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27 results on '"J. Wiederhold"'

1. Collectivity at the prolate-oblate transition: The 21+ lifetime of 190W

Author

E. Şahin, V. Werner, A.K. Mistry, M. Rudigier, K. Nomura, J. Jolie, N. Pietralla, P.H. Regan, G. Ağgez, H.M. Albers, U. Ahmed, Ö. Aktaş, A. Algora, S. Alhomaidhi, C. Appleton, T. Arıcı, M. Armstrong, A. Banerjee, J. Benito, G. Benzoni, A. Blazhev, P. Boutachkov, A.M. Bruce, B. Cederwall, M.M.R. Chishti, M.L. Cortés, F. Crespi, B. Das, T. Davinson, T. Dickel, M. Doncel, A. Ertoprak, A. Esmaylzadeh, L.M. Fraile, E.R. Gamba, J. Gerl, M. Górska, J. Ha, E. Haettner, O. Hall, H. Heggen, C. Hornung, N. Hubbard, S. Jazrawi, P.R. John, C.E. Jones, V. Karayonchev, E. Kazantseva, R. Kern, L. Knafla, I. Kojouharov, P. Koseoglou, G. Kosir, D. Kostyleva, N. Kurz, N. Kuzminchuk, M. Llanos-Expósito, R. Lozeva, D. Mengoni, T.J. Mertzimekis, M. Mikolajczuk, A.I. Morales, I. Mukha, J.R. Murias, B.S. Nara-Singh, S.E.A. Orrigo, J. Pellumaj, S. Pelonis, S. Pietri, S. Pigliapoco, Zs. Podolyák, M. Polettini, K. Rezynkina, H.A. Rösch, H. Schaffner, Ch. Scheidenberger, L. Sexton, P.-A. Söderström, Y.K. Tanaka, J.J. Valiente-Dobón, P. Vasileiou, J. Vasiljević, J. Vesic, H. Weick, J. Wiederhold, A. Yaneva, G. Zhang, J. Zhao, and A. Zyriliou

Subjects
Nuclear structure, γ-ray spectroscopy, Isomer spectroscopy, Shape phase transition, DESPEC, NUSTAR, Physics, QC1-999
Abstract

The neutron-rich rare isotope 190W is discussed as a candidate for a prolate-oblate transitional nucleus with maximum γ-softness. The collectivity of this isotope is assessed for the first time by the measurement of the reduced E2 transition probability of its first 2+ state to the ground state. The experiment employed the FAst TIming Array (FATIMA), comprised of 36 LaBr3(Ce) scintillators, which was part of the DESPEC setup at GSI, Darmstadt. The 41+ and 21+ states of 190W were populated subsequently to the decay of its 127(12) μs isomeric Jπ=10− state. The mean lifetime of the 21+ state was determined to be τ=274(28) ps, which corresponds to a B(E2;21+→01+) value of 95(10) W.u. The results motivated a revision of previous calculations within an energy-density functional-based interacting boson model-2 approach, yielding E2 transition properties and spectroscopic quadrupole moments for tungsten isotopes. From comparison to theory, the new data suggest that 190W is at the transition from prolate to oblate structure along the W isotopic chain, which had previously been discussed as a nuclear shape-phase transition.

Published
2024
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2. The shape of the Tz = +1 nucleus 94Pd and the role of proton-neutron interactions on the structure of its excited states

Author

A. Yaneva, S. Jazrawi, M. Mikołajczuk, M. Górska, P.H. Regan, B. Das, H.M. Albers, S. Alhomaidhi, T. Arici, A. Banerjee, G. Benzoni, B. Cederwall, M.M.R. Chishti, D.D. Dao, T. Davinson, A. Gargano, J. Gerl, O. Hall, N. Hubbard, J. Jolie, I. Kojouharov, A.K. Mistry, F. Nowacki, M. Polettini, M. Rudigier, E. Şahin, H. Schaffner, A. Sharma, M. Armstrong, H.J. Wollersheim, P. Boutachkov, T. Dickel, E. Haettner, H. Heggen, Ch. Hornung, R. Knöbel, D. Kostyleva, N. Kurz, N. Kuzminchuk, I. Mukha, S. Pietri, W.R. Plass, Zs. Podolyák, C. Scheidenberger, Y.K. Tanaka, J. Vesic, H. Weick, U. Ahmed, Ö. Aktas, A. Algora, C. Appleton, J. Benito, A. Blazhev, A. Bracco, A.M. Bruce, M. Brunet, R. Canavan, A. Esmaylzadeh, L.M. Fraile, G. Häfner, K.P. Hucka, P.R. John, D. Kahl, V. Karayonchev, R. Kern, G. Košir, R. Lozeva, P. Napiralla, B.S. Nara Singh, R. Page, C.M. Petrache, N. Pietralla, J.-M. Régis, H. Rösch, P. Ruotsalainen, V. Sanchez-Temble, L. Sexton, R. Shearman, M. Si, V. Werner, J. Wiederhold, K. Wimmer, W. Witt, P. Woods, and G. Zimba

Subjects
γ spectroscopy, Fast-timing γ-ray coincidences, pn interaction, Isovector vs. isoscalar pairing, Shell model, Physics, QC1-999
Abstract

Reduced transition probabilities have been extracted between excited, yrast states in the N=Z+2 nucleus 94Pd. The transitions of interest were observed following decays of the Iπ=14+, Ex=2129-keV isomeric state, which was populated following the projectile fragmentation of a 124Xe primary beam at the GSI Helmholtzzentrum für Schwerionenforschung accelerator facility as part of FAIR Phase-0. Experimental information regarding the reduced E2 transition strengths for the decays of the yrast 8+ and 6+ states was determined following isomer-delayed Eγ1−Eγ2−△T2,1 coincidence method, using the LaBr3(Ce)-based FATIMA fast-timing coincidence gamma-ray array, which allowed direct determination of lifetimes of states in 94Pd using the Generalized Centroid Difference (GCD) method. The experimental value for the half-life of the yrast 8+ state of 755(106) ps results in a reduced transition probability of B(E2:8→+6+) = 205−25+34 e2fm4, which enables a precise verification of shell-model calculations for this unique system, lying directly between the N=Z line and the N=50 neutron shell closure. The determined B(E2) value provides an insight into the purity of (g9/2)n configurations in competition with admixtures from excitations between the (lower) N=3pf and (higher) N=4gds orbitals for the first time. The results indicate weak collectivity expected for near-zero quadrupole deformation and an increasing importance of the T=0 proton-neutron interaction at N=48.

