The WISArD experiment aims to probe possible manifestations of new physics in the weak interaction sector of the Standard Model through precision studies of beta decay. In particular, the experiment targets the angular correlation parameter a and the Fierz interference term b, which are sensitive to exotic scalar and tensor currents beyond the vector and axial-vector interactions of the...
By introducing spin polarisation into ฮฒ-decay studies, one can overcome the difficulty of conventional ฮฒ-decay spectroscopy to firmly determine the spins and parities of nuclear states involved in allowed transitions. This is because the sign and degree of asymmetry in ฮฒ-decay from polarised nuclei depends on the spin difference between the initial and final states.
This novel approach to ...
Helium-3 gas-filled proportional counters are extensively used as neutron detectors for measurements in a wide range of applications. A recent example are ($\alpha$,n) reactions measured by the MANY collaboration using the miniBELEN detector [1]. This kind of neutron counters are also commonplace as neutron monitors, both for the study of cosmic rays and solar weather [2], as well as...
Regions near closed shells in areas of the nuclear chart far from stability are very interesting from the point of view of nuclear structure, since a shell model description based on single-particle states can be challenged by collective effects. One of the most interesting regions is the one around the doubly-magic $^{78}$Ni nucleus, with $Z=28$ and $N=50$ [1].
The systematics of...
The Apparatus for Surface Physics and Interfaces at CERN (ASPIC) was previously installed in the solid-state physics section of the ISOLDE experimental hall, where it operated under ultra-high vacuum conditions (UHV, $\leq 10^{-8}$ mbar). ASPIC enabled studies of metallic surfaces, magnetic thin films, and interface dynamics, and supported experiments using radioactive isotopes and a range of...
Exploring ground-state nuclear properties is a powerful tool to investigate our understanding of nuclear structure. Laser spectroscopy gives access to nuclear ground-state properties, such as the nuclear spin, electromagnetic moments and changes in the mean-squared charge radius of short-lived ($\geq$10 ms) nuclei by measuring the hyperfine $A$-and $B$-parameters and isotope shift [1]....
$^{225}$Ac has been identified as a promising isotope for Targeted Alpha Therapy (TAT) treatment of metastasized tumors [1]. For logistic and medical purposes, a better understanding of the nuclear data along the entire $^{225}$Ac decay chain is required. Currently discrepancies are observed when measuring the activity using techniques that utilize different daughter nuclides and different...
The IS685 experiment studies exotic, neutron-rich In isotopes populated in the Cd $\beta$ decay using high-resolution $\gamma$-ray spectroscopy and fast-timing techniques~[1]. Understanding nuclear structure in this region requires the systematic investigation of nuclei around the double $Z=50$ and $N=82$ shell closure, where collective effects set in with only few extra nucleons. Exotic...
The $RbNdNb_{2}O_{7}$ (RNNO) and $CsNdNb_2O_7$ (CNNO) systems exhibit a sequence of phase transitions before reaching their hig temperature $P4/mmm$ aristotype phase. In RNNO, the structure evolves from a polar $I2cm$ phase at room temperature to an antipolar $Cmca$ phase at $790\,K$, and finally to a distorted $I4/mcm$ structure at $865\,K$ [1]. These transitions arise from rotations and...
The beta decay of 8He was measured at IDS in 2022. 16% of decays populate excited states in 8Li which decay by neutron emission and alpha-neutron-triton breakup. Due to significant background the double alpha breakup of 8Be following the beta decay of 8Li, a triple coincidence must be made to identify alpha-neutron-triton events. Owing to the complexity of detecting neutrons, the response and...
The ISOLDE Superconducting Recoil Separator (ISRS)[1] under development at CERN aims to achieve unprecedented mass resolution and transmission efficiency through a compact, Fixed Field Alternating Gradient (FFAG) storage ring composed of Canted Cosine Theta (CCT) multifunction superconducting magnets. Each MAGDEM prototype integrates combined dipole and quadrupole fields within a cryogen-free...
The ISOLDE Superconducting Linear Spectrometer (ILS) [1] marks the start of the operational phase of the ISOLDE Superconducting Recoil Separator (ISRS) [2-3] project. Designed as the first operational stage of ISRS, the ILS provides a compact experimental platform to test the key superconducting magnet and beam optics technologies that will be implemented in the full separator. The system,...
