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5 results on '"Iskra Łukasz W."'

1. Shape transition in the neutron-rich Y nuclei and its evolution across the isotopic chain

Author

Iskra Łukasz W., Fornal Bogdan, Leoni Silvia, Michelagnoli Caterina, Bottoni Simone, Cieplicka‒ Oryńczak Natalia, Jentschel Michael, Kandzia Felix, Kim Yung Hee, Köster Ulli, and Porzio Carlotta

Subjects
Physics, QC1-999
Abstract

The evolution of the deformation across the Y isotopic chain, in the vicinity of N = 60 boundary, has been studied using gamma spectroscopy methods. The nuclei of interest have been produced by neutron induced fission of 235U and 241Pu targets, during two experimental campaigns named EXILL and FIPPS at the Institute Laue-Langevin in Grenoble. The emitted gamma rays have been collected by HPGe and LaBr3 detectors providing the identification of the high-spin levels in the 94Y and 96Y isotopes up to 6 MeV excitation energy, as well as information about the half-lives of the in-band states in the 98Y nucleus. The obtained results shed new light on the onset of deformation in the neutron-rich Y isotopes and, in general, in the A ≈ 100 region.

Published
2019
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2. The γ-ray spectroscopy studies of low-spin structures in 210Bi and 206Tl using cold neutron capture reactions

Author

Cieplicka-Oryńczak Natalia, Leoni Silvia, Fornal Bogdan, Bazzacco Dino, Blanc Aurelien, Benzoni Giovanna, Bottoni Simone, Bracco Angela, Crespi Fabio C. L., de France Gilles, Iskra Łukasz W., Jentschel Michael, Köster Ulli, Michelagnoli Caterina, Mutti Paolo, Pietralla Norbert, Simpson Gary, Soldner Torsten, Ur Calin, Urban Waldemar, and Werner Volker

Subjects
Physics, QC1-999
Abstract

The γ-coincidence studies of low-spin structures of 210Bi and 206Tl are presented. The 210Bi nucleus, populated in thermal neutron capture reaction, was investigated using EXILL HPGe array at Institut Laue-Langevin in Grenoble. The experimental results were compared to the shell-model calculations allowing to draw the conclusions on the nature of the low-spin excitations populated below the neutron binding energy in 210Bi (4.6 MeV). It has been found that some levels cannot be described by the valence proton and neutron couplings, but may arise from couplings of valence particles to the 3- octupole phonon of the doubly magic 208Pb core. Moreover, preliminary results of a low-spin structure measurements of 206Tl by the γ-coincidence technique, making use of the 205Tl(n,γ)206Tl reaction at the FIPPS prompt γ-ray spectroscopy facility of ILL are shown. The population of a large number of excited states of 206Tl above the ground state up to the neutron binding energy (at 6.5 MeV), within a few units of spin is expected. The analysis involving double and triple γ-coincidences and γγ-angular correlations will allow to significantly extend the experimental information on the energy and spin-parity of the levels in 206Tl. This will help shedding light on the proton-hole and neutron-hole couplings near the doubly magic core 208Pb.

Published
2018
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3. Two-neutron and core-excited states in 210Pb: Tracing E3 collectivity and evidence for a new β-decaying isomer in 210Tl

Author

Broda, Rafał, Iskra, Łukasz W., Janssens, Robert V.F., Brown, B.A., Fornal, Bogdan, Wrzesiński, Jacek, Cieplicka-Oryńczak, Natalia, Carpenter, M.P., Chiara, C. J., Hoffman, C. R., Kondev, F. G., Lane, G. J., Lauritsen, T., Podolyák, Zs., Seweryniak, D., Walters, W. B., and Zhu, S.

