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1. Population of the 2(ms)(+) mixed-symmetry state of Ba-140 with the alpha-transfer reaction

Author

Stahl, C., Leske, J., Bauer, C., Bazzacco, D., Farnea, E., Gottardo, A., John, P. R., Michelagnoli, C., Pietralla, N., Reese, M., Sahin, E., Birkenbach, B., Bracco, A., Crespi, F. C. L., Angelis, G., Desesquelles, P., Eberth, J., Gadea, A., Goergen, A., Grebosz, J., Hess, H., Jolie, J., Jungclaus, A., Wolfram KORTEN, Lenzi, S. M., Lunardi, S., Menegazzo, R., Mengoni, D., Modamio, V., Napoli, D. R., Pullia, A., Quintana, B., Recchia, F., Reiter, P., Rosso, D., Salsac, M. D., Soderstrom, P. A., Stezowski, O., Theisen, Ch, Ur, C. A., Valiente-Dobon, J. J., Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM SNO), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Saclay-Univ. Paris-Sud, 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 de Physique Nucléaire de Lyon (IPNL), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Université 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
CE-142, [PHYS]Physics [physics], NUCLEI, Atom and Molecular Physics and Optics, INELASTIC NEUTRON-SCATTERING, ND-144, Atom- och molekylfysik och optik, INTERACTING-BOSON MODEL, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], PROTON, STRUCTURAL CHARACTERISTICS
Abstract

International audience; Background: Identification of proton-neutron mixed-symmetric one-quadrupole phonon excitations (the 2(ms)(+) states) of atomic nuclei provides information on the isovector part of the residual nucleon-nucleon interaction. It was predicted that the 2(ms)(+) state of particular nuclei close to the U(5) limit of the interacting boson model, in particular Ba-140, should be considerably populated by alpha-transfer reactions [C. E. Alonso et al., Phys. Rev. C 78, 017301 (2008)].Purpose: We aim at the identification of the 2(ms)(+) mixed-symmetry state (MSS) of radioactive Ba-140 and investigate its population by the alpha-transfer reaction as a suitable tool to selectively populate MSSs and as a potential new signature for its mixed-symmetric character.Method: A gamma-ray spectroscopy experiment was performed in inverse kinematics in order to populate the 2(ms)(+) state of Ba-140 by alpha-transfer from a C-nat target on Xe-136 beam ions. The population of the candidate for the 2(ms)(+) state of Ba-140 was measured relative to the population of the 2(1)(+) state.Results: The candidate for the 2(ms)(+) state of Ba-140 was populated by a transfer three times weaker than predicted. Another 2(+) state that can be ruled out as the MSS was in turn as strongly populated by the a transfer as predicted for the MSS.Conclusions: The relative population of 2(+) states by alpha-transfer cannot serve as a new signature for MSSs, since other 2(+) states are also strongly populated. Nevertheless, the substantial population of the MSS candidate of Ba-140 by alpha transfer qualifies this type of reaction as suitable tool to excite MSSs and study their electromagnetic decay properties.

Published
2015
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2. Light and heavy transfer products in Xe136+U238 multinucleon transfer reactions

Author

Vogt, A., Birkenbach, B., Reiter, P., Corradi, L., Mijatovic, T., Montanari, D., Szilner, S., Bazzacco, D., Bowry, M., Bracco, A., Bruyneel, B., Crespi, F. C. L., Angelis, G., Desesquelles, P., Eberth, J., Farnea, E., Fioretto, E., Gadea, A., Geibel, K., Gengelbach, A., Giaz, A., Gorgen, A., Gottardo, A., Grebosz, J., Hess, H., John, P. R., Jolie, J., Judson, D. S., Jungclaus, A., Wolfram KORTEN, Leoni, S., Lunardi, S., Menegazzo, R., Mengoni, D., Michelagnoli, C., Montagnoli, G., Napoli, D., Pellegri, L., Pollarolo, G., Pullia, A., Quintana, B., Radeck, F., Recchia, F., Rosso, D., Sahin, E., Salsac, M. D., Scarlassara, F., Soderstrom, P. A., Stefanini, A. M., Steinbach, T., Stezowski, O., Szpak, B., Theisen, Ch, Ur, C., Valiente-Dobon, J. J., Vandone, V., Wiens, A., 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, 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), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, 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), 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), CSNSM SNO, 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)-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)-Centre de Sciences Nucléaires et de Sciences de la Matière (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), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon

Subjects
[PHYS]Physics [physics], COLLISIONS, CM-248, NUCLEI, Nuclear Theory, U-238, GAMMA-RAY TRACKING, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], MAGNETIC SPECTROMETER PRISMA, Physical Sciences, ACTINIDE PRODUCTION, Fysik, SCATTERING, AGATA, Nuclear Experiment, DETECTOR
Abstract

International audience; Background: Multinucleon transfer reactions (MNT) are a competitive tool to populate exotic neutron-rich nuclei in a wide region of nuclei, where other production methods have severe limitations or cannot be used at all.Purpose: Experimental information on the yields of MNT reactions in comparison with theoretical calculations are necessary to make predictions for the production of neutron-rich heavy nuclei. It is crucial to determine the fraction of MNT reaction products which are surviving neutron emission or fission at the high excitation energy after the nucleon exchange.Method: Multinucleon transfer reactions in Xe-136 + U-238 have been measured in a high-resolution gamma-ray/particle coincidence experiment. The large solid-angle magnetic spectrometer PRISMA coupled to the high-resolution Advanced Gamma Tracking Array (AGATA) has been employed. Beamlike reaction products after multinucleon transfer in the Xe region were identified and selected with the PRISMA spectrometer. Coincident particles were tagged by multichannel plate detectors placed at the grazing angle of the targetlike recoils inside the scattering chamber.Results: Mass yields have been extracted and compared with calculations based on the GRAZING model for MNT reactions. Kinematic coincidences between the binary reaction products, i.e., beamlike and targetlike nuclei, were exploited to obtain population yields for nuclei in the actinide region and compared to x-ray yields measured by AGATA.Conclusions: No sizable yield of actinide nuclei beyond Z = 93 is found to perform nuclear structure investigations. In-beam gamma-ray spectroscopy is feasible for few-neutron transfer channels in U and the -2p channel populating Th isotopes.

Published
2015
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3. Isospin Character of Low-Lying Pygmy Dipole States in Pb208 via Inelastic Scattering of O17 Ions

Author

Crespi, F. C. L., Bracco, A., Nicolini, R., Mengoni, D., Pellegri, L., Lanza, E. G., Leoni, S., Maj, A., Kmiecik, M., Avigo, R., Benzoni, G., Blasi, N., Boiano, C., Bottoni, S., Brambilla, S., Camera, F., Ceruti, S., Giaz, A., Million, B., Morales, A. I., Vandone, V., Wieland, O., Bednarczyk, P., Ciemala, M., Grebosz, J., Krzysiek, M., Mazurek, K., Zieblinski, M., Bazzacco, D., Bellato, M., Birkenbach, B., Bortolato, D., Calore, E., Cederwall, B., Charles, L., Angelis, G., Desesquelles, P., Eberth, J., Farnea, E., Gadea, A., Gorgen, A., Gottardo, A., Isocrate, R., Jolie, J., Jungclaus, A., Karkour, N., Wolfram KORTEN, Menegazzo, R., Michelagnoli, C., Molini, P., Napoli, D. R., Pullia, A., Recchia, F., Reiter, P., Rosso, D., Sahin, E., Salsac, M. D., Siebeck, B., Siem, S., Simpson, J., Soderstrom, P. A., Stezowski, O., Theisen, Ch, Ur, C., Valiente-Dobon, J. J., Istituto Nazionale di Fisica Nucleare, Sezione di Catania (INFN), Università degli studi di Catania = University of Catania (Unict), 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), CSNSM SNO, Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse (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)-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)-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), CSNSM ELEC, 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)-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 de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, 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), Università degli studi di Catania [Catania], Université de Strasbourg (UNISTRA)-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)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11)-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)-Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), 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
[PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 24.30.Cz, 24.10.Eq, 25.55.Ci, 27.80.+w
Abstract

The properties of pygmy dipole states in Pb208 were investigated using the Pb208(O17, O17'γ) reaction at 340 MeV and measuring the γ decay with high resolution with the AGATA demonstrator array. Cross sections and angular distributions of the emitted γ rays and of the scattered particles were measured. The results are compared with (γ, γ′) and (p, p′) data. The data analysis with the distorted wave Born approximation approach gives a good description of the elastic scattering and of the inelastic excitation of the 2+ and 3− states. For the dipole transitions a form factor obtained by folding a microscopically calculated transition density was used for the first time. This has allowed us to extract the isoscalar component of the 1− excited states from 4 to 8 MeV.