Published
2024
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3. Nature of seniority symmetry breaking in the semimagic nucleus Ru-94

Author

B. Das, B. Cederwall, C. Qi, M. Górska, P. H. Regan, Ö. Aktas, H. M. Albers, A. Banerjee, M. M. R. Chishti, J. Gerl, N. Hubbard, S. Jazrawi, J. Jolie, A. K. Mistry, M. Polettini, A. Yaneva, S. Alhomaidhi, J. Zhao, T. Arici, S. Bagchi, G. Benzoni, P. Boutachkov, T. Davinson, T. Dickel, E. Haettner, O. Hall, Ch. Hornung, J. P. Hucka, P. R. John, I. Kojouharov, R. Knöbel, D. Kostyleva, N. Kuzminchuk, I. Mukha, W. R. Plass, B. S. Nara Singh, J. Vasiljević, S. Pietri, Zs. Podolyák, M. Rudigier, H. Rösch, E. Sahin, H. Schaffner, C. Scheidenberger, F. Schirru, A. Sharma, R. Shearman, Y. Tanaka, J. Vesić, H. Weick, H. J. Wollersheim, U. Ahmed, A. Algora, C. Appleton, J. Benito, A. Blazhev, A. Bracco, A. M. Bruce, M. Brunet, R. Canavan, A. Esmaylzadeh, L. M. Fraile, G. Häfner, H. Heggen, D. Kahl, V. Karayonchev, R. Kern, A. Korgul, G. Kosir, N. Kurz, R. Lozeva, M. Mikolajczuk, P. Napiralla, R. Page, C. M. Petrache, N. Pietralla, J.-M. Régis, P. Ruotsalainen, L. Sexton, V. Sanchez-Temble, M. Si, J. Vilhena, V. Werner, J. Wiederhold, W. Witt, P. J. Woods, and G. Zimba

Subjects
Nuclear Theory, Física nuclear, Nuclear Experiment
Abstract

Direct lifetime measurements via gamma -gamma coincidences using a fast timing detector array consisting of LaBr3(Ce) scintillators has been applied to determine the lifetime of low-lying states in the semimagic (N = 50) nucleus Ru-94. The experiment was carried out as the first in a series of "FAIR-0" experiments with the DESPEC experimental setup at the Facility for Antiproton and Ion Research (FAIR). Excited states in Ru-94 were populated primarily via the beta-delayed proton emission of Pd-95 nuclei, produced in the projectile fragmentation of an 850 MeV/nucleon Xe-124 beam impinging on a 4 g/cm(2) Be-9 target. While the deduced E2 strength for the 2(+) -> 0(+) transition in the yrast cascade follows the expected behavior for conserved seniority symmetry, the intermediate 4(+) -> 2(+) transition exhibits a drastic enhancement of transition strength in comparison with pure-seniority model predictions as well as standard shell model predictions in the f pg proton hole space with respect to doubly magic Sn-100. The anomalous behavior is ascribed to a subtle interference between the wave function of the lowest seniority v = 2, I-pi = 4(+) state and that of a close-lying v = 4 state that exhibits partial dynamic symmetry. In addition, the observed strongly prohibitive 6(+) -> 4(+) transition can be attributed to the same mechanism but with a destructive interference. It is noted that such effects may provide stringent tests of the nucleon-nucleon interactions employed in state-of-the-art theoretical model calculations.

Published
2022

4. E2 decay characteristics of the M1 scissors mode of Sm152

Author

O. Papst, M. Weinert, U. Friman-Gayer, K. E. Ide, M. Berger, Andreas Zilges, J. Kleemann, Deniz Savran, Norbert Pietralla, Krishichayan, B. Löher, Werner Tornow, J. Wiederhold, T. Beck, V. Werner, and Sean Finch

Subjects
Physics, Proton, Astrophysics::High Energy Astrophysical Phenomena, Quadrupole, Neutron, Parity (physics), Atomic physics, Interacting boson model, Multipole expansion, Quantum number, Boson
Abstract

The $E2/M1$ multipole mixing ratio of the ${1}_{\text{sc}}^{+}\ensuremath{\rightarrow}{2}_{1}^{+}\phantom{\rule{4pt}{0ex}}\ensuremath{\gamma}$-ray transition and therefore the $F$-vector $E2$ decay of the scissors mode of the shape-phase transitional nucleus $^{152}\mathrm{Sm}$ have been measured with the nuclear resonance fluorescence method at the High-Intensity $\ensuremath{\gamma}$-ray Source ($\mathrm{HI}\ensuremath{\gamma}\mathrm{S}$). Furthermore, parity quantum numbers of several dipole-excited states have been remeasured, making use of the polarized $\ensuremath{\gamma}$-ray beam at $\mathrm{HI}\ensuremath{\gamma}\mathrm{S}$, and partially reassigned. The new data enable an unambiguous determination of the proton and neutron effective boson quadrupole charges within the proton-neutron interacting boson model. With the well-constrained parameter set, a new mixed-symmetry state is predicted.

Published
2021
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5. Spectroscopy and lifetime measurements in Te134,136,138 isotopes and implications for the nuclear structure beyond N=82

Author

D. Verney, D. Ralet, J. Wiederhold, S. Bottoni, L. Matthieu, B. Fornal, A. Blazhev, P. H. Regan, C. Schmitt, R.L. Canavan, K. Rezynkina, D. Reygadas Tello, A. Lopez-Martens, K. Hauschild, B. Wasilewska, I. Matea, A. Korgul, C. Henrich, J. Jolie, V. Guadilla, M. Lebois, M. Babo, Th. Kröll, L. M. Fraile, J. Benito, G. Benzoni, T. Kurtukian-Nieto, L. Qi, Stephan Oberstedt, C. Porzio, M. Bunce, N. Warr, R. B. Gerst, P. A. Söderström, Y. Popovitch, W. Paulsen, F. Ibrahim, Ł. W. Iskra, G. Häfner, J. N. Wilson, S. Jazwari, M. S. Yavahchova, R. Chakma, C. Delafosse, A. Boso, R. Lozeva, N. Jovančević, V. Sanchez, H. Naïdja, M. Rudigier, P. Adsley, L. Le-meur, N. Cieplicka-Oryńczak, I. Homm, E. Adamska, G. Tocabens, K. Belvedere, D. Gjestvang, D. Thisse, M. L. Cortés, P. Koseoglou, P. Davies, V. Vedia, J. Nemer, M. Piersa, Muriel Fallot, C. Sürder, K. Miernik, S. M. Collins, S. Ziliani, D. Etasse, Fabio Zeiser, and J. Ljungvall

Subjects
Physics, Spectrometer, Isotope, 010308 nuclear & particles physics, Fission, Nuclear structure, Context (language use), 7. Clean energy, 01 natural sciences, Excited state, 0103 physical sciences, Neutron source, Atomic physics, 010306 general physics, Spectroscopy
Abstract

We report on spectroscopic information and lifetime measurements of even-even neutron-rich Te isotopes. Excited states were populated in fast-neutron induced fission of U238 at the ALTO facility of IJCLab with the LICORNE neutron source and detected using the hybrid ν-ball spectrometer. We provide first results on lifetimes of the 61+ state in Te136 and the (61+), (41+), and (21+) states in Te138 and discuss the results in the context of large-scale shell-model calculations. The level schemes of Te136 and Te138 are revised in terms of lifetimes of their 21+,41+ states and updated information on the (42+) state in Te136 is presented. In addition, previously reported data on spectroscopy and lifetimes in Te134 are reexamined. This work provides new insights into the evolution of collectivity for Te isotopes with N=82,84,86.

