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1. The mutable nature of particle-core excitations with spin in the one-valence-proton nucleus 133Sb

Author

G. Bocchi, S. Leoni, B. Fornal, G. Colò, P.F. Bortignon, S. Bottoni, A. Bracco, C. Michelagnoli, D. Bazzacco, A. Blanc, G. de France, M. Jentschel, U. Köster, P. Mutti, J.-M. Régis, G. Simpson, T. Soldner, C.A. Ur, W. Urban, L.M. Fraile, R. Lozeva, B. Belvito, G. Benzoni, A. Bruce, R. Carroll, N. Cieplicka-Oryǹczak, F.C.L. Crespi, F. Didierjean, J. Jolie, W. Korten, T. Kröll, S. Lalkovski, H. Mach, N. Mărginean, B. Melon, D. Mengoni, B. Million, A. Nannini, D. Napoli, B. Olaizola, V. Paziy, Zs. Podolyák, P.H. Regan, N. Saed-Samii, B. Szpak, and V. Vedia

Subjects
Neutron induced fission, Gamma spectroscopy, Nuclear state lifetime, Large Ge array, Particle-core couplings, Physics, QC1-999
Abstract

The γ-ray decay of excited states of the one-valence-proton nucleus 133Sb has been studied using cold-neutron induced fission of 235U and 241Pu targets, during the EXILL campaign at the ILL reactor in Grenoble. By using a highly efficient HPGe array, coincidences between γ-rays prompt with the fission event and those delayed up to several tens of microseconds were investigated, allowing to observe, for the first time, high-spin excited states above the 16.6 μs isomer. Lifetimes analysis, performed by fast-timing techniques with LaBr3(Ce) scintillators, revealed a difference of almost two orders of magnitude in B(M1) strength for transitions between positive-parity medium-spin yrast states. The data are interpreted by a newly developed microscopic model which takes into account couplings between core excitations (both collective and non-collective) of the doubly magic nucleus 132Sn and the valence proton, using the Skyrme effective interaction in a consistent way. The results point to a fast change in the nature of particle-core excitations with increasing spin.

Published
2016
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2. Low-spin states in Ge80 populated in the β decay of the Ga80 3− isomer

Author

M. Rudigier, Brian Bucher, B. Olaizola, Z. Meliani, G. S. Simpson, R. Lica, L. M. Fraile, S. Sekal, José Antonio Briz, Ioana Gheorghe, D. Ghiţă, W. B. Walters, L. Stroe, Henryk Mach, V. Paziy, J. Jolie, T. Sava, Ulli Köster, C. Benchouk, W. Kurcewicz, Z. Dlouhý, J.-M. Régis, M. J. G. Borge, N. Marginean, C. J. Chiara, M. Stanoiu, P. Hoff, Ani Aprahamian, C. Bernards, and R. Mărginean

Subjects
Physics, Spin states, 010308 nuclear & particles physics, 0103 physical sciences, Atomic physics, 010306 general physics, 01 natural sciences
Published
2021
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3. Lifetime measurements in the odd−A nucleus Hf177

Author

G. Häfner, W. Korten, L. M. Fraile, N. Saed-Samii, A. Esmaylzadeh, Gheorghe Pascovici, Paolo Mutti, J. F. Smith, Zs. Podolyák, W. Urban, Torsten Soldner, Aurelien Blanc, G. S. Simpson, N. Warr, V. Paziy, Ulli Köster, V. Karayonchev, Michael Jentschel, C. A. Ur, C. Townsley, S. Ilieva, Henryk Mach, J. Jolie, A. Vancraeyenest, N. Mǎrginean, L. Knafla, G. Thiamova, Alison Bruce, S. Leoni, J.-M. Régis, S. Lalkovski, P. H. Regan, Petr Alexa, Oliver J. Roberts, and T. Kröll

Subjects
Physics, medicine.anatomical_structure, Spectrometer, 010308 nuclear & particles physics, 0103 physical sciences, Rare earth, Nuclear structure, medicine, Atomic physics, Nanosecond, 010306 general physics, 01 natural sciences, Nucleus
Abstract

Lifetimes of low- and high-spin states in the odd-A nucleus Hf-177 were measured during the EXILL&FATIMA campaign using a spectrometer equipped with eight HPGe-Clover detectors and 16 fast-timing LaBr3(Ce) detectors. For the determination of lifetimes in the pico- to nanosecond regime, the well-established generalized centroid difference method was used. Lifetimes of the 9/2(-), 9/2(+), 11/2(-), 11/2(+) states were remeasured, the lifetimes of the 13/2(-), 17/2(-), 13/2(+), 15/2(+), and 17/2(+) states were determined for the first time and an upper limit for the 19/2(+) state has been established. From these lifetimes absolute reduced transition probabilities were extracted and compared to particle-rotor-model calculations and quasiparticle-phonon-model calculations showing the importance of including multipole-multipole interactions in the description of odd-A nuclei in the rare earth region.

Published
2020
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4. Fast-timing study of Ga81 from the β decay of Zn81

Author

V. Paziy, L. M. Fraile, H. Mach, B. Olaizola, G. S. Simpson, A. Aprahamian, C. Bernards, J. A. Briz, B. Bucher, C. J. Chiara, Z. Dlouhý, I. Gheorghe, D. Ghiţǎ, P. Hoff, J. Jolie, U. Köster, W. Kurcewicz, R. Licǎ, N. Mǎrginean, R. Mǎrginean, J.-M. Régis, M. Rudigier, T. Sava, M. Stǎnoiu, L. Stroe, and W. B. Walters

Subjects
Physics, Decay scheme, Valence (chemistry), Neutron emission, Astrophysics::High Energy Astrophysical Phenomena, Excited state, Neutron, Gamma spectroscopy, MAGIC (telescope), Atomic physics, 7. Clean energy, Beta decay
Abstract

The beta-decay of Zn-81 to the neutron magic N = 50 nucleus Ga-81, with only three valence protons with respect to Ni-78, was investigated. The study was performed at the ISOLDE facility at CERN by means of gamma spectroscopy. The 81Zn half-life was determined to be T-1/2 = 290(4) ms while the beta-delayed neutron emission probability was measured as P-n = 23(4)%. The analysis of the beta-gated gamma-ray singles and gamma-gamma coincidences from the decay of Zn-81 provides 47 new levels and 70 new transitions in Ga-81. The beta(-)n decay of Zn-81 was observed and a new decay scheme into the odd-odd Ga-80 nucleus was established. The half-lives of the first and second excited states of Ga-81 were measured via the fast-timing method using LaBr3(Ce) detectors. The level scheme and transition rates are compared to large-scale shell-model calculations. The low-lying structure of (81)Gais interpreted in terms of the coupling of the three valence protons outside the doubly magic Ni-78 core.

