Nuclear structure of Au-181 studied via beta(+)/EC decay of Hg-181 at ISOLDE

The $\beta ^+$/EC decay of mass separated samples of $^{181}$Hg was studied employing the TATRA spectrometer at the ISOLDE facility at CERN. The decay scheme was constructed for the first time. A Broad Energy Germanium detector was used to achieve this by combination of high-gain $\gamma$-ray singles spectroscopy and $\gamma$–$\gamma$ coincidences. The systematics of excited states associated with the 1$h_{11/2}$ proton-hole configuration in odd-Au isotopes was extended

New systematic features in the neutron-deficient Au isotopes

A recently developed portable, on-line capability for γ-ray and conversion-electron spectroscopy, HIGH-TATRA is demonstrated with its application to the study of 183Hg $\to$ 183Au at ISOLDE. Key details of the low-energy level scheme of the neutron-deficient nuclide 183Au populated in this decay are presented. A broad energy germanium detector is employed to achieve this (the first-ever use of such a device in decay-scheme spectroscopy), by way of a combination of high-gain γ-ray singles spectroscopy and γ–γ coincidence spectroscopy. Further, by combining the γ-ray detectors with a liquid-nitrogen-cooled Si(Li) detector operated under high vacuum, conversion-electron singles and e–γ coincidences are obtained. These data lead to the determination of transition multipolarities and the location of a highly converted (E0 + M1 + E2) transition in the 183Au decay scheme, suggesting a possible new shape coexisting structure in this nucleus. Identification of new intruder and normal states fixes their relative energies in 183Au for the first time. New systematic features in the odd-Au isotopes are presented

Change in structure between the I = 1/2 states in 181Tl and 177,179Au

The first accurate measurements of the α-decay branching ratio and half-life of the Iπ=1/2+ ground state in 181Tl have been made, along with the first determination of the magnetic moments and I=1/2 spin assignments of the ground states in 177,179Au. The results are discussed within the complementary systematics of the reduced α-decay widths and nuclear g factors of low-lying, Iπ=1/2+ states in the neutron-deficient lead region. The findings shed light on the unexpected hindrance of the 1/2+→1/2+, 181Tl→g177Aug α decay, which is explained by a mixing of π3s1/2 and π2d3/2 configurations in 177Aug, whilst 181Tlg remains a near-pure π3s1/2. This conclusion is inferred from the g factor of 177Aug which has an intermediate value between those of π3s1/2 and π2d3/2 states. A similar mixed configuration is proposed for the Iπ=1/2+ ground state of 179Au. This mixing may provide evidence for triaxial shapes in the ground states in these nuclei

Production of intense mass separated C-11 beams for PET-aided hadron therapy

© 2019 Elsevier B.V. A novel production system based on the Isotope Separation On-Line (ISOL) method is being developed to produce intense mass separated 11C beams for PET-aided hadron therapy. In this work, we present a systematic study of the target that was developed for optimized 11C beam production. A solid boron nitride target (BN) with approximately 21% open porosity was manufactured by spark plasma sintering to provide maximized in-target production yield with enhanced isotope release properties. Operational limitations with respect to high temperatures and oxidizing atmospheres were studied, revealing that the BN target can withstand temperatures up to 1500 °C and can be operated with a controlled O2 leak, providing O2 potentials up to −300 kJ/mol, measured at 1000 °C.A novel production system based on the Isotope Separation On-Line (ISOL) method is being developed to produce intense mass separated 11C beams for PET-aided hadron therapy. In this work, we present a systematic study of the target that was developed for optimized 11C beam production. A solid boron nitride target (BN) with approximately 21% open porosity was manufactured by spark plasma sintering to provide maximized in-target production yield with enhanced isotope release properties. Operational limitations with respect to high temperatures and oxidizing atmospheres were studied, revealing that the BN target can withstand temperatures up to 1500 °C and can be operated with a controlled O2 leak, providing O2 potentials up to −300 kJ/mol, measured at 1000 °C.nrpages: 5status: publishe