Published
2021
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6. Angular momentum generation in nuclear fission

Author

B. Fornal, M. S. Yavahchova, C. Delafosse, A. Boso, V. Sánchez-Tembleque, K. Rezynkina, M. Lebois, K. Hauschild, T. Kröll, Muriel Fallot, P. Adsley, J. Ljungvall, Ł. W. Iskra, F. Ibrahim, E. Adamska, C. Henrich, A. Gottardo, Stephan Oberstedt, R. Chakma, C. Sürder, V. Guadilla, C. Porzio, P. H. Regan, J. Benito, A. Korgul, R. Lozeva, L. Le Meur, M. Piersa, P. Ivanov, V. Vedia, J. Nemer, B. Wasilewska, N. Jovančević, Y. Popovitch, W. Paulsen, C. Schmitt, N. Cieplicka-Oryńczak, R. B. Gerst, Sunniva Siem, G. Tocabens, P. A. Söderström, K. Belvedere, S. Courtin, S. Ziliani, R. Canavan, D. Gjestvang, L. Qi, D. Etasse, P. Koseoglou, G. Häfner, I. Matea, I. Homm, M. Heine, L. M. Fraile, T. Kurtukian-Nieto, Fabio Zeiser, P. Davies, D. Thisse, M. L. Cortés, A. Blazhev, S. Jazrawi, M. Bunce, A. Lopez-Martens, K. Miernik, Alejandro Algora, M. Rudigier, J. N. Wilson, N. Warr, J. Wiederhold, D. Verney, D. Ralet, M. Babo, L. Gaudefroy, G. Benzoni, S. Bottoni, S. Leoni, Laboratoire de Physique des 2 Infinis Irène Joliot-Curie (IJCLab), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), University of Oslo (UiO), Department of Physics, University of Surrey, University of Surrey (UNIS), Technische Universität Darmstadt - Technical University of Darmstadt (TU Darmstadt), Laboratoire de physique corpusculaire de Caen (LPCC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), CEA, Bruyeres le Chatel, France, affiliation inconnue, University of Warsaw (UW), Facultat de Fisica [València] (UV), Universitat de València (UV), Universidad Complutense de Madrid = Complutense University of Madrid [Madrid] (UCM), Università degli Studi di Milano = University of Milan (UNIMI), Institut für Kernphysik der Universität zu Köln, Universität zu Köln = University of Cologne, National Physical Laboratory [Teddington] (NPL), Instytut Fizyki Jądrowej PAN (IFJ), Polskiej Akademii Nauk, 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), RIKEN - Institute of Physical and Chemical Research [Japon] (RIKEN), University of Manchester [Manchester], Laboratoire de physique subatomique et des technologies associées (SUBATECH), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-IMT Atlantique (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Istituto Nazionale di Fisica Nucleare, Sezione di Padova (INFN, Sezione di Padova), Istituto Nazionale di Fisica Nucleare (INFN), Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), 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), European Commission - Joint Research Centre [Geel] (JRC), 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), Horia Hulubei Natl Inst Phys & Nucl Engn IFIN HH, ELI NP Dept, Reactorului Str 30, Magurele 077125, Romania, Софийски университет = Sofia University, Technische Universität Darmstadt (TU Darmstadt), Universidad Complutense de Madrid [Madrid] (UCM), Università degli studi di Milano [Milano], Universität zu Köln, 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 Nantes - Faculté des Sciences et des Techniques, Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Technical University Darmstadt (TU), 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), 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), University of Sofia, Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Università degli Studi di Milano [Milano] (UNIMI), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Direction des Applications Militaires (DAM), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)

Subjects
Physics, [PHYS]Physics [physics], Angular momentum, Multidisciplinary, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], Spins, 010308 nuclear & particles physics, Fission, Nuclear Theory, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 7. Clean energy, 01 natural sciences, Nuclear physics, Nuclear fission, 0103 physical sciences, Atomic nucleus, Nuclear Experiment, 010306 general physics, Nucleon, Excitation, ComputingMilieux_MISCELLANEOUS, Spin-½
Abstract

When a heavy atomic nucleus splits (fission), the resulting fragments are observed to emerge spinning1; this phenomenon has been a mystery in nuclear physics for over 40 years2,3. The internal generation of typically six or seven units of angular momentum in each fragment is particularly puzzling for systems that start with zero, or almost zero, spin. There are currently no experimental observations that enable decisive discrimination between the many competing theories for the mechanism that generates the angular momentum4–12. Nevertheless, the consensus is that excitation of collective vibrational modes generates the intrinsic spin before the nucleus splits (pre-scission). Here we show that there is no significant correlation between the spins of the fragment partners, which leads us to conclude that angular momentum in fission is actually generated after the nucleus splits (post-scission). We present comprehensive data showing that the average spin is strongly mass-dependent, varying in saw-tooth distributions. We observe no notable dependence of fragment spin on the mass or charge of the partner nucleus, confirming the uncorrelated post-scission nature of the spin mechanism. To explain these observations, we propose that the collective motion of nucleons in the ruptured neck of the fissioning system generates two independent torques, analogous to the snapping of an elastic band. A parameterization based on occupation of angular momentum states according to statistical theory describes the full range of experimental data well. This insight into the role of spin in nuclear fission is not only important for the fundamental understanding and theoretical description of fission, but also has consequences for the γ-ray heating problem in nuclear reactors13,14, for the study of the structure of neutron-rich isotopes15,16, and for the synthesis and stability of super-heavy elements17,18. γ-ray spectroscopy experiments on the origin of spin in the products of nuclear fission of spin-zero nuclei suggest that the fission fragments acquire their spin after scission, rather than before.

Published
2021
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7. First lifetime investigations of $N>82$ iodine isotopes: The quest for collectivity

Author

A. Korgul, J. Wiederhold, Th. Kröll, S. Leoni, P. Adsley, Muriel Fallot, M. Babo, J. Benito, G. Benzoni, V. Vedia, K. Miernik, L. Qi, J. Nemer, V. Guadilla, C. Sürder, S. Bottoni, D. Verney, S. Jazwari, N. Warr, A. Boso, K. Rezynkina, D. Ralet, J. Ljungvall, F. Ibrahim, L. M. Fraile, T. Kurtukian-Nieto, M. Lebois, Fabio Zeiser, R. Chakma, A. Blazhev, P. H. Regan, R. Lozeva, C. Schmitt, L. Matthieu, R.L. Canavan, M. Piersa-Siłkowska, A. Algora, N. Jovančević, J. N. Wilson, Y. Popovitch, N. Cieplicka-Oryńczak, W. Paulsen, E. Adamska, G. Tocabens, P. Davies, K. Belvedere, D. Gjestvang, S. M. Collins, S. Ziliani, D. Etasse, M. Bunce, C. Henrich, R. B. Gerst, A. Lopez-Martens, M. Rudigier, Ł. W. Iskra, G. Häfner, B. Wasilewska, Stephan Oberstedt, C. Porzio, P. A. Söderström, C. Delafosse, V. Sánchez-Tembleque, L. Le-meur, H. Naïdja, M. S. Yavahchova, P. Koseoglou, I. Homm, D. Thisse, M. L. Cortés, D. Reygadas Tello, K. Hauschild, Laboratoire de Physique des 2 Infinis Irène Joliot-Curie (IJCLab), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire de physique corpusculaire de Caen (LPCC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-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 des technologies associées (SUBATECH), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-IMT Atlantique (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), 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), 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), 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), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), 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), 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), ILL, and Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Isotope, 010308 nuclear & particles physics, Fission, chemistry.chemical_element, Context (language use), [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Iodine, 01 natural sciences, chemistry, Excited state, 0103 physical sciences, Neutron source, Física nuclear, Atomic physics, 010306 general physics
Abstract

International audience; We report on spectroscopic information and lifetime measurements in the neutron-rich I135,137,139 isotopes. This is the first lifetime data on iodine isotopes beyond N=82. Excited states were populated in fast neutron-induced fission of U238 at the ALTO facility of IJCLab with the LICORNE neutron source and detected using the hybrid ν-ball spectrometer. The level schemes of the I135,137,139 isotopes are revised in terms of excited states with up to maximum spin-parity of (33/2+), populated for the first time in fast neutron-induced fission. We provide first results on the lifetimes of the (9/21+) and (13/21+) states in I137 and I139, and the (17/21+) state in I137. In addition, we give upper lifetime limits for the (11/21+) states in I135−139, the (15/21+) state in I137, the (17/21+) state in I139, and reexamine the (29/21+) state in I137. The isomeric data in I135 are reinvestigated, such as the previously known (15/21+) and (23/21−) isomers with T1/2 of 1.64(14) and 4.6(7) ns, respectively, as obtained in this work. The new spectroscopic information is compared to that from spontaneous or thermal-neutron induced fission and discussed in the context of large scale shell-model (LSSM) calculations for the region beyond Sn132, indicating the behavior of collectivity for the three valence-proton iodine chain with N=82,84,86.

