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1. Medium-spin states of the neutron-rich nucleus $^{87}$Br

Author

Michael Jentschel, Ulli Köster, A. Krasznahorkay, Aurelien Blanc, P. Bączyk, L. Atanasova, Paolo Mutti, M. Czerwiński, T. Rząca-Urban, Gary Simpson, T. Soldner, Zs. Dombradi, B. M. Nyakó, D. L. Balabanski, Kamila Sieja, D. Sohler, T. G. Tornyi, M. Csatlós, István Kuti, C. A. Ur, W. Urban, János Timár, Institute for Nuclear Research [Budapest] (ATOMKI), Hungarian Academy of Sciences (MTA), University of Warsaw (UW), Medical University of Sofia [Bulgarie], Institut Pluridisciplinaire Hubert Curien (IPHC), 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), 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), Laboratoire de Physique Subatomique et de Cosmologie (LPSC), 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), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), ILL, 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 Université de Strasbourg (UNISTRA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Valence (chemistry), Spin states, Spins, Proton, 010308 nuclear & particles physics, Fission, FOS: Physical sciences, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Structure, Space (mathematics), 01 natural sciences, 7. Clean energy, Excited state, 0103 physical sciences, Neutron, Nuclear Experiment (nucl-ex), Atomic physics, Nuclear Experiment, 010306 general physics
Abstract

Medium-spin excited states of the neutron-rich nucleus $^{87}\mathrm{Br}$ were observed and studied for the first time. They were populated in fission of $^{235}\mathrm{U}$ induced by the cold-neutron beam of the PF1B facility of the Institut Laue-Langevin, Grenoble. The measurement of $\ensuremath{\gamma}$ radiation following fission was performed using the EXILL array of Ge detectors. The observed level scheme was compared with results of large valence space shell model calculations. The medium-spin level scheme consists of three bandlike structures, which can be understood as bands built on the $\ensuremath{\pi}{f}_{5/2}$, $\ensuremath{\pi}({p}_{3/2}+{f}_{5/2})$, and $\ensuremath{\pi}{g}_{9/2}$ configurations. The behavior of the observed $\ensuremath{\pi}{g}_{9/2}$ band at high spins shows a considerable deviation from the shell model predictions. This deviation in this band is probably the result of an increased collectivity, which can be understood assuming that the $\ensuremath{\pi}{g}_{9/2}$ high-$\mathit{j}$ proton polarizes the core.

Published
2021

2. Structure of even-even Sr isotopes with $50{\le}N{\le}58$ neutrons

Author

W. Urban, K. Sieja, T. Rząca-Urban, J. Wiśniewski, A. Blanc, M. Jentschel, P. Mutti, U. Köster, T. Soldner, G. de France, G. S. Simpson, C. A. Ur, A. G. Smith, J. P. Greene, Institut Pluridisciplinaire Hubert Curien (IPHC), 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), 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), Laboratoire de Physique Subatomique et de Cosmologie (LPSC), 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), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), ILL, 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
010308 nuclear & particles physics, 0103 physical sciences, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 010306 general physics, 01 natural sciences
Abstract

International audience; Excited levels in Sr90, Sr92, Sr94, and Sr96 nuclei were reinvestigated using high-statistics multiple-γ coincidence data from neutron-induced fission of U235 and spontaneous fission of Cf252, measured using Exogam at Institut Laue Langevin and Gammasphere arrays, respectively. The experimental goal was the search for new excited levels and firm spin-parity assignments to known levels. A total of 23 new levels with 30 new or corrected decays and 39 new or improved spin-parity assignments were obtained in the four nuclei. Negative-parity structures on top of 3− excitation were firmly identified and extended to higher spins. New positive-parity structures in Sr94 and Sr96 were observed with 3+ excitations characteristic of γ collectivity. The 277.7-keV, E2 decay from the 1507.0-keV level to the second 0+ level in Sr96, found in this paper, completes the coexisting deformed band in this nucleus. To learn about the microscopic structure of levels in the Sr88−96 nuclei, we performed large-scale shell-model calculations. The calculations compared to the experiment, helped the discussion of the evolution of collectivity in strontium isotopes, highlighting the important role of various single-particle excitations in phase transitions and shape coexistence in the region. The special role of the neutron 9/2+[404] extruder as a catalyst of the deformation change in the region is highlighted.

Published
2021

3. 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

4. EXOGAM at the ILL: the EXILL campaign

Author

G. de France, A. Blanc, F. Drouet, M. Jentschel, U. Köster, P. Mutti, J.M. Régis, G. Simpson, T. Soldner, O. Stezowski, C.A. Ur, W. Urban, A. Vancrayenest, 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 National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Centre National de la Recherche Scientifique (CNRS), 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), 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 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]), 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, History, 010308 nuclear & particles physics, Radiative capture, Nuclear Theory, Measure (physics), chemistry.chemical_element, Germanium, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Computer Science Applications, Education, Complement (complexity), Nuclear physics, chemistry, 0103 physical sciences, Neutron, 010306 general physics, Spectroscopy, Nuclear Experiment
Abstract

International audience; A combination of germanium detectors has been installed at the PF1B neutronguide of the ILL to perform the prompt spectroscopy of neutron-rich nuclei produced in theneutron-capture induced-fission of 235U and 241Pu. Radiative capture reactions on rare targetshave also been performed. LaBr3 detectors from the FATIMA collaboration have also beeninstalled in complement with the EXOGAM clovers to measure lifetimes of low-lying excitedstates. The measured characteristics indicate very good performances of the overall setup. Somerecent results will be discussed.

Published
2017

5. Study of parity-doublet structure in the $^{147}$La nucleus

Author

John P. Greene, T. Rząca-Urban, G. S. Simpson, J. F. Smith, A. G. Smith, I. Ahmad, W. Urban, J. Wiśniewski, 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 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 ), and Université Grenoble Alpes (UGA)

Subjects
Physics, Angular momentum, 010308 nuclear & particles physics, QC1-999, Spontaneous symmetry breaking, Nuclear Theory, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Excited state, 0103 physical sciences, Atomic nucleus, Nuclear force, Neutron, Gammasphere, Atomic physics, Nuclear Experiment, 010306 general physics, Nucleon
Abstract

Only a small percentage of know nuclei has spherical symmetry, most of them are deformed. The problem of nuclear deformation was rst investigated in 1952 by the A.A. Bohr [1] who suggested that atomic nuclei can acquire shapes other than spherical through a process called spontaneous symmetry breaking (SSB). Because shapes of atomic nuclei largely depend on the interactions between nucleons, nuclear-deformation studies can provide valuable information on nuclear forces, including the so-called residual interactions, responsible for nuclear deformation. In case of octupole deformation, studied in this work, residual interactions correlate nucleons moving on orbits which dier by three units of angular momentum ( ` = 3), and have dierent parities. If the Fermi level of a nucleus is located between such levels octupole deformation may occur. This happens for aparticular numbers of protons and neutrons, called octupole magic numbers (N;Z = 34; 56; 88; 134). Because the wave functions describing octupole-deformed nuclei do not have well-dened parity in the intrinsic frame, in the laboratory frame one ob- serves specic pattern of excited states, called parity doublet. The aim of the present study was to reinvestigate the presence of octupole deformation in the 147La nucleus. The 147La nuclei were produced in spontaneous ssion of 252Cf and measured using the GAMMASPHERE array of Ge detectors. Taking as a starting point schemes proposed in previous works ([2] and [3]), a new scheme of excited states has been proposed for 147La, in which levels and transitions were arranged into a parity-doublet structure, thanks to newly observed transitions with energies 558.8, 436.5, 421.4 and 414.25 keV. In order to determine spins and parities of levels, angular correlation were analysed. Intensities of transitions allowed the determination of dipole moments and gyromagnetic coecients. The properties of excited levels in 147La, which are consistent with analogous properties observed in octupole-deformed nuclei around 147La, support octupole deformation in 147La.

Published
2017

6. New nuclear structure data after fission: The g.s. of $^{136}$Sb

Author

R. Lozeva, Aurelien Blanc, Teresa Kurtukian-Nieto, M. Ramdhane, F. Didierjean, Paolo Mutti, G. Duchêne, W. Urban, Francois Le Blanc, Torsten Soldner, Jean-Michel Daugas, Ulli Köster, Xiuquan Li, Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), 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), Institut Laue-Langevin (ILL), ILL, Direction des Applications Militaires (DAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), Université Sciences et Technologies - Bordeaux 1-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 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), 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), Université Sciences et Technologies - Bordeaux 1 (UB)-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]), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), 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)-Université Grenoble Alpes (UGA)

Subjects
Physics, Proton, Scope (project management), 010308 nuclear & particles physics, Fission, QC1-999, Nuclear Theory, Nuclear structure, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Nuclear physics, medicine.anatomical_structure, 0103 physical sciences, medicine, Neutron, 010306 general physics, Nuclear Experiment, Nucleus
Abstract

Nuclei in the neutron-rich region beyond 132Sn have been produced recently by various experiments using fission. Using isomer and β-decay studies nuclear structure data has been collected on the orbital evolution and collectivity in the region with both the increase of proton and neutron numbers. Examples on particular questions related to the g.s. of the A=136 odd-odd 136Sb nucleus and its heavier neighbours are given in the scope of expectations by shell-model theory.

