A comparative vacuum ultraviolet spectroscopy study conducted at ISOLDE-CERN of the radiative decay of the ^{229m}Th nuclear clock isomer embedded in different host materials is reported. The ratio of the number of radiative decay photons and the number of ^{229m}Th embedded are determined for single crystalline CaF_{2}, MgF_{2}, LiSrAlF_{6}, AlN, and amorphous SiO_{2}. For the latter two materials, no radiative decay signal was observed and an upper limit of the ratio is reported. The radiative decay wavelength was determined in LiSrAlF_{6} and CaF_{2}, reducing its uncertainty by a factor of 2.5 relative to our previous measurement. This value is in agreement with the recently reported improved values from laser excitation.

Mass measurements with the ISOLTRAP mass spectrometer at CERN-ISOLDE improve mass uncertainties of neutron-deficient tin isotopes towards doubly magic Sn100. The mass uncertainty of Sn103 was reduced by a factor of 4, and the new value for the mass excess of −67104(18)keV is compared with nuclear and density functional theory calculations. Based on these results and local trends in the mass surface, the masses of Sn101,103, as determined through their QEC values, were found to be inconsistent with the new results. From our measurement for Sn103, we extrapolate the mass excess of Sn101 to −60005(300)keV, which is significantly more bound than previously suggested. By correcting the mass values for Sn101,103, we also adjust the values of Sb104, Te105,107, I108, Xe109,111, and Cs112 near the proton drip line which are connected through their α and proton Q values. The results show an overall smoothening of the mass surface, suggesting the absence of deformation energy above the N=50 shell closure. Published by the American Physical Society 2025

This paper reports on the measurement of the ground-state spin and nuclear magnetic dipole moment of 61Cr. The radioactive ion beam was produced at the CERN-ISOLDE facility and was probed using high-resolution resonance ionization laser spectroscopy with the collinear resonance ionization spectroscopy (CRIS) apparatus. The present ground-state spin measurement I = 12, differing from the previously adopted I = (52 ), has significant consequences on the interpretation of existing beta decay data and nuclear structure in the region. The structure and shape of 61Cr is interpreted with state-of-the-art Large-Scale Shell-Model and Discrete NonOrthogonal Shell-Model calculations. From the measured magnetic dipole moment mu (61Cr) = +0.541(6)mu N and the theoretical findings, its configuration is understood to be driven by two-particle-two-hole neutron excitations with an unpaired 1p1/2 neutron. This establishes the western border of the N = 40 island of inversion, characterized by four-particle-four-hole neutron components. We discuss the shape evolution along the Cr isotopic chain as a second-order quantum phase transition at the entrance of the N = 40 island of inversion.

The radiative lifetime of the A (2)Pi(1/2) (v = 0) state in radium monofluoride (RaF) is measured to be 35(1) ns. The lifetime of this state and the related decay rate Gamma = 2.86(8) . 86(8) x 107 7 s-1 - 1 are of relevance to the laser cooling of RaF via the optically closed A (2)Pi(1/2) <- X (2)Sigma(1/2) transition, which makes the molecule a promising probe to search for new physics. RaF is found to have a comparable photon-scattering rate to homoelectronic laser-coolable molecules. Owing to its highly diagonal Franck-Condon matrix, it is expected to scatter an order of magnitude more photons than other molecules when using just three cooling lasers, before it decays to a dark state. The lifetime measurement in RaF is benchmarked by measuring the lifetime of the 8P3/2 P 3 / 2 state in Fr to be 83(3) ns, in agreement with literature.

A two-step resonance photo-ionization scheme has been used to ionize samarium atoms in the SPES tantalum hot-cavity ion source. The effect of the ion load on the ion beam time structure and the laser enhancement of the ion yield has been studied at different ion source temperatures. Generally, the introduction of more positive ions (ion load) affects negatively the overall confinement of the laser ions inside the volume of the ion source. Possible enhancement of the laser ion confinement through the introduction of neutrals is observed as well. The ion load is also observed to affect the confinement in the transfer line much more than in the hot cavity. Measurement of the time structure with inverted polarity of the cavity DC heating supply confirmed the significance of the longitudinal potential for ion extraction. The laser enhancements of the ion yield are found to be sensitive to the ion load at low operating temperature of the ion source i.e. 1800 degrees C, whereas at 2050 degrees C and 2200 degrees C, they are relatively stable till an ion load value of 1.2 mu A.

