| 1. |
- Barzakh, A., et al.
(författare)
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Large Shape Staggering in Neutron-Deficient Bi Isotopes
- 2021
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Ingår i: Physical Review Letters. - 0031-9007. ; 127:19
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Tidskriftsartikel (refereegranskat)abstract
- The changes in the mean-square charge radius (relative to Bi209), magnetic dipole, and electric quadrupole moments of Bi187,188,189,191 were measured using the in-source resonance-ionization spectroscopy technique at ISOLDE (CERN). A large staggering in radii was found in Bi187,188,189g, manifested by a sharp radius increase for the ground state of Bi188 relative to the neighboring Bi187,189g. A large isomer shift was also observed for Bi188m. Both effects happen at the same neutron number, N=105, where the shape staggering and a similar isomer shift were observed in the mercury isotopes. Experimental results are reproduced by mean-field calculations where the ground or isomeric states were identified by the blocked quasiparticle configuration compatible with the observed spin, parity, and magnetic moment. © 2021 authors.
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| 2. |
- Hoshino, Ayuko, et al.
(författare)
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Extracellular Vesicle and Particle Biomarkers Define Multiple Human Cancers
- 2020
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Ingår i: Cell. - : CELL PRESS. - 0092-8674 .- 1097-4172. ; 182:4, s. 1044-
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Tidskriftsartikel (refereegranskat)abstract
- There is an unmet clinical need for improved tissue and liquid biopsy tools for cancer detection. We investigated the proteomic profile of extracellular vesicles and particles (EVPs) in 426 human samples from tissue explants (TEs), plasma, and other bodily fluids. Among traditional exosome markers, CD9, HSPA8, ALIX, and HSP90AB1 represent pan-EVP markers, while ACTB, MSN, and RAP1B are novel pan-EVP markers. To confirm that EVPs are ideal diagnostic tools, we analyzed proteomes of TE- (n =151) and plasma-derived (n =120) EVPs. Comparison of TE EVPs identified proteins (e.g., VCAN, TNC, and THBS2) that distinguish tumors from normal tissues with 90% sensitivity/94% specificity. Machine-learning classification of plasma-derived EVP cargo, including immunoglobulins, revealed 95% sensitivity/90% specificity in detecting cancer Finally, we defined a panel of tumor-type-specific EVP proteins in TEs and plasma, which can classify tumors of unknown primary origin. Thus, EVP proteins can serve as reliable biomarkers for cancer detection and determining cancer type.
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| 3. |
- Andel, B., et al.
(författare)
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β -delayed fission of isomers in Bi 188
- 2020
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Ingår i: Physical Review C. - 2469-9985. ; 102:1
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Tidskriftsartikel (refereegranskat)abstract
- β-delayed fission (βDF) decay of a low-spin (ls) and a high-spin (hs) isomer in Bi188 was studied at the ISOLDE facility at CERN. Isomer-selective laser ionization and time gating were employed to investigate each isomer separately and their βDF partial half-lives were determined: T1/2p,βDF(188Bihs)=5.6(8)×103 s and T1/2p,βDF(188Bils)=1.7(6)×103 s. This work is the first βDF study of two states in one isotope and allows the spin dependence of low-energy fission to be explored. The fission fragment mass distribution of a daughter nuclide Pb188, following the β decay of the high-spin isomer, was deduced and indicates a mixture of symmetric and asymmetric fission modes. Experimental results were compared with self-consistent mean-field calculations based on the finite-range Gogny D1M interaction. To reproduce the measured T1/2p,βDF(188Bihs), the calculated fission barrier of Pb188 had to be reduced by ≈30%. After this reduction, the measured T1/2p,βDF(188Bils) was in agreement with calculations for a few possible configurations for Bils188. Theoretical βDF probabilities for these configurations were found to be lower by a factor of 4-9 than the βDF probability of Bihs188. The fission fragment mass distribution of Pb188 was compared to the scission-point model SPY and the calculations based on the finite-range liquid-drop model. The first observation of βDF for Bi190 is also reported. © 2020 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
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| 4. |
- Rothe, S., et al.
(författare)
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Targets and ion sources at CERN-ISOLDE - Facilities and developments
- 2023
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Ingår i: Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions with Materials and Atoms. - 0168-583X. ; 542, s. 38-44
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Tidskriftsartikel (refereegranskat)abstract
- At the CERN-ISOLDE radioactive ion beam facility, thick targets are irradiated using a beam of 1.4-GeV protons. One of ISOLDE's key features is the large choice of ion source types and target materials available, enabling us to select the ideal combination for optimal intensity and purity of the isotopes requested by ISOLDE users. The ever-increasing demands in terms of isotope production yield, beam purity, and overall reliability of the employed systems are driving the continuous development efforts.Over the past few years, CERN has invested heavily in facilities and infrastructure that facilitate ongoing developments required for ISOLDE. A dedicated offline laboratory (Offline 2) has been recently equipped with high repetition rate nanosecond tunable lasers required for scheme development and developments of specialized laser ion source types such as VADLIS, LIST and PI-LIST. Moreover, it hosts a twin setup of the ISOLDE RFQ cooler and buncher (ISCOOL), which is envisaged to be used for studies of molecular beam creation and breakup, as well as the development of improved RFQ services and operational modes. For material development, particularly for nanostructured materials, the new nano laboratory has just been commissioned and will enable the production and development of nano actinide targets for ISOLDE. In this contribution we describe the infrastructure required for target and ion source developments, highlight recent efforts and experimental results on both target material development and ion source development, and provide an outlook on what to expect in the near future.
