12 results on '"Ghys, L."'
Search Results
2. α-decay branching ratio of 180Pt
- Author
-
Cubiss, JG, Harding, RD, Andreyev, AN, Althubiti, N, Andel, B, Antalic, S, Barzakh, AE, Cocolios, TE, Goodacre, TD, Farooq-Smith, GJ, Fedorov, DV, Fedosseev, VN, Gaffney, LP, Ghys, L, Huyse, M, Lynch, KM, Marsh, BA, Martinez Palenzuela, Y, Molkanov, PL, Rossel, RE, Rothe, S, Seliverstov, MD, Sels, S, Spagnoletti, P, Van Beveren, C, Van Duppen, P, Veinhard, M, Verstraelen, E, and Zadvornaya, A
- Abstract
ispartof: Physical Review C vol:101 issue:1 pages:014314-014314 status: published
- Published
- 2020
3. Inverse odd-even staggering in nuclear charge radii and possible octupole collectivity in 217,218,219At revealed by in-source laser spectroscopy
- Author
-
Barzakh, A. E., Cubiss, J. G., Andreyev, A. N., Seliverstov, M. D., Andel, B., Antalic, S., Ascher, P., Atanasov, D., Beck, D., Bieroifmmode nelse, J., Blaum, K., Borgmann, Ch., Breitenfeldt, M., Capponi, L., Cocolios, T. E., Day Goodacre, T., Derkx, X., De Witte, H., Elseviers, J., Fedorov, D. V., Fedosseev, V. N., Fritzsche, S., Gaffney, L. P., George, S., Ghys, L., Heßberger, F. P., Huyse, M., Imai, N., Kalaninová, Z., Kisler, D., Köster, U., Kowalska, M., Kreim, S., Lane, J. F. W., Liberati, V., Lunney, D., Lynch, K. M., Manea, V., Marsh, B. A., Mitsuoka, S., Molkanov, P. L., Nagame, Y., Neidherr, D., Nishio, K., Ota, S., Pauwels, D., Popescu, L., Radulov, D., Rapisarda, E., Revill, J. P., Rosenbusch, M., Rossel, R. E., Rothe, S., Sandhu, K., Schweikhard, L., Sels, S., Truesdale, V. L., Van Beveren, C., Van den Bergh, P., Van Duppen, P., Wakabayashi, Y., Wendt, K. D. A., Wienholtz, F., Whitmore, B. W., Wilson, G. L., Wolf, R. N., and Zuber, K.
- Subjects
Physics::Atomic Physics ,Präzisionsexperimente - Abteilung Blaum ,Nuclear Experiment - Abstract
© 2019 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. Hyperfine-structure parameters and isotope shifts for the 795-nm atomic transitions in At217,218,219 have been measured at CERN-ISOLDE, using the in-source resonance-ionization spectroscopy technique. Magnetic dipole and electric quadrupole moments, and changes in the nuclear mean-square charge radii, have been deduced. A large inverse odd-even staggering in radii, which may be associated with the presence of octupole collectivity, has been observed. Namely, the radius of the odd-odd isotope At218 has been found to be larger than the average of its even-N neighbors, At217,219. The discrepancy between the additivity-rule prediction and experimental data for the magnetic moment of At218 also supports the possible presence of octupole collectivity in the considered nuclei. ispartof: Physical Review C vol:99 issue:5 status: published
- Published
- 2019
4. Charge radii and electromagnetic moments of $^{195--211}\mathrm{At}$
- Author
-
Cubiss, JG, Barzakh, AE, Seliverstov, MD, Andreyev, AN, Andel, B, Antalic, S, Ascher, P, Atanasov, D, Beck, D, Bieroń, J, Blaum, K, Borgmann, C, Breitenfeldt, M, Capponi, L, Cocolios, TE, Day Goodacre, T, Derkx, X, De Witte, H, Elseviers, J, Fedorov, DV, Fedosseev, VN, Fritzsche, S, Gaffney, LP, George, S, Ghys, L, Heßberger, FP, Huyse, M, Imai, N, Kalaninová, Z, Kisler, D, Köster, U, Kowalska, M, Kreim, S, Lane, JFW, Liberati, V, Lunney, D, Lynch, KM, Manea, V, Marsh, BA, Mitsuoka, S, Molkanov, PL, Nagame, Y, Neidherr, D, Nishio, K, Ota, S, Pauwels, D, Popescu, L, Radulov, D, Rapisarda, E, Revill, JP, Rosenbusch, M, Rossel, RE, Rothe, S, Sandhu, K, Schweikhard, L, Sels, S, Truesdale, VL, Van Beveren, C, Van den Bergh, P, Wakabayashi, Y, Van Duppen, P, Wendt, KDA, Wienholtz, F, Whitmore, BW, Wilson, GL, Wolf, RN, and Zuber, K
- Subjects
Nuclear Experiment - Abstract