Published
2017

7. New isomer in $^{96}$Y marking the onset of deformation at N = 57

Author

T. Kröll, Zs. Podolyák, C. A. Ur, Michael Jentschel, S. Bottoni, W. Korten, D. Mengoni, D. Bazzacco, F. C. L. Crespi, B. Melon, Torsten Soldner, Ulli Köster, C. Porzio, S. Lalkovski, N. Marginean, Aurelien Blanc, G. Benzoni, G. Bocchi, N. Cieplicka-Oryńczak, P. H. Regan, P. Mutti, B. Fornal, L. M. Fraile, B. Szpak, S. Leoni, Alison Bruce, J.-M. Régis, D. R. Napoli, C. Michelagnoli, A. Nannini, G. S. Simpson, Ł. W. Iskra, W. Urban, A. Petrovici, B. Million, 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), 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 de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, 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, Shape change, 010308 nuclear & particles physics, General Physics and Astronomy, chemistry.chemical_element, Yttrium, Deformation (meteorology), [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Molecular physics, Nuclear magnetic resonance, chemistry, Cascade, Excited state, 0103 physical sciences, 010306 general physics, Excitation
Abstract

EXILL experimental campaign; International audience; The level scheme of 96Y was significantly extended and a new 201 ns isomer was located at 1655 keV excitation energy, with spin-parity assignment of 5± or 6−. The isomer decays to spherical low-spin structure by transitions with large hindrance and is fed by a short cascade which resembles the beginning of a rotational band. This is in analogy with the feeding and decay pattern of the 4− isomer in 98Y, here confirmed, by lifetime analysis, as a bandhead of a rotational structure with sizable deformation. It is suggested that the new isomer in 96Y arises from a shape change between deformed and spherical configurations, which indicates the appearance of deformation already at N = 57 in the yttrium chain. The experimental findings for 96Y are strengthened by theoretical calculations based on the complex Excited Vampir model.

Published
2017

8. Identification of excited states and collectivity in $^{88}$Se

Author

I. N. Gratchev, G. S. Simpson, G. Thiamova, M. Ramdhane, K. Sieja, A. Blanc, M. Jentschel, U. Köster, P. Mutti, T. Soldner, G. de France, C. A. Ur, W. Urban, 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, Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg (UNISTRA)-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 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), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), 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 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]), 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, Decay scheme, 010308 nuclear & particles physics, Fission, Deformation (meteorology), [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Nuclear physics, medicine.anatomical_structure, Excited state, 0103 physical sciences, Quadrupole, medicine, 010306 general physics, Nucleus, Beam (structure)
Abstract

International audience; The γ decays of excited states in the very neutron-rich nucleus Se88 have been observed following the neutron-induced fission of U235. The measurement was performed using the EXILL array of Ge detectors at the PF1B cold-neutron beam facility of the Institut Laue-Langevin, Grenoble. The level scheme of Se88 was established using γ-γ-γ coincidences. A low (21+) energy hints at the onset of quadrupole deformation, and the identification of possible members of a (22+) band provide evidence for γ vibrations. Shell-model calculations using a Ni78 core reproduce the decay scheme well. Equivalent deformation and B(E2) values have previously been predicted for Se88 using pseudo-SU(3), shell-model, and beyond mean-field frameworks implying that interactions between particles in the πf5/2p and νsd orbits are mostly responsible for the collectivity present.

Published
2017

9. Medium and high spin structure in the $^{94}$Y isotope produced in fission induced by cold neutrons

Author

Ł W Iskra, B Fornal, S Leoni, G Bocchi, A Blanc, S Bottoni, N Cieplicka-Oryńczak, M Jentschel, U Köster, C Michelagnoli, P Mutti, T Soldner, G de France, G S Simpson, C A Ur, W Urban, 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), 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 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]), 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 ), and Université Grenoble Alpes (UGA)

Subjects
Physics, Cold fission, Cluster decay, Isotope, 010308 nuclear & particles physics, Fission, Neutron emission, Astrophysics::High Energy Astrophysical Phenomena, Fission product yield, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Condensed Matter Physics, 7. Clean energy, 01 natural sciences, Fast fission, Atomic and Molecular Physics, and Optics, Nuclear physics, 0103 physical sciences, Neutron, 010306 general physics, Mathematical Physics
Abstract

International audience; The level scheme of the neutron-rich 94Y isotope has been extended up to the 5324 keV excitation energy. During the analysis, a structure above the previously known (5+) isomer, at 1202 keV, was extended by employing multifold gamma-ray coincidence relationships measured with the EXILL array. For some of the new states, the spin-parity assignment has been proposed on the basis of gamma angular correlations and shell-model considerations. The newly identified structure is characteristic of spherical or nearly spherical configurations and no evidence for new isomers and rotational patterns was found.

Published
2017

10. 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

11. Interplay between particle and core ecitations in $^{133}$Sb

Author

G. Bocchi, S. Leoni, B. Fornal, G. Colò, P.F. Bortignon, D. Bazzacco, A. Blanc, S. Bottoni, N. Cieplicka-Oryńczak, F.C.L. Crespi, G. De France, M. Jentschel, U. Koster, C. Michelagnoli, P. Mutti, J.-M. Régis, G. Simpson, T. Soldner, B. Szpak, C.A. Ur, W. Urban, 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), 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]), ILL, 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 National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, medicine.anatomical_structure, Valence (chemistry), Fission, Excited state, medicine, General Physics and Astronomy, Scintillator, Atomic physics, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment, Nucleus, Semiconductor detector
Abstract

International audience; The decay of the one-proton valence nucleus 133Sb is studied usingthe cold-neutron induced fission of 235U and 241Pu targets. The experimentis performed at the ILL reactor in Grenoble, using a highly efficient HPGearray, also coupled to fast LaBr3(Ce) scintillators. High-spin excited statesabove the 16.6 s isomer are observed, and the lifetime of the 13/2+ and15/2+ states is measured by fast-timing techniques, revealing a complexnature of the wave functions. The experimental results are well-interpretedby a newly developed microscopic model which takes into account the couplingbetween the valence proton and excitations (both collective and noncollective)of the doubly magic 132Sn core.

Published
2016

12. Excitations of one-valence-proton, one-valence-neutron nucleus $^{210}$Bi from cold-neutron capture

Author

N. Cieplicka-Oryńczak, B. Fornal, S. Leoni, D. Bazzacco, A. Blanc, G. Bocchi, S. Bottoni, G. de France, M. Jentschel, U. Köster, P. Mutti, G. Simpson, T. Soldner, B. Szpak, C. Ur, W. Urban, 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), 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), 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, Valence (chemistry), Proton, 010308 nuclear & particles physics, Testing procedures, Nuclear Theory, Excited state reaction dynamics, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, 7. Clean energy, Neutron capture, medicine.anatomical_structure, Lead, 0103 physical sciences, medicine, Neutron, Atomic physics, 010306 general physics, Hpge detector, Gamma detection, Nuclear Experiment, Nucleus, Excitation
Abstract

International audience; The low-spin structure of one-proton, one-neutron $^{210}$Bi nucleus was investigated in cold-neutron capture reaction on$^{209}$Bi. The $\gamma$-coincidence measurements were performed with use of EXILL array consisted of 16 HPGe detectors. The experimentalresults were compared to shell-model calculations involving valence particles excitations. The $^{210}$Bi nucleus offers the potentialto test the effective proton-neutron interactions because most of the states should arise from the proton-neutron excitations. Additionally,it was discovered that a few states should come from the couplings of valence particles to the $3^-$ octupole vibration in$^{208}$Pb which provides also the possibility of testing the calculations involving the core excitations.

Published
2015

13. 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

14. Neutron-capture experiment on 77Se with EXILL at ILL Grenoble

Author

Ch. Lorenz, R. John, R. Massarczyk, R. Schwengner, A. Blanc, G. de France, M. Jentschel, U. Köster, P. Mutti, G. Simpson, T. Soldner, W. Urban, S. Valenta, T. Belgya, 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), 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), Vernay, Emmanuelle, 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, Neutron capture, [PHYS.NUCL] Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], 010308 nuclear & particles physics, Physics::Instrumentation and Detectors, QC1-999, Astrophysics::High Energy Astrophysical Phenomena, Detector, gamma-spectroscopy, 030204 cardiovascular system & hematology, 7. Clean energy, 01 natural sciences, Engineering physics, Nuclear physics, 03 medical and health sciences, 0302 clinical medicine, 0103 physical sciences, Neutron, Detector array, Nuclear Experiment
Abstract

International audience; The neutron capture reaction at 77Se has been studied with cold neutrons in the course of the EXILL campaign at the high-flux reactor of the Institut Laue-Langevin Grenoble. A simulation of the detector array with Geant4 has been accomplished and evaluated. The detector response has been deduced and measured spectra were unfolded, which have been compared with simulations using γDex to determine strength functions.

