R. E. Rossel
A5079105450- Atomic and Molecular Physics
- Nuclear physics research studies
- Nuclear Physics and Applications
- Mass Spectrometry Techniques and Applications
- Astronomical and nuclear sciences
- X-ray Spectroscopy and Fluorescence Analysis
- Advanced Chemical Physics Studies
- Laser Design and Applications
- Laser-induced spectroscopy and plasma
- Radiation Therapy and Dosimetry
- Photocathodes and Microchannel Plates
- Laser-Plasma Interactions and Diagnostics
- Radiopharmaceutical Chemistry and Applications
- Particle Accelerators and Free-Electron Lasers
- Radioactive element chemistry and processing
- Particle accelerators and beam dynamics
- Nuclear reactor physics and engineering
- Boron Compounds in Chemistry
- Electron and X-Ray Spectroscopy Techniques
- Advanced Electron Microscopy Techniques and Applications
- Advanced X-ray Imaging Techniques
- Particle Detector Development and Performance
- Chemical Thermodynamics and Molecular Structure
- Atomic and Subatomic Physics Research
- Radioactive Decay and Measurement Techniques
European Organization for Nuclear Research
2015-2024
Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati
2024
Johannes Gutenberg University Mainz
2013-2023
University of Latvia
2023
Riga Stradiņš University
2023
Riga Technical University
2023
University of Manchester
2022
RheinMain University of Applied Sciences
2013-2017
Petersburg Nuclear Physics Institute
2017
Technical University of Darmstadt
2016
The radioactive element astatine exists only in trace amounts nature. Its properties can therefore be explored by study of the minute quantities artificially produced isotopes or performing theoretical calculations. One most important influencing chemical behaviour is energy required to remove one electron from valence shell, referred as ionization potential. Here we use laser spectroscopy probe optical spectrum near threshold. observed series Rydberg states enabled first determination...
Abstract One of the most important properties influencing chemical behavior an element is electron affinity (EA). Among remaining elements with unknown EA astatine, where one its isotopes, 211 At, remarkably well suited for targeted radionuclide therapy cancer. With At − anion being involved in many aspects current astatine labeling protocols, knowledge this prime importance. Here we report measured value to be 2.41578(7) eV. This result compared state-of-the-art relativistic quantum...
The mean-square charge radii of $^{207,208}\mathrm{Hg}$ ($Z=80$, $N=127$, 128) have been studied for the first time and those $^{202,203,206}\mathrm{Hg}$ ($N=122$, 123, 126) remeasured by application in-source resonance-ionization laser spectroscopy at ISOLDE (CERN). characteristic kink in $N=126$ neutron shell closure has revealed, providing information on its behavior below $Z=82$ proton closure. A theoretical analysis performed within relativistic Hartree-Bogoliubov nonrelativistic...
The resonance ionization laser ion source (RILIS) produces beams for the majority of experiments at ISOLDE on-line isotope separator. A substantial improvement in RILIS performance has been achieved through a series upgrade steps: replacement copper vapor lasers by Nd:YAG laser; old homemade dye new commercial lasers; installation complementary Ti:Sapphire system. combined and system with harmonics is capable generating any wavelength range 210–950 nm. In total, isotopes 31 different...
We show in experiments that a long, underdense, relativistic proton bunch propagating plasma undergoes the oblique instability, which we observe as filamentation. determine threshold value for ratio between transverse size and skin depth instability to occur. At threshold, outcome of experiment alternates filamentation self-modulation (evidenced by longitudinal modulation into microbunches). Time-resolved images density distribution reveal grows an observable level late along bunch,...
The magnetic moments and isotope shifts of the neutron-deficient francium isotopes (202-205)Fr were measured at ISOLDE-CERN with use collinear resonance ionization spectroscopy. A production-to-detection efficiency 1% was for (202)Fr. background from nonresonant collisional maintained below one ion in 10(5) beam particles. Through a comparison charge radii predictions spherical droplet model, it is concluded that ground-state wave function remains down to (205)Fr, departure observed (203)Fr (N=116).
New technical developments have led to a 2 orders of magnitude improvement the resolution collinear resonance ionization spectroscopy (CRIS) experiment at ISOLDE, CERN, without sacrificing high efficiency CRIS technique. Experimental linewidths 20(1) MHz were obtained on radioactive beams francium, allowing us for first time determine electric quadrupole moment short lived [t_{1/2}=22.0(5) ms] ^{219}Fr Q_{s}=-1.21(2) eb, which would not been possible advantages offered by new method. This...
The neutron-deficient Hg isotopes have been a paradigm for nuclear shape coexistence. ground states of these nuclei exhibit striking structural differences from the neighboring Pb isotopes, and are very challenging to study experimentally. Here, new state-of-the-art data extend information on charge radii (and electromagnetic moments) lightest ever measured using laser spectroscopy. results suggest sudden decrease in deformation an end region ground-state staggering. These provide...
Experimental results show that hosing of a long particle bunch in plasma can be induced by wakefields driven short, misaligned preceding bunch. Hosing develops the plane misalignment, self-modulation perpendicular plane, at frequencies close to electron frequency, and are reproducible. Development depends on misalignment direction, its growth extent proton charge. Results have main characteristics theoretical model, relevant other plasma-based accelerators represent first characterization...