Published
2014
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4. Shape evolution in the neutron-rich osmium isotopes: Prompt gamma-ray spectroscopy of Os196

Author

John, P. R., Modamio, V., Valiente-Dobon, J. J., Mengoni, D., Lunardi, S., Rodriguez, T. R., Bazzacco, D., Gadea, A., Wheldon, C., Alexander, T., Angelis, G., Ashwood, N., Barr, M., Benzoni, G., Birkenbach, B., Bizzeti, P. G., Bizzeti-Sona, A. M., Bottoni, S., Bowry, M., Bracco, A., Browne, F., Bunce, M., Camera, F., Cederwall, B., Corradi, L., Crespi, F. C. L., Desesquelles, P., Eberth, J., Farnea, E., Fioretto, E., Goergen, A., Gottardo, A., Grebosz, J., Grente, L., Hess, H., Jungclaus, A., Kokalova, Tz, Korichi, A., Wolfram KORTEN, Kusoglu, A., Lenzi, S., Leoni, S., Ljungvall, J., Maron, G., Meczynski, W., Melon, B., Menegazzo, R., Michelagnoli, C., Mijatovic, T., Million, B., Molini, P., Montagnoli, G., Montanari, D., Napoli, D. R., Nolan, P., Oziol, Ch, Podolyak, Zs, Pollarolo, G., Pullia, A., Quintana, B., Recchia, F., Reiter, P., Roberts, O. J., Rosso, D., Sahin, E., Salsac, M. D., Scarlassara, F., Sferrazza, M., Simpson, J., Soderstrom, P. A., Stefanini, A. M., Stezowski, O., Szilner, S., Theisen, Ch, Ur, C. A., and Walshe, J.

Subjects
Nuclear Theory, Nuclear Experiment
Abstract

The shape transition in the neutron-rich Os isotopes is studied by investigating the neutron-rich 196Os nucleus through in-beam γ-ray spectroscopy using a two-proton transfer reaction from a 198Pt target to a 82Se beam. The beam-like recoils were detected and identified with the large-acceptance magnetic spectrometer PRISMA, and the coincident γ rays were measured with the advanced gamma tracking array (AGATA) demonstrator. The de-excitation of the low-lying levels of the yrast-band of 196Os were identified for the first time. The results are compared with state-of-the-art beyond-mean-field calculations, performed for the even-even 188-198Os isotopes. The new results suggest a smooth transition in the Os isotopes from a more axial rotational behavior towards predominately vibrational nuclei through triaxial configurations. An almost perfect γ-unstable/triaxial rotor yrast band is predicted for 196Os which is in agreement with the experimentally measured excited states

Published
2014

5. Collective nature of low-lying excitations in Zn-70,Zn-72,Zn-74 from lifetime measurements using the AGATA spectrometer demonstrator