Published
2014

15. From EXILL (EXogam at the ILL) to FIPPS (FIssion Product Prompt γ-ray Spectrometer)

Author

A. Blanc, A. Chebboubi, G. de France, F. Drouet, H. Faust, M. Jentschel, G. Kessedjian, U. Köster, S. Leoni, T. Materna, P. Mutti, S. Panebianco, C. Sage, G. Simpson, T. Soldner, C. A. Ur, W. Urban, A. Vancraeyenest, 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), 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, 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 fission product, Fission products, Spectrometer, Fission, QC1-999, Astrophysics::High Energy Astrophysical Phenomena, Neutron radiation, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Collimated light, Nuclear physics, Neutron, Spectroscopy, Nuclear Experiment
Abstract

International audience; Within the EXILL campaign a large and efficient cluster of Ge-detectors was installed around a very well collimated neutron beam. This has allowed to carry out rather complete spectroscopic studies close to the line of stability using the (n,γ) reaction. Neutron rich isotopes were produced by neutron induced fission and prompt spectroscopy was carried out. The isotope selection in this setup was based on a partially known level scheme and the use of triple coincidences. The latter is limiting the statistical sensitivity in the case of weak production yields. Based on the experiences of these campaigns we are currently developing a new setup: FIPPS (FIssion Product Prompt Spectroscopy). This setup combines a collimated neutron beam, a highly efficient cluster of Ge detectors, a gas filled magnet and auxiliary detectors. The presence of the gas filled magnet will allow us to identify fission products directly and should give access to a new quality of studies if compared to the EXILL campaign. The EXILL campaign and the FIPPS project are presented.

Published
2014

16. 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

17. The EXILL campaign

Author

G DE FRANCE, A BLANC, F DROUET, M JENTSCHEL, U KÖSTER, P MUTTI, J M RÉGIS, G SIMPSON, T SOLDNER, O STEZOWSKI, S LEONI, W URBAN, A VANCRAYENEST, 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 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 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), EXILL, 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 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 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, 23.20.Lv, 21.10.Pc, 21.10.Tg, 25.40.Lw, 25.85.Ec, Physics::Instrumentation and Detectors, Astrophysics::High Energy Astrophysical Phenomena, Nuclear Theory, Radiative capture, General Physics and Astronomy, chemistry.chemical_element, Germanium, radiative capture, γ -ray spectroscopy, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 7. Clean energy, Spectral line, Nuclear physics, chemistry, neutron-rich nuclei, Excited state, neutron-induced fission, Neutron, Nuclear Experiment, Spectroscopy
Abstract

International audience; A combination of germanium detectors was installed at the PF1B neutron guide ofthe ILL to perform prompt spectroscopy of neutron-rich nuclei produced in the neutron-captureinduced-fission of $^{235}$U and ^${241}$Pu. In addition, La$Br_3$ detectors from the FATIMA Collaborationwere installed to complement with the EXOGAM clovers to measure lifetimes of low-lying excitedstates. The measured characteristics and online spectra indicate very good performances of theoverall set-up.

Published
2014

18. Spectroscopy of neutron rich nuclei using cold neutron induced fission of actinide targets at the ILL : the EXILL campaign

Author

A. Blanc, G. de France, F. Drouet, M. Jentschel, U. Köster, C. Mancuso, P. Mutti, J.M. Régis, G. Simpson, T. Soldner, C.A. Ur, W. Urban, A. Vancraeyenest, 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 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), 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), F. Farget, A. Chatillon, H. Faust, G. Fioni, D. Goutte, H. Goutte, ILL, 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 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), 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
Fission, Physics::Instrumentation and Detectors, QC1-999, Astrophysics::High Energy Astrophysical Phenomena, Nuclear Theory, chemistry.chemical_element, Germanium, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Structure, 01 natural sciences, 7. Clean energy, Spectral line, Nuclear physics, 0103 physical sciences, Neutron, 010306 general physics, Spectroscopy, Nuclear Experiment, ComputingMilieux_MISCELLANEOUS, Physics, 010308 nuclear & particles physics, Nuclear structure, Actinide, chemistry, Excited state, Atomic physics
Abstract

One way to explore exotic nuclei is to study their structure by performing γ-ray spectroscopy. At the ILL, we exploit a high neutron flux reactor to induce the cold fission of actinide targets. In this process, fission products that cannot be accessed using standard spontaneous fission sources are produced with a yield allowing their detailed study using high resolution γ-ray spectroscopy. This is what was pursued at the ILL with the EXILL (for EXOGAM at the ILL) campaign. In the present work, the EXILL setup and performance will be presented.

Published
2013

19. Recent Results from Lohengrin on Fission Yields and Related Decay Properties

Author

C. Sage, Alain Letourneau, C. Amouroux, W. Urban, S. Panebianco, M. Rudigier, J.-M. Régis, Olivier Serot, L. Mathieu, Adrien Bidaud, F. Martin, N. Capellan, U. Koester, H. Faust, S. Chabod, A. Ebran, Olivier Litaize, T. Materna, Grégoire Kessedjian, 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), Institut Laue-Langevin (ILL), ILL, Aval du cycle et Energie Nucléaire (ACEN), Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), Université Sciences et Technologies - Bordeaux 1-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Vernay, Emmanuelle

Subjects
Physics, Nuclear and High Energy Physics, Fission products, Nuclear fission product, Cluster decay, [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], Fission, Neutron emission, Fission product yield, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 7. Clean energy, Nuclear physics, Neutron cross section, Neutron, Nuclear Experiment, ComputingMilieux_MISCELLANEOUS
Abstract

communication - http://hal.in2p3.fr/in2p3-00797284; International audience; The Lohengrin mass spectrometer is one of the 40 instruments built around the reactor of the Institute Laue-Langevin (France) which delivers a very intense thermal neutron flux. Usually, Lohengrin was combined with a high-resolution ionization chamber in order to obtain good nuclear charge discrimination within a mass line, yielding an accurate isotopic yield determination. Unfortunately, this experimental procedure can only be applied for fission products with a nuclear charge less than about 42, i.e. in the light fission fragment region. Since 2008, a large collaboration has started with the aim of studying various fission aspects, mainly in the heavy fragment region. For that, a new experimental setup which allows isotopic identification by γ-ray spectrometry has been developed and validated. This technique was applied on the 239Pu(nth,f) reaction where about 65 fission product yields were measured with an uncertainty that has been reduced on average by a factor of 2 compared with what was that previously available in nuclear data libraries. The same γ-ray spectrometric technique is currently being applied to the study of the 233U(nth,f) reaction. Our aim is to deduce charge and mass distributions of the fission products and to complete the experimental data that exist mainly for light fission fragments. The measurement of 41 mass yields from the 241Am(2nth,f) reaction has been also performed. In addition to these activities on fission yield measurements, various new nanosecond isomers were discovered. Their presence can be revealed from a strong deformed ionic charge distribution compared to a 'normal' Gaussian shape. Finally, a new neutron long-counter detector designed to have a detection efficiency independent of the detected neutron energy has been built. Combining this neutron device with a Germanium detector and a beta-ray detector array allowed us to measure the beta-delayed neutron emission probability Pn of some important fission products for reactor applications.

Published
2013

20. Low-spin excitations in the 109Tc nucleus

Author

Tommi Eronen, Ari Jokinen, Heikki Penttilä, Iain Moore, Anu Kankainen, A. Płochocki, Juha Äystö, W. Urban, Jani Hakala, Christine Weber, Viki-Veikko Elomaa, Juho Rissanen, J. A. Pinston, Antti Saastamoinen, J. Kurpeta, Institut Laue-Langevin (ILL), ILL, Laboratoire de Physique Subatomique et de Cosmologie (LPSC), and 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)

Subjects
Nuclear and High Energy Physics, Fission, Prolate spheroid, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], kiihdytinpohjainen fysiikka, 01 natural sciences, ydinrakenne, Double beta decay, 0103 physical sciences, medicine, 010306 general physics, Spectroscopy, nuclear spectroscopy, Physics, ta114, accelerator-based physics, 010308 nuclear & particles physics, Parity (physics), medicine.anatomical_structure, nuclear structure, ydinspektroskopia, Atomic physics, ydinfysiikka, Ground state, Nucleus, Excitation
Abstract

Monoisotopic samples of ${}^{109}$Mo nuclei, produced in the deuteron-induced fission of ${}^{238}$U and separated using the IGISOL mass separator coupled to a Penning trap, were used to perform $\ensuremath{\beta}$- and $\ensuremath{\gamma}$-coincidence spectroscopy of ${}^{109}$Tc. Spin and parity 5/2${}^{+}$ for the ground state of ${}^{109}$Mo, proposed earlier, are supported in the present work. Three new low-energy levels observed in ${}^{109}$Tc are interpreted as bandheads of the $\ensuremath{\pi}3/{2}^{\ensuremath{-}}$[301], $\ensuremath{\pi}5/{2}^{\ensuremath{-}}$[303], and $\ensuremath{\pi}1/{2}^{+}$[431] configurations, respectively. A further three levels observed around 0.4 MeV are interpreted as $K=1/2$ triaxial excitations. A similar interpretation is proposed for an analogous set of three levels observed in ${}^{107}$Tc in another ${\ensuremath{\beta}}^{\ensuremath{-}}$ decay work. The systematics of these excitations breaks down in ${}^{111}$Tc, most likely due to a transition from prolate to oblate deformation. An excitation at 745.0 keV in ${}^{109}$Tc and 850.7 keV in ${}^{107}$Tc is interpreted as the $\ensuremath{\pi}$7/2${}^{+}$[413] configuration. Quasiparticle-rotor model calculations support the proposed interpretations.