Published
2020
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6. Low- Z boundary of the N=88 –90 shape phase transition: Ce148 near the critical point

Author

Tamara Nikšić, Zs. Podolyák, V. Werner, E. Wilson, P. H. Regan, N. Marginean, Petr Alexa, W. Korten, D. Wilmsen, Ulli Köster, Paolo Mutti, S. Lalkovski, C. Bernards, N. Cooper, Torsten Soldner, C. A. Ur, Oliver J. Roberts, Dario Vretenar, Aurelien Blanc, P. Koseoglou, V. Paziy, T. Kröll, Norbert Pietralla, Michael Jentschel, Zena Patel, M. Thürauf, L. M. Fraile, N. Saed-Samii, Alison Bruce, S. Ilieva, W. Urban, Henryk Mach, J. Jolie, G. S. Simpson, R. B. Cakirli, and J.-M. Régis

Subjects
Physics, Phase transition, 010308 nuclear & particles physics, Fission, Nuclear structure, 7. Clean energy, 01 natural sciences, Coincidence, medicine.anatomical_structure, 13. Climate action, Critical point (thermodynamics), Excited state, 0103 physical sciences, medicine, Atomic physics, 010306 general physics, Spectroscopy, Nucleus
Abstract

Excited states of the neutron-rich nucleus 148Ce have been populated by neutron-induced fission of 235U and 241Pu samples. Their electromagnetic decays were studied by means of γ-ray coincidence spectroscopy with fast-timing capabilities. Lifetimes of the 2+1 and 4+1 states of 148Ce were obtained and their E2 decay rates deduced. The B4=2 = B(E2; 4+1 → 2+1)=B(E2; 2+1 → 0+1) ratio indicates that 148Ce is a transitional nucleus while the N = 88/90 shape phase transition evolves into a gradual change of nuclear deformation for proton numbers Z < 60.

Published
2020
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7. The mutable nature of particle-core excitations with spin in the one-valence-proton nucleus 133Sb

Author

B. Fornal, Alison Bruce, G. Benzoni, W. Korten, Raymond J. Carroll, R. Lozeva, Zs. Podolyák, G. Bocchi, A. Nannini, D. R. Napoli, B. Olaizola, Henryk Mach, J. Jolie, D. Mengoni, G. S. Simpson, V. Vedia, D. Bazzacco, Michael Jentschel, F. Didierjean, B. Belvito, N. Saed-Samii, C. A. Ur, N. Cieplicka-Oryǹczak, B. Melon, W. Urban, J.-M. Régis, Torsten Soldner, P. H. Regan, N. Marginean, F. C. L. Crespi, V. Paziy, L. M. Fraile, C. Michelagnoli, B. Szpak, B. Million, T. Kröll, Aurelien Blanc, P. Mutti, A. Bracco, Ulli Köster, Pier Francesco Bortignon, S. Leoni, Gianluca Colò, S. Bottoni, S. Lalkovski, Grand Accélérateur National d'Ions Lourds (GANIL), Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Institut Laue-Langevin (ILL), ILL, Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg (UNISTRA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Département de Physique Nucléaire (ex SPhN) (DPHN), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Nuclear and High Energy Physics, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], Nuclear Theory, Large Ge array, Fission, Neutron induced fission, FOS: Physical sciences, Scintillator, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Nuclear physics, Nuclear Theory (nucl-th), Gamma spectroscopy, Nuclear state lifetime, Particle-core couplings, 0103 physical sciences, medicine, Nuclear Experiment (nucl-ex), 010306 general physics, Nuclear Experiment, Physics, Valence (chemistry), 010308 nuclear & particles physics, Yrast, lcsh:QC1-999, medicine.anatomical_structure, Excited state, Física nuclear, Atomic physics, Nucleus, Order of magnitude, lcsh:Physics
Abstract

The gamma-ray decay of excited states of the one-valence-proton nucleus Sb-133 has been studied using cold-neutron induced fission of U-235 and Pu-241 targets, during the EXILL campaign at the ILL reactor in Grenoble. By using a highly efficient HPGe array, coincidences between gamma-rays prompt with the fission event and those delayed up to several tens of microseconds were investigated, allowing to observe, for the first time, high-spin excited states above the 16.6 mu s isomer. Lifetimes analysis, performed by fast-timing techniques with LaBr3(Ce) scintillators, revealed a difference of almost two orders of magnitude in B(M1) strength for transitions between positive-parity medium-spin yrast states. The data are interpreted by a newly developed microscopic model which takes into account couplings between core excitations (both collective and non-collective) of the doubly magic nucleus Sn-132 and the valence proton, using Skyrme effective interaction in a consistent way. The results point to a fast change in the nature of particle-core excitations with increasing spin. (C) 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license.

Published
2016
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8. Lifetimes and shape-coexisting states of $^{99}Zr$

Author

J. F. Smith, N. Saed-Samii, R. Lica, G. S. Simpson, V. Werner, L. M. Fraile, C. Bernards, W. Korten, S. Lalkovski, P. H. Regan, T. Kröll, N. Marginean, A. Vancraeyenest, Torsten Soldner, Paolo Mutti, P. Spagnoletti, V. Paziy, F. Drouet, C. Townsley, Marcus Scheck, Liam Gaffney, Henryk Mach, J. Jolie, G Thiamova, M. Zielińska, J.-M. Régis, C. A. Ur, N. Warr, S. Ilieva, Michael Jentschel, S. Kisyov, W. Urban, Aurelien Blanc, Zs. Podolyák, Ulli Köster, D. Ghita, Alison Bruce, C. Larijarni, D. Bucurescu, V. Vedia, Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Institut Laue-Langevin (ILL), ILL, Grand Accélérateur National d'Ions Lourds (GANIL), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), and Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])

Subjects
Physics, 010308 nuclear & particles physics, Fission, Nuclear structure, Shell (structure), Deformation (meteorology), [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Structure, 01 natural sciences, medicine.anatomical_structure, Beamline, Excited state, 0103 physical sciences, Quadrupole, medicine, Física nuclear, Nuclear Physics - Experiment, Atomic physics, 010306 general physics, Nucleus
Abstract

Lifetimes of intermediate-spin states in two rotational bands of 99Zr have been measured. These states were populated following the neutron-induced fission of 235U at the PF1B beamline of the Institut Laue-Langevin, Grenoble, during the EXILL-FATIMA campaign. The nucleus 99Zr59 exhibits shape coexistence and lies precisely on the border of an abrupt change in ground-state deformation when going from N=58 to N=60, making its study interesting for understanding the mechanisms involved in the rapid onset of deformation here. The B(E2) values extracted for decays in the ν3/2[541] band allow quadrupole deformations of β2=0.34(1) and 0.26(3) to be determined for the 821.6- and 1236.6-keV members, whereas β2=0.32(3) was found for the 850.5-keV member of the ν3/2[411]band. Some of the excited states known in 99Zr have been reasonably described with interacting boson-fermion model (IBFM) calculations. Type-II shell evolution is proposed to play a major role in modifying single-particle energies in 99Zr.

