-art Fayans and Gogny calculations.Having 6 protons and 4 holes on his valence shell, palladium is located at themid-shell πg9/2, between the strongly deformed systems around zirconium (Z=40,N=60) and the spherical systems close to tin (Z=50). Pd isotopes are thus expectedto exhibit a rather transitional character. The interpretation of the results obtainedin this work have been done using axial and triaxial perspectives. The mean squarecharge radii have been extracted for the ground state of the even-even palladiumisotopes in the mass region 98 ≤ A ≤ 118, together with the magnetic dipolemoments, electric quadrupole moments, nuclear spins, and mean square chargeradii of the odd-A 99,101,113,115Pd and the isomeric state of 115Pd. These newresults on the mean-square charge radii and quadrupole moment sheed light onthe evolution of deformation on the palladium chain, suggesting a triaxial softnucleus on the neutron rich side.Complementing this work, this thesis includes development work with Fabry-P´erotinterferometers to support future laser spectroscopy measurements.To prepare future experiments towards the proton drip line, laser resonant ionizationspectroscopy measurements of stable palladium isotopes have been performedusing two different approaches. On one side, the production study of stable palladiumisotopes using a hot-cavity catcher is presented. On the other side, the offlinetest and development of resonant ionization schemes for palladium has beenperformed at the GISELE offline laser laboratory, looking for transitions moresensitive to the nuclear observables.