Abstract

https://journals.aps.org/prc/abstract/10.1103/PhysRevC.98.024324, Yrast and near-yrast levels up to an I = 17¯h spin value and a 6-MeV excitation energy have been delineated in the “two-neutron” 210Pb nucleus following deep-inelastic reactions involving 208Pb targets and a number of heavy-ion beams at energies ∼25% above the Coulomb barrier. The level scheme was established on the basis of multifold prompt and delayed coincidence relationships measured with the Gammasphere array. In addition to the previously known states, many new levels were identified. For most of the strongly populated states, spin-parity assignments are proposed on the basis of angular distributions. The reinvestigation of the ν(g9/2 )2, 8+ isomeric decay results in the firm identification of the low-energy E2 transitions involved in the 8+ → 6+ → 4+ cascade, and in a revised 6+ level half-life of 92(10) ns, nearly a factor of 2 longer than previously measured. Among the newly identified states figure spin I = 4–10¯h levels associated with the νg9/2i11/2 multiplet, as well as yrast states involving νg9/2j15/2, νi11/2j15/2, and ν(j15/2 )2 neutron couplings. The highest-spin excitations are understood as 1p-1h core excitations and the yrast population is found to be fragmented to the extent that levels of spin higher than I = 17¯h could not be reached. Four E3 transitions are present in the 210Pb yrast decay; three of these involve the g9/2 → j15/2 octupole component, as reflected in the 21(2) and >10 Weisskopf unit enhancements of the B(E3) rates of the first two. The fourth, 16+ → 13− E3 transition corresponds to the 3− core octupole excitation built on the νi11/2j15/2 state, in analogy to a similar E3 coupling to the νj15/2 level in 209Pb. Shell-model calculations performed for two-neutron states and 1p-1h 208Pb core excitations are in good agreement with the data. Evidence was found for the existence of a hitherto unknown high-spin β- decaying isomer in 210Tl. Shell-model calculations of the 210Tl levels suggest the possibility of a 11+ long-lived, β-decaying state, and the delayed yields observed in various reactions fit rather well with a 210Tl assignment.

Published
2018

4. Shape transition in the neutron-rich Y nuclei and its evolution across the isotopic chain.

Author

de Angelis, G., Corradi, L., Iskra, Łukasz W., Fornal, Bogdan, Leoni, Silvia, Michelagnoli, Caterina, Bottoni, Simone, Cieplicka‒ Oryńczak, Natalia, Jentschel, Michael, Kandzia, Felix, Kim, Yung Hee, Köster, Ulli, and Porzio, Carlotta

Subjects
NEUTRONS, SPECTRUM analysis, NUCLEAR rotational states, NEUTRON beams, GAMMA rays
Abstract

The evolution of the deformation across the Y isotopic chain, in the vicinity of N = 60 boundary, has been studied using gamma spectroscopy methods. The nuclei of interest have been produced by neutron induced fission of 235U and 241Pu targets, during two experimental campaigns named EXILL and FIPPS at the Institute Laue-Langevin in Grenoble. The emitted gamma rays have been collected by HPGe and LaBr3 detectors providing the identification of the high-spin levels in the 94Y and 96Y isotopes up to 6 MeV excitation energy, as well as information about the half-lives of the in-band states in the 98Y nucleus. The obtained results shed new light on the onset of deformation in the neutron-rich Y isotopes and, in general, in the A ≈ 100 region. [ABSTRACT FROM AUTHOR]

Published
2019
Full Text
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5. The γ-ray spectroscopy studies of low-spin structures in 210Bi and 206Tl using cold neutron capture reactions.

Author

Köster, U., Cieplicka-Oryńczak, Natalia, Leoni, Silvia, Fornal, Bogdan, Bazzacco, Dino, Blanc, Aurelien, Benzoni, Giovanna, Bottoni, Simone, Bracco, Angela, Crespi, Fabio C. L., de France, Gilles, Iskra, Łukasz W., Jentschel, Michael, Köster, Ulli, Michelagnoli, Caterina, Mutti, Paolo, Pietralla, Norbert, Simpson, Gary, Soldner, Torsten, and Ur, Calin

Subjects
BISMUTH, NUCLEAR spin, COLD neutrons, BINDING energy, NEUTRON capture, THERMAL neutrons
Abstract

The γ-coincidence studies of low-spin structures of 210Bi and 206Tl are presented. The 210Bi nucleus, populated in thermal neutron capture reaction, was investigated using EXILL HPGe array at Institut Laue-Langevin in Grenoble. The experimental results were compared to the shell-model calculations allowing to draw the conclusions on the nature of the low-spin excitations populated below the neutron binding energy in 210Bi (4.6 MeV). It has been found that some levels cannot be described by the valence proton and neutron couplings, but may arise from couplings of valence particles to the 3- octupole phonon of the doubly magic 208Pb core. Moreover, preliminary results of a low-spin structure measurements of 206Tl by the γ-coincidence technique, making use of the 205Tl(n,γ)206Tl reaction at the FIPPS prompt γ-ray spectroscopy facility of ILL are shown. The population of a large number of excited states of 206Tl above the ground state up to the neutron binding energy (at 6.5 MeV), within a few units of spin is expected. The analysis involving double and triple γ-coincidences and γγ-angular correlations will allow to significantly extend the experimental information on the energy and spin-parity of the levels in 206Tl. This will help shedding light on the proton-hole and neutron-hole couplings near the doubly magic core 208Pb. [ABSTRACT FROM AUTHOR]

Published
2018

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