Published
2021
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8. Prompt and delayed γ spectroscopy of neutron-rich Kr94 and observation of a new isomer

Author

R. Chakma, N. Cieplicka-Oryńczak, P. Adsley, G. Tocabens, Muriel Fallot, K. Belvedere, D. Gjestvang, L. Qi, J. Wiederhold, S. Leoni, C. Sürder, J. Benito, J. N. Wilson, K. Hauschild, R. B. Gerst, Stephan Oberstedt, Ł. W. Iskra, C. Porzio, P. A. Söderström, G. Häfner, M. Rudigier, I. Matea, C. Henrich, D. Verney, R.L. Canavan, K. Miernik, V. Vedia, D. Ralet, J. Nemer, P. Koseoglou, M. Piersa, N. Warr, R. Lozeva, L. Le Meur, A. Algora, M. Lebois, N. Jovančević, K. Rezynkina, S. Jazrawi, A. Blazhev, S. Courtin, M. Bunce, S. Bottoni, P. H. Regan, A. Boso, A. Lopez-Martens, C. Schmitt, B. Fornal, P. Ivanov, B. Wasilewska, L. M. Fraile, F. Ibrahim, M. Babo, T. Kurtukian-Nieto, A. Gottardo, G. Benzoni, T. Kröll, D. Reygadas-Tello, E. Adamska, J. Ljungvall, V. Guadilla, A. Korgul, Y. Popovitch, W. Paulsen, I. Homm, D. Thisse, M. L. Cortés, M. Heine, Fabio Zeiser, C. Delafosse, V. Sánchez-Tembleque, P. Davies, M. Yavachova, S. Ziliani, and D. Etasse

Subjects
Physics, Spectrometer, 010308 nuclear & particles physics, Fission, Astrophysics::High Energy Astrophysical Phenomena, Yrast, Nuclear Theory, 01 natural sciences, 7. Clean energy, Atomic orbital, Nuclear fission, 0103 physical sciences, Physics::Atomic and Molecular Clusters, Neutron, Atomic physics, Nuclear Experiment, 010306 general physics, Spin (physics), Spectroscopy
Abstract

Prompt and delayed γ -ray spectroscopy of the neutron-rich 94 Kr was performed, as part of the fission campaign at the ALTO facility of the IPN Orsay, using the fast-neutron-induced fission reaction 238 U ( n , f ) in combination with the ν -Ball array, a novel hybrid γ spectrometer for energy and lifetime measurements. Several new yrast and nonyrast transitions were observed for the first time, extending the previously known level scheme. Additionally, we report on the observation of a new short-lived isomer at 3444 keV with a half-life of 32(3) ns. The analysis of the Nilsson orbitals obtained from Gogny cranked Hartree-Fock-Bogoliubov calculations suggests a ( 9 − ) spin and an oblate deformation for this isomer corresponding to a two-quasineutron state, indicating an isomeric structure very similar to that of the neighboring isotones 96 Sr and 92 Se

Published
2020
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9. Coulomb Excitation of Proton-rich N=80 Isotones at HIE-ISOLDE

Author

D. Kocheva, E. Giannopoulos, Hilde De Witte, J. Jolie, O. Möller, Marcus Scheck, J. Snäll, S. Thiel, Herbert Hess, A. Welker, P. A. Söderström, J. M. Keatings, K. A. Gladnishki, J. G. Cubiss, Norbert Pietralla, R. Stegmann, G. Rainovski, Janne Pakarinen, Liam Gaffney, A. Vogt, A. Blazhev, V. Werner, C. Fransen, R. Kern, Joakim Cederkäll, G. G. O'Neill, L. Kaya, D. Rosiak, T. Kröll, P. Reiter, M. Stoyanova, P. Spagnoletti, J. Wiederhold, V. Karayonchev, M. Djongolov, Radostina Zidarova, N. Warr, and Amar Boukhari

Subjects
History, Ion beam, Proton, Silicon, Physics::Instrumentation and Detectors, chemistry.chemical_element, Coulomb excitation, hiukkasfysiikka, 01 natural sciences, Education, Ion, Nuclear physics, 0103 physical sciences, Nuclear Physics - Experiment, 010306 general physics, Nuclear Experiment, Physics, Large Hadron Collider, 010308 nuclear & particles physics, Projectile, Charged particle, Computer Science Applications, chemistry, Physics::Accelerator Physics, ydinfysiikka
Abstract

A projectile Coulomb-excitation experiment was performed at the radioactive ion beam facility HIE-ISOLDE at CERN. The radioactive 140Nd and 142Sm ions were post accelerated to the energy of 4.62 MeV/A and impinged on a 1.45 mg/cm2-thin 208Pb target. The γ rays depopulating the Coulomb-excited states were recorded by the HPGe-array MINIBALL. The scattered charged particles were detected by a double-sided silicon strip detector in forward direction. Experimental γ-ray intensities were used for the determination of electromagnetic transition matrix elements. Preliminary results for the reduced transition strength of the B ( M 1 ; 2 3 + → 2 1 + ) = 0.35 ( 19 ) μ N 2 of 140Nd and a first estimation for 142Sm have been deduced using the Coulomb-excitation calculation software GOSIA. The 2 3 + states of 140Nd and 142Sm show indications of being the main fragment of the proton-neutron mixed-symmetry 2 1 , ms + state.

Published
2020

10. Shape coexistence in neutron-deficient Hg188 investigated via lifetime measurements

Author

P. R. John, J. J. Valiente-Dobón, M. Zielińska, J. Pakarinen, I. Deloncle, A. Boso, B. Melon, D. Mengoni, D. A. Testov, B. de Canditiis, R. Menegazzo, Thomas Braunroth, A. Goasduff, S. M. Lenzi, Sophie Péru, A. Nannini, I. Zanon, G. Jaworski, G. de Angelis, A. Gadea, D. R. Napoli, F. Galtarossa, N. Cieplicka-Oryńczak, A. Vogt, B. Birkenbach, D. Ashad, F. Recchia, Liam Gaffney, G. Benzoni, W. Witt, D. Quero, D. Bazzacco, A. Gozzelino, P. Koseoglou, K. Hadyńska-Klȩk, F. Davide, M. Siciliano, P. K. Rath, J. Wiederhold, J. Libert, Magda Cicerchia, G. Colucci, Tomás R. Rodríguez, and M. Rocchini

Subjects
Physics, Spectrometer, Isotope, 010308 nuclear & particles physics, Nuclear structure, chemistry.chemical_element, 01 natural sciences, 7. Clean energy, Molecular physics, symbols.namesake, medicine.anatomical_structure, chemistry, Excited state, 0103 physical sciences, medicine, symbols, Neutron, 010306 general physics, Hamiltonian (quantum mechanics), Nucleus, Polonium
Abstract