Author

Louchart, C., Obertelli, A., Goergen, A., Wolfram KORTEN, Bazzacco, D., Birkenbach, B., Bruyneel, B., Clement, E., Coleman-Smith, P. J., Corradi, L., Curien, D., Angelis, G., France, G., Delaroche, J. P., Dewald, A., Didierjean, F., Doncel, M., Duchene, G., Eberth, J., Erduran, M. N., Farnea, E., Finck, C., Fioretto, E., Fransen, C., Gadea, A., Girod, M., Gottardo, A., Grebosz, J., Habermann, T., Hackstein, M., Huyuk, T., Jolie, J., Judson, D., Jungclaus, A., Karkour, N., Klupp, S., Kruecken, R., Kusoglu, A., Lenzi, S. M., Libert, J., Ljungvall, J., Lunardi, S., Maron, G., Menegazzo, R., Mengoni, D., Michelagnoli, C., Million, B., Molini, P., Moeller, O., Montagnoli, G., Montanari, D., Napoli, D. R., Orlandi, R., Pollarolo, G., Prieto, A., Pullia, A., Quintana, B., Recchia, F., Reiter, P., Rosso, D., Rother, W., Sahin, E., Salsac, M. D., Scarlassara, F., Schlarb, M., Siem, S., Singh, P. P., Soderstrom, P. A., Stefanini, A. M., Stezowski, O., Sulignano, B., Szilner, S., Theisen, Ch, Ur, C. A., Valiente-Dobon, J. J., and Zielinska, M.

Subjects
Subatomär fysik, Subatomic Physics
Abstract

WOS: 000318527400007 Background: Neutron-rich nuclei with protons in the fp shell show an onset of collectivity around N=40. Spectroscopic information is required to understand the underlying mechanism and to determine the relevant terms of the nucleon-nucleon interaction that are responsible for the evolution of the shell structure in this mass region. Methods: We report on the lifetime measurement of the first 2(+) and 4(+) states in Zn-70,Zn-72 ,Zn-74 and the first 6(+) state in Zn-72 using the recoil distance Doppler shift method. The experiment was carried out at the INFN Laboratory of Legnaro with the AGATA demonstrator, first phase of the Advanced Gamma Tracking Array of highly segmented, high-purity germanium detectors coupled to the PRISMA magnetic spectrometer. The excited states of the nuclei of interest were populated in the deep inelastic scattering of a Ge-76 beam impinging on a U-238 target. Results: The maximum of collectivity along the chain of Zn isotopes is observed for Zn-72 at N=42. An unexpectedly long lifetime of 20(-5.2)(+1.8) ps was measured for the 4(+) state in Zn-74. Conclusions: Our results lead to small values of the B(E2;4(1)(+) -> 21(+))/B(E2;2(1)(+->)0(1)(+)) ratio for Zn-72,Zn-74, suggesting a significant noncollective contribution to these excitations. These experimental results are not reproduced by state-of-the-art microscopic models and call for lifetime measurements beyond the first 2(+) state in heavy zinc and nickel isotopes. European Union Seventh Framework Program FP7/2007-2013 [DPN/N190/AGATA/2009]; Polish MNiSW [DPN/N190/AGATA/2009]; Spanish Ministerio de Ciencia e Innovacion [FPA2011-29854-C04]; BMBF [05P12RDFN8, 06DA9040I]; [262010 ENSAR]; Science and Technology Facilities Council [ST/F004052/1, ST/J000108/1] The authors are grateful to the ALPI accelerator team for quality of the beam delivered during the experiment. B. Lommel and J. Steiner from the GSI are acknowledged for their help in preparing the Uranium target and the opportunity to use the GSI target laboratory. The authors would like to thank F. Nowacki and K. Sieja for enlightening discussions and their suggestions to improve the manuscript. This work has been partly financed by the European Union Seventh Framework Program FP7/2007-2013 under Grant Agreement No. 262010 ENSAR, the Polish MNiSW under Grant No. DPN/N190/AGATA/2009, the Spanish Ministerio de Cienciae Innovacion under Contract No. FPA2011-29854-C04, and the BMBF under Grant Nos. 05P12RDFN8 and 06DA9040I.