Published
2012

21. Near-yrast structure of odd-A, neutron-rich Pr isotopes

Author

T. Malkiewicz, A. G. Smith, T. Materna, M. Ramdhane, Ulli Köster, John P. Greene, G. Thiamova, Gary Simpson, T. Rząca-Urban, J. Genevey, I. Ahmad, W. Urban, J. A. Pinston, 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), and ILL

Subjects
Physics, Nuclear and High Energy Physics, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], 010308 nuclear & particles physics, Praseodymium, Yrast, chemistry.chemical_element, Fermi surface, 01 natural sciences, 7. Clean energy, chemistry, Excited state, 0103 physical sciences, Quadrupole, Gammasphere, Neutron, Atomic physics, 010306 general physics, Spin (physics)
Abstract

The neutron-rich praseodymium isotopes ${}^{151}$Pr and ${}^{153}$Pr have been studied by prompt $\ensuremath{\gamma}$-ray spectroscopy using ${}^{248}$Cm and ${}^{252}$Cf spontaneous-fission sources placed inside the EUROGAM-II and Gammasphere germanium arrays, respectively. Rotational bands based on $3/{2}^{\ensuremath{-}}$[541] states, with similar structures, have been assigned to these nuclei. These bands decay by intraband $E2$ transitions. Interband $E1$ transitions, reported in other works, were not observed. Delayed conversion-electron and $\ensuremath{\gamma}$-ray spectroscopy of an $A=151$ nucleus has been performed at the Lohengrin mass spectrometer. A previously reported 35.1-keV isomer of ${}^{151}$Pr has been determined to decay by an $E1$ transition, and its half-life of 50(8) $\ensuremath{\mu}$s has been measured. Calculations performed using a reflection-symmetric quasi-particle-rotor model successfully reproduce the energies of the excited states of these nuclei and their decay patterns. The spin of the isomer has been assigned to be (1/2${}^{+}$, 3/2${}^{+}$) from a comparison with the calculations. The long half-life of this isomer and the lack of intraband $E1$ transitions show an absence of strong octupole correlations in the observed states of ${}^{151,153}$Pr. This is explained in terms of increasing quadrupole deformation reducing the number of Nilsson orbitals close to the Fermi surface available to form octupole collectivity.

Published
2012

22. Two quasiparticle isomers and bands of 154,156Nd, 156,158Sm

Author

G. S. Simpson, W. Urban, J. Genevey, R. Orlandi, J. A. Pinston, A. Scherillo, A. G. Smith, J. F. Smith, I. Ahmad, J. P. Greene, Audrey Chatillon, Herbert Faust, Gabriele Fioni, Dominique Goutte, Héloise Goutte, 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
Physics, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], 020206 networking & telecommunications, 02 engineering and technology, Mass spectrometry, 7. Clean energy, Physics::Atomic and Molecular Clusters, 0202 electrical engineering, electronic engineering, information engineering, Quasiparticle, 020201 artificial intelligence & image processing, Gamma spectroscopy, Physics::Chemical Physics, Atomic physics, Nuclear Experiment, Spectroscopy, ComputingMilieux_MISCELLANEOUS, Spontaneous fission
Abstract

The decay of a new 3.2 μs, (4−) isomeric state at 1298.0 keV has been observed using γ‐ray spectroscopy at the Lohengrin mass spectrometer of the Institut Laue‐Langevin. Prompt γ‐ray data from a spontaneous fission experiment have also been analyzed allowing the observation of a collective band on top of this isomeric state, the identification of a new band on top of the previously reported (5−) isomer of 156Nd and the extension of collective bands on top of (5−) isomers of the neighboring 156,158Sm nuclei. Quasiparticle rotor model calculations correctly predict the energies and decay patterns of these bands.

Published
2009

23. New information on medium-spin structure of 133Sb

Author

T. Rząca-Urban, W. Urban, A. Złomaniec, G. S. Simpson, H. Faust, Michael Jentschel, Institut Laue-Langevin (ILL), ILL, Laboratoire de Physique Subatomique et de Cosmologie (LPSC), and 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)

Subjects
Physics, Nuclear and High Energy Physics, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], 010308 nuclear & particles physics, Fission, SHELL model, Nuclear Theory, Spin structure, 21.10.Pc, 23.20.Lv, 27.60.+j, 01 natural sciences, Neutron temperature, Excited state, 0103 physical sciences, Uranium-235, Physics::Atomic and Molecular Clusters, Atomic physics, 010306 general physics, Spin (physics), Nuclear Experiment, Excitation
Abstract

Excited states in the nucleus $^{133}\mathrm{Sb}$, populated in the fission of $^{235}\mathrm{U}$ induced by thermal neutrons were studied using the Lohengrin fission-fragment separator. A new 4191.8 keV level in $^{133}\mathrm{Sb}$, populated in the decay of the 16.6 \ensuremath{\mu}s isomer, was observed. The level is interpreted as the ${11/2}^{+}$ member of the $\ensuremath{\pi}{g}_{7/2}\ensuremath{\bigotimes}\mathrm{core}$ configuration, predicted by the shell model at 4095 keV. Levels corresponding to octupole excitation of the $^{132}\mathrm{Sn}$ core, identified previously in prompt-$\ensuremath{\gamma}$ measurement, were now observed in the isomeric decay.

Published
2009

24. Isomers in fission fragments

Author

W. Urban, H. Faust, M. Jentschel, U. Köster, J. Krempel, Th. Materna, P. Mutti, T. Soldner, J. Genevey, J. A. Pinston, G. Simpson, T. Rza̧ca-Urban, A. Złomaniec, M. Łukasiewicz, K. Sieja, F. Nowacki, O. Dorvaux, B. J. P. Gall, B. Roux, J. A. Dare, J. L. Durell, A. G. Smith, B. J. Varley, I. Tsekhanovich, J. Jolie, A. Linnemann, A. Scherillo, R. Orlandi, J. F. Smith, I. Ahmad, Jan Jolie, Andreas Zilges, Nigel Warr, Andrey Blazhev, Institut Laue-Langevin (ILL), ILL, 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), Département Recherches Subatomiques (DRS-IPHC), Institut Pluridisciplinaire Hubert Curien (IPHC), and Université de Strasbourg (UNISTRA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Nuclear reaction, Fission products, Cluster decay, 010308 nuclear & particles physics, Chemistry, Fission, Yrast, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Nuclear physics, 0103 physical sciences, Neutron, Gammasphere, 010306 general physics, Spontaneous fission
Abstract

International audience; The structure of neutron‐rich nuclei produced as secondary fission fragments was investigated using the EUROGAM and GAMMASPHERE ACS arrays, the LOHENGRIN fission‐fragment mass separator and the FIFI fission‐fragment identifier. Fission products were populated in spontaneous fission of 248Cm and 252Cf and in thermal neutron‐induced fission of 233U, 235U and 241Pu at ILL Grenoble. Particularly useful in such studies are isomeric states, well populated in fission due to their yrast character, easy to detect due to their long half lives and easy to interpret because of their relatively simple composition. We discuss their role in studies of neutron‐rich nuclei, giving examples of isomers found in our recent experiments. A special type of K‐isomers, resulting from 'crossing' of extruder and intruder orbitals plays a role in the mechanism of a sudden onset of deformation in the A = 100 and A = 150 regions. We present evidence for these isomers in both regions. Possible further studies in this field are proposed.