Published
2019
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9. The boundary of the N=90 shape phase transition: 148Ce

Author

P. Koseoglou, V. Werner, N. Pietralla, S. Ilieva, M. Thürauf, C. Bernards, A. Blanc, A. M. Bruce, R. B. Cakirli, N. Cooper, L. M. Fraile, G. de France, M. Jentschel, J. Jolie, U. Koester, W. Korten, T. Kröll, S. Lalkovski, H. Mach, N. Mărginean, P. Mutti, Z. Patel, V. Paziy, Z. Podolyák, P. H. Regan, J.-M. Régis, O. J. Roberts, N. Saed-Samii, G. S. Simpson, T. Soldner, C. A. Ur, W. Urban, D. Wilmsen, E. Wilson, Institut Laue-Langevin (ILL), ILL, Grand Accélérateur National d'Ions Lourds (GANIL), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), and Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])

Subjects
Physics, History, Phase transition, Spectrometer, 010308 nuclear & particles physics, Fission, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Computer Science Applications, Education, Semiconductor detector, Critical point (thermodynamics), Picosecond, 0103 physical sciences, Atomic nucleus, ddc:530, Física nuclear, Interacting boson model, Atomic physics, 010306 general physics, Nuclear Experiment
Abstract

Journal of physics / Conference Series Conference Series 1023, 012022 - (2018). doi:10.1088/1742-6596/1023/1/012022, Published by IOP Publ., Bristol

Published
2018
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10. Experimental study of the lifetime and phase transition in neutron-rich Zr98,100,102

Author

O. Stezowski, Tomoaki Togashi, S. Ansari, F. Drouet, N. Saed-Samii, G. S. Simpson, E. Wilson, S. Ilieva, C. A. Ur, W. Korten, V. Paziy, M. D. Salsac, C. Townsley, A. Vancraeyenest, L. M. Fraile, Marcus Scheck, Paolo Mutti, Emyr Clement, B. Olaizola, Henryk Mach, J. Jolie, J.-M. Régis, J. F. Smith, V. Vedia, Oliver J. Roberts, M. Zielińska, Raymond J. Carroll, Zs. Podolyák, W. Urban, Takaharu Otsuka, A. Ignatov, S. Lalkovski, P. H. Regan, N. Marginean, T. Soldner, C. Larijani, Alison Bruce, Yusuke Tsunoda, A.-L. Hartig, T. Kröll, Noritaka Shimizu, Aurelien Blanc, Ulli Köster, N. Warr, and Michael Jentschel

Subjects
Physics, Phase transition, 010308 nuclear & particles physics, Fission, Context (language use), Neutron radiation, 01 natural sciences, 7. Clean energy, Excited state, 0103 physical sciences, Neutron, Atomic physics, Interacting boson model, Nuclear Experiment, 010306 general physics, Line (formation)
Abstract

Rapid shape changes are observed for neutron-rich nuclei with A around 100. In particular, a sudden onset of ground-state deformation is observed in the Zr and Sr isotopic chains at N = 60: Low-lying states in $N\ensuremath{\le}58$ nuclei are nearly spherical, while those with $N\ensuremath{\ge}60$ have a rotational character. Nuclear lifetimes as short as a few picoseconds can be measured using fast-timing techniques with ${\mathrm{LaBr}}_{3}$(Ce) scintillators, yielding a key ingredient in the systematic study of the shape evolution in this region. We used neutron-induced fission of $^{241}\mathrm{Pu}$ and $^{235}\mathrm{U}$ to study lifetimes of excited states in fission fragments in the $A\ensuremath{\sim}100$ region with the EXILL-FATIMA array located at the PF1B cold neutron beam line at the Institut Laue-Langevin. In particular, we applied the generalized centroid difference method to deduce lifetimes of low-lying states for the nuclei $^{98}\mathrm{Zr}$ (N = 58), $^{100}\mathrm{Zr}$, and $^{102}\mathrm{Zr}$ ($N\ensuremath{\ge}60$). The results are discussed in the context of the presumed phase transition in the Zr chain by comparing the experimental transition strengths with the theoretical calculations using the interacting boson model and the Monte Carlo shell model.

Published
2017
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11. Search for the Ga73 ground-state doublet splitting in the β decay of Zn73

Author

W. B. Walters, R. Lica, G. S. Simpson, P. Hoff, J.-M. Régis, L. M. Fraile, Ani Aprahamian, Z. Dlouhý, W. Kurcewicz, Ulli Köster, Brian Bucher, L. Stroe, V. Vedia, José Antonio Briz, T. Sava, M. Rudigier, R. Mărginean, Henryk Mach, J. Jolie, N. Marginean, C. J. Chiara, V. Paziy, C. Bernards, B. Olaizola, M. Stanoiu, D. Ghiţă, and Ioana Gheorghe

Subjects
Physics, Work (thermodynamics), Large Hadron Collider, 010308 nuclear & particles physics, New energy, Coulomb excitation, State (functional analysis), 01 natural sciences, Excited state, 0103 physical sciences, Atomic physics, 010306 general physics, Ground state, Spectroscopy
Abstract

The existence of two close-lying nuclear states in ⁷³Ga has recently been experimentally determined: a 1/2⁻ spin-parity for the ground state was measured in a laser spectroscopy experiment, while a J_π = 3/2⁻ level was observed in transfer reactions. This scenario is supported by Coulomb excitation studies, which set a limit for the energy splitting of 0.8 keV. In this work, we report on the study of the excited structure of ⁷³Ga populated in the β decay of ⁷³Zn produced at ISOLDE, CERN. Using β-gated, γ-ray singles, and γ –γ coincidences, we have searched for energy differences to try to delimit the ground-state energy splitting, providing a more stringent energy difference limit. Three new half-lives of excited states in ⁷³Ga have been measured using the fast-timing ;method with LaBr₃(Ce) detectors. From our study, we help clarify the excited structure of ⁷³G and we extend the existing ⁷³Zn decay to ⁷³Ga with 8 new energy levels and 35 γ transitions. We observe a 195-keV transition consistent with a γ ray de-exciting a short-lived state in the β-decay parent ⁷³Zn.