Published
2013

6. Lifetime measurements on fission fragments in the A similar to 100 region

Author

Grente, L., Salsac, M. D., Wolfram KORTEN, Goergen, A., Hagen, T. W., Braunroth, T., Bruyneel, B., Celikovic, I., Clement, E., Delaune, O., Dijon, A., Drouart, A., Ertuerk, S., Farget, F., France, G., Gottardo, A., Hackstein, M., Jacquot, B., Libert, J., Litzinger, J., Ljungvall, J., Louchart, C., Michelagnoli, C., Napoli, D. R., Navin, A., Pillet, N., Pipidis, A., Recchia, F., Rejmund, M., Rother, W., Sahin, E., Schmitt, C., Siem, S., Sulignano, B., Valiente-Dobon, J. J., Zell, K. O., Chatillon, A, Farget, F, Faust, H, Fioni, G, Goutte, D, Goutte, H, Napoli, Daniel Ricardo -- 0000-0002-8154-6958, KORTEN, Wolfram -- 0000-0002-3940-0816, Delaune, Olivier -- 0000-0002-1087-2342, Celikovic, Igor -- 0000-0002-5642-4393, Gorgen, Andreas -- 0000-0003-1916-9941, Recchia, Francesco -- 0000-0002-8428-0112, de France, Gilles -- 0000-0002-7439-1759, Clement, Emmanuel -- 0000-0003-1887-717X, Sahin, Eda -- 0000-0003-0683-5140, GOTTARDO, Andrea -- 0000-0002-0390-5767, and [Grente, L. -- Salsac, M. -D. -- Korten, W. -- Bruyneel, B. -- Drouart, A. -- Louchart, C. -- Sulignano, B.] CEA Saclay, IRFU Serv Phys Nucl, F-91191 Gif Sur Yvette, France -- [Goergen, A. -- Hagen, T. W. -- Siem, S.] Univ Oslo, Dept Phys, N-0316 Oslo, Norway -- [Braunroth, T. -- Hackstein, M. -- Litzinger, J. -- Rother, W. -- Zell, K. O.] Univ Cologne, Inst Kernphys, D-50937 Cologne, Germany -- [Celikovic, I. -- Clement, E. -- Delaune, O. -- Dijon, A. -- Farget, F. -- de France, G. -- Jacquot, B. -- Navin, A. -- Rejmund, M. -- Schmitt, C.] GANIL, CEA DSM, CNRS IN2P3, F-14706 Caen, France -- [Celikovic, I.] Univ Belgrade, Inst Nucl Sci VINCA, YU-11000 Belgrade, Serbia -- [Ertuerk, S.] Nigde Univ, Fac Sci, Nigde, Turkey -- [Gottardo, A. -- Michelagnoli, C. -- Napoli, D. R. -- Pipidis, A. -- Recchia, F. -- Sahin, E. -- Valiente-Dobon, J. J.] Ist Nazl Fis Nucl, Lab Nazl Legnaro, I-35020 Legnaro, Italy -- [Libert, J. -- Pillet, N.] CEA, DAM, DIF, F-91297 Arpajon, France -- [Ljungvall, J.] Univ Paris 11, F-91405 Orsay, France -- [Ljungvall, J.] CNRS, CSNSM, IN2P3, F-91405 Orsay, France

Subjects
Nuclear Theory, Nuclear Experiment
Abstract

5th International Workshop on Nuclear Fission and Fission Product Spectroscopy (FISSION) -- MAY 28-31, 2013 -- Caen, FRANCE, WOS: 000342384500002, Lifetimes of first 4(+) and 6(+) states have been measured in neutron-rich isotopes of Zr, Mo, Ru and Pd using the recoil distance Doppler shift method at GANIL. The nuclei were produced through a fusion-fission reaction in inverse kinematics. The fission fragments were fully identified in the large-acceptance VAMOS spectrometer and gamma -rays were detected in coincidence with the EXOGAM germanium array. Lifetimes of excited states in the range of 1-100 ps were measured with the Cologne plunger. Preliminary lifetime results are presented as well as a discussion on the evolution of the collectivity in this region., ILL, CEA DSM & DAM, CNRS IN2P3, ENSICAEN, GANIL, Scientific and Technological Council of Turkey [210T043], S. Erturk acknowledges the Scientific and Technological Council of Turkey for their support with project number 210T043.

