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Physics Opportunities with the S3 Low-Energy Branch
With the construction of the new heavy-ion linear accelerator coupled to the Super Separator Spectrometer (S3) facility (SPIRAL2 project – GANIL), neutron- deficient isotopes over a wide range of the nuclear chart can be produced with unprecedented intensities. This gives new opportunities for nuclear-structure studies in these poorly explored regions of the nuclear landscape.
Laser spectroscopy studies provide key ingredients to test and validate nuclear models (nuclear-charge radii, spins and nuclear moments). Moreover, in the super- heavy element region, these studies provide often first information on atomic levels and ionization potentials.
The S3 Low-Energy Branch (S3-LEB) aims at performing laser ionization and mass spectroscopy studies as well as to produce (isomerically) pure beams for subsequent studies. In the focal plane of S3, the reaction products are thermalized in a buffer gas cell, embedded in a homogeneous, low-density and temperature supersonic gas-jet and ionized with two or three step resonant laser ionization. The ions are captured in radio frequency ion guides and further transported to a Multi- Reflection Time of Flight system for mass measurements and/or further purification. Finally, the decay of the reaction products will be measured in a dedicated decay station. To perform laser spectroscopy studies on these rarely produced exotic isotopes, high efficiencies in combination with high spectral resolution are required.
The In Gas Laser Ionization and Spectroscopy (IGLIS) technique that is being implemented in the S3-LEB project has been developed and validated with, amongst others, a study of the neutron-deficient actinium isotopes, including the semi-magic (N=126) 215Ac (T1/2=0.17 s) isotope [1]. An improvement in spectral resolution from a typical 5 GHz, as obtained in studies using hot cavity approaches for e.g. the mercury isotopes at ISOLDE [2] or in-gas cell approaches establishing first atomic information in nobelium at GSI [3], to 400 MHz was evidenced.
Recent laser spectroscopy results of the heavy elements will be discussed together with the ongoing developments to improve the performance of the IGLIS technique with respect to efficiency and spectral resolution [4]. Finally, the prospects for nuclear and atomic physics studies along the N=Z line and of the heavy and super- heavy element region at the S3-LEB will be presented.

[1] R. Ferrer,- Nature Communications (2017)
[2] B. Marsh,- Nature Physics (2018)
[3] M. Laatiaoui,-, Nature (2016)
[4] S. Zadvornaya,-, Phys. Rev. X (2018)

Piet Van Duppen
KU Leuven
14/12/2018 à 11:00
IPN Orsay, salle des Conseils, bâtiment 100

Notes de dernières minutes :

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Institut de Physique Nucléaire Orsay - 15 rue Georges CLEMENCEAU - 91406 ORSAY (FRANCE)
UMR 8608 - CNRS/IN2P3

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