Published
2017
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12. Erratum: Abrupt shape transition at neutron number N=60 : B(E2) values in Sr94,96,98 from fast γ−γ timing [Phys. Rev. C 95 , 054319 (2017)]

Author

J.-M. Régis, J. Jolie, N. Saed-Samii, N. Warr, M. Pfeiffer, A. Blanc, M. Jentschel, U. Köster, P. Mutti, T. Soldner, G. S. Simpson, F. Drouet, A. Vancraeyenest, G. de France, E. Clément, O. Stezowski, C. A. Ur, W. Urban, P. H. Regan, Zs. Podolyák, C. Larijani, C. Townsley, R. Carroll, E. Wilson, L. M. Fraile, H. Mach, V. Paziy, B. Olaizola, V. Vedia, A. M. Bruce, O. J. Roberts, J. F. Smith, M. Scheck, T. Kröll, A.-L. Hartig, A. Ignatov, S. Ilieva, S. Lalkovski, W. Korten, N. Mărginean, T. Otsuka, N. Shimizu, T. Togashi, and Y. Tsunoda

Subjects
Physics, Neutron number, Atomic physics
Published
2017
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13. Abrupt shape transition at neutron number N=60 : B(E2) values in Sr94,96,98 from fast γ−γ timing

Author

J.-M. Régis, J. Jolie, N. Saed-Samii, N. Warr, M. Pfeiffer, A. Blanc, M. Jentschel, U. Köster, P. Mutti, T. Soldner, G. S. Simpson, F. Drouet, A. Vancraeyenest, G. de France, E. Clément, O. Stezowski, C. A. Ur, W. Urban, P. H. Regan, Zs. Podolyák, C. Larijani, C. Townsley, R. Carroll, E. Wilson, L. M. Fraile, H. Mach, V. Paziy, B. Olaizola, V. Vedia, A. M. Bruce, O. J. Roberts, J. F. Smith, M. Scheck, T. Kröll, A.-L. Hartig, A. Ignatov, S. Ilieva, S. Lalkovski, W. Korten, N. Mărginean, T. Otsuka, N. Shimizu, T. Togashi, and Y. Tsunoda

Subjects
Physics, Fission products, Proton, Isotope, 010308 nuclear & particles physics, Fission, Yrast, Nuclear Theory, Monte Carlo method, 7. Clean energy, 01 natural sciences, Nuclear physics, 13. Climate action, Neutron number, 0103 physical sciences, Neutron, Atomic physics, Nuclear Experiment, 010306 general physics
Abstract

Lifetimes of low-lying yrast states in neutron-rich 94,96,98Sr have been measured by Germanium-gated γ−γ fast timing with LaBr3(Ce) detectors using the EXILL&FATIMA spectrometer at the Institut Laue-Langevin. Sr fission products were generated using cold-neutron-induced fission of 235U and stopped almost instantaneously within the thick target. The experimental B(E2) values are compared with results of Monte Carlo shell-model calculations made without truncation on the occupation numbers of the orbits spanned by eight proton and eight neutron orbits and show good agreement. Similarly to the Zr isotopes, the abrupt shape transition in the Sr isotopes near neutron number N=60 is identified as being caused by many-proton excitations to its g9/2 orbit.

Published
2017
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14. Publisher's Note: Half-life of the 15/2+ state of I135 : A test of E2 seniority relations [Phys. Rev. C 95 , 021302(R) (2017)]

Author

W. Korten, V. Vedia, T. Soldner, T. Kroell, Henryk Mach, J. Jolie, U. Koester, Paolo Mutti, P. Spagnoletti, W. Urban, S. Lalkovski, P. H. Regan, N. Marginean, G. S. Simpson, J.-M. Régis, R. Lica, A. Gargano, G. Thiamova, S. Ilieva, Michael Jentschel, L. M. Fraile, A. Vancraeyenest, P. Van Isacker, N. Saed-Samii, Liam Gaffney, Marcus Scheck, Raymond J. Carroll, C. A. Ur, Zs. Podolyák, D. Ghita, C. Townsley, Alison Bruce, V. Paziy, C. Larijani, Aurelien Blanc, and F. Drouet

Subjects
Physics, Seniority, State (functional analysis), Test (assessment), Mathematical physics
Published
2017
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15. Half-life of the15/2+state ofI135: A test ofE2seniority relations

Author

P. Spagnoletti, G. S. Simpson, R. Carroll, J.-M. Régis, A. Blanc, M. Jentschel, U. Köster, P. Mutti, T. Soldner, G. de France, C. A. Ur, W. Urban, A. M. Bruce, F. Drouet, L. M. Fraile, L. P. Gaffney, D. G. Ghită, S. Ilieva, J. Jolie, W. Korten, T. Kröll, C. Larijarni, S. Lalkovski, R. Lică, H. Mach, N. Mărginean, V. Paziy, Zs. Podolyák, P. H. Regan, M. Scheck, N. Saed-Samii, G. Thiamova, C. Townsley, A. Vancraeyenest, V. Vedia, A. Gargano, and P. Van Isacker

Subjects
Physics, 010308 nuclear & particles physics, Component (thermodynamics), Fission, Operator (physics), Half-life, Value (computer science), State (functional analysis), 7. Clean energy, 01 natural sciences, Nuclear physics, medicine.anatomical_structure, 0103 physical sciences, medicine, Seniority, Atomic physics, 010306 general physics, Nucleus
Abstract

The half-life of the 15/2+ 1 state of the 3-valence-proton nucleus 135I has been measured to be 1.74(8) ns using the EXILL-FATIMA mixed array of Ge and LaBr3 detectors. The nuclei were produced following the cold neutron-induced fission of a 235U target at the PF1B beam line of the Institut Laue-Langevin. The extracted B(E2; 15/2+ → 11/2+) value enabled a test of seniority relations for the first time between E2 transition rates. Large-scale shell-model calculations were performed for 134Te and 135I, and reinterpreted in a single-orbit approach. The results show that the two-body component of the E2 operator can be large whereas energy shifts due to the three-body component of the effective interaction are small.

Published
2017
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16. Fast timing study of a CeBr3 crystal: Time resolution below 120ps at 60Co energies

Author

Jose Manuel Udias, E. Picado, L. M. Fraile, V. Vedia, B. Olaizola, V. Paziy, and Henryk Mach

Subjects
Physics, Nuclear and High Energy Physics, Photomultiplier, business.industry, Resolution (electron density), Detector, Constant fraction discriminator, Scintillator, Particle detector, Full width at half maximum, Optics, Scintillation counter, business, Instrumentation
Abstract

We report on the time response of a novel inorganic scintillator, CeBr3. The measurements were performed using a cylindrical crystal of 1-in. in height and 1-in. in diameter at 22Na and 60Co photon energies. The time response was measured against a fast reference BaF2 detector. Hamamatsu R9779 and Photonis XP20D0 fast photomultipliers (PMTs) were used. The PMT bias voltages and Constant Fraction Discriminator settings were optimized with respect to the timing resolution. The Full Width at Half Maximum (FWHM) time resolution for an individual CeBr3 crystal coupled to Hamamatsu PMT is found here to be as low as 119 ps at 60Co energies, which is comparable to the resolution of 107 ps reported for LaBr3(Ce). For 511 keV photons the measured FWHM time resolution for CeBr3 coupled to the Hamamatsu PMT is 164 ps.