Background: Shape coexistence in the Z≈82 region has been established in mercury, lead, and polonium isotopes. For even-even mercury isotopes with 100≤N≤106 multiple fingerprints of this phenomenon are observed, which seems to be no longer present for N≥110. According to a number of theoretical calculations, shape coexistence is predicted in the Hg188 isotope. Purpose: The aim of this work was to measure lifetimes of excited states in Hg188 to infer their collective properties, such as the deformation. Extending the investigation to higher-spin states, which are expected to be less affected by band-mixing effects, can provide additional information on the coexisting structures. Methods: The Hg188 nucleus was populated using two different fusion-evaporation reactions with two targets, Gd158 and Gd160, and a beam of S34 provided by the Tandem-ALPI accelerator complex at the Laboratori Nazionali di Legnaro. The channels of interest were selected using the information from the Neutron Wall array, while the γ rays were detected using the GALILEO γ-ray spectrometer. Lifetimes of excited states were determined using the recoil-distance Doppler-shift method, employing the dedicated GALILEO plunger device. Results: Lifetimes of the states up to spin 16ℏ were measured and the corresponding reduced transition probabilities were calculated. Assuming two-band mixing and adopting, as done commonly, the rotational model, the mixing strengths and the deformation parameters of the unperturbed structures were obtained from the experimental results. In order to shed light on the nature of the observed configurations in the Hg188 nucleus, the extracted transition strengths were compared with those resulting from state-of-the-art beyond-mean-field calculations using the symmetry-conserving configuration-mixing approach, limited to axial shapes, and the five-dimensional collective Hamiltonian, including the triaxial degree of freedom. Conclusions: The first lifetime measurement for states with spin ≥6 suggested the presence of an almost spherical structure above the 121+ isomer and allowed elucidating the structure of the intruder band. The comparison of the extracted B(E2) strengths with the two-band mixing model allowed the determination of the ground-state band deformation. Both beyond-mean-field calculations predict coexistence of a weakly deformed band with a strongly prolate-deformed one, characterized by elongation parameters similar to those obtained experimentally, but the calculated relative position of the bands and their mixing strongly differ.

Published
2020

11. Lifetimes of the 41+ states of Po206 and Po204 : A study of the transition from noncollective seniority-like mode to collectivity

Author

A. Blazhev, A. Dewald, M. Ley, A. Esmaylzadeh, L. Knafla, S. Herb, Marcus Scheck, R. Kern, L. M. Gerhard, J.-M. Régis, P. R. John, J. Jolie, J. Sinclair, Th. Kröll, P. Spagnoletti, M. Beckers, K. M. Mashtakov, J. Wiederhold, G. Rainovski, V. Werner, D. Kocheva, N. Warr, C. Sürder, L. Kornwebel, K. A. Gladnishki, C. Müller-Gatermann, K. Schomacker, V. Karayonchev, M. Djongolov, M. Stoyanova, Norbert Pietralla, J. M. Keatings, and C. Fransen

Subjects
Physics, Mode (statistics), Seniority, Atomic physics
Published
2019
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12. $\gamma$-ray Spectroscopy of $^{85}$Se Produced in $^{232}$Th Fission

Author

I. Homm, M. Ciemała, Stephan Oberstedt, K. Rezynkina, P. A. Söderström, B. Fornal, A. Lopez-Martens, M. Bunce, V. Vedia, D. Verney, J. N. Wilson, J. Nemer, B. Wasilewska, A. Algora, M. Babo, R. B. Gerst, L. M. Fraile, Y. Popovitch, R. Chakma, T. Kurtukian-Nieto, Ł. W. Iskra, W. Paulsen, E. Adamska, D. Ralet, G. Häfner, M. Piersa, G. Benzoni, M. Rudigier, A. Fijałkowska, A. Blazhev, S. Leoni, D. Reygadas Tello, K. Hauschild, P. H. Regan, M. S. Yavahchova, J. Wiederhold, V. Guadilla, N. Warr, C. Delafosse, C. Schmitt, R.L. Canavan, V. Sánchez-Tembleque, K. Miernik, R. Lozeva, I. Matea, P. Davies, Muriel Fallot, N. Jovančević, S. Bottoni, M. Lebois, N. Cieplicka-Oryńczak, P. Adsley, C. Henrich, G. Tocabens, K. Belvedere, D. Gjestvang, T. Kröll, L. Cortes, C. Sürder, L. Qi, S. M. Collins, D. Etasse, M. Heine, Fabio Zeiser, A. Boso, F. Ibrahim, J. Benito, A. Korgul, J. Ljungvall, D. Thisse, L. Le-meur, A. Gottardo, P. Koseoglou, Laboratoire de physique corpusculaire de Caen (LPCC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Laboratoire de Physique des 2 Infinis Irène Joliot-Curie (IJCLab), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), 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), Laboratoire de physique subatomique et des technologies associées (SUBATECH), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Institut Pluridisciplinaire Hubert Curien (IPHC), 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 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), 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), Normandie Université (NU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université de Nantes (UN)-Université de Nantes (UN)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-IMT Atlantique (IMT Atlantique), 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), 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, Spectrometer, Isotope, 010308 nuclear & particles physics, Fission, Yrast, Astrophysics::High Energy Astrophysical Phenomena, Nuclear Theory, Aucun, General Physics and Astronomy, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 7. Clean energy, 01 natural sciences, Nuclear physics, Excited state, 0103 physical sciences, Neutron source, Gamma spectroscopy, Nuclear Experiment
Abstract

International audience; Excited states in the neutron-rich 85Se nucleus have been studied using for the first time a fast neutron-induced fission of 232Th. The experiment was performed at the ALTO facility of the IPN Orsay. Coupling of the LICORNE directional neutron source with the ν-ball high-resolution γ-ray spectrometer provided unique access to high-spin states in neutron-rich fission fragments from the 232Th(n, f) reaction. A preliminary level scheme of 85Se was established by the analysis of prompt γ–γ–γ coincidences. Identification of the all known yrast states in 85Se is the first step towards studies of more neutron-rich Se isotopes.

Published
2019
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13. Evolution of E2 strength in the rare-earth isotopes Hf174,176,178,180

Author

D. Bucurescu, I. O. Mitu, Terver Daniel, F. Naqvi, S. Pascu, Ralitsa Ilieva, R. Lica, C. R. Nita, C. Mihai, N. Cooper, Raymond J. Carroll, S. Stegemann, N. Florea, R-B. Gerst, J. Wiederhold, L. A. Gurgi, V. Werner, D. Ghita, R. Kern, R. Mărginean, M. Rudigier, P. H. Regan, N. Marginean, Norbert Pietralla, D. M. Filipescu, and J. Jolie

Subjects
Physics, Scintillation, Isotope, 010308 nuclear & particles physics, Yrast, Rare earth, Coulomb excitation, 7. Clean energy, 01 natural sciences, 13. Climate action, Excited state, Neutron number, 0103 physical sciences, Neutron, Atomic physics, 010306 general physics
Abstract

Mean lifetimes of yrast states of the isotopes 174,176,178,180Hf have been measured using fast- electronic scintillation timing. Excited states of 74,176,178Hf were populated via β decay, while 180Hf was populated via Coulomb excitation. The lifetimes of the 2+ 1 and 4+ 1 states of all isotopes and the lifetimes of the 6+ 1 states of 174,178Hf were measured, using the slope and the centroid shift methods. The mean lifetime, τ (4+ 1 ) = 85(13) ps, of 178Hf has been determined for the first time. In addition, the mean lifetimes of the 2− 1 and the 3− 1 states of 176Hf have been determined. Systematic uncertainties on the evolution of data as a function of neutron number were reduced by using the same setup for all the isotopes of interest. The data are in agreement with other recent lifetime measurements where available and shows a shift of the maximum of collectivity for the Hf isotopic chain from neutron midshell at N = 104 to N = 100.