The changes in the mean-squared charge radius of Tlg209 (N=128) and Tlm207 (N=126) relative to Tl205 have been measured for the first time using the in-source laser resonance-ionization spectroscopy technique with the Laser Ion Source and Trap (LIST) at ISOLDE (CERN). The application of the LIST suppresses the dominant background from isobaric francium isotopes and allows access to thallium nuclides with A⩾207. The characteristic kink in the charge radii at the N=126 neutron shell closure, as well as the odd-even effect similar to that in the adjacent bismuth, lead, and mercury isotopic chains, have been observed. The self-consistent theory of finite Fermi systems based on the energy density functional by Fayans reproduces the behavior of charge radii in these isotopic chains near N=126. The comparison with calculations in the framework of the relativistic mean field (RMF) approach is also presented. In the case of the Fayans functional it is a specific form of pairing interaction with the dependence on the density gradient that is essential to provide agreement with the experimental charge radii. In particular, the kink is reproduced without the inversion of g9/2 and i11/2 neutron single-particle states, which is a prerequisite to correctly describe the kink in the RMF models. Published by the American Physical Society 2024

CERN-MEDICIS is an isotope mass separation facility dedicated to biomedical research located in a type A work sector, receiving on average 50% of the 1.4 GeV protons delivered by the Proton Synchrotron Booster (PSB). It was commissioned with Radioactive Ion Beams (RIB’s) in 2017. MEDICIS has operated for the past 5 years in batch mode, with targets irradiated in a station located at the HRS beam dump, and with external sources provided by MEDICIS cyclotrons and nuclear reactors partners, notably during the Long Shutdown (LS2). Additional features of the facility include the MELISSA laser ion source, radiochemistry on implanted radionuclides and an online gamma-ray spectroscopy implantation monitoring. In 2022, we introduced Key Performance Indicators (KPI’s) to monitor the operation of the facility for collected efficiencies, the optimisation of the radiological risks and evaluate impact of possible modifications of the station, paralleling for instance LHC’s integrated luminosity. Defined KPI’s cover aspects in the operation cycle, e.g. planning in CERN schedule, target irradiations, duration of the process, radiological risk mitigation, facility up-time, developments and maintenance. MEDICIS KPI’s can help distinguish which of the operation and infrastructure life cycle requires immediate intervention, developments or consolidation. Those are related to the irradiation stations and irradiation possibilities, the beamlines (parallel collections), target and ion sources (reliability), robot handling and infrastructure, or the separation process itself.

The SPES laser ion source has been tested at ISOLDE Offline 2, CERN. A two-step single resonance photo-ionization scheme has been used to ionize gallium atoms in the SPES tantalum hot-cavity ion source. The ion beam time structure, laser enhancement of ion yield, and ionization efficiency are investigated in relation to the ion source temperature and ion load. From the time structures, it is inferred that a significant fraction of the extracted ions are generated in the transfer line rather than just in the hot cavity. The effect of the electrostatic axial field on the movement of ions inside the ion source is discussed. Generally, there is an inverse relationship between total ion load and the laser enhancement factor. This dependency is enhanced at lower operating temperature of the ion source. This is explained by the influence of thermionic electron emission and ion density on the transverse laser-ion confinement, and therefore the survival of ions as they drift towards the extraction region of the ion source. At 2200 °C, the nominal temperature for on-line operation of the ion source, the ratio of laser-ionized to surface-ionized gallium was stable around 55 during the measurement campaign, and independent of the total extracted ion current up to the measured value of 1.1 μA. A resonance laser ionization efficiency value of 27.2% for gallium has been measured.

