COLLAPS (COLlinear LAser SPectroscopy) is a small experiment located at the “isotope factory” ISOLDE at CERN. Its aim is the investigation of ground state properties of exotic, short lived nuclei, such as spins, electro-magnetic moments and charge radii. All these observables contribute widely to our understanding of the nuclear force – they give valuable information about the coupling between nucleons, about symmetry of the nuclear wave-functions and thus about the symmetry of the nuclear interaction itself."