Published
2019
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14. Spectroscopy of Neutron Induced Reactions with the $\nu $-ball Spectrometer

Author

S. Bottoni, M. Lebois, L. Qi, D. Reygadas Tello, R. Shearman, I. Homm, R. B. Gerst, J. N. Wilson, T. Kröll, D. Verney, A. Boso, A. Oberstedt, I. Matea, P. Koseoglou, P. A. Söderström, M. Babo, G. Häfner, M. Piersa, D. Thisse, B. Fornal, M. Rudigier, V. Sanchez, J. Wiederhold, C. Henrich, P. H. Regan, A. Lopez-Martens, F. Ibrahim, K. Miernik, J. Ljungvall, N. Cieplicka-Oryńczak, M. Diakaki, P. Inavov, A. Algora, C. Delafosse, N. Warr, G. Tocabens, J. Benito Garcia, K. Belvedere, S. Leoni, Y. Popovitch, Muriel Fallot, J. Nemer, K. Rezynkina, W. Paulson, C. Sürder, M. Bunce, D. Gestvang, D. Knezevic, V. Guadilla-Gomez, K. Hauschild, Zs. Podolyák, L. Cortes, D. Ralet, A. Gottardo, A. Dragic, E. Adamska, G. Benzoni, R. Lozeva, R. Chakma, N. Jovančević, S. Oberstedt, R. Canavan, F. Adsley, P. Davies, M. Yavachova, C. Schmitt, M. Heine, Fabio Zeiser, D. Etasse, L. M. Fraile, T. Kurtukian-Nieto, A. Blazhev, L. Iskra, Institut de Physique Nucléaire d'Orsay (IPNO), 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), Université Paris-Saclay, 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), Laboratoire de physique corpusculaire de Caen (LPCC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Laboratoire de physique subatomique et des technologies associées (SUBATECH), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), 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), Normandie Université (NU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université de Nantes - Faculté des Sciences et des Techniques, and Université de Nantes (UN)-Université de Nantes (UN)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique)

Subjects
Physics, education.field_of_study, Spectrometer, 010308 nuclear & particles physics, Fission, Astrophysics::High Energy Astrophysical Phenomena, Population, Aucun, General Physics and Astronomy, Shields, chemistry.chemical_element, Germanium, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 7. Clean energy, 01 natural sciences, chemistry, 0103 physical sciences, Neutron source, Neutron, Atomic physics, 010306 general physics, education, Spectroscopy, Nuclear Experiment
Abstract

The ʋ-ball is a high-efficiency hybrid spectrometer which consists of both germanium (Ge) detectors and associated anti-Compton BGO shields, coupled to lanthanum bromide (LaBr3) detectors. The hybrid configuration provides a combination of both excellent energy and timing resolutions. The ʋ-ball geometry allows the coupling with the LICORNE directional neutron source at the ALTO facility of the IPN, Orsay. This opens the possibility to perform precise spectroscopy of neutron induced reactions and was used for two experiments during the recent experimental campaign. These two experiments are described here: 1. Spectroscopy of the neutron-rich fission fragments produced in the 238U(n; f) and 232Th(n; f) reactions; 2. Spectroscopy above the shape isomer in 238U. The 238U(n; f) and 232Th(n; f) reactions produce hundreds of neutron-rich nuclei on which gamma-ray spectroscopy can be performed. The main goal of the experiment aiming to populate the shape isomer in 238U is the measurement of the gamma-ray and fission decay branches as well as determination of level scheme in the super-deformed minimum. The shape isomer is populated by 238U(n; n') reaction, which gives a very advantageous population cross section over other reactions. More detailed descriptions of these two ʋ-ball experiments will be presented here.

Published
2019
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15. Fast-Timing Lifetime Measurement of $$^{174,176,178,180}$$ 174 , 176 , 178 , 180 Hf

Author

T. Daniel, L. A. Gurgi, R. S. Ilieva, S. Stegemann, C. Mihai, I. O. Mitu, R. Kern, N. Florea, C. R. Nita, N. Marginean, D. Ghita, R. Lica, J. Wiederhold, R.-B. Gerst, F. Naqvi, J. Jolie, P. H. Regan, D. Bucurescu, V. Werner, Norbert Pietralla, D. M. Filipescu, R. Marginean, N. Cooper, Raymond J. Carroll, M. Rudigier, and S. Pascu

Subjects
Physics, Scintillation, Isotope, Yrast, Centroid, Coulomb excitation, Atomic physics
Abstract

Lifetimes of yrast band states of \(^{174,176,178,180}\)Hf have been measured using fast-electronic scintillation timing or Coulomb excitation. The lifetimes of the \(2^+_1\), \(4^+_1\) states and apart from \(^{176}\)Hf also of the \(6^+_1\) states have been determined, using the slope and the centroid shift methods. By using the same setup for all isotopes of interest systematic uncertainties were reduced.

Published
2019
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17. Thermal Isomerizations of Diethynyl Cyclobutadienes and Implications for Fullerene Formation

Author

Robert J. McMahon, Stephanie J. Thompson, Andrew J. Wiederhold, Frank Lee Emmert, Brian J. Esselman, and Lyudmila V. Slipchenko

Subjects
Fullerene, Diradical, Chemistry, Intramolecular force, Organic Chemistry, Thermal, Enediyne, Moiety, Model system, Photochemistry, Cycloaddition
Abstract

The mechanism by which carbon condenses to form PAHs or fullerenes is a problem that has garnered considerable theoretical and experimental attention. The ring-coalescence and annealing model for the formation of C(60) involves a [2 + 2] cycloaddition reaction of a cyclopolyyne to form a tetraalkynyl cyclobuta-1,3-diene intermediate, followed by a Bergman cycloaromatization reaction of the enediyne moiety. Intramolecular trapping of the incipient p-benzyne diradical across a diyne moiety of the macrocyclic ring affords an aromatic ring that must undergo further intramolecular reactions via polyradical intermediates to produce a condensed graphitic structure or fullerene. Computational studies of a model system for the intriguing tetraalkynylcyclobuta-1,3-diene intermediate, however, reveal that the corresponding p-benzyne diradical lies in a shallow minimum with a very low barrier to ring opening to cyclooctadienediyne. This pathway has not been previously considered in the mechanism for carbon condensation.

Published
2015
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18. Search for Isovector Valence-Shell Excitations in 140 Nd and 142 Sm via Coulomb excitation reactions of radioactive ion beams

Author

Herbert Hess, P. Reiter, J. Jolie, J. Wiederhold, A. Blazhev, K. A. Gladnishki, Radostina Zidarova, E. Giannopoulos, D. Kocheva, P. A. Söderström, N. Warr, T. Kröll, M. Stoyanova, J. M. Keatings, Amar Boukhari, P. Spagnoletti, V. Werner, G. G. O'Neill, V. Karayonchev, A. Vogt, M. Djongolov, D. Rosiak, S. Thiel, G. Rainovski, Liam Gaffney, Norbert Pietralla, C. Fransen, L. Kaya, R. Kern, A. Welker, J. Snäll, Janne Pakarinen, J. G. Cubiss, R. Stegmann, Hilde De Witte, O. Möller, Joakim Cederkäll, Marcus Scheck, Arsenyev, N, Bezbakh, A, Rogov, I, Shneidman, T, Vdovin, A, Arsenyev, N., Bezbakh, A., Rogov, I., Shneidman, T., and Vdovin, A.