Published
2008

25. Investigation of lifetimes in quadrupole bands of $^{142}$Gd

Author

W. Urban, R. Menegazzo, A. Dewald, Ch. Droste, D. R. Napoli, E. O. Lieder, V.M. Mikhajlov, G. Duchêne, A.D. Efimov, B. G. Carlsson, A. Gadea, A. A. Pasternak, T. Rzaca-Urban, R. M. Lieder, S. Chmel, Ingemar Ragnarsson, S. Lunardi, G. de Angelis, T. Morek, Ts. Venkova, W. Gast, D. Bazzacco, Département Recherches Subatomiques (DRS-IPHC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), EUROBALL, and Publica

Subjects
lifetime, Physics, Nuclear and High Energy Physics, properties of nuclei, Spectrometer, 010308 nuclear & particles physics, Attenuation, Nuclear Theory, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], nuclear energy level, collective level, 01 natural sciences, width, 0103 physical sciences, Quadrupole, 21.10.-k - 21.10.Re - 21.10.Tg - 27.60.+j, Atomic physics, 010306 general physics, Beam energy, Principal axis theorem, Boson
Abstract

For a level scheme investigation of ^{142}Gd an experiment with the $\gamma$-spectrometer EUROBALLIII has been carried out and lifetimes have been measured with EUROBALL IV using the Doppler-shift attenuation method. The high-spin states have been populated in these experiments by means of the ^{99}Ru(^{48}Ti, 2p3n) reaction at a beam energy of 240MeV and the ^{114}Sn(^{32}S, 2p2n) reaction at 160MeV, respectively. Reduced E2 transition probabilities B(E2) were determined for 15 members of four quadrupole bands. For the interpretation of the positive-parity even-spin quadrupole bands, calculations in the cranked Nilsson-Strutinsky as well as interacting boson models have been performed. From the former calculations it was concluded that the high-spin states of the (+ , 0)_{1} band in ^{142}Gd represent a triaxial nucleus rotating around the longest principal axis.

Published
2008

26. New information on the $T_{1/2}$ = 47 s isomer in the $^{136}I$ nucleus

Author

S. K. Sarkar, John Durell, J. A. Pinston, I. Ahmad, T. Rzaca-Urban, Gary Simpson, M. Saha Sarkar, W. Urban, J. Genevey, A. G. Smith, 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), Institut Laue-Langevin (ILL), and ILL

Subjects
Physics, 21.10.-k, 21.10.Tg, 25.85.Ca, 27.60.+j, Nuclear and High Energy Physics, iodine 136, 010308 nuclear & particles physics, Hadron, nuclear energy levels, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Nuclei, medicine.anatomical_structure, spontaneous fission, 0103 physical sciences, medicine, lifetimes, Gamma spectroscopy, Atomic physics, 010306 general physics, Spectroscopy, Spin (physics), Nucleus, Multiplet, Spontaneous fission
Abstract

The 136I nucleus, populated in the spontaneous fission of 248Cm, was studied by means of prompt γ-ray spectroscopy using the EUROGAM2 array. The observation in this work of the 42.6keV prompt-γ, M1 + E2 transition de-exciting the 7- level in 136I indicates that this level, interpreted as the $(\ensuremath \pi g_{7/2}^3 \nu f_{7/2})_{7^-}$ configuration, does not correspond to the T = 47s, β-decaying isomer in 136I. The isomer is placed 42.6keV below the 7- level. It has spin 6- and is interpreted as the $\ensuremath(\pi g_{7/2}^2 d_{5/2} \nu f_{7/2})_{6^-}$ configuration. This and other members of both multiplets can be reproduced properly only if one assumes that the πd5/2 orbital in 136I is located 400keV lower than in 133Sb. Possible mechanisms causing this effect are discussed.

Published
2006

27. Investigation of lifetimes in dipole bands of $^{142}$Gd

Author

G. de Angelis, T. Morek, D. Bazzacco, A. Dewald, D. R. Napoli, G. Duchêne, S. Chmel, S. Lunardi, W. Gast, T. Rzaca-Urban, Ingemar Ragnarsson, A. A. Pasternak, V.M. Mikhajlov, Ts. Venkova, B. G. Carlsson, Ch. Droste, Roberto Menegazzo, A.D. Efimov, A. Gadea, E. O. Lieder, R. M. Lieder, W. Urban, Institut de Recherches Subatomiques (IReS), and Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Nuclear and High Energy Physics, Spectrometer, 010308 nuclear & particles physics, Nuclear Theory, Hadron, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 7. Clean energy, 01 natural sciences, Dipole, 0103 physical sciences, Quadrupole, Nuclear fusion, Interacting boson model, Atomic physics, 010306 general physics, Principal axis theorem, Boson, 21.10.-k-Properties of nuclei, nuclear energy levels
Abstract

For a level scheme investigation of 142Gd an experiment with the γ -spectrometer EUROBALLIII has been carried out and lifetimes have been measured with EUROBALL IV using the Doppler-shift attenuation method. The high-spin states have been populated in these experiments by means of the 99Ru(48Ti, 2p3n) reaction at a beam energy of 240MeV and the 114Sn(32S, 2p2n) reaction at 160MeV, respectively. Reduced E2 transition probabilities B(E2) were determined for 15 members of four quadrupole bands. For the interpretation of the positive-parity even-spin quadrupole bands, calculations in the cranked Nilsson-Strutinsky as well as interacting boson models have been performed. From the former calculations it was concluded that the high-spin states of the (+ , 0)1 band in 142Gd represent a triaxial nucleus rotating around the longest principal axis.

Published
2005

28. New Spins for ground states and isomers in $^{115}$Pd and $^{117}$Pd

Author

T. Rzaca-Urban, J. A. Pinston, John Durell, I. Ahmad, B. J. Varley, W. Urban, A. Złomaniec, G. S. Simpson, A. G. Smith, N. Schulz, J. Kurpeta, 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 de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), 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
Physics, Nuclear and High Energy Physics, Spins, Spin states, 010308 nuclear & particles physics, Hadron, nuclear energy levels, Parity (physics), [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, electromagnetic transitions, spontaneous fission, 0103 physical sciences, lifetimes, Nuclear fusion, Gamma spectroscopy, collective levels, Properties of nuclei, 21.10.-k, 23.20.-g, 25.85.Ca, 27.60.+j, Atomic physics, 010306 general physics, Nuclear Experiment, gamma transitions and level energies, Excitation, Spontaneous fission
Abstract

Levels in 115Pd and 117Pd nuclei, populated in the spontaneous fission of 248Cm were studied by means of prompt gamma spectroscopy using the EUROGAM2 array of Anti-Compton spectrometers. Negative-parity, I = 9/2 excitations were identified, which are associated with the long-lived isomers in these nuclei, reported previously as 11/2- excitations. The new data indicate spin and parity 3/2 + for ground states in 115Pd and 117Pd instead of 5/2 + proposed in previous works. This result implicates changes of spin assignments to other levels in both nuclei.

Published
2004

29. The $\nu$9/2[404] orbital and the deformation in the A $\sim$ 100 region

Author

A. Złomaniec, Gary Simpson, T. Rzaca-Urban, John Durell, W. Urban, J. Genevey, I. Ahmad, J. A. Pinston, B. J. Varley, A. G. Smith, W.R. Phillips, N. Schulz, 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), Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), 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)-Université Grenoble Alpes (UGA)

Subjects
Physics, Nuclear and High Energy Physics, 010308 nuclear & particles physics, Hadron, shell model, Deformation (meteorology), [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, medicine.anatomical_structure, spontaneous fission, 23.20.Lv, 21.60.Cs, 25.85.Ca, 27.60.+j, 0103 physical sciences, Quadrupole, medicine, Nuclear fusion, Neutron, Atomic physics, 010306 general physics, Nucleus, gamma transitions and level energies, Excitation, Spontaneous fission
Abstract

A T 1/2 = 16(2) ns isomeric level, populated in the spontaneous fission of $^{248}$Cm, has been found in $^{101}$Zr at 941.8 keV in a measurement of prompt $\gamma$-rays using the EUROGAM2 array. The level is interpreted as a K-isomer corresponding to the 9/2[404] neutron-hole excitation. The quadrupole moment, Q0 = 3.6(4) eb, deduced for the new band indicates a large deformation of $\beta_2$=0.38(4), which is produced by a specific shape-coexistence mechanism. This is another observation of the $\nu$9/2[404] orbital in the mass A $\sim$ 100 region, confirming the presence of the effect reported first in our previous work. The 9/2[404] neutron-hole excitation is also confirmed in the $^{97}$Sr nucleus and the deformation $\beta_2$=0.44(2) is determined for this configuration. The properties of the 9/2[404] neutron orbital and its influence on the onset of deformation in the A $\sim^100 region are discussed.

