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Laser spectroscopy with LINO (Laser Induced Nuclear Orientation)

Contact : Deyan Yordanov :


We aim to explore the synergies between laser spectroscopy and mass spectrometry in terms of low-energy beam manipulation and handling, namely the installation of a specialized radio-frequency quadrupole Paul trap adapted for the requirements of both techniques. Furthermore, the scientific overlap between the two methods is critical for nuclear charge ­radii measurements where accurate atomic masses are needed to support the data on atomic isotope shifts from laser spectroscopy. In addition, both techniques are capable of discovering and probing nuclear isomers while their scientific output is completely complementary allowing for comprehensive characterization of the nuclear states by laser spectroscopy, and determining the energy-level orderings from mass measurements. In parallel to the installation of the MLLTrap mass spectrometer we are aiming at the construction of an instrument for collinear laser spectroscopy on radioactive nuclei. Electromagnetic moments and rms charge radii of ground and long-lived isomeric states in the neutron-rich silver isotopes have never been studied experimentally. Recent results on the neighboring cadmium chain highlight the occurrence of simple structure in complex nuclei. With an additional proton hole silver offers a testing ground of this concept for odd-Z nuclei. The silver chain will be the first high-resolution measurement we will perform using the instrumentation for collinear laser spectroscopy currently under construction at ALTO.


Collinear laser spectroscopy is a versatile experimental technique capable of high-precision measurement of nuclear properties by means of atomic laser excitations. The electromagnetic interaction of the atomic nucleus with the electron shells results in a splitting of the atomic energy levels, about a million times smaller than the fine structure. This hyperfine structure carries information on the nuclear spin, charge radius, and electromagnetic moments, which are critical probes for nuclear-structure studies. The ion-beam velocity is made variable in order to scan for the hyperfine-structure components via the corresponding variation in the Doppler shift. The atomic excitations are then identified through the beam fluorescence. This method has produced outstanding results in the past. However, the efficiency for photon counting is relatively low, which limits the sensitivity of this type of spectroscopy.


A number of variations of the collinear-laser-spectroscopy technique have been devised throughout the years in order to reach exotic nuclides inaccessible by fluorescence. Generally, the approach has been to replace the detection of photos with detection of charged particles. The alternative approach to this charged-particle detection is to increase the sensitivity of the fluorescence spectroscopy by vastly reducing the background originating mostly from laser scattering. This meant implementing photon-ion coincidence.



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

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