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| 5. |
- Udrescu, S. M., et al.
(författare)
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Precision spectroscopy and laser-cooling scheme of a radium-containing molecule
- 2024
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Ingår i: NATURE PHYSICS. - 1745-2473 .- 1745-2481.
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Tidskriftsartikel (refereegranskat)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.
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| 6. |
- Rodriguez, L. , V, et al.
(författare)
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Doubly-magic character of Sn-132 studied via electromagnetic moments of( 13)(3)Sn
- 2020
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Ingår i: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 102:5
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Tidskriftsartikel (refereegranskat)abstract
- We report the first measurement of the magnetic dipole and electric quadrupole moment of the exotic nucleus Sn-133 by high-resolution laser spectroscopy at ISOLDE/CERN. These, in combination with state-of-the-art shell-model calculations, demonstrate the single-particle character of the ground state of this short-lived isotope and, hence, the doubly-magic character of its immediate neighbor Sn-132. The trend of the electromagnetic moments along the N = 83 isotonic chain, now enriched with the values of tin, are discussed on the basis of realistic shell-model calculations.
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| 7. |
- Koszorús, Agota, et al.
(författare)
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Charge radii of exotic potassium isotopes challenge nuclear theory and the magic character of N = 32
- 2021
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Ingår i: Nature Physics. - : Springer Science and Business Media LLC. - 1745-2481 .- 1745-2473. ; 17:4, s. 439-443
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Tidskriftsartikel (refereegranskat)abstract
- Nuclear charge radii are sensitive probes of different aspects of the nucleon–nucleon interaction and the bulk properties of nuclear matter, providing a stringent test and challenge for nuclear theory. Experimental evidence suggested a new magic neutron number at N = 32 (refs. 1–3) in the calcium region, whereas the unexpectedly large increases in the charge radii4,5 open new questions about the evolution of nuclear size in neutron-rich systems. By combining the collinear resonance ionization spectroscopy method with β-decay detection, we were able to extend charge radii measurements of potassium isotopes beyond N = 32. Here we provide a charge radius measurement of 52K. It does not show a signature of magic behaviour at N = 32 in potassium. The results are interpreted with two state-of-the-art nuclear theories. The coupled cluster theory reproduces the odd–even variations in charge radii but not the notable increase beyond N = 28. This rise is well captured by Fayans nuclear density functional theory, which, however, overestimates the odd–even staggering effect in charge radii. These findings highlight our limited understanding of the nuclear size of neutron-rich systems, and expose problems that are present in some of the best current models of nuclear theory.
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| 8. |
- Urquiza-González, M., et al.
(författare)
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Benchmark evaluation for a single frequency continuous wave OPO seeded pulsed dye amplifier for high-resolution laser spectroscopy
- 2023
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9781510659032
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Konferensbidrag (refereegranskat)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.
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| 9. |
- Vernon, A. R., et al.
(författare)
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Nuclear moments of indium isotopes reveal abrupt change at magic number 82
- 2022
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 607:7918, s. 260-265
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Tidskriftsartikel (refereegranskat)abstract
- In spite of the high-density and strongly correlated nature of the atomic nucleus, experimental and theoretical evidence suggests that around particular ‘magic’ numbers of nucleons, nuclear properties are governed by a single unpaired nucleon1,2. A microscopic understanding of the extent of this behaviour and its evolution in neutron-rich nuclei remains an open question in nuclear physics3–5. The indium isotopes are considered a textbook example of this phenomenon6, in which the constancy of their electromagnetic properties indicated that a single unpaired proton hole can provide the identity of a complex many-nucleon system6,7. Here we present precision laser spectroscopy measurements performed to investigate the validity of this simple single-particle picture. Observation of an abrupt change in the dipole moment at N = 82 indicates that, whereas the single-particle picture indeed dominates at neutron magic number N = 82 (refs. 2,8), it does not for previously studied isotopes. To investigate the microscopic origin of these observations, our work provides a combined effort with developments in two complementary nuclear many-body methods: ab initio valence-space in-medium similarity renormalization group and density functional theory (DFT). We find that the inclusion of time-symmetry-breaking mean fields is essential for a correct description of nuclear magnetic properties, which were previously poorly constrained. These experimental and theoretical findings are key to understanding how seemingly simple single-particle phenomena naturally emerge from complex interactions among protons and neutrons. © 2022, The Author(s), under exclusive licence to Springer Nature Limited.
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| 10. |
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