Published
2013
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17. Measurement of picosecond lifetimes in neutron-rich Xe isotopes

Author

S. Ilieva, Th. Kröll, J.-M. Régis, N. Saed-Samii, A. Blanc, A. M. Bruce, L. M. Fraile, G. de France, A.-L. Hartig, C. Henrich, A. Ignatov, M. Jentschel, J. Jolie, W. Korten, U. Köster, S. Lalkovski, R. Lozeva, H. Mach, N. Mărginean, P. Mutti, V. Paziy, P. H. Regan, G. S. Simpson, T. Soldner, M. Thürauf, C. A. Ur, W. Urban, N. Warr, Institut Laue-Langevin (ILL), ILL, Grand Accélérateur National d'Ions Lourds (GANIL), Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg (UNISTRA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Isotope, 010308 nuclear & particles physics, Fission, Nuclear Theory, chemistry.chemical_element, Scintillator, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Nuclear physics, Xenon, chemistry, Neutron number, Excited state, 0103 physical sciences, Quadrupole, Neutron, Física nuclear, Atomic physics, 010306 general physics, Nuclear Experiment
Abstract

EXILL&FATIMA campaign; International audience; Background: Lifetimes of nuclear excited states in fission fragments have been studied in the past followingisotope separation, thus giving access mainly to the fragments’ daughters and only to long-lived isomeric statesin the primary fragments. For the first time now, short-lived excited states in the primary fragments, producedin neutron-induced prompt fission of 235U and 241Pu, were studied within the EXILL&FATIMA campaign at theintense neutron-beam facility of the Institute Laue-Langevin in Grenoble.Purpose: We aim to investigate the quadrupole collective properties of neutron-rich even-even 138,140,142Xeisotopes lying between the double shell closure N = 82 and Z = 50 and a deformed region with octupolecollectivity.Method: The γ rays emitted from the excited fragments were detected with a mixed array consisting of 8 HPGeEXOGAM Clover detectors (EXILL) and 16 LaBr3(Ce) fast scintillators (FATIMA). The detector system hasthe unique ability to select the interesting fragment making use of the high resolution of the HPGe detectorsand determine subnanosecond lifetimes using the fast scintillators. For the analysis the generalized centroiddifference method was used.Results: We show that quadrupole collectivity increases smoothly with increasing neutron number above theclosed N = 82 neutron shell. Our measurements are complemented by state-of-the-art theory calculations basedon shell-model descriptions.Conclusions: The observed smooth increase in quadrupole collectivity is similar to the evolution seen in themeasured masses of the xenon isotopic chain and is well reproduced by theory. This behavior is in contrast tohigher Z even-even nuclei where abrupt change in deformation occurs around N = 90.

Published
2016
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18. Lifetime measurement in neutron-rich A~100 nuclei

Author

Oliver J. Roberts, L. M. Fraile, W. Korten, Takaharu Otsuka, E. Wilson, N. Warr, O. Stezowski, M. Zielińska, Aurelien Blanc, Ulli Köster, F. Drouet, Tomoaki Togashi, W. Urban, Paolo Mutti, Torsten Soldner, S. Ansari, J.-M. Régis, Michael Jentschel, Yusuke Tsunoda, T. Kröll, N. Saed-Samii, C. A. Ur, S. Ilieva, V. Paziy, Noritaka Shimizu, C. Townsley, Henryk Mach, J. Jolie, G. S. Simpson, A.-L. Hartig, J. F. Smith, M. D. Salsac, A. Vancraeyenest, C. Larijani, Marcus Scheck, Eric Clément, Raymond J. Carroll, A. Ignatov, Alison Bruce, Zs. Podolyák, S. Lalkovski, P. H. Regan, N. Marginean, V. Vedia, B. Olaizola, Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut Laue-Langevin (ILL), ILL, Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Grand Accélérateur National d'Ions Lourds (GANIL), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique Nucléaire de Lyon (IPNL), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)

Subjects
Physics, 010308 nuclear & particles physics, Fission, QC1-999, SHELL model, Monte Carlo method, Nuclear Theory, Centroid, Deformation (meteorology), [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, 7. Clean energy, Nuclear physics, Excited state, 0103 physical sciences, Neutron, 010306 general physics, Nuclear Experiment
Abstract

Lifetimes of excited states of the 98;100;102Zr nuclei were measured by using the Generalized Centroid Difference Method. The nuclei of interest were populated via neutron-induced fission of 241Pu and 235U during the EXILL-FATIMA campaign. The obtained lifetimes were used to calculate the B(E2) transition strengths and β deformation parameters which were then compared with the recent theoretical predictions obtained with Monte Carlo Shell Model.

Published
2018
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19. The γ-γ fast-timing technique and the EXILL&FATIMA campaign

Author

J.-M. Régis, G.S. Simpson, H. Mach, A. Blanc, M. Jentschel, U. Köster, P. Mutti, T. Soldner, G. de France, C.A. Ur, W. Urban, J. Jolie, N. Saed-Samii, N. Warr, L.M. Fraile, V. Paziy, P.H. Regan, Zs. Podolyák, S. Lalkovski, A.M. Bruce, T. Kröll, W. Korten, and N. Marginean

Subjects
Physics, Fission products, 010308 nuclear & particles physics, Fission, QC1-999, Detector, Centroid, 01 natural sciences, Spectral line, Semiconductor detector, Nuclear physics, Excited state, 0103 physical sciences, Nuclear Experiment, 010306 general physics, Spectroscopy
Abstract

At the Institut Laue-Langevin in Grenoble, germanium-gated γ-γ fast-timing lifetime measurements of nuclear excited states in neutron-rich nuclei have been performed within a prompt γ-ray spectroscopy experimental campaign. We report on results obtained from the cold-neutron induced fission of 235 U. The excited secondary fission products were stopped almost instantaneously within the thick target and the γ rays emitted were collected triggerlessly using the EXILL&FATIMA mixed array of HPGe and LaBr 3 (Ce) detectors. Precise lifetimes could be determined by analysing the γ-γ time difference spectra using the generalized centroid difference method. This picosecondsensitive method provides many advantages and is briefly explained. Still, the major source of systematic errors is related to the contribution of time-correlated Compton background. The EXILL&FATIMA results are discussed with respect to the typical energy-dependent timing behaviour of the background. According to the time response of the background, appropriate methods and a time correction for the sub-nanosecond regime are proposed.