The radiative lifetime of the AΠ1/22 (v=0) state in radium monofluoride (RaF) is measured to be 35(1) ns. The lifetime of this state and the related decay rate Γ=2.86(8)×107 s−1 are of relevance to the laser cooling of RaF via the optically closed AΠ1/22←XΣ1/22 transition, which makes the molecule a promising probe to search for new physics. RaF is found to have a comparable photon-scattering rate to homoelectronic laser-coolable molecules. Owing to its highly diagonal Franck-Condon matrix, it is expected to scatter an order of magnitude more photons than other molecules when using just three cooling lasers, before it decays to a dark state. The lifetime measurement in RaF is benchmarked by measuring the lifetime of the 8P3/2 state in Fr to be 83(3) ns, in agreement with literature. Published by the American Physical Society 2024

The magnetic dipole moments (μ) of 209Tlg (N=128) and 207Tlm (N=126) have been measured for the first time using the in-source laser resonance-ionization spectroscopy technique with the Laser Ion Source and Trap (LIST) at ISOLDE (CERN). The application of the LIST suppresses the usually overwhelming background of the isobaric francium isotopes and allows access to heavy thallium isotopes with A⩾207. The self-consistent theory of finite Fermi systems based on the energy density functional by Fayans et al. well describes the N dependence of μ for 1/2+ thallium ground states, as well as μ for the 11/2− isomeric states in europium, gold and thallium isotopes. The inclusion of particle-vibration coupling leads to a better agreement between the theory and experiment for μ(Tlg, Iπ=1/2+). It is shown that beyond mean-field contributions to μ cannot be neglected at least for thallium isotopes with Iπ=1/2+.

The excited structure of A = 128 isobars populated in the beta decay of Cd-128 has been investigated by means of high-resolution gamma-spectroscopy and fast-timing measurements. The experiment was performed at the ISOLDE facility at CERN profiting from the production of intense and pure Cd beams by means of a temperature-controlled quartz transfer line, capable of suppressing surface-ionized species. The production yields and purity of Cd beams are presented. Results on sub-nanosecond lifetimes for excited states in In-128 and Te-128 are discussed.

The radiative lifetime of the A ^2 Π_1/2 (v=0) state in radium monofluoride (RaF) is measured to be 35(1) ns. The lifetime of this state is of relevance to the laser cooling of RaF via the optically closed A ^2 Π_1/2← X ^2Σ_1/2 transition, which is an advantageous aspect of the molecule for its promise as a probe for new physics. The radiative decay rate Γ = 2.9(2)× 10^7 s^-1 is extracted using the lifetime, which determines the natural linewidth of 4.6(3) MHz and the maximum photon scattering rate of 4.1(3)× 10^6 s^-1 of the laser-cooling transition. RaF is thus found to have a comparable photon-scattering rate with other laser-cooled molecules, while thanks to its highly diagonal Franck-Condon matrix it is expected to scatter an order of magnitude more photons when using 3 cooling lasers before it decays to a dark state. The lifetime measurement in RaF is benchmarked by measuring the lifetime of the 8P_3/2 state in Fr to be 83(3) ns, in agreement with literature.

ISOLDE's Offline 2 laboratory has been upgraded to facilitate development for the production and study of molecular ion beams. New gas injection systems have been implemented for both molecular formation in the ion source and in the radio-frequency quadrupole ion trap used for beam preparation. MagneToF detectors and time-resolved single ion counting data acquisition have been implemented for low intensity beams and studies of laser-atom or laser-molecule interactions. We present a study of the formation and ionization of BaF+ using the upgraded facility.