Published
2013

7. Shape coexistence in light krypton isotopes

Author

Clement, E., Gorgen, A., Bouchez, E., Chatillon, A., Wolfram KORTEN, Le Coz, Y., Theisen, C., Andreoiu, C., Becker, F., Blank, B., Borcea, C., Buta, A., Butler, P., Casandjian, J. M., Catford, W. N., Czosnyka, T., Emsallem, A., France, G., Genevey, J., Gerl, J., Hannachi, F., Hauschild, K., Herzberg, R. D., Hurstel, A., Iwanicki, J., Jenkins, D., Jones, G., Lewitowicz, M., Lucas, R., Matea, I., Negoita, F., Santos, F. D., Pantelica, D., Pinston, J., Rahkila, P., Rejmund, M., Sletten, G., Stanoiu, M., Timis, C., Wadsworth, R., Wilson, J. N., Zielinska, M., Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée (DAPNIA), 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), 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 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), 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), 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), D. Seweryniak, Teng Lek Khoo, 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), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université Claude Bernard Lyon 1 (UCBL), 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), 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 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
Yrast, Krypton, 27.50.+e, 23.20.Lv, Isotopes of krypton, chemistry.chemical_element, deformed nuclei, 020206 networking & telecommunications, electron spectroscopy, 02 engineering and technology, Coulomb excitation, nuclear fragmentation, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Electron spectroscopy, nuclei with mass number 59 to 89, Matrix (mathematics), nuclear isomerism, chemistry, Excited state, Diagonal matrix, 0202 electrical engineering, electronic engineering, information engineering, 020201 artificial intelligence & image processing, Atomic physics, isotopes, nuclear shape, krypton
Abstract

Matière Nucléaire - Commune avec NEX et ENL; International audience; Shape coexistence in the light krypton isotopes was studied in a series of experiments at GANIL using various experimental techniques. A new low-lying $0^+$ state, a so-called shape isomer, was found in delayed conversion-electron spectroscopy after fragmentation reactions. The systematics of such low-lying $0+^$ states suggests that the ground states of the isotopes $^{78}$Kr and $^{76}$Kr have prolate deformation, while states with prolate and oblate shape are practically degenerate and strongly mixed in $^{74}$Kr, and that the oblate configuration becomes the ground state in $^{72}$Kr. This scenario was tested in experiments performing low-energy Coulomb excitation of radioactive $^{76}$Kr and $^{74}$Kr beams from the SPIRAL facility. Both transitional and diagonal electromagnetic matrix elements were extracted from the observed $\gamma$-ray yields. The results find the prolate shape for the ground-state bands in $^{76}$Kr and $^{74}$Kr and an oblate deformation for the excited $2^{+}_{2}$ state in $^{74}$Kr, confirming the proposed scenario of shape coexistence

Published
2004
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8. Investigation of shape-coexistence in $^{74}$Kr, $^{74}$Se

Author

Becker, F., Wolfram KORTEN, Hannachi, F., Paris, P., Buforn, N., Chandler, C., Jansen, A., Houry, M., Le Coz, Y., Liang, C. F., Lopez-Martens, A., Lucas, R., Mergel, E., Regan, P. H., Schonwasser, G., Theisen, C., Lorgeril, Jocelyne, 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
[PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]
Published
1999

9. Hot superheavy nuclei seen with the GDR gamma-decay

Author

Maj, A., Tveter, T. S., Gaardhoje, J. J., Herskind, B., Sletten, G., Ramsoy, T., Atac, A., Wolfram KORTEN, Bracco, A., Camera, F., Mattiuzzi, M., Million, B., Pignanelli, M., Bacelar, J., Buda, A., Ploeg, H. V. D., Krolas, W., Nifenecker, H., Schussler, F., Pinston, J. A., Menthe, A., Paul, P., Hofman, D. J., Dioszegi, I., Schadmand, S., bibliotheque, LPSC, 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
[PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]
Published
1995

10. Thallium isotopes a set of identical superdeformed bands

Author

Azaiez, F., Beausang, C. W., Deboer, J., Deleplanque, M. A., Diamond, R. M., Draper, J. E., Kelly, W. H., Wolfram KORTEN, Macchiavelli, A. O., Rubel, E., Rohn, M., Stephens, F. S., Becker, J. A., Brinkman, M. J., Cizewski, J. A., Henry, E. A., Kuhnert, A., Wang, T. F., Yates, S. W., 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), and Blanchet, Marie-Christine

Subjects
[PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]
Published
1991

11. Coulomb excitation studies of shape coexistence in atomic nuclei.

Author

Andreas Görgen and Wolfram Korten

Subjects
*COULOMB excitation, *NUCLEAR excitation, *ATOMIC nucleus, *QUADRUPOLE moments, *ELECTROMAGNETIC theory
Abstract