Published
2004

30. New bands and spin-parity assignments in $^{111}$Ru

Author

A. G. Smith, W.R. Phillips, B. J. Varley, W. Urban, T. Rzaca-Urban, Stanisław G. Rohoziński, I. Ahmad, John Durell, J. A. Pinston, N. Schulz, Ch. Droste, Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), 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), 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)-Université Grenoble Alpes (UGA)

Subjects
Physics, Nuclear and High Energy Physics, 010308 nuclear & particles physics, Linear polarization, level energies, Hadron, shell model, gamma transitions, Elementary particle, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Atomic orbital, spontaneous fission, 23.20.Lv, 21.60.Cs, 25.85.Ca, 27.60.+j, 0103 physical sciences, Neutron, Gamma spectroscopy, Atomic physics, 010306 general physics, Spectroscopy, Spontaneous fission
Abstract

The $^{111}$Ru nucleus, populated in the spontaneous fission of $^{248}$Cm has been studied by means of prompt gamma spectroscopy using the EUROGAM2 array. Spin and parity assignments, based on angular correlations, linear polarization, and conversion coefficient measurements differ from those available in the literature. New bands are reported, which incorporate $\gamma$ transitions seen previously but not placed in the scheme of $^{111}$Ru or placed incorrectly. The bands are interpreted as neutron excitations into subshells originating predominantly from the h 11/2, g 7/2 and s 1/2 spherical orbitals. The s 1/2 band, strongly mixed with the d 3/2, d 5/2 and g 7/2 configurations, is observed for the first time in this region.

Published
2004

31. First observation of excited states in the $^{110}$Mo nucleus

Author

John Durell, W.R. Phillips, I. Ahmad, B. J. Varley, T. Rzaca-Urban, A. G. Smith, W. Urban, N. Schulz, 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), Département Recherches Subatomiques (DRS-IPHC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Heyd, Yvette, 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), Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), and EUROGAM

Subjects
Physics, Nuclear and High Energy Physics, Isotope, [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], 010308 nuclear & particles physics, level energies, Gamma ray, gamma transitions, 23.20.Lv - 21.60.Cs - 25.85.Ca - 27.60.+j, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Nuclear physics, Shell model, spontaneous fission, Excited state, Neutron number, 0103 physical sciences, Gamma spectroscopy, Neutron, Atomic physics, 010306 general physics, Spectroscopy, Spontaneous fission
Abstract

The ground-state band in 110Mo has been observed for the first time. The band, comprising six levels, has been populated in the spontaneous fission of 248Cm and studied by means of prompt \(\gamma\)-ray spectroscopy using the EUROGAM2 array. The ratio \(E_{\rm exc}(4^ + )/ E_{\rm exc}(2^ + )\) suggests that the deformation of 110Mo is smaller than that in 108Mo but may stabilize at higher neutron number, where an oblate shape is expected. The new data suggests that the deformation of Sr and Zr isotopes decreases above neutron number N = 64.

Published
2004

32. First observation of the $\nu$9/2[404] orbital in the A $\sim$ 100 mass region

Author

John Durell, B. J. Varley, W.R. Phillips, N. Schulz, A. G. Smith, W. Urban, Gary Simpson, J. A. Pinston, T. Rzaca-Urban, I. Ahmad, A. Złomaniec, 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), Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), 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)-Université Grenoble Alpes (UGA)

Subjects
Physics, Nuclear and High Energy Physics, Angular momentum, 010308 nuclear & particles physics, Hadron, Gamma ray, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, 0103 physical sciences, Quadrupole, Nuclear fusion, Atomic physics, 010306 general physics, Spectroscopy, Excitation, Spontaneous fission
Abstract

A new band, populated by the spontaneous fission of 248Cm and studied by means of prompt γ-ray spectroscopy using the EUROGAM2 array, was observed in 99Zr. The 1038.8 keV band head with a half-life T 1/2 = 54(10) ns is interpreted as a K-isomer, corresponding to the 9/2[404] neutron-hole excitation. It is the first observation of this orbital in the mass A ∼ 100 region. The quadrupole moment, Q 0 = 3.9(3) eb deduced for the new band indicates a large deformation of β = 0.41, which is produced by a specific shape-coexistence mechanism, known in other regions and now found in the A ∼ 100 nuclei.

Published
2003

33. The strength of octupole correlations in neutron-rich Xe isotopes

Author

John Durell, T. Rzaca-Urban, B. J. Varley, W.R. Phillips, I. Ahmad, N. Schulz, W. Urban, A. G. Smith, Heyd, Yvette, Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), and EUROGAM

Subjects
Physics, Nuclear and High Energy Physics, Isotope, [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], Hadron, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear physics, Electric dipole moment, Neutron number, Excited state, Nuclear fusion, Neutron, Atomic physics, Spontaneous fission
Abstract

Excited levels in 140Xe and 142Xe nuclei, populated in the spontaneous fission of 248Cm, were studied by means of prompt γ-ray spectroscopy, using EUROGAM2 array. We report the first observation of an octupole band in 142Xe and extend the octupole band in 140Xe. Level schemes of 140Xe and 142Xe obtained in this work show patterns characteristic of ocupole-vibrational bands. Properties of octupole bands in Xe isotopes indicate that octupole correlations in these nuclei are lower than in the corresponding Ba nuclei. The electric dipole moment of 142Xe was found to be larger than in other Xe isotopes, contrary to theoretical predictions. This may be due to the special role of the N = 88 neutron number.

Published
2003

34. First observation of excited states in $^{139}$I

Author

W. Urban, Matthew Jones, I. Ahmad, M. J. Leddy, N. Schulz, T. Rzaca-Urban, A. Korgul, B. J. Varley, A. G. Smith, John Durell, W.R. Phillips, L. R. Morss, Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), and Heyd, Yvette

Subjects
Physics, Nuclear and High Energy Physics, [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], 010308 nuclear & particles physics, SHELL model, Gamma ray, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Nuclear physics, Excited state, 0103 physical sciences, Atomic physics, 010306 general physics, Spontaneous fission
Published
2002

35. The neutron and proton two-particle nucleus $^{134}$Sb : New low-spin states observed in the decay of $^{134}$Sn and an estimate of the energy of the 7$^-$ isomer

Author

K.I. Erokhina, W. Urban, W. Kurcewicz, F. Coraggio, W.R. Phillips, Birger Fogelberg, J. Blomqvist, J. Galy, B. J. Varley, A. Covello, A. G. Smith, A. Korgul, L. R. Morss, M. Górska, V. I. Isakov, A. Gargano, Henryk Mach, N. Schulz, John Durell, T. Rzaca-Urban, I. Ahmad, H. Gausemel, P. Hoff, F. Andreozzi, Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), and Heyd, Yvette

Subjects
Physics, Nuclear and High Energy Physics, Decay scheme, Proton, [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], 010308 nuclear & particles physics, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 7. Clean energy, 01 natural sciences, Beta-decay stable isobars, Nuclear physics, Internal conversion, Double beta decay, Excited state, 0103 physical sciences, Neutron, Atomic physics, Proton emission, Nuclear Experiment, 010306 general physics
Abstract

Excited states in the 134Sb nucleus, populated in the β−-decay of 134Sn, have been studied at the mass separator OSIRIS. The 134Sn activity was produced via fast neutron-induced fission of 238U target. A main result was the discovery of a very low-lying first-excited state of 134Sb, at 13 keV, which has led to a strong revision of the level scheme. The new results are compared with different theoretical calculations and with the known data for the analogous neutron and proton two-particle nucleus in the 208Pb region. On the basis of this comparison, the energy of the (πg 7/2νf 7/2)7− isomer is estimated to be about 250 keV, some 100 keV lower than previously reported.

Published
2002

36. First measurements of yrast excitations in $^{137}$I and the missing12$^{+}$ isomer in $^{136}$Te

Author

A. Korgul, E. Lubkiewicz, T. Rzaca-Urban, W. Urban, John Durell, M. Bentaleb, A. G. Smith, M. Górska, W.R. Phillips, B. J. Varley, N. Schulz, I. Ahmad, M. J. Leddy, L. R. Morss, Matthew Jones, Heyd, Yvette, Institut de Recherches Subatomiques (IReS), and Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Nuclear and High Energy Physics, [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], Yrast, Nuclear Theory, Hadron, SHELL model, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear physics, medicine.anatomical_structure, medicine, Nuclear fusion, Atomic physics, Spectroscopy, Nucleus, Excitation pattern, Spontaneous fission
Abstract

The 137I nucleus, populated in the spontaneous fission of 248Cm has been studied by means of prompt γ-ray spectroscopy using the EUROGAM2 array. Medium-spin yrast excitations in 137I were observed for the first time. The experimental level scheme is compared to the shell model calculation with modified Kuo-Herling interaction. The theoretical predictions differ significantly from the experimental results, indicating that the excitation pattern in 137I deviates significantly from the shell model scheme.

Published
2001

37. Properties of N=84, even-even nuclei populated in the spontaneous fission of $^{248}$Cm

Author

M. Bentaleb, John Durell, I. Ahmad, M. Rejmund, T. Rząca-Urban, Matthew Jones, W.R. Phillips, E. Lubkiewicz, N. Schulz, W. Urban, M. J. Leddy, A. Korgul, B. J. Varley, A. G. Smith, L. R. Morss, Lorgeril, Jocelyne, Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse (CSNSM), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), and Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Nuclear and High Energy Physics, Spins, 010308 nuclear & particles physics, [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Theory, Hadron, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Excited state, 0103 physical sciences, Quasiparticle, Nuclear fusion, Neutron, Atomic physics, Nuclear Experiment, 010306 general physics, Excitation, Spontaneous fission
Abstract

Excited states in the neutron-rich, N=84 nuclei 134Sn, 136Te and 138Xe, populated in the spontaneous fission of 248Cm, were studied to medium spins using the EUROGAM2 array. OXBASH code calculations support the experimental identification of maximum aligned configurations in these isotopes. Empirical shell model calculations agree with the proposed excitation energy of the neutron h9/2 excitation in the 132Sn region. A discrepancy between the observed and calculated excitation energy of the Iπ= 12+ level in 136Te indicates possible admixtures of collective excitations in this nucleus. Clear signs of collective excitations are observed in 138Xe.

