Heavy Element Laser Ionization Spectroscopy (HELIOS)
Heavy Element Laser Ionization Spectroscopy
Start date: Mar 1, 2012,
End date: Feb 28, 2017
The aim of this proposal is to develop a novel laser-spectroscopy method and to study nuclear and atomic properties of heaviests elements in order to address the following key questions:- Is the existence of the heaviest isotopes determined by the interplay between single-particle and collective nucleon degrees of freedom in the atomic nucleus?- How do relativistic effects and isotopic composition influence the valence atomic structure of the heaviest elements?The new approach is based on in-gas jet, high-repetition, high-resolution laser resonance ionization spectroscopy of short-lived nuclear-reaction products stopped in a buffer gas cell. The final goal is to couple the new system to the strongest production facility under construction at the ESFRI-listed SPIRAL-2 facility at GANIL (France) and to study isotopes from actinium to nobelium and heavier elements.An increase of the primary intensity, efficiency, selectivity and spectral resolution by one order of magnitude compared to present-day techniques is envisaged, which is essential to obtain the required data .The challenges are:- decoupling the high-intensity heavy ion production beam (> 10^14 particles per second) from the low-intensity reaction products (few atoms per second)- cooling of the reaction products from MeV/u to meV/u within less then hundred milliseconds- separating the wanted from the, by orders of magnitude overwhelming, unwanted isotopes- performing high-resolution laser spectroscopy on a minute amount of atoms in an efficient way.Nuclear properties (charge radii, nuclear moments and spins) as well as atomic properties (transition energies and ionization potentials) will be deduced in regions of the nuclear chart where they are not known: the neutron-deficient isotopes of the actinide elements, up to nobelium (Z = 102) and beyond. The data will validate state-of-the-art calculations, identify critical weaknesses and guide further theoretical developments.
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