© 2018 authors. Hyperfine-structure parameters and isotope shifts of At195-211 have been measured for the first time at CERN-ISOLDE, using the in-source resonance-ionization spectroscopy method. The hyperfine structures of isotopes were recorded using a triad of experimental techniques for monitoring the photo-ion current. The Multi-Reflection Time-of-Flight Mass Spectrometer, in connection with a high-resolution electron multiplier, was used as an ion-counting setup for isotopes that either were affected by strong isobaric contamination or possessed a long half-life; the ISOLDE Faraday cups were used for cases with high-intensity beams; and the Windmill decay station was used for short-lived, predominantly α-decaying nuclei. The electromagnetic moments and changes in the mean-square charge radii of the astatine nuclei have been extracted from the measured hyperfine-structure constants and isotope shifts. This was only made possible by dedicated state-of-the-art large-scale atomic computations of the electronic factors and the specific mass shift of atomic transitions in astatine that are needed for these extractions. By comparison with systematics, it was possible to assess the reliability of the results of these calculations and their ascribed uncertainties. A strong deviation in the ground-state mean-square charge radii of the lightest astatine isotopes, from the trend of the (spherical) lead isotopes, is interpreted as the result of an onset of deformation. This behavior bears a resemblance to the deviation observed in the isotonic polonium isotopes. Cases for shape coexistence have been identified in At197,199, for which a significant difference in the charge radii for ground (9/2-) and isomeric (1/2+) states has been observed. ispartof: Physical Review C vol:97 issue:5 status: Published online
- Published
- 2018
5. In-source laser spectroscopy with the laser ion source and trap: first direct study of the ground-state properties of Po-217,Po-219
- Author
-
Fink, D.A., Cocolios, T.E., Andreyev, A. N., Antalic, S., Barzakh, A.E., Bastin, B., Fedorov, D.V., Fedosseev, V.N., Flanagan, K.T., Ghys, L., Gottberg, A., Wendt, K. D. A., SCOAP, Japan Atomic Energy Agency, Slovak Research and Development Agency, European Commission, Belgian Science Policy Office, Research Foundation - Flanders, Federal Ministry of Education and Research (Germany), and Science and Technology Facilities Council (UK)
- Subjects
Atomic and molecular physics ,Nuclear Physics - Abstract
D. A. Fink et al.; 15 págs.; 17 figs.; 3 tabs.; Open Access funded by Creative Commons Atribution Licence 3.0, A Laser Ion Source and Trap (LIST) for a thick-target, isotope-separation on-line facility has been implemented at CERN ISOLDE for the production of pure, laser-ionized, radioactive ion beams. It offers two modes of operation, either as an ion guide, which performs similarly to the standard ISOLDE resonance ionization laser ion source (RILIS), or as a more selective ion source, where surface-ionized ions from the hot ion-source cavity are repelled by an electrode, while laser ionization is done within a radiofrequency quadrupole ion guide. The first physics application of the LIST enables the suppression of francium contamination in ion beams of neutron-rich polonium isotopes at ISOLDE by more than 1000 with a reduction in laser-ionization efficiency of only 20. Resonance ionization spectroscopy is performed directly inside the LIST device, allowing the study of the hyperfine structure and isotope shift of 217Po for the first time. Nuclear decay spectroscopy of 219Po is performed for the first time, revealing its half-life, α- to-β-decay branching ratio, and α-particle energy. This experiment demonstrates the applicability of the LIST at radioactive ion-beam facilities for the production and study of pure beams of exotic isotopes. Published by the American Physical Society, This work was supported by the Bundesministerium für Bildung und Forschung (BMBF, Germany) within the Wolfgang- Gentner programme as well as through the consecutive project fundings of 06Mz9181I, 06Mz7177D, and 05P12UMCIA, by FWO-Vlaanderen (Belgium), by GOA/2010/010 (BOF-KULeuven), by the IUAP-Belgian State Belgian Science Policy (BRIX network P7/12), by the U.K. Science and Technology Facilities Council (STFC), by the European Union within FP7 (ENSAR No. 262010), by the Slovak Research and Development Agency (Contract No. APVV-0105-10), by the Slovak grant agency VEGA, and the Reimei Foundation of JAEA (Contract No. 1/0576/13). T. E. C. was supported by STFC Ernest Rutherford Grant No. ST/J004189/1.
