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18 results on '"Stefanova E.A."'

1. Fast-timing measurements in neutron-rich odd-mass zirconium isotopes using LaBr3:Ce detectors coupled with Gammasphere

Author

Gamba E.R., Lalkovski S., Rudigier M., Bruce A.M., Bottoni S., Carpenter M.P., Zhu S., Ayangeakaa A.D., Anderson J.T., Berry T.A., Burrows I., Carroll R.J., Copp P., Carmona Gallardo M., Cullen D.M., Daniel T., Greene J.P., Gurgi L.A., Hartley D.J., Ilieva R., Ilieva S., Janssens R.V.F., Kondev F.G., Kröll T., Lane G.J., Lauritsen T., Lazarus I., Lotay G., Fernández Martínez G., Podolyák Zs., Pucknell V., Reed M., Regan P.H., Rohrer J., Sethi J., Seweryniak D., Shand C.M., Simpson J., Smolen