Published
2000

38. Shapes of the neutron-rich $^{88-94}$Kr nuclei

Author

A. Kaczor, Matthew Jones, John Durell, B. J. Varley, A. G. Smith, I. Ahmad, M. Bentaleb, T. Rzaca-Urban, L. R. Morss, E. Lubkiewicz, N. Schulz, W. Urban, W.R. Phillips, M. J. Leddy, Heyd, Yvette, Institut de Recherches Subatomiques (IReS), and Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Nuclear and High Energy Physics, Isotope, Spins, [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], Excited state, Hadron, Quadrupole, Nuclear fusion, Neutron, Atomic physics, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Spontaneous fission
Abstract

Neutron-rich, 88-94Kr nuclei, populated in spontaneous fission of 248Cm, have been studied with EUROGAM 2, by measuring prompt γ-rays. Many new excited states in even-even Kr isotopes have been identified. For the first time spins and parities were determined experimentally in these nuclei. Our results indicate that the quadrupole deformation of Kr isotopes will appear only above N = 58, as observed in Sr and Zr nuclei. The newly found 3- level at 1506.4 keV in 90Kr suggests the exsistence of a new region of increased octupole correlations, probably associated with the ν(d 5/2 h 11/2) pair of Δl = Δj = 3 orbitals.

Published
2000

39. First observation of excited states in the neutron-rich nucleus $^{138}$Te

Author

John Durell, W. Urban, L. R. Morss, B. J. Varley, N. Schulz, M. Bentaleb, Matthew Jones, A. G. Smith, W.R. Phillips, I. Ahmad, M. J. Leddy, F. Hoellinger, E. Lubkiewicz, B. J. P. Gall, Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), and Heyd, Yvette

Subjects
Physics, Nuclear and High Energy Physics, Isotope, [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], Astrophysics::High Energy Astrophysical Phenomena, Nuclear Theory, Hadron, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], medicine.anatomical_structure, Excited state, medicine, Nuclear fusion, Neutron, Atomic physics, Nuclear Experiment, Ground state, Nucleus, Spontaneous fission
Abstract

The very neutron-rich nucleus 138Te produced in the spontaneous fission of 248Cm has been investigated using the EUROGAM II γ-ray multidetector array. The excited states of 138Te observed for the first time indicate that the region of ground state deformation beyond the doubly magic nucleus 132Sn has yet not been reached.

Published
1999

40. New excitation scheme of $^{139}$Cs

Author

N. Schulz, E. Lubkiewicz, Matthew Jones, M. Bentaleb, Henryk Mach, A. Nowak, L. R. Morss, John Durell, M. J. Leddy, W. Urban, W. Kurcewicz, A. G. Smith, W.R. Phillips, T. Rzaca-Urban, Birger Fogelberg, B. J. Varley, I. Ahmad, Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), and Heyd, Yvette

Subjects
Nuclear physics, Physics, Nuclear and High Energy Physics, [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], Excited state, Hadron, Nuclear fusion, Separator (oil production), Gamma spectroscopy, Atomic physics, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Excitation, Spontaneous fission
Abstract

Excited levels in 139Cs, populated in spontaneous fission of 248Cm, have been studied by means of prompt gamma spectroscopy, using the EUROGAMM 2 array. New level scheme of 139Cs, different from the one proposed recently, has been established. To confirm the new scheme, additional study of 139Cs has been performed, where γ-rays following β-decay of 139Xe to 139Cs have been measured at the mass separator OSIRIS.

Published
1999

41. Structure of $^{136}$Te and the problem of mass of $^{134}$Te

Author

B. J. Varley, L. R. Morss, E. Lubkiewicz, A. Nowak, Matthew Jones, John Durell, M. Bentaleb, A. G. Smith, I. Ahmad, M. J. Leddy, W.R. Phillips, N. Schulz, W. Urban, M. Rejmund, Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), and Heyd, Yvette

Subjects
Physics, Nuclear and High Energy Physics, Spins, [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Theory, SHELL model, Hadron, Structure (category theory), [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], medicine.anatomical_structure, Excited state, medicine, Nuclear fusion, Atomic physics, Nuclear Experiment, Nucleus, Spontaneous fission
Abstract

Neutron-rich, N=84 nuclei from the 132Sn region, populated in spontaneous fission of 248Cm, have been studied with EUROGAM 2. Excited states and their spins and parities in the 136Te nucleus were established up to 17ħ. OXBASH code calculations support the experimental identification of maximum aligned configurations in 136Te. Empirical shell model calculations for the Iπ= 14+ level in 136Te indicate that the adopted mass of the 134Te nucleus should be lowered by 200(80) keV.

Published
1998

42. Parities and multipolarities of gamma rays in neutron-rich odd-mass Ba nuclei

Author

W. Urban, I. Ahmad, M. Bentaleb, John Durell, B. J. Varley, Matthew Jones, E. Lubkiewicz, A. G. Smith, N. Schulz, W.R. Phillips, L. R. Morss, M. J. Leddy, Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), and Heyd, Yvette

Subjects
Physics, Moment (mathematics), Nuclear and High Energy Physics, Dipole, [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], Phase (waves), Gamma ray, Neutron, Atomic physics, Electric dipole transition, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Internal conversion coefficient, Spontaneous fission
Abstract

The nuclei 143,145,147 Ba produced in the spontaneous fission of 248 Cm have been studied using the EUROGAM phase II array. The parities and multipolarities of γ rays in these nuclei have been assigned from triple angular correlation, directional linear-polarisation correlation and internal conversion coefficient measurements. These data confirm an alternating-parity sequence connected by strong electric dipole transitions in 143 Ba. They also reveal a more weakly populated, complementary alternating-parity sequence. The two sequences together exhibit some characteristics of parity-doublet bands. Interpreting the E1 strengths in terms of a rotating intrinsic dipole moment gives a moment similar in size to that observed in 142 Ba and 144 Ba. No well-developed similar structure is seen in 145 Ba, although E1 transitions are observed, from which a value of the dipole moment is obtained. This value is smaller than the moment observed in 143 Ba. No features appropriate to strong octupole correlations were observed in 147 Ba.

Published
1996

43. Study of high-spin states in $^{150}$Eu and $^{151}$Eu

Author

J.R. Jongman, J. Nyberg, Ch. Vieu, J. C. S. Bacelar, J.M. Lagrange, G. Sletten, J.S. Dionisio, W. Urban, Michèle Pautrat, J.H.G. van Pol, Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse (CSNSM), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Institut de Physique Nucléaire d'Orsay (IPNO), and Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Nuclear reaction, Nuclear and High Energy Physics, Spin states, 010308 nuclear & particles physics, 0103 physical sciences, Parity (physics), Atomic physics, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 010306 general physics, 01 natural sciences, Instability, Spectral line
Abstract

High-spin states in 150,151 Eu were populated by the 136 Xe( 19 F, x n) 155− x n Eu reaction. Extensive eγ-, γγ-measurements led to new level schemes of 150,151 Eu. Most observed excitations are interpreted as quasi-rotational bands built on top of multi-p-h states. Enhanced E1 decays competing with E2 transitions indicate an octupole instability of these nuclei at medium spin. Furthermore, a few negative parity bands of 151 Eu decay through large M1 interband transitions which are interpreted as rotations of a triaxial shape. The observed structures at high spin, especially for 151 Eu, show the coexistence of axial and non-axial symmetric shapes.

Published
1995

44. Study of the high-spin structure of $^{146}$Pm

Author

C. J. Pearson, J. C. S. Bacelar, John Durell, Ch. Vieu, Ch.P. Hess, W.J. Vermeer, B. J. Varley, T. Rza̧ca-Urban, Michèle Pautrat, J.S. Dionisio, W. Urban, W.R. Phillips, Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse (CSNSM), and Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11)

Subjects
Nuclear reaction, Physics, Nuclear and High Energy Physics, Spins, 010308 nuclear & particles physics, Yrast, Nuclear Theory, Spin structure, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, 7. Clean energy, Excited state, 0103 physical sciences, Atomic physics, Nuclear Experiment, 010306 general physics, Spectroscopy, Excitation, Energy (signal processing)
Abstract

Excited states in 146Pm have been investigated through the 136Xe(15N,5n) and the 146Nd(d,xn) compound-nucleus reactions. A level scheme extending up to 6.9 MeV of excitation energy and ( I = 25 h ) is proposed. Most of the high-spin levels are interpreted in terms of multi-particle-hole states but at medium spins octupole-phonon excitations are identified. The results are discussed and the level scheme compared with analogous states in neighbouring nuclei. Yrast configurations in 146Pm are described by the shell-model calculation involving empirical single-particle energies and two-body interactions.