Published
2018
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20. Test of the SO(6) selection rule in $^{196}$Pt using cold-neutron capture

Author

M. Pfeiffer, D. Wilmsen, Zs. Podolyák, R. Lica, Alison Bruce, F. Drouet, J.-M. Régis, W. Korten, A. Vancraeyenest, S. Kisyov, W. Urban, Ulli Köster, N. Saed-Samii, D. Ivanova, Aurelien Blanc, Michael Jentschel, A. Ignatov, J. Jolie, Torsten Soldner, G.S. Simpson, P. Mutti, Th. Kröll, V. Paziy, L. M. Fraile, P. H. Regan, N. Marginean, E. Wilson, N. Warr, C. A. Ur, Oliver J. Roberts, S. Lalkovski, Institut Laue-Langevin (ILL), Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS), Grand Accélérateur National d'Ions Lourds (GANIL), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, ILL, Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)

Subjects
Physics, Nuclear and High Energy Physics, Detector, State (functional analysis), Scintillator, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Collimated light, Nuclear physics, Neutron capture, Beamline, Interacting boson model, Atomic physics, Beam (structure), ComputingMilieux_MISCELLANEOUS
Abstract

At the PF1B cold-neutron beam line of the Institut Laue Langevin, the EXILL&FATIMA array, consisting of EXOGAM Ge detectors and fast LaBr3(Ce) scintillators, was used to perform fast electronic timing measurements after the 195Pt(n, γ) reaction using a highly collimated cold-neutron beam. An upper lifetime limit was obtained for the third 0 + state in 196Pt. As this state is the lowest state of the σ = N − 2 set of SO(6) states, the selection rule which forbids E2 transitions to the lower lying σ = N could be tested.

Published
2015
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21. The (n,γ) campaigns at EXILL

Author

R. Lica, S. Kisyov, W. Urban, D. Curien, M. Zielinska, G. Bocchi, M. Czerwinski, Michael Jentschel, M. Pfeiffer, Henryk Mach, J. Jolie, G. Benzoni, G.S. Simpson, B. Szpak, N. Saed-Samii, S. Leoni, D. Ivanova, W. Korten, R. Leguillon, P. H. Regan, N. Marginean, S. Lalkovski, C. Bernards, N. Cieplicka, P. G. Thirolf, L. Sengele, S. Bottoni, T. Rzaca-Urban, R. B. Cakirli, Paolo Mutti, Ralph Massarczyk, S. Ilieva, C. Lorenz, Dietrich Habs, A. Korgul, P. Ba̧czyk, R. F. Casten, Marcus Scheck, N. Warr, Oliver J. Roberts, Ulli Köster, L. M. Fraile, C. M. Petrache, J.-M. Régis, F. C. L. Crespi, V. Paziy, Zs. Podolyák, A. Ignatov, Th. Kröll, B. Fornal, D. Wilmsen, Alison Bruce, R. Lozeva, T. Soldner, S. Ahmed, M. D. Salsac, A. Vancraeyenest, C. A. Ur, V. Werner, C. Mazzocchi, F. Drouet, Ronald Schwengner, M. Thürauf, Aurelien Blanc, R. John, and N. Cooper

Subjects
Nuclear physics, Physics, Astrophysics::High Energy Astrophysical Phenomena, QC1-999, Astrophysics, Neutron radiation, Scintillator, Coincidence, Collimated light
Abstract

At the PF1B cold neutron beam line at the Institut Laue Langevin, the EXILL array consisting of EXOGAM, GASP and ILL-Clover detectors was used to perform (n,$\gamma$) measurements at very high coincidence rates. About ten different reactions were measured in autumn 2012 using a highly collimated cold neutron beam. In spring 2013, the EXOGAM array was combined with 16 LaBr3(Ce) scintillators in the EXILL&FATIMA campaign for the measurement of lifetimes using the generalised centroid difference method. We report on the properties of the set-ups and present first results from both campaigns.

Published
2015

22. B(E2;21+→01+)value inKr90

Author

J.-M. Régis, J. Jolie, N. Saed-Samii, N. Warr, M. Pfeiffer, A. Blanc, M. Jentschel, U. Köster, P. Mutti, T. Soldner, G. S. Simpson, F. Drouet, A. Vancraeyenest, G. de France, E. Clément, O. Stezowski, C. A. Ur, W. Urban, P. H. Regan, Zs. Podolyák, C. Larijani, C. Townsley, R. Carroll, E. Wilson, L. M. Fraile, H. Mach, V. Paziy, B. Olaizola, V. Vedia, A. M. Bruce, O. J. Roberts, J. F. Smith, T. Kröll, A.-L. Hartig, A. Ignatov, S. Ilieva, M. Thürauf, S. Lalkovski, D. Ivanova, S. Kisyov, W. Korten, M.-D. Salsac, M. Zielińska, N. Mărginean, D. G. Ghită, R. Lică, C. M. Petrache, A. Astier, and R. Leguillon

Subjects
Physics, Nuclear and High Energy Physics, 010308 nuclear & particles physics, 0103 physical sciences, Atomic physics, 010306 general physics, 01 natural sciences, Sudden onset
Abstract

A smooth onset of collectivity in ${}^{88,92,94,96}\mathrm{Kr}$ has been determined from reported $B(E2;{2}_{1}^{+}\ensuremath{\rightarrow}{0}_{1}^{+})$ and $E({2}_{1}^{+})$ values. This is in contrast to the sudden onset in even-even Zr, Mo, and Sr isotopes. Our objective was to complete the systematics by determining the $B(E2;{2}_{1}^{+}\ensuremath{\rightarrow}{0}_{1}^{+})$ value in $^{90}\mathrm{Kr}$, which was produced by cold-neutron-induced fission of ${}^{235}\mathrm{U}$. The lifetime of the ${2}_{1}^{+}$ state in $^{90}\mathrm{Kr}$ was measured via the electronic $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ timing technique using the EXILL and FATIMA spectrometers. Based on the measured mean lifetime of $\ensuremath{\tau}$ = 15(10) ps, the $B(E2;{2}_{1}^{+}\ensuremath{\rightarrow}{0}_{1}^{+})$ value of $13{}_{\ensuremath{-}5}^{+26}$ W.u. in $^{90}\mathrm{Kr}$ is determined for the first time and the smooth onset of deformation in the even-even Kr isotopes beyond neutron number $N=50$ is confirmed.