Subjects
Silicon, Physics::Instrumentation and Detectors, QC1-999, chemistry.chemical_element, Coulomb excitation, 01 natural sciences, Ion, 0103 physical sciences, Nuclear Physics - Experiment, Nuclear Experiment, 010306 general physics, Coulomb excitation experiments, Physics, Large Hadron Collider, Isovector, ta114, 010308 nuclear & particles physics, Projectile, Detector, chemistry, Physics::Accelerator Physics, Atomic physics, Valence electron, ydinfysiikka
Abstract

Projectile Coulomb excitation experiments were performed at HIE-ISOLDE at CERN with the radioactive ion beams of 140Nd and 142Sm. Ions with an energy of 4:62 MeV/A were impinging on a 1.45 mg/cm2 thick 208Pb target. The γ-rays depopulating the Coulomb-excited states were recorded by the HPGe-array MINIBALL and scattered particles were detected by a double-sided silicon strip detector. Experimental intensities were used for the determination of electromagnetic transition matrix elements. A preliminary result of the B(M1; 2+3 → 2+1) of 140Nd and an upper limit for the case of 142Sm are revealing the main fragments of the proton-neutron mixed-symmetry 2+1;ms states.

Published
2018
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19. SORCERER: A novel particle-detection system for transfer-reaction experiments at ROSPHERE

Author

O. Papst, A. Turturica, L. Stan, N. Marginean, T. Beck, W. Witt, R. Lica, C. Mihai, C. Costache, R.E. Mihai, S. Pascu, Norbert Pietralla, C. Sotty, J. Wiederhold, and V. Werner

Subjects
Physics, Nuclear and High Energy Physics, 010308 nuclear & particles physics, Transfer (computing), 0103 physical sciences, Particle, Gamma spectroscopy, 010306 general physics, 01 natural sciences, Instrumentation, Order of magnitude, Computational physics
Abstract

A customizable and cost-efficient particle-detection system for transfer experiments at ROSPHERE has been designed and tested. Results from the commissioning experiment employing the 2 n -transfer reaction 94Zr(18O, 16O)96Zr are presented and discussed. The device allows for an efficient suppression of contributions from fusion-evaporation reactions and an improvement of the peak-to-background ratio by about one order of magnitude. The construction, characteristics, and performance are presented and further developments are outlined.

Published
2020
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20. Fast-timing lifetime measurement ofGd152

Author

S. Toma, D. Ghita, S. Pascu, R. Lica, R. Mărginean, A. Negret, Norbert Pietralla, N. Florea, J. Wiederhold, N. Marginean, R. V. Jolos, C. R. Nita, C. Mihai, V. Werner, R. Kern, R. E. Mihai, A. Turturica, C. Lizarazo, L. Stroe, D. Bucurescu, A. Olacel, I. O. Mitu, and T. Glodariu

Subjects
Quantum phase transition, Physics, Transition strength, chemistry, 010308 nuclear & particles physics, 0103 physical sciences, Lanthanum bromide, chemistry.chemical_element, Germanium, Atomic physics, 010306 general physics, Ground state, 01 natural sciences
Abstract

The lifetime $\ensuremath{\tau}({0}_{2}^{+})$ of $^{152}\mathrm{Gd}$ has been measured using fast electronic scintillation timing (FEST) with an array of high-purity germanium (HPGe) and cerium-doped lanthanum bromide (${\mathrm{LaBr}}_{3}$) detectors. $^{152}\mathrm{Gd}$ was produced via an $(\ensuremath{\alpha},n)$ reaction on a gold backed $^{149}\mathrm{Sm}$ target. The measured lifetime of $\ensuremath{\tau}({0}_{2}^{+})=96(6)\phantom{\rule{4pt}{0ex}}\mathrm{ps}$ corresponds to a reduced transition strength of $B(E2;{0}_{2}^{+}\ensuremath{\rightarrow}{2}_{1}^{+})=111(7)$ W.u. and an $E0$ transition strength of ${\ensuremath{\rho}}^{2}(E0)=39(3)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ to the ground state. This result provides experimental support for the validity of a correlation that would be a novel indicator for a quantum phase transition (QPT).

Published
2016
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21. Shape transitions between and within Zr isotopes

Author

T. Beck, C. Sotty, Rares Suvaila, J. Wiederhold, A. Turturica, P. Koseoglou, C. Costache, R. Mărginean, L. Stan, M. Boromiza, W. Witt, S. Toma, R.E. Mihai, S. Pascu, C. R. Nita, C. Mihai, N. Marginean, V. Werner, I.E. Dinescu, C. Clisu, S. Ujeniuc, Norbert Pietralla, P.R. John, A. Mitu, Andreea Iren Serban, A. Ionescu, A. Olacel, and A. Negret

Subjects
Materials science, Isotope, Physics, QC1-999, Rapid onset, SHELL model, Isotopes of zirconium, Neutron, Experimental work, Ground state, Molecular physics, Excitation
Abstract

The Zirconium isotopes across the N=56,58 neutron sub­shell closures have been of special interest since years, sparked by the near doubly-magic features of 96Zr and the subsequent rapid onset of collectivity with a deformed ground-state structure already in 100Zr. Recent state-of-the-art shell model approaches did not only correctly describe this shape-phase transition in the Zr isotopic chain, but alsothe coexistence of non-collective structures and pronounced collectivity especially in 96,98Zr. Theisotope 98Zr is located on the transition from spherical to deformed ground state structures. We summarize recent experimental work to obtain the B(E2) excitation strengths of the first 2+ state of98Zr, including a new experiment employing the recoil-distance Doppler-shift method following a two-neutron transfer reaction.

Published
2019
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22. A study on the transition between seniority-type and collective excitations in 204Po and 206Po

Author

J. Jolie, J.-M. Régis, T. Kröll, K. A. Gladnishki, A. Blazhev, Lisa Gerhard, D. Kocheva, Chistian Sürder, J. M. Keatings, G. Rainovski, V. Werner, J. Wiederhold, M. Stoyanova, Marcus Scheck, Kerstin Schomacker, V. Karayonchev, M. Djongolov, J. Sinclair, Konstantin Mashtakov, Norbert Pietralla, A. Esmaylzadeh, R. Kern, and O. Möller

Subjects
Physics, Isotope, 010308 nuclear & particles physics, QC1-999, Yrast, chemistry.chemical_element, 01 natural sciences, chemistry, TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY, Excited state, 0103 physical sciences, Quasiparticle, Seniority, Atomic physics, 010306 general physics, Polonium
Abstract

Low-lying yrast states in 204Po and 206Po have been investigated by the γ-γ fast timing technique with LaBr3(Ce) detectors. Excited states of these nuclei were populated in the 197Au(11B,4n) and the 198Pt(12C,4n) fusion-evaporation reactions, respectively, at the FN-Tandem Facility at the University of Cologne. The lifetimes of the 4+1 states in both nuclei were measured, along with an upper limit for the 2+1 state in 204Po. The preliminary results are discussed in the scope of the systematic behavior of the transition strengths between yrast states in polonium isotopes.

