COLLAPS is the COLlinear LAser SPectroscopy beam line located at the “radioactive isotope factory” ISOLDE at CERN. Collinear laser spectroscopy is a powerful tool to measure nuclear spins, magnetic moments, quadrupole moments and mean-square charge radii of short-lived isotopes far from stability, the so-called exotic nuclei.
These observables provide important insights in the ground state nuclear structure, in particular, they give information on shape and size and shape of the nucleus (collectivity) and on the configuration and couping of the protons and the neutrons within the nucleus (single-particle effects). As such, they help to improve our understanding of the nuclear force itself. For example, the discovery that the nuclei can possess a spectroscopic nuclear moment gave the decisive proof for the existence of non-central parts of the nucleon-nucleon force. Recent highlights of discoveries at COLLAPS can be found in the "news" and "publication" section.
COLLAPS combines expertise in atomic and nuclear physics. Due to the hyperfine interaction between the nucleus and the surrounding electron cloud, information about the nucleus can be obtained by manipulating the atomic electrons. Laser light with a very precise wavelength is used to induce electron-transitions in atoms or ions, and from the hyperfine splitting (HFS) or isotope shifts (IS), the nuclear spins, moments and charge radii can be extracted. Furthermore, lasers can also be used to produce spin-polarized beams necessary for a complementary method: the beta-NMR technique.
COLLAPS collaboration 2019