| 1. |
- Kirsebom, O. S., et al.
(author)
-
Measurement of the 2+→0+ ground-state transition in the β decay of F 20
- 2019
-
In: Physical Review C. - 2469-9985. ; 100:6
-
Journal article (peer-reviewed)abstract
- We report the first detection of the second-forbidden, nonunique, 2+→0+, ground-state transition in the β decay of F20. A low-energy, mass-separated F+20 beam produced at the IGISOL facility in Jyväskylä, Finland, was implanted in a thin carbon foil and the β spectrum measured using a magnetic transporter and a plastic-scintillator detector. The β-decay branching ratio inferred from the measurement is bβ=[0.41±0.08(stat)±0.07(sys)]×10-5 corresponding to logft=10.89(11), making this one of the strongest second-forbidden, nonunique β transitions ever measured. The experimental result is supported by shell-model calculations and has significant implications for the final evolution of stars that develop degenerate oxygen-neon cores. Using the new experimental data, we argue that the astrophysical electron-capture rate on Ne20 is now known to within better than 25% at the relevant temperatures and densities.
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
- Udrescu, S. M., et al.
(author)
-
Precision spectroscopy and laser-cooling scheme of a radium-containing molecule
- 2024
-
In: NATURE PHYSICS. - 1745-2473 .- 1745-2481.
-
Journal article (peer-reviewed)abstract
- Molecules containing heavy radioactive nuclei are predicted to be extremely sensitive to violations of the fundamental symmetries of nature. The nuclear octupole deformation of certain radium isotopes massively boosts the sensitivity of radium monofluoride molecules to symmetry-violating nuclear properties. Moreover, these molecules are predicted to be laser coolable. Here we report measurements of the rovibronic structure of radium monofluoride molecules, which allow the determination of their laser cooling scheme. We demonstrate an improvement in resolution of more than two orders of magnitude compared to the state of the art. Our developments allowed measurements of minuscule amounts of hot molecules, with only a few hundred per second produced in a particular rotational state. The combined precision and sensitivity achieved in this work offer opportunities for studies of radioactive molecules of interest in fundamental physics, chemistry and astrophysics. Measurements of the rovibronic structure of radium monofluoride molecules allow the identification of a laser cooling scheme. This will enable precise tests of fundamental physics, such as searches for parity or time-reversal symmetry violation.
|
|
| 5. |
- Urquiza-González, M., et al.
(author)
-
Benchmark evaluation for a single frequency continuous wave OPO seeded pulsed dye amplifier for high-resolution laser spectroscopy
- 2023
-
In: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9781510659032
-
Conference paper (peer-reviewed)abstract
- 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.
|
|
| 6. |
- Gärdenfors, Peter, et al.
(author)
-
Pantomime als Grundlage für Ritual und Sprache
- 2018
-
In: "Ein Symbol dessen, was wir sind" : Liturgische Perspektiven zur Frage der Sakramentalität - Liturgische Perspektiven zur Frage der Sakramentalität. - 9783791725857 ; 48:1-2, s. 23-40
-
Book chapter (peer-reviewed)
|
|
| 7. |
- Nichols, M., et al.
(author)
-
Investigating radioactive negative ion production via double electron capture
- 2023
-
In: Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions with Materials and Atoms. - 0168-583X. ; 541, s. 264-267
-
Journal article (peer-reviewed)abstract
- The relative cross sections for radioactive negative ion production via double electron capture have been measured for collisions between a 40 keV projectile beam of uranium-238 and potassium vapor. This was performed at the collinear resonance ionization spectroscopy (CRIS) experiment at CERN-ISOLDE and is a step towards measuring the electron affinities (EAs) of elements that cannot be efficiently produced in negative ion sources at radioactive ion beam (RIB) facilities. This includes short-lived radioactive isotopes that have low production quantities and heavy and superheavy elements that systematically have smaller EAs than work functions of available ion source materials. Negative ions are particularly sensitive to electron-electron correlation effects, which make such studies ideal for benchmarking atomic structure models that go beyond the independent particle model. While the EAs of most light elements have been measured, experimental investigations on heavier elements, namely the actinides, remain scarce due to their radioactive nature and production difficulty. By developing negative ion production by charge exchange, we aim to make these studies feasible at RIB facilities.
|
|