The study of the atomic spectrum via resonant laser excitation provides access to underlying effects caused by the nuclear structure, which is of special interest in short-lived radioisotopes produced at Isotope Separator On-Line (ISOL) facilities. Current implementations of resonant laser ionization techniques often limit the extraction of the nuclear observables due to the low spectral resolution of the pulsed laser systems deployed. Several high-resolution spectroscopy techniques demand spectral widths in the order of hundreds of MHz and below. A proven solution to reduce this linewidth is the pulsed amplification of a narrow-band continuous wave (cw) laser. This work presents the demonstration of a pulsed dye amplifier seeded by a commercially available cw Optical Parametric Oscillator (OPO). The performance of this system was compared with competing setups using a cw dye laser seed source as well as a frequency mixing technique using a combination of an injection-locked titanium:sapphire (Ti:Sa) and a Nd:YVO4 laser. Spectral bandwidths of the systems were measured using a high finesse Fabry-Perot Interferometer, resulting in comparable optical linewidths between 140 to 156 MHz at a wavelength of 328 nm for the different laser setups. Suitability for on-line experiments was validated by performing high-resolution spectroscopy of radioactive silver isotopes in the Collinear Resonance Ionization Spectroscopy (CRIS) experiment at the Isotope Separator On-Line Device (ISOLDE), at the European Organization for Nuclear Research (CERN). The quality of the hyperfine spectra was similar for the dye and the OPO seed and the deduced hyperfine splitting was in good agreement with literature, while the frequency mixing technique exhibited less precise results attributed to the frequency instabilities and mode-hops of the single-mode Nd:YVO4 laser.

We report the spectroscopy of the 14 lowest excited electronic states in the radioactive molecule radium monofluoride (RaF). The observed excitation energies are compared with fully relativistic state-of-the-art Fock-space coupled cluster (FS-RCC) calculations, which achieve an agreement of >=99.64% (within ~12 meV) with experiment for all states. Guided by theory, a firm assignment of the angular momentum and term symbol is made for 10 states and a tentative assignment for 4 states. The role of high-order electron correlation and quantum electrodynamics effects in the excitation energy of excited states is studied, found to be important for all states. Establishing the simultaneous accuracy and precision of calculations is an important step for research at the intersection of particle, nuclear, and chemical physics, including searches of physics beyond the Standard Model, for which RaF is a promising probe.

Since its commissioning in December 2017, the CERN-MEDICIS facility has been providing non-conventional radionuclides for research in nuclear medicine. Benefitting from decades of experience in the production of radioactive ion beams and in the mass separation process from the ISOLDE facility at CERN, MEDICIS quickly became a worldwide key player in the supply of novel medical isotopes dedicated to research in the fields of cancer imaging, diagnostics, and radiation therapy. After a few years of operation, successful collections have been performed on a large panel of radionuclides such as 128Ba, 149,152,155Tb, 153Sm, 165,167Tm, 169Er, 175Yb, 191Pt, and 225,227Ac. Several milestones have been achieved on the output of the facility, such as the collection of 0.5 GBq of 175Yb, and a total separation efficiency higher than 50% reached for 167Tm in 2020. These collections led to notable recent in-vitro and preclinical results in targeted radionuclide therapy achieved with high molar activity 175Yb and 153Sm products. Constant developments are ongoing, such as innovative target designs, molecular formation to improve the release of some specific isotopes, laser development in the dedicated MELISSA laboratory, study of new implantation foil materials, and post-collection radiochemistry.

Terbium-152 is one of four terbium radioisotopes that together form a potential theranostic toolbox for the personalised treatment of tumours. As 152 Tb decay by positron emission it can be utilised for diagnostics by positron emission tomography. For use in radiopharmaceuticals and for activity measurements by an activity calibrator a high radionuclide purity of the material and an accurate and precise knowledge of the half-life is required. Mass-separation and radiochemical purification provide a production route of high purity 152Tb. In the current work, two mass-separated samples from the CERN-ISOLDE facility have been assayed at the National Physical Laboratory to investigate the radionuclide purity. These samples have been used to perform four measurements of the half-life by three independent techniques: high-purity germanium gamma-ray spectrometry, ionisation chamber measurements and liquid scintillation counting. From the four measurement campaigns a half-life of 17.8784(95) h has been determined. The reported half-life shows a significant difference to the currently evaluated half-life (ζ-score = 3.77), with a relative difference of 2.2 % and an order of magnitude improvement in the precision. This work also shows that under controlled conditions the combination of mass-separation and radiochemical separation can provide high-purity 152Tb.