Published
2014
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23. Low-lying isomeric states in Ga80 from the β− decay of Zn80

Author

R. Lică, N. Mărginean, D. G. Ghiţă, H. Mach, L. M. Fraile, G. S. Simpson, A. Aprahamian, C. Bernards, J. A. Briz, B. Bucher, C. J. Chiara, Z. Dlouhý, I. Gheorghe, P. Hoff, J. Jolie, U. Köster, W. Kurcewicz, R. Mărginean, B. Olaizola, V. Paziy, J. M. Régis, M. Rudigier, T. Sava, M. Stănoiu, L. Stroe, and W. B. Walters

Subjects
Physics, Nuclear and High Energy Physics, medicine.anatomical_structure, Double beta decay, medicine, Observable, Atomic physics, Ground state, Nucleus, Beta decay, Excitation
Abstract

A new level scheme of 80Ga has been determined. This nucleus was populated following the β− decay of 80Zn at ISOLDE, CERN. The proposed level scheme is significantly different compared to the previously reported one and contains 26 levels up to 3.4 MeV in excitation energy. The present study establishes that the previously identified 1.9-s β− -decaying 6− isomer is the ground state of 80Ga and the 1.3-s β− -decaying 3− isomer lies at an excitation energy of 22.4 keV. A new isomeric level was identified at 707.8 keV and its half-life was measured to be 18.3(5) ns, allowing the 685.4-keV transition de-exciting this state to be assigned anM2 multipolarity. The newly measured spectroscopic observables are compared with shell-model calculations using the jj44bpn and JUN45 interactions.

Published
2014
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24. Lifetime Measurements in Neutron-rich Xe Isotopes - Evolution of Quadrupole Collectivity Beyond $^{132}$Sn

Author

S. Ilieva, S. Bönig, A.-L. Hartig, C. Henrich, A. Ignatov, Th. Kröll, M. Thürauf, J. Jolie, J.-M. Régis, N. Saed-Samii, A. Blanc, G. de France, M. Jentschel, U. Köster, P. Mutti, G. S. Simpson, T. Soldner, W. Urban, N. Mǎrginean, C. A. Ur, H. Mach, L. M. Fraile, V. Paziy, P. H. Regan, A. M. Bruce, S. Lalkovski, W. Korten, Institut Laue-Langevin (ILL), Grand Accélérateur National d'Ions Lourds (GANIL), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)

Subjects
Isotope, Chemistry, Fission, Astrophysics::High Energy Astrophysical Phenomena, Nuclear Theory, Lifetimes of excited states, quadrupole collectivity, neutron-rich Xe isotopes, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear physics, Picosecond, Excited state, Quadrupole, Neutron, MAGIC (telescope), Atomic physics, Nuclear Experiment, Spectroscopy
Abstract

EXILL&FATIMA and IS411 collaborations; International audience; Picosecond lifetimes of excited states in neutron-rich Xe isotopes were measured at the Institut Laue-Langevin via $\gamma$-ray spectroscopy of fission fragments from neutron-induced fission of 235U and 241Putargets. The data collected with the recently installed fast timing array FATIMA in combination withthe EXOGAM Ge array were analysed using the new generalized centroid difference method. Ouraim is to study the quadrupole and octupole collectivity, arising in the mass region beyond the doublymagic 132Sn, by means of transition probabilities. These can be calculated from the directly measuredlifetimes.

Published
2014
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25. Fast-Timing Study in the 78Ni Region: β-Decay of 81Zn

Author

Z. Dlouhý, Brian Bucher, C. J. Chiara, B. Olaizola, R. Mărginean, J. M. Udías, N. Mărginean, P. Hoff, I. Gheorghe, L. M. Fraile, V. Paziy, M. Rudigier, Henryk Mach, J. Jolie, J. M. Régis, Gary Simpson, Ani Aprahamian, R. Lica, C. Bernards, D. Ghiţă, M. Stanoiu, T. Sava, W. Kurcewicz, Ulli Köster, W. B. Walters, L. Stroe, José Antonio Briz, Institut Laue-Langevin (ILL), ILL, Laboratoire de Physique Subatomique et de Cosmologie (LPSC), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)

Subjects
Nuclear physics, Physics, Large Hadron Collider, medicine.anatomical_structure, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], Excited state, medicine, Limit (mathematics), Nucleus
Abstract

International audience; The neutron-rich nucleus 81Ga was populated from the β-decay of 81Zn produced at the ISOLDE (CERN) facility. The analysis of β-gated γ-ray singles and γ-γ coincidences permits to extend significantly the level scheme of 81Ga as well as to provide a new half-life for 81Zn. A preliminary upper limit was obtained for the half-life of the first excited state in 81Ga.

Published
2014
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26. Structure of [sup 81]Ga populated from the β− decay of [sup 81]Zn

Author

T. Sava, M. Stanoiu, P. Hoff, I. Gheorghe, Z. Dlouhy, W. B. Walters, H. Mach, R. Lica, José Antonio Briz, B. Bucher, G. S. Simpson, R. Mărginean, C. Bernards, L. Stroe, C. J. Chiara, V. Paziy, L. M. Fraile, J. M. Udías, N. Mărginean, B. Olaizola, A. Aprahamian, W. Kurcewicz, J. M. Régis, M. Rudigier, Ulli Köster, and D. Ghita

Subjects
Physics, Nuclear physics, Decay scheme, Large Hadron Collider, Nuclear structure, Nuclear shell model, Half-life, Gamma spectroscopy, Nuclear Experiment, Beta decay, Radioactive decay
Abstract

We report on the results of the β-decay of 81Zn. The experiment was performed at the CERN ISOLDE facility in the framework of a systematic ultra-fast timing investigation of neutron-rich nuclei populated in the decay of Zn. The present analysis included β-gated γ-ray singles and γ-γ coincidences from the decay of 81Zn to 81Ga and leads to a new and much more extensive level scheme of 81Ga. A new half-life of 81Zn is provided.

Published
2013
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27. Time resolution of a 1-inch cylindrical CeBr[sub 3] crystal at [sup 60]Co energies

Author

V. Vedia, J. M. Udías, Henryk Mach, E. Picado, B. Olaizola, V. Paziy, and L. M. Fraile

Subjects
Crystal, Photomultiplier, Materials science, Optics, business.industry, Detector, Scintillation counter, Resolution (electron density), Analytical chemistry, Constant fraction discriminator, Scintillator, business, Particle detector
Abstract

We have measured time resolutions of a cylindrical CeBr3 scintillator of 1-inch in height and 1-inch in diameter coupled to two different fast photomultiplier tubes, Hamamatsu R9779 and Photonis XP20D0, as a function of applied high voltages and different settings of a Constant Fraction Discriminator ORTEC 935. The time resolution was measured using a time-delayed coincidence set-up involving a fast reference detector. The best result of 119(2) ps at 60Co energies was obtained for the CeBr3 crystal coupled to the Hamamatsu PMT. This result is comparable to the resolution of 107 ps reported for a LaBr3(Ce) crystal of the same size. For the coupling of the CeBr3 scintillator to the Photonis PMT we got the time resolution of 146(2) ps.