Over the past several years, extensive studies have been devoted to the structure of neutron-rich tin isotopes, which possess a closed proton shell, with ยนยณยฒSn being a doubly magic nucleus. For this reason, these nuclei play a particularly important role in testing the validity of the nuclear shell model and serve as a benchmark for theoretical predictions. Information obtained in this region...
The investigation of $\beta$-decay properties of neutron-rich nuclei in the A $\approx $ 120 region provides essential input for testing modern nuclear-structure models and for constraining astrophysical r-process simulations. In this context, the $\beta^-$ decay of $^{118}$Pd (Z = 46, N~=~72) populating excited states in $^{118}$Ag was studied at the Ion Guide Isotope Separator On-Line...
Resonant laser ionization is an efficient and highly selective method for producing radioisotopes. In the laser ion source of ISOLDE โ RILIS (Resonance Ionization Laser Ion Source), the laser interaction region is inside a metal tube which is heated to temperatures of up to 2200 degrees Celsius. This heating induces surface ionization from the walls of this so-called โhot cavityโ. If the...
A comprehensive optics model of the ISOLDE low-energy transfer lines has been developed and validated to support improved beam delivery for experiments such as PUMA. The model, implemented in MAD-X and Xsuite, incorporates survey data, apertures, and CST-validated electrostatic quadrupole fields. Benchmarking through quadrupole scans, kick-response measurements, and tomographic reconstruction...
Demands with respect to yield, purity, reliability are driving development efforts. Recent years focus on nanomaterials: release bottleneck in RIB production where nanometric size is promising for diffusion-limited isotopes. This often goes hand in hand with increase in surface area, which significantly impact effusion efficiency for open pores. Nanotechnology has been considered for...
Abstract
Octupole deformations are predicted to occur in nuclei in the region $130\leq N \leq 140$ and $85 \leq Z \leq 92$ [1]. Nuclei that exhibit octupole deformations are of interest for ongoing searches for permanent atomic electric-dipole-moments and beyond Standard Model physics.
Recent studies suggest the octupole deformed region north-east of $^{208}$Pb extends down to At...
L. F. de Almeida (โ1), A. C. Miranda (1,2), P. Rocha Rodrigues (1), N. L. Prasannan (1), J. G. Correia (2), A. Cesario (1), P. A. Sousa (1), J. M. A. Pereira (1), J. P. Araujo (1), A. M. L. Lopes (1)
1-IFIMUP and LaPMET, Department of Physics and Astronomy, Faculty of Sciences of the University of Porto, Porto, Portugal;
2-C2TN, DECN, Instituto Superior Tecnico, Lisboa,...
This work presents the engineering design and analysis of the upgraded beta-NMR end station at the VITO beamline. The upgrade was aimed at enabling studies of air-sensitive samples in a wide range of temperatures in 4.7 T magnetic field. This led to the requirements of non-magnetic materials, ultra-high vacuum, load-lock system for sample changes, and heating and cooling capability. The...
Development and testing of nanostructured uranium carbide targets for ISOLDE physics
Authors: V. Berlin$^1$, M. Au$^1$, E. Aubert$^1$, A. Boucherie$^1$, N. Conan$^1$, B. Crepieux$^1$, A. Dorsival$^1$, M.A. Grasser$^1$, L. Lambert$^1$, E. Reis$^1$$^,$$^2$, S. Rothe$^1$, S. Stegemann$^1$, J. Vollaire$^1$, S. Usta$^1$, J. Zucchi$^1$
$^1$ Center for European Nuclear Research,...
Laser spectroscopy of neutron-deficient lutetium isotopes (Z=71) can provide insights into the evolution of nuclear structure towards the proton drip line, independent of any nuclear models. Probing the hyperfine structure with laser spectroscopy allows the measurement of nuclear spins, magnetic moments, quadrupole moments and isotope shifts of these exotic nuclei. The isotope shift can then...
Silicon carbide (SiC) has historically been employed as a target material at ISOLDE (CERN) [1] and ISAC (TRIUMF) [2] and is currently under evaluation and development at emerging facilities including ISOL@MYRRHA (SCK CEN) [3] and SPES (INFN) [4]. Thanks to its high thermal conductivity, excellent emissivity, and chemical stability at elevated temperatures, SiC is under investigation for...