- Published
- 2015
6. Empirical description of β-delayed fission partial half-lives.
- Author
-
Ghys, L., Andreyev, A. N., Antalic, S., Huyse, M., and Van Duppen, P.
- Subjects
- *
NUCLEAR fission , *THOMAS-Fermi model , *NUCLEAR liquid drop model , *NILSSON model , *NUCLEOSYNTHESIS - Abstract
Background: The process of β-delayed fission (βDF) provides a versatile tool to study low-energy fission in nuclei far away from the β-stability line, especially for nuclei which do not fission spontaneously. Purpose: The aim of this paper is to investigate systematic trends in βDF partial half-lives. Method: A semi-phenomenological framework was developed to systematically account for the behavior of βDF partial half-lives. Results: The βDF partial half-life appears to exponentially depend on the difference between the Q value for β decay of the parent nucleus and the fission-barrier energy of the daughter (after β decay) product. Such dependence was found to arise naturally from some simple theoretical considerations. Conclusions: This systematic trend was confirmed for experimental βDF partial half-lives spanning over seven orders of magnitude when using fission barriers calculated from either the Thomas-Fermi or the liquid-drop fission model. The same dependence was also observed, although less pronounced, when comparing to fission barriers from the finite-range liquid-drop model or the Thomas-Fermi plus Strutinsky integral method. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
7. Evolution of fission-fragment mass distributions in the neutron-deficient lead region.
- Author
-
Ghys, L., Andreyev, A. N., Huyse, M., Van Duppen, P., Sels, S., Andel, B., Antalic, S., Barzakh, A., Capponi, L., Cocolios, T. E., Derkx, X., De Witte, H., Elseviers, J., Fedorov, D. V., Fedosseev, V. N., Hessberger, F. P., Kalaninová, Z., Köster, U., Lane, J. F. W., and Liberati, V.
- Subjects
- *
NUCLEAR research , *NEUTRONS , *NUCLEAR reactors , *ACTINIDE elements , *RADIOACTIVE substances - Abstract
Low-energy β-delayed fission of 194,196At and 200,202Fr was studied in detail at the mass separator ISOLDE at CERN. The fission-fragment mass distributions of daughter nuclei 194,196Po and 202Rn indicate a triple-humped structure, marking the transition between asymmetric fission of 178,180Hg and symmetric fission in the light Ra-Rn nuclei. Comparison with the macroscopic-microscopic finite-range liquid-drop model and the self-consistent approach employing the Gogny D1S energy density functional yields discrepancies. This demonstrates once more the need for dynamical fission calculations, because for both models the potential-energy surfaces lack pronounced structures, in contrast to those for the actinide region. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
8. α-decay properties of 200,202Fr.
- Author
-
Ghys, L.