Published
2013
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28. Assessment of new photosensors for fast timing applications with large scintillator detectors

Author

B. Olaizola, Henryk Mach, L. M. Fraile, J. M. Udías, E. Picado, Juan José Vaquero, V. Vedia, J.J. Sanchez, and V. Paziy

Subjects
Physics, Photomultiplier, Solid scintillation detectors, Medicina, business.industry, Detector, Photodetectors, Bromine compound, Photodetector, Scintillator, Lanthanum compounds, Nuclear energy level transitions, Photomultipliers, Nuclear physics, Phototube, Silicon radiation detectors, Silicon photomultiplier, Barium compounds, Optoelectronics, Photonics, business, Biología y Biomedicina, Radioactive decay
Abstract

Proceedings of: 2011 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC). Valencia, Spain, 23-29 October 2011 The measurement of absolute nuclear transition probabilities is a very sensitive tool to study the structure of the atomic nucleus. Direct access to transition rates can be achieved via the lifetime of the nuclear levels de-populated in radioactive decay. The Advanced Time-Delayed (ATD) method, or Fast Timing, is a well-established technique to measure lifetimes down to a few ps. The development of the technique was based on the use of BaF_2 detectors, but a recent major breakthrough occurred with the introduction of LaBr_3(Ce) crystals, uniting excellent time response with much superior energy resolution than BaF_2 crystals. Relatively large LaBr_3(Ce) cylindrical detectors of typically 1.5"×1.5" are employed for fast timing, in combination with fast 2-inch photomultiplier tubes from Photonis such as the linear focused 8-stage XP20D0. Another option for a 2-inch fast phototube is the 8-stage Hamamatsu R9779, whose timing properties have already been tested with small LSO crystals. New possibilities are also offered by novel photosensors such as silicon photomultipliers, which are intrinsically fast. In this work we have investigated the performance of the Hamamatsu R9779 photomultiplier tube, and the viability of CeBr_3 crystals for fast-timing applications. This work was supported in part by Comunidad de Madrid (ARTEMIS S2009/DPI-1802) and the Spanish Ministry of Science and Innovation (grants FPA201O-l7l42 and CSPD-2007-00042, Ingenio2010). Publicado

Published
2011
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29. The Generalized Centroid Difference method for lifetime measurements viaγ-γcoincidences using large fast-timing arrays

Author

F. Drouet, Zs. Podolyák, Aurelien Blanc, Alison Bruce, O. Stezowski, Gheorghe Pascovici, T. Kröll, W. Korten, T. Soldner, J.-M. Régis, S. Mărginean, Henryk Mach, N. Warr, Ulli Köster, J. Jolie, P.H. Regan, M. Rudigier, Paolo Mutti, G.S. Simpson, W. Urban, Michael Jentschel, V. Paziy, S. Lalkovski, M. Pfeiffer, C. A. Ur, A. Vancraeyenest, S. Ilieva, L. M. Fraile, N. Saed-Samii, A. Blazhev, Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), Institut Laue-Langevin (ILL), ILL, Grand Accélérateur National d'Ions Lourds (GANIL), Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut de Physique Nucléaire de Lyon (IPNL), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, business.industry, QC1-999, Detector, Centroid, Observable, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Scintillator, Spectral line, Computational physics, Superposition principle, Optics, Cascade, Excited state, business
Abstract

This is an Open Access article distributed under the terms of the Creative Common Attribution Licence 4.0 which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.; International audience; A novel method for direct electronic "fast-timing" lifetime measurements of nuclear excited statesvia γ-γ coincidences using an array equipped with N very fast high-resolution LaBr3(Ce) scintillator detectorsis presented. The generalized centroid difference method provides two independent “start” and “stop” timespectra obtained without any correction by a superposition of the N(N − 1)/2 calibrated γ-γ time differencespectra of the N detector fast-timing system. The two fast-timing array time spectra correspond to a forwardand reverse gating of a specific γ-γ cascade and the centroid difference as the time shift between the centroidsof the two time spectra provides a picosecond-sensitive mirror-symmetric observable of the set-up. The energydependentmean prompt response difference between the start and stop events is calibrated and used as a singlecorrection for lifetime determination. These combined fast-timing array mean γ-γ zero-time responses can bedetermined for 40 keV < Eγ < 1.4 MeV with a precision better than 10 ps using a 152Eu γ-ray source. Thenew method is described with examples of (n,γ) and (n,f,γ) experiments performed at the intense cold-neutronbeam facility PF1B of the Institut Laue-Langevin in Grenoble, France, using 16 LaBr3(Ce) detectors withinthe EXILL&FATIMA campaign in 2013. The results are discussed with respect to possible systematic errorsinduced by background contributions.

Published
2015
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30. First results of the (n,γ) EXILL campaigns at the Institut Laue Langevin using EXOGAM and FATIMA

Author

J Jolie, J-M Régis, D Wilmsen, S Ahmed, M Pfeiffer, N Saed-Samii, N Warr, A Blanc, M Jentschel, U Köster, P Mutti, T Soldner, G Simpson, G de France, W Urban, A M Bruce, O J Roberts, L M Fraile, V Paziy, A Ignatov, S Ilieva, Th Kröll, M Scheck, M Thürauf, D Ivanova, S Kisyov, S Lalkovski, Zs Podolyak, P H Regan, W Korten, D Habs, P G Thirolf, C A Ur, Institut Laue-Langevin (ILL), ILL, Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS), Grand Accélérateur National d'Ions Lourds (GANIL), Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), EXOGAM, and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Nuclear physics, History, Optics, business.industry, Scintillator, Neutron radiation, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], business, Computer Science Applications, Education
Abstract

At the PF1B cold neutron beam line at the Institut Laue Langevin the EXILL array consisting of EXOGAM, GASP and LOHENGRIN detectors was used to perform (n,γ) measurements under very high coincidence rates. About ten different reactions were then measured in autumn 2012. In spring 2013 the EXOGAM array was combined with 16 LaBr3(Ce) scintillators in the FATIMA@EXILL campaign for the measurement of lifetimes using the generalised centroid difference method. We report on the properties of both set-ups and present first results on Pt isotopes from both campaigns.

Published
2014
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