This paper reports on the hyperfine-structure and radioactive-decay studies of neutron-deficient francium isotopes $^{202-206}$Fr performed with Collinear Resonance Ionization Spectroscopy (CRIS) experiment at ISOLDE facility, CERN. The high resolution innate to collinear laser spectroscopy is combined efficiency ion detection provide a highly-sensitive technique probe hyperfine structure exotic isotopes. decay-assisted presented, whereby isomeric beam deflected decay station for alpha-decay...
The CRIS setup at CERN-ISOLDE is a laser spectroscopy experiment dedicated to the high-resolution study of spin, hyperfine structure and isotope shift radioactive nuclei with low production rates (a few per second). It combines Doppler-free resolution in-flight collinear geometry high detection efficiency resonant ionisation. A recent commissioning campaign has demonstrated 1% experimental efficiency, as 0.001% non-resonant current status its achievements beams francium isotopes are...
This article summarizes the current specifications and latest features of CERN-ISOLDE resonance ionization laser ion source (RILIS). includes a description optical layout newly designed reference system. The schemes for ionized beams at ISOLDE are tabulated, including six new elements. All RILIS also made publicly available in elements on-line database. Finally, we announce paradigm shift operation – combination machine protection monitoring control system has enabled on-call selected 2014...
Hyperfine-structure parameters and isotope shifts of $^{195--211}\mathrm{At}$ have been measured for the first time at CERN-ISOLDE, using in-source resonance-ionization spectroscopy method. The hyperfine structures isotopes were recorded a triad experimental techniques monitoring photo-ion current. Multi-Reflection Time-of-Flight Mass Spectrometer, in connection with high-resolution electron multiplier, was used as an ion-counting setup that either affected by strong isobaric contamination...
We show experimentally that an effect of motion ions, observed in a plasma-based accelerator, depends inversely on the plasma ion mass. The appears within single wakefield event and manifests itself as bunch tail, occurring only when sufficient ions suppresses wakefields. Wakefields are driven resonantly by multiple bunches, simulation results indicate ponderomotive force causes ions. In this case, is also expected to depend amplitude wakefields, confirmed through variations drive charge....
The magnetic dipole moments and changes in mean-square charge radii of the neutron-rich ${}^{218m,219,229,231}\mathrm{Fr}$ isotopes were measured with newly installed Collinear Resonance Ionization Spectroscopy (CRIS) beam line at On-Line Isotope Mass Separator (ISOLDE), CERN, probing $7{s}^{2}{S}_{1/2}$ to $8{p}^{2}{P}_{3/2}$ atomic transition. $\ensuremath{\delta}{\ensuremath{\langle}{r}^{2}\ensuremath{\rangle}}^{A,221}$ values for ${}^{218m,219}\mathrm{Fr}$ ${}^{229,231}\mathrm{Fr}$...
Hyperfine-structure constants for the $6s{\phantom{\rule{0.28em}{0ex}}}^{2}{S}_{1/2}$ and $6p{\phantom{\rule{0.28em}{0ex}}}^{2}{P}_{1/2}$ atomic states of ${I}^{\ensuremath{\pi}}=11/{2}^{\ensuremath{-}}$ gold isomers $^{177,191,193,195}\mathrm{Au}^{m}$ have been measured at CERN-ISOLDE, using in-source laser resonance-ionization spectroscopy technique. From hyperfine differences between anomalies these deduced. These differential anomaly values used to determine $6s$-state relative stable...
With their high quantum efficiency (QE) and excellent photoemissive properties, cesium telluride (Cs-Te) photocathodes are the current workhorse in average electron accelerators around globe. Their ability to generate brightness charge beams has opened doorway numerous applications, including fundamental particle physics research, radiation therapy, high-energy experiments, repetition rate free-electron lasers (FELs). long-term performance is critical. In this work, we analyze systematic...
The hyperfine spectra of $^{51,53-64}$Mn were measured in two experimental runs using collinear laser spectroscopy at ISOLDE, CERN. Laser was performed on the atomic $3d^5\ 4s^2\ ^{6}\text{S}_{5/2}\rightarrow 3d^5\ 4s4p\ ^{6}\text{P}_{3/2}$ and ionic 4s\ ^{5}\text{S}_2 \rightarrow 4p\ ^{5}\text{P}_3$ transitions, yielding sets isotope shifts. mass field shift factors for both transitions have been calculated multiconfiguration Dirac-Fock framework combined with a King plot analysis order to...
At radioactive ion beam facilities like ISOLDE at CERN, a high purity of the element interest in is essential for most experiments on exotic nuclei. Due to its unique combination ionization efficiency and ultimate elemental selectivity, Resonance Ionization Laser Ion Source, RILIS, has become frequently used source majority similar worldwide. However, isobaric contamination predominantly stemming from unspecific surface may still introduce severe limitations. By applying highly selective...
For the first time, laser resonance photo-ionization technique has been applied inside a FEBIAD-type ion source at an ISOL facility. This was achieved by combining ISOLDE RILIS with variant of FEBIAD (the VADIS) in series off-line and on-line tests CERN. The immediate applications these developments include coupling molten targets introduction two new modes operation: element selective mode + VADIS for increased efficiency compared to operation alone. functionality demonstrated gallium...