- Subjects
- *
NUCLEAR structure , *RADIOACTIVE nuclear beams , *ION beams , *MAGNITUDE (Mathematics) , *ISOMERISM , *FINE structure (Physics) - Abstract
Background: The neutron-deficient lead region provides a range of nuclear phenomena, including isomerism at low energies. This phenomenon can be studied by α decay because the degree of hindrance of α decay provides information on the change in nuclear structure of connected states. Purpose: The aim of this work was to investigate the α-decay properties of 200,202Fr and daughter products. Method: Neutron-deficient francium nuclei are produced at ISOLDE-CERN bombarding a UCx target with 1.4 GeV protons. Surface ionization and mass-separation techniques were employed to provide a pure radioactive ion beam at a radiation-detection setup. Results: Due to the very high statistics and the high beam purity, improved decay data for 202Fr and its daughters were obtained. In particular, this data set allowed us to identify many fine-structure α lines with a relative reduced α-decay width up to five orders of magnitude lower as the strongest ground-to-ground state or isomeric-to-isomeric state α-decay transition. In addition, several half-life values were extracted with similar or better precision as compared with the literature. Conclusions: The observation of crossover transitions positioned the isomeric high-spin level of 198At at an excitation energy of 265(3) keV. Half-life values of 4.47(5) s and 1.28(10) s were extracted for the ground state and isomeric state of 198At and 52(3) ms for the ground-state decay of 200Fr. Furthermore, α-decay schemes for 202Fr and its daughter 198At could be constructed. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
9. ß-delayed fission of 180T1.
- Author
-
Elseviers, J., Andreyev, A. N., Huyse, M., Van Duppen, P., Antalic, S., Barzakh, A., Bree, N., Cocolios, T. E., Comas, V. F., Diriken, J., Fedorov, D., Fedosseev, V. N., Franchoo, S., Ghys, L., Heredia, J. A., Ivanov, O., Köster, U., Marsh, B. A., Nishio, K., and Page, R. D.
- Subjects
- *
NUCLEAR fission , *NUCLEAR physics experiments , *IONIZATION (Atomic physics) , *KINETIC energy , *ISOTOPE separators , *RADIOACTIVE decay - Abstract
The detailed analysis of the ß-delayed fission data of 180T1 is presented. The experiment was performed by producing, a pure beam of 180T1 by means of highly selective resonance laser ionization followed by mass separation with the ISOLDE (CERN, Geneva) isotope separator. A surprising asymmetric mass distribution of fission fragments from 180Hg, the daughter of 180T1 ß decays, was observed. Here, the energy calibration of the silicon detectors, which is crucial for a proper determination of the fission fragments' energy and mass split, is presented and the total kinetic energy and its dependence on the mass split ratio is discussed. A more precise ß-delayed fission probability PßDF(I80T1) = 3.2(2) x 10-3% was deduced. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
10. β-delayed fission of 230Am.
- Author
-
Wilson, G. L., Takeyama, M., Andreyev, A. N., Andel, B., Antalic, S., Catford, W. N., Ghys, L., Haba, H., Heßberger, F. P., Huang, M., Kaji, D., Kalaninova, Z., Morimoto, K., Morita, K., Murakami, M., Nishio, K., Orlandi, R., Smith, A. G., Tanaka, K., and Wakabayashi, Y.
- Subjects
- *
AMERICIUM , *GAMMA decay , *NEUTRONS - Abstract
The exotic decay process of β-delayed fission (βDF) has been studied in the neutron-deficient isotope 230Am. The 230Am nuclei were produced in the complete fusion reaction 207Pb(27Al,4n)230Am and separated by using the GARIS gas-filled recoil ion separator. A lower limit for the βDF probability PβDF(230Am)>0.30 was deduced, which so far is the highest value among all known βDF nuclei. The systematics of βDF in the region of 230Am will be discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