We present the status of the design and simulations of a future end-station at the VITO beamline aimed at performing collinear Laser-Radiofrequency (RF) Double-Resonance Spectroscopy. The future experiment is intended to significantly enhance the precision in determining the Hyperfine Structure (HFS) constants of short-lived exotic nuclei (e.g., K isotopes), with an expected reduction in...
The Resonance Ionisation Laser Ion Source (RILIS) continues to be the ion source chosen most often to provide radioactive ion beams (RIBs) for experiments at CERN-ISOLDE, as ionisation through optical resonance offers high chemical selectivity and efficiency [1,2]. To suppress potentially contaminating surface ionisation whilst maintaining laser ionisation, Laser Ion Source and Trap (LIST) was...
Uranium carbide (UCโ), thorium carbide (ThCโ), and lanthanum carbide (LaCโ) constitute approximately 85% of the target materials used at CERN-ISOLDE. These carbides are highly pyrophoric and must be chemically stabilized after proton irradiation to enable their safe handling and disposal as radioactive waste, preventing ignition and thermal runaway upon exposure to ambient air or oxidizing...
Colour centres based on group-IV impurities (SiV, GeV, SnV, and PbV) in diamond are intensively investigated in the context of quantum nanophotonic applications, with some of their attractive properties stemming from the inversion symmetry of their split-vacancy configuration and their high Debye-Waller factor. In addition to inheriting the inversion symmetric properties of a split-vacancy...
The Collinear Resonance Ionization Spectroscopy (CRIS) experiment at CERN ISOLDE is used to perform hyperfine structure and isotope shift measurements [1]. The resonance ionization in collinear geometry provides selectivity over different nuclear isomeric states, which decay can be measured at the Decay Spectroscopy Station (DSS). The DSS setup has been under development over the years [2,3]...
High resolution laser spectroscopy has been used to study the atomic hyperfine structure of thulium isotopes (Z=69) leading towards the proton emitter 147Tm. This technique results in a model independent measurement of the nuclear magnetic dipole moments, electric quadrupole moments and change in mean-square charge radii, with respect to the stable 169Tm. Collinear laser spectroscopy...
The nuclear shell model, combined with pairing correlations, offers a straightforward explanation of the low-energy spectra of semi-magic nuclei. In a single high-$j$ orbital with more than two particles, low-lying $J>0$ states arise from recoupling of unpaired nucleons and group into multiplets labeled by seniority $\nu$โthe number of unpaired particles. The generalized seniority scheme is...
In the past few years, spectroscopy of radioactive molecules has been performed at ISOLDE (CERN) using the Collinear Resonance Ionization Spectroscopy (CRIS) experiment [1]. Given their structure and chemical properties, radioactive molecules are promising candidates for studies in different fields [2], including for more efficient extraction of refractory elements from ISOLDE targets...
As part of the IS708 experiment carried out at ISOLDE, safe Coulomb excitation measurements with the Miniball detector were performed to investigate octupole and quadrupole collectivity in neutron rich 144Ba. The data from this experiment also provided the opportunity to study such deformation in a selection of other observed A=144 isobars including stable 144Nd, 144Sm as well as radioactive...
A new ion-implantation chamber has been commissioned at the General Low Mass (GLM) beamline of ISOLDE to improve operational efficiency and safety in handling radioactive ion beams. Replacing the former single-chamber system, the new setup features a dual-chamber load-lock design comprising an implantation chamber and a loading/unloading chamber, separated by a DN200 gate valve. Each chamber...
The main purpose of Offline 2 mass separator as part of the CERN-ISOLDE offline facilities is to perform preparatory studies and to benchmark new beam production and manipulation techniques or new beam instrumentation before their online implementation.
Similarly to GPS and HRS, the Offline 2 frontend comprises a gas mixing system to allow the introduction of reactant gases into the target...
The ISOLTRAP setup is a high-precision mass spectrometer designed to measure the masses of short-lived, exotic radionuclides far from the valley of stability. Utilizing both multi-reflection time-of-flight (MR-ToF) and Penning-trap mass spectrometry, ISOLTRAP performs precise absolute and relative mass measurements. Converting these measured masses into nuclear binding energies (via the...