Published
2018
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23. Cladosporium species recovered from clinical samples in the United States

Author

Universitat Rovira i Virgili, Sandoval-Denis M; Sutton D; Martin-Vicente A; Cano-Lira J; Wiederhold N; Guarro J; Gené J, Universitat Rovira i Virgili, and Sandoval-Denis M; Sutton D; Martin-Vicente A; Cano-Lira J; Wiederhold N; Guarro J; Gené J

Abstract

© 2015 American Society for Microbiology. All Rights Reserved. Cladosporium species are ubiquitous, saprobic, dematiaceous fungi, only infrequently associated with human and animal opportunistic infections. We have studied a large set of Cladosporium isolates recovered from clinical samples in the United States to ascertain the predominant species there in light of recent taxonomic changes in this genus and to determine whether some could possibly be rare potential pathogens. A total of 92 isolates were identified using phenotypic and molecular methods, which included sequence analysis of the internal transcribed spacer (ITS) region and a fragment of the large subunit (LSU) of the nuclear ribosomal DNA (rDNA), as well as fragments of the translation elongation factor 1 alpha (EF-1-) and actin (Act) genes. The most frequent species was Cladosporium halotolerans (14.8%), followed by C. tenuissimum (10.2%), C. subuliforme (5.7%), and C. pseudocladosporioides (4.5%). However, 39.8% of the isolates did not correspond to any known species and were deemed to comprise at least 17 new lineages for Cladosporium. The most frequent anatomic site of isolation was the respiratory tract (54.5%), followed by superficial (28.4%) and deep tissues and fluids (14.7%). Species of the two recently described cladosporiumlike genera Toxicocladosporium and Penidiella are reported for the first time from clinical samples. In vitro susceptibility testing of 92 isolates against nine antifungal drugs showed a variety of results but high activity overall for the azoles, echinocandins, and terbinafine.

Published
2015

24. Level lifetimes and quadrupole moments from Coulomb excitation in the Ba chain and the N = 80 isotones

Author

G. Rainovski, O. Möller, E. Rapisarda, S. Zhu, D. Seweryniak, J. Wiederhold, Janne Pakarinen, Christian Bauer, C. Stahl, J. Leske, T. Möller, R. Stegmann, G. Guastalla, and Norbert Pietralla

Subjects
Isotope, Chemistry, Phonon, Physics, QC1-999, Nuclear Theory, Monte Carlo method, Shell (structure), chemistry.chemical_element, Barium, Coulomb excitation, Quadrupole, Atomic physics, Nuclear Experiment, Excitation
Abstract

The chain of Barium isotopes enables us to study experimentally the evolution of nuclear quadrupole collectivity from the shell closure at N = 82 towards neutron-deficient or neutron-rich deformed nuclei. The TU Darmstadt group has investigated several nuclei from stable 130;132 Ba up to radioactive 140;142 Ba with the projectile-Coulomb excitation technique including the use of the Doppler-shift attenuation method (DSAM). Lifetimes of quadrupole-collective states of 132 Ba and 140 Ba were obtained for the first time as well as the static electric quadrupole moments Q(2 + ) for 130;132 Ba and 140;142 Ba. The results are compared to Monte Carlo shell model and Beyond-Mean-Field calculations. The phenomenon of shell stabilization in the N = 80 isotones is further investigated by measurements of the B(E2;2 + ! 0 + ) values of 140 Nd and 142 Sm and comparison to the quasi-particle phonon model and shell-model calculations.

Published
2012
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25. Restoring the valence-shell stabilization in Nd 140

Author

H. De Witte, J. Snäll, O. Möller, Liam Gaffney, E. Giannopoulos, J. G. Cubiss, A. Blazhev, Radostina Zidarova, Amar Boukhari, D. Rosiak, V. Karayonchev, P. Reiter, M. Djongolov, N. Warr, P. Spagnoletti, A. Vogt, J. Jolie, D. Kocheva, M. Stoyanova, G. G. O'Neill, V. Werner, S. Thiel, P. A. Söderström, G. Rainovski, J. Wiederhold, Herbert Hess, K. A. Gladnishki, Norbert Pietralla, Marcus Scheck, Th. Kröll, Joakim Cederkäll, R. Stegmann, R. Kern, J. M. Keatings, A. Welker, C. Fransen, L. Kaya, Janne Pakarinen, and Helsinki Institute of Physics

Subjects
Physics, Science & Technology, Proton, 010308 nuclear & particles physics, Projectile, MIXED-SYMMETRY, Stochastic matrix, Analytical chemistry, Coulomb excitation, PROTON, 114 Physical sciences, 01 natural sciences, Physics, Nuclear, STATES, Physical Sciences, 0103 physical sciences, Matrix element, 010306 general physics, Valence electron, Beam (structure), Mixing (physics)
Abstract

A projectile Coulomb-excitation experiment was performed at the radioactive-ion beam facility HIE-ISOLDE at CERN to obtain E2 and M1 transition matrix elements of Nd-140 using the multistep Coulomb-excitation code GOSIA. The absolute M1 strengths, B(M1; 2(2)(-) -> 2(1)(+)) = 0.033(8)mu(2)(N), B(M1 ; 2(3)(+) -> 2(1)(+)) = 0.26(-0.10)(+0.11)mu(2)(N), and B(M1; 2(4)+ -> 2(1)(+))

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27. Angular momentum generation in nuclear fission.

Author

Wilson JN, Thisse D, Lebois M, Jovančević N, Gjestvang D, Canavan R, Rudigier M, Étasse D, Gerst RB, Gaudefroy L, Adamska E, Adsley P, Algora A, Babo M, Belvedere K, Benito J, Benzoni G, Blazhev A, Boso A, Bottoni S, Bunce M, Chakma R, Cieplicka-Oryńczak N, Courtin S, Cortés ML, Davies P, Delafosse C, Fallot M, Fornal B, Fraile L, Gottardo A, Guadilla V, Häfner G, Hauschild K, Heine M, Henrich C, Homm I, Ibrahim F, Iskra ŁW, Ivanov P, Jazrawi S, Korgul A, Koseoglou P, Kröll T, Kurtukian-Nieto T, Le Meur L, Leoni S, Ljungvall J, Lopez-Martens A, Lozeva R, Matea I, Miernik K, Nemer J, Oberstedt S, Paulsen W, Piersa M, Popovitch Y, Porzio C, Qi L, Ralet D, Regan PH, Rezynkina K, Sánchez-Tembleque V, Siem S, Schmitt C, Söderström PA, Sürder C, Tocabens G, Vedia V, Verney D, Warr N, Wasilewska B, Wiederhold J, Yavahchova M, Zeiser F, and Ziliani S

Abstract

When a heavy atomic nucleus splits (fission), the resulting fragments are observed to emerge spinning 1 ; this phenomenon has been a mystery in nuclear physics for over 40 years 2,3 . The internal generation of typically six or seven units of angular momentum in each fragment is particularly puzzling for systems that start with zero, or almost zero, spin. There are currently no experimental observations that enable decisive discrimination between the many competing theories for the mechanism that generates the angular momentum 4-12 . Nevertheless, the consensus is that excitation of collective vibrational modes generates the intrinsic spin before the nucleus splits (pre-scission). Here we show that there is no significant correlation between the spins of the fragment partners, which leads us to conclude that angular momentum in fission is actually generated after the nucleus splits (post-scission). We present comprehensive data showing that the average spin is strongly mass-dependent, varying in saw-tooth distributions. We observe no notable dependence of fragment spin on the mass or charge of the partner nucleus, confirming the uncorrelated post-scission nature of the spin mechanism. To explain these observations, we propose that the collective motion of nucleons in the ruptured neck of the fissioning system generates two independent torques, analogous to the snapping of an elastic band. A parameterization based on occupation of angular momentum states according to statistical theory describes the full range of experimental data well. This insight into the role of spin in nuclear fission is not only important for the fundamental understanding and theoretical description of fission, but also has consequences for the γ-ray heating problem in nuclear reactors 13,14 , for the study of the structure of neutron-rich isotopes 15,16 , and for the synthesis and stability of super-heavy elements 17,18 .

Published
2021
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