Published
1995

45. High-spin states in $^{148}$Eu

Author

J.R. Jongman, A. Balanda, J. C. S. Bacelar, J.M. Lagrange, Ch. Vieu, J.S. Dionisio, M.J.A. De Voigt, G. Sletten, W. Urban, J. Nyberg, Michèle Pautrat, Th. Steenbergen, R.F. Noorman, Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse (CSNSM), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Institut de Physique Nucléaire d'Orsay (IPNO), and Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Nuclear reaction, Nuclear and High Energy Physics, IN-BEAM, M(GAMMA), Spin states, LA-139(C-13,4N) EU-148, INTERNAL CONVERSION ELECTRON, chemistry.chemical_element, OCTUPOLE DEFORMATION, 4N) EU-148, E = 61 MEV, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, BAF2 MULTIPLICITY FILTER, DCO RATIOS, YRAST STATES, 0103 physical sciences, Lanthanum, medicine, GAMMA-RAY LINEAR POLARIZATION, LA-139(C-13, 010306 general physics, EXCITATION FUNCTION, GD-146, Physics, Excitation function, NUCLEI, 010308 nuclear & particles physics, MEASURED E(GAMMA), M(GAMMA), GAMMA-GAMMA-T, State (functional analysis), MEASURED E(GAMMA), NORDBALL MULTI-GE DETECTOR ARRAY, ONE-PHONON, medicine.anatomical_structure, GAMMA-GAMMA-T, chemistry, Nuclear spectroscopy, Quasiparticle, 2-PHONON, Atomic physics, Nucleus
Abstract

High-spin states in the odd-odd nucleus 148 Eu, populated by a carbon-13 induced reaction on a lanthanum target, were investigated with several different tools of in-beam nuclear spectroscopy. The low-energy levels show collective excitations, interpreted as 3 − octupole-phonon couplings to multi-particle-hole states. A probable two-octupole-phonon state is identified. Otherwise most 148 Eu high-spin levels are interpreted in terms of fully aligned multi-particle-hole states rather well described both by a semi-empirical shell model and a deformed independent-particle model.

Published
1995

46. Study of excited levels in $^{147}$Pm

Author

Michèle Pautrat, Ch.P. Hess, W. Urban, C. J. Pearson, Matthew Jones, J. C. S. Bacelar, B. J. Varley, John Durell, J.S. Dionisio, W.R. Phillips, W.J. Vermeer, Ch. Vieu, Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse (CSNSM), and Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11)

Subjects
Nuclear reaction, Physics, Nuclear and High Energy Physics, 010308 nuclear & particles physics, chemistry.chemical_element, Electron, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Xenon, chemistry, Excited state, 0103 physical sciences, Quadrupole, Conversion coefficients, Atomic physics, 010306 general physics
Abstract

Excited states in 147 Pm have been studied through the 136 Xe( 15 N,4n) and 148 Nd(d,3n) compound nucleus reactions. A solid xenon target has been used to populate high-spin states in 147 Pm. Conversion coefficients of weak transitions were determined measuring electron-γ coincidences. The half-life of the isomeric level at 649.3 keV has been remeasured to be 27 ± 3 ns. An extended level scheme is proposed, which is discussed in terms of single-particle excitations and collective quadrupole and octupole vibrations coupled to them. The possible presence of octupole deformation is considered.

Published
1995

47. Search for octupole deformation in neutron-rich Cs nuclei

Author

B. J. Varley, E. Lubkiewicz, N. Schulz, T. Rza̧ca-Urban, C.W. Williams, John Durell, C. J. Lister, J. A. Shannon, W. Urban, M. Bentaleb, C. J. Pearson, L. R. Morss, I. Ahmad, W.R. Phillips, K.L. Nash, Heyd, Yvette, Institut de Recherches Subatomiques (IReS), and Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS)

Subjects
Nuclear physics, Physics, Nuclear and High Energy Physics, Fission, [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], Excited state, Neutron, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Atomic physics, Deformation (meteorology)
Abstract

Partial level schemes of the very neutron-rich nuclei 141,143,145 Cs have been determined from the study of γ-γ-γ coincidences in 248 Cm fission fragments. Excited states of 143,145 Cs nuclei were observed for the first time. The possible existence of octupole deformation in the Cs nuclear ground states is discussed.

Published
1995

48. Target structure and in-beam electron spectra

Author

J.R. Jongman, John Durell, C. Schück, H. Folger, J. C. S. Bacelar, R Meunier, M Pautrat, J.M Lagrange, B. J. Varley, J.S. Dionisio, Ch. Vieu, W.R. Phillips, W. Urban, Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse (CSNSM), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Lorgeril, Jocelyne

Subjects
Physics, Nuclear and High Energy Physics, Photon, Spectrometer, Ion beam, 010308 nuclear & particles physics, [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], Electron, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Spectral line, Ion, Internal conversion, 0103 physical sciences, Physics::Accelerator Physics, Atomic physics, 010306 general physics, Instrumentation, Doppler broadening
Abstract

The main features of the interplay between the target structure and the accelerated ion beam characteristics suitable for an in-beam e-gamma measurement are discussed in detail. In particular, the different types of ''spurious'' electron (and photon) spectra overlapped with in-beam internal conversion electrons (and discrete gamma-rays) are reviewed as well as the most efficient experimental methods used for their attenuation. Furthermore, the general characteristics of particle beams, targets and electron spectrometers required for prompt and delayed in-beam e, gamma and e-gamma measurements are also compared. Moreover, the relative magnitude of the electron line Doppler broadening corresponding to the perpendicular and the collinear geometry is briefly discussed and illustrated by a few in-beam e-gamma studies of Pm and Eu isotopes produced by accelerated ions (H-2(1) and Li-7(3)) bombarding very thin Nd(+C) backed targets. Finally the most recent developments made at Orsay towards multi e-gamma detector assemblies lead to a broad discussion concerning the most suitable targets to be inserted within such instrumental arrangements.

Published
1994

49. The role of triaxiality in the ground states of even-even neutron-rich Ru isotopes

Author

W. Urban, B. J. Varley, N. Schulz, John Durell, E. Lubkiewicz, M. Bentaleb, C. J. Lister, W.R. Phillips, I. Ahmad, L. R. Morss, C.W. Williams, K.L. Nash, J. A. Shannon, C. J. Pearson, Heyd, Yvette, Institut de Recherches Subatomiques (IReS), and Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Nuclear and High Energy Physics, Isotope, Fission, [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Theory, Quadrupole, Neutron, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Spin-up, Atomic physics, Branching (polymer chemistry)
Abstract

Partial decay schemes for the very neutron-rich nuclei 108,110,112 Ru and 114 Ru, about which nothing was previously known, have been determined from the study of prompt, triple-γ coincidences in 248 Cm fission fragments. Levels with probable spin up to 10ħ have been observed and γ-ray branching ratios obtained. Ratios of reduced electric quadrupole transition probabilities obtained from the branching ratios are in good agreement with predictions of a simple model of a rigid triaxial rotor.

Published
1994

50. Lifetimes in neutron-rich nd isotopes measured by a doppler profile method

Author

N. Schulz, W. Urban, E. Lubkiewicz, C. J. Lister, J. A. Shannon, B. J. Varley, I. Ahmad, M. Bentaleb, C.W. Williams, L. R. Morss, K.L. Nash, C. J. Pearson, W.R. Phillips, John Durell, A. G. Smith, Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), and Heyd, Yvette

Subjects
Nuclear reaction, Nuclear physics, Physics, [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], Yrast, Quadrupole, Nuclear structure, General Physics and Astronomy, Neutron, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Spin (physics), Radioactive decay, Spontaneous fission
Abstract

The Eurogam-1 array has been used to study $\ensuremath{\gamma}$ rays emitted following the spontaneous fission of a $^{248}\mathrm{Cm}$ source. Yrast level schemes for the neutron-rich nuclei $^{152,154,156}\mathrm{Nd}$ have been constructed. The stopping of the Nd fragments in the source material leads to Doppler-broadened line shapes for those states that have lifetimes comparable to the stopping time. This paper describes the first measurements of lifetimes of medium-spin states in very neutron-rich nuclei obtained from the analysis of these line shapes. The transition quadrupole moments for the yrast states in the spin range $(10\ensuremath{-}16)\ensuremath{\hbar}$ have been deduced to be 5.88 \ifmmode\pm\else\textpm\fi{} 0.08 e b ($^{152}\mathrm{Nd}$), 5.75 \ifmmode\pm\else\textpm\fi{} 0.10 e b ($^{154}\mathrm{Nd}$), and 5.33 \ifmmode\pm\else\textpm\fi{} 0.16 e b ($^{156}\mathrm{Nd}$).

Published
1994

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