Laser spectroscopy of indium Rydberg atom bunches by electric field ionization

This work reports on the application of a novel electric field-ionization setup for high-resolution laser spectroscopy measurements on bunched fast atomic beams in a collinear geometry. In combination with multi-step resonant excitation to Rydberg states using pulsed lasers, the field ionization technique demonstrates increased sensitivity for isotope separation and measurement of atomic parameters over previous non-resonant laser ionization methods. The setup was tested at the Collinear Resonance Ionization Spectroscopy experiment at ISOLDE-CERN to perform high-resolution measurements of transitions in the indium atom from the [Formula: see text] and [Formula: see text] states to [Formula: see text]p [Formula: see text]P and [Formula: see text]F Rydberg states, up to a principal quantum number of [Formula: see text]. The extracted Rydberg level energies were used to re-evaluate the ionization potential of the indium atom to be [Formula: see text]. The nuclear magnetic dipole and nuclear electric quadrupole hyperfine structure constants and level isotope shifts of the [Formula: see text] and [Formula: see text] states were determined for [Formula: see text]In. The results are compared to calculations using relativistic coupled-cluster theory. A good agreement is found with the ionization potential and isotope shifts, while disagreement of hyperfine structure constants indicates an increased importance of electron correlations in these excited atomic states. With the aim of further increasing the detection sensitivity for measurements on exotic isotopes, a systematic study of the field-ionization arrangement implemented in the work was performed at the same time and an improved design was simulated and is presented. The improved design offers increased background suppression independent of the distance from field ionization to ion detection.status: publishe

A new control system for high-precision In-Gas Laser Ionization and Spectroscopy experiments at KU Leuven

A new automated control system is developed for the In-Gas Laser Ionization and Spectroscopy (IGLIS) laboratory at KU Leuven. The IGLIS Control System is capable of stabilizing a narrowband single-mode tunable diode laser with a standard deviation of 1.14 MHz. Furthermore, the system controls and synchronizes all data acquisition for multiple techniques from resonant laser spectroscopy in gas cell or in gas jet to atomic Planar-Laser Induced Fluorescence (PLIF) spectroscopy of copper atoms seeded in a supersonic gas jet. The IGLIS Control System is validated by measuring the hyperfine splitting parameters of the ground state transition at 327 nm in 63Cu.A new automated control system is developed for the In-Gas Laser Ionization and Spectroscopy (IGLIS) laboratory at KU Leuven. The IGLIS Control System is capable of stabilizing a narrowband single-mode tunable diode laser with a standard deviation of 1.14 MHz. Furthermore, the system controls and synchronizes all data acquisition for multiple techniques from resonant laser spectroscopy in gas cell or in gas jet to atomic Planar-Laser Induced Fluorescence (PLIF) spectroscopy of copper atoms seeded in a supersonic gas jet. The IGLIS Control System is validated by measuring the hyperfine splitting parameters of the ground state transition at 327 nm in 63Cu.status: publishe

Laser spectroscopy of indium Rydberg atom bunches by electric field ionization

© 2020, The Author(s). This work reports on the application of a novel electric field-ionization setup for high-resolution laser spectroscopy measurements on bunched fast atomic beams in a collinear geometry. In combination with multi-step resonant excitation to Rydberg states using pulsed lasers, the field ionization technique demonstrates increased sensitivity for isotope separation and measurement of atomic parameters over previous non-resonant laser ionization methods. The setup was tested at the Collinear Resonance Ionization Spectroscopy experiment at ISOLDE-CERN to perform high-resolution measurements of transitions in the indium atom from the 5s25d2D5/2 and 5s25d2D3/2 states to 5s 2np 2P and 5s2nf2F Rydberg states, up to a principal quantum number of n= 72. The extracted Rydberg level energies were used to re-evaluate the ionization potential of the indium atom to be 46,670.107(4)cm-1. The nuclear magnetic dipole and nuclear electric quadrupole hyperfine structure constants and level isotope shifts of the 5s25d2D5/2 and 5s25d2D3/2 states were determined for 113 , 115In. The results are compared to calculations using relativistic coupled-cluster theory. A good agreement is found with the ionization potential and isotope shifts, while disagreement of hyperfine structure constants indicates an increased importance of electron correlations in these excited atomic states. With the aim of further increasing the detection sensitivity for measurements on exotic isotopes, a systematic study of the field-ionization arrangement implemented in the work was performed at the same time and an improved design was simulated and is presented. The improved design offers increased background suppression independent of the distance from field ionization to ion detection