Understanding nuclear structure requires precise experimental data on ground-state properties across isotopic chains. Collinear Laser Spectroscopy (CLS) provides a powerful means to determine nuclear spins, magnetic dipole and electric quadrupole moments, and changes in the mean square charge radii through measurements of hyperfine structures and isotope shifts. However, extending these...
Ab initio calculations of NMR shielding constants have made it possible to re-evaluate nuclear magnetic dipole moments from NMR experiments, offering a substantial improvement over traditional diamagnetic corrections.
In this work, we report accurate ab initio NMR shielding constants for selenium and tellurium compounds: (1) Se(CH$_3$)$_2$ and Te(CH$_3$)$_2$, which define the current NMR...
Due to the ever-increasing demands and the interconnectedness of the different machines operating at ISOLDE, a general timing system is proposed for the facility to synchronize the operation for the different sub-systems, such as the new mass separator beamline RC6, the HRS and GPS beamgates, the upcoming central beamline switching, ISCOOL, RILIS laser trigger generation, etc. The different...
The growing field of nuclear medicine theranostics relies on radionuclides that combine diagnostic and therapeutic functions [1]. Among these, the four isotopes of Terbium Tb-149, Tb-152, Tb-155, and Tb-161 offer complementary decay modes suitable for PET, SPECT, and targeted alpha and beta therapy, earning Terbium the title of the โSwiss army knifeโ of nuclear medicine [2,3].
To produce...
The neutron-rich lanthanides are expected to exhibit octupole collectivity, which can lead to asymmetric nuclear shapes. The study of low-lying negative-parity states in the even-even nuclei in this region is key to understanding the magnitude of collectivity and whether the nucleus adopts a static or dynamic asymmetric shape. Lifetimes of these states are particularly sensitive to...
Isotope shift measurements and the King plot are an established method to determine the nuclear charge radius [1]. Nonlinear effects in King plots have recently gained additional interest as probes for higher-order nuclear deformation and beyond-standard-model physics [2,3]. Methods like the generalized King plot allow to extract multiple effects such as higher-order nuclear deformation and...
The generalised seniority scheme is a truncated version of the nuclear shell model [1]. It is able to describe the structure of atomic nuclei in the vicinity of shell closures. The number of unpaired nucleons, the seniority $\nu$, is considered a good quantum number.
The region of the even-even Po-Rn-Ra nuclei with $N=124$ exhibits strong signs of seniority-like behaviour. This can be...
Technical poster on the future flexible ion source for COLLAPS, detailing the specific and unique requirements of an ion source for fast beam spectroscopic purposes. This source will function as a metal ion source capable of vapourising a variety of metals into atomic gasses using a fibre laser before ionising them using electron impact ionisation. This technique will also allow the source to...
The isotope $^{229}$Th is of particular interest because of its exceptionally low-energy isomeric state (8.2 eV), which can be probed via vacuum ultraviolet (VUV) spectroscopy and holds significant potential for the development of a nuclear clock [1,2]. Understanding this isomerโs properties, including its excitation and decay modes, is hereby essential and involves investigating the nuclear...
The radionuclides used in targeted radionuclide therapy emit charged particles, such as ฮฑ, ฮฒ- and Auger electron, that makes possible the delivery of a significant dose to the tumour cells while sparring the healthy tissues surrounding them. The radioisotope 111Ag (T1/2 = 7.45 days, Emax,ฮฒ- = 1.04 MeV) is a ฮฒ- emitter that is promising for this kind of application. Its low energy ฮฒ- has a...
The region of the nuclear chart centred around $^{32}$Mg, known as the Island of Inversion (IOI), is characterised by the onset of deformed configurations in the ground states due to particle excitations across a weakening N=20 shell gap. The IOI has been described using numerous observables, but information regarding the single-particle structure of nuclei in this region is limited. The aim...
We report several advances in the field of ion beam development towards the study of radioactive molecules. Radioactive molecules are predicted to be powerful tools in the study of physics beyond the standard model, as they potentially enhance permanent dipole moments in the leptonic (electron electric dipole moment - eEDM) or hadronic (Nuclear Schiff moment, Magnetic Quadrupole Moment - NSM,...
