Collinear laser spectroscopy at ISOLDE: new methods and highlights

Abstract

Over three and a half decades of collinear laser spectroscopy and the COL-LAPS setup have played a major role in the ISOLDE physics programme. Based on a general experimental principle and diverse approaches towards higher sensitivity, it has provided unique access to basic nuclear properties such as spins, magnetic moments and electric quadrupole moments as well as isotopic variations of nuclear mean square charge radii. While previous methods of outstanding sensitivity were restricted to selected chemical elements with special atomic properties or nuclear decay modes, recent developments have yielded a breakthrough in sensitivity for nuclides in wide mass ranges. These developments include the use of bunched beams from the radiofrequency quadrupole cooler-buncher ISCOOL, which allows a suppression of background by several orders of magnitude. Very recently, the combination of collinear laser spectroscopy with the principle of laser resonance ionisation took shape in the new CRIS setup, providing a very selective and efficient detection of optical resonance. We outline the basic experimental developments and discuss important results on nuclei or chains of isotopes in different mass ranges.

Investigating the large deformation of the 5/2+ isomeric state in Zn73 : An indicator for triaxiality

“…The experiment was performed at the collinear laser spectroscopy (COLLAPS) setup [26] at CERN-ISOLDE, as detailed in earlier publications [18,19]. The Zn isotopes were produced by impinging 1.4-GeV protons onto a neutron converter [27] of a UC x target, laser resonantly ionized by the resonant ionization laser-ion source [28], and accelerated up to 30 keV.…”

From Calcium to Cadmium: Testing the Pairing Functional through Charge Radii Measurements of Cd100−130

“…Neutron-deficient isotopes were produced in a separate run by proton-induced spallation in a molten Sn target combined with a plasma ion source. The ions were accelerated to 30 keV and mass separated, prior to study using the COLLAPS beam line [30].…”

Spins and electromagnetic moments of Cd101–109

“…The measurements were carried out with the instrumentation for collinear laser spectroscopy (COLLAPS) at ISOLDE-CERN [6]. high-energy protons impinging on a molten tin target and ionized using a plasma source.…”

“…Chronologically, this was the first instance of frequency quadrupling being utilized for collinear laser spectroscopy. Atomic excitations were detected by the ion-beam fluorescence as a function of the Doppler-shifted laser frequency [6]. The timing structure of the ion beam mentioned above facilitated a background suppression with a factor of the order of 10 4 .…”