11. Deformation versus Sphericity in the Ground States of the Lightest Gold Isotopes.
- Author
-
Cubiss JG, Andreyev AN, Barzakh AE, Van Duppen P, Hilaire S, Péru S, Goriely S, Al Monthery M, Althubiti NA, Andel B, Antalic S, Atanasov D, Blaum K, Cocolios TE, Day Goodacre T, de Roubin A, Farooq-Smith GJ, Fedorov DV, Fedosseev VN, Fink DA, Gaffney LP, Ghys L, Harding RD, Huyse M, Imai N, Joss DT, Kreim S, Lunney D, Lynch KM, Manea V, Marsh BA, Martinez Palenzuela Y, Molkanov PL, Neidherr D, O'Neill GG, Page RD, Prosnyak SD, Rosenbusch M, Rossel RE, Rothe S, Schweikhard L, Seliverstov MD, Sels S, Skripnikov LV, Stott A, Van Beveren C, Verstraelen E, Welker A, Wienholtz F, Wolf RN, and Zuber K
- Abstract
The changes in mean-squared charge radii of neutron-deficient gold nuclei have been determined using the in-source, resonance-ionization laser spectroscopy technique, at the ISOLDE facility (CERN). From these new data, nuclear deformations are inferred, revealing a competition between deformed and spherical configurations. The isotopes ^{180,181,182}Au are observed to possess well-deformed ground states and, when moving to lighter masses, a sudden transition to near-spherical shapes is seen in the extremely neutron-deficient nuclides, ^{176,177,179}Au. A case of shape coexistence and shape staggering is identified in ^{178}Au which has a ground and isomeric state with different deformations. These new data reveal a pattern in ground-state deformation unique to the gold isotopes, whereby, when moving from the heavy to light masses, a plateau of well-deformed isotopes exists around the neutron midshell, flanked by near-spherical shapes in the heavier and lighter isotopes-a trend hitherto unseen elsewhere in the nuclear chart. The experimental charge radii are compared to those from Hartree-Fock-Bogoliubov calculations using the D1M Gogny interaction and configuration mixing between states of different deformation. The calculations are constrained by the known spins, parities, and magnetic moments of the ground states in gold nuclei and show a good agreement with the experimental results.
- Published
- 2023
- Full Text
- View/download PDF
12. Laser Spectroscopy of Neutron-Rich ^{207,208}Hg Isotopes: Illuminating the Kink and Odd-Even Staggering in Charge Radii across the N=126 Shell Closure.
- Author
-
Day Goodacre T, Afanasjev AV, Barzakh AE, Marsh BA, Sels S, Ring P, Nakada H, Andreyev AN, Van Duppen P, Althubiti NA, Andel B, Atanasov D, Billowes J, Blaum K, Cocolios TE, Cubiss JG, Farooq-Smith GJ, Fedorov DV, Fedosseev VN, Flanagan KT, Gaffney LP, Ghys L, Huyse M, Kreim S, Lunney D, Lynch KM, Manea V, Martinez Palenzuela Y, Molkanov PL, Rosenbusch M, Rossel RE, Rothe S, Schweikhard L, Seliverstov MD, Spagnoletti P, Van Beveren C, Veinhard M, Verstraelen E, Welker A, Wendt K, Wienholtz F, Wolf RN, Zadvornaya A, and Zuber K
- Abstract
The mean-square charge radii of ^{207,208}Hg (Z=80, N=127, 128) have been studied for the first time and those of ^{202,203,206}Hg (N=122, 123, 126) remeasured by the application of in-source resonance-ionization laser spectroscopy at ISOLDE (CERN). The characteristic kink in the charge radii at the N=126 neutron shell closure has been revealed, providing the first information on its behavior below the Z=82 proton shell closure. A theoretical analysis has been performed within relativistic Hartree-Bogoliubov and nonrelativistic Hartree-Fock-Bogoliubov approaches, considering both the new mercury results and existing lead data. Contrary to previous interpretations, it is demonstrated that both the kink at N=126 and the odd-even staggering (OES) in its vicinity can be described predominately at the mean-field level and that pairing does not need to play a crucial role in their origin. A new OES mechanism is suggested, related to the staggering in the occupation of the different neutron orbitals in odd- and even-A nuclei, facilitated by particle-vibration coupling for odd-A nuclei.
- Published
- 2021
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.