Low-energy Coulomb excitation provides a well-understood means of exciting atomic nuclei and allows measuring electromagnetic moments that can be directly related to the nuclear shape. The availability of radioactive ion beams (RIBs) at energies near the Coulomb barrier has made it possible to study shape coexistence in a variety of short-lived exotic nuclei. This review presents a short overview of the methods related to multi-step Coulomb excitation experiments, followed by a discussion of several examples. The focus is on two mass regions where recent Coulomb excitation experiments have contributed to the quantitative understanding of shape coexistence: nuclei with mass near the N = Z line and nuclei with near neutron number N = 60. Experimental results are summarized and their significance for understanding shape coexistence is discussed. Experimental observables such as quadrupole moments and electromagnetic transition strengths represent furthermore important benchmarks for advancing theoretical nuclear structure models. With several new RIB facilities planned and under construction, Coulomb excitation will remain to be an important tool to extend the studies of nuclear shapes toward more exotic systems, and to obtain a more comprehensive and quantitative understanding of shape coexistence. [ABSTRACT FROM AUTHOR]

Published
2016
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12. Shape evolution in neutron-rich Zr, Mo and Ru isotopes around mass A=100

Author

Ansari, Saba, STAR, ABES, Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, 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), Université Paris-Saclay, Wolfram Korten, 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 Paris Saclay (COmUE)

Subjects
[PHYS.NUCL] Physics [physics]/Nuclear Theory [nucl-th], Temps de vie, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], Physique nucléaire, [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear physics, Spectroscopie gamma, Lifetimes, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Gamma spectroscopy, Structure nucléaire, [PHYS.PHYS.PHYS-INS-DET] Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Nuclear structure, Déformation et collectivité, Deformation and collectivity
Abstract

The shape of an atomic nucleus, ie. the deviation of its mass distribution from sphericity, is a fundamental property and governed by a delicate interplay of macroscopic and microscopic effects, such as the liquid-drop like binding energy and the nuclear shell structure, respectively. Studying nuclear shape properties using gamma ray spectroscopic methods allows detailed tests of different nuclear models, which were originally developed for stable nuclei. We proposed a project to study the evolution of nuclear shapes in exotic nuclei, far from the valley of stability, specifically in neutron-rich nuclei in the isotopic chains from Zr (Z=40) to Pd (Z=46). Usually, nuclear shapes are slowly evolving from spherical shapes around closed-shell or (doubly-) magic nuclei to elongated (prolate) shapes in nuclei with many valence nucleons. The nuclei of interest, however, show rapidly evolving patterns of excited states, which can be interpreted as rapid variations of the nuclear shape, including the rare observation of oblate (disk-like) and triaxial shapes. So far the known properties for these nuclei are (mainly) limited to excitation energies. Information on the nuclear collectivity, which can be deduced from the lifetime of the excited states, are sparse, while direct information of the shape is practically non existing. The simplest estimate of nuclear deformation in even-even nuclei can be obtained from the energy of the first 2⁺ state. For Sr (Z = 38) and Zr (Z = 40) isotopes this energy is observed to decrease dramatically at N = 60, while its evolution is much more gradual in Mo nuclei (Z = 42). Precise lifetime measurements provide a key ingredient in the systematic study of the evolution of nuclear deformation and the degree of collectivity in this region. Neutron-rich nuclei in the mass region of A = 100-120 were populated through the fusion-fission reaction of a ²³⁸U beam at 6.2 MeV/u on a ⁹Be target. The compound nucleus ²⁴⁷Cm was produced at an excitation energy of around 45 MeV before undergoing fission. The setup used for this study comprised the high-resolution mass spectrometer VAMOS in order to identify the nuclei in Z and A, the Advanced gamma ray Tracking Array AGATA of 35 germanium detectors to perform gamma ray spectroscopy, as well as a plunger mechanism to measure lifetimes down to a few ps using the Recoil Distance Doppler Shift method (RDDS). In addition, the target was surrounded by 24 Lanthanum Bromide (LaBr₃) detectors for a fast-timing measurement of lifetimes longer than 100 ps. The sophisticated set of spectrometers used in this experiment allowed measurement of nuclear lifetimes in a range from 100’s of picoseconds down to a few picoseconds. In this thesis, we will report on new lifetime results for short-lived states in neutron-rich (A ~ 100) nuclei, with an emphasis on the Zr, Mo and Ru chains. We will discuss the experimental techniques used to evaluate the lifetimes as well as their interpretation in terms of state-of-the-art nuclear structure models., La forme d’un noyau, ou la déviation de la distribution en masse par rapport à une forme sphérique, est une des propriétés fondamentales du noyau. Elle est gouvernée à la fois par des effets macroscopiques et microscopiques, tels que l'énergie de liaison donnée par le modèle de la goutte liquide ou la structure en couche du noyau, respectivement. L’étude de la forme des noyaux exotiques par spectrométrie gamma permet de tester finement différents modèles théoriques initialement développés pour les noyaux stables. L’objectif de cette thèse est l’étude de l’évolution de la forme des noyaux exotiques riches en neutrons dans les chaînes isotopiques allant du Zr (Z=40) au Pd (Z=46). Le plus souvent, la forme des noyaux évolue lentement de la forme sphérique, près des fermetures de couche ou des noyaux magiques (ou doublement magiques), à des formes allongées (prolate), pour des noyaux avec de nombreux nucléons de valence. Cependant, Les noyaux auxquels nous nous intéressons ont tendance à avoir des états excités qui évoluent rapidement en fonction du nombre de neutrons, ce qui peut être interprété comme des variations rapides de la forme du noyau. Ceci inclue dans de rares cas l'observation d'états de forme aplatie (oblate) et triaxiale. Jusqu'à présent, les propriétés connues de ces noyaux se limitent (principalement) aux énergies d'excitation. Les informations sur le degré de collectivité nucléaire (que l'on peut déduire de la durée de vie des états excités) sont rares, tandis que les informations directes de forme sont pratiquement inexistantes. L'estimation la plus simple de la déformation nucléaire dans les noyaux pairs peut être obtenue à partir de l'énergie du premier état 2⁺. Pour les isotopes du Sr (Z = 38) et du Zr (Z = 40), il a été observé que cette énergie diminue considérablement à N = 60, alors que son évolution est beaucoup plus progressive pour les isotopes du Mo (Z = 42). Des mesures précises de durée de vie constituent un élément clé de l'étude systématique de l'évolution de la déformation nucléaire et du degré de collectivité dans cette région. Des noyaux riches en neutrons dans la région de masse A = 100-120 ont été peuplés par la réaction de fusion-fission d'un faisceau de ²³⁸U à 6,2 MeV/u sur une cible ⁹Be. Le noyau composé ²⁴⁷Cm était produit à une énergie d'excitation de ∼45 MeV avant de fissionner. Le dispositif expérimental utilisé pour cette étude comprenait le spectromètre de masse de haute résolution VAMOS pour l'identification les noyaux en Z et A, le réseau de 35 détecteurs au germanium AGATA (Advanced γ-ray Tracking Array) AGATA, pour la spectroscopie de rayons γ, ainsi qu'un mécanisme de "plunger" pour mesurer la durée de vie jusqu'à quelques ps par la méthode RDDS (Recoil Distance Doppler Shift). De plus, la cible était entourée de 24 détecteurs LaBr₃ (Bromure de lanthane) pour mesurer des durées de vie plus de 100 ps avec la méthode du "fast-timing". La combinaison de spectromètres sophistiqués utilisée dans cette expérience a permis de mesurer des durées de vie d'états nucléaires allant de 100 picosecondes à quelques picosecondes. Dans cette thèse, nous exposerons de nouveaux résultats pour les états à courte durée de vie dans les noyaux riches en neutrons A∼100, en mettant l'accent sur les chaînes des Zr, Mo et Ru. Nous discuterons des techniques expérimentales utilisées pour évaluer les durées de vie ainsi que l'interprétation de celles-ci à l'aide de modèles de structures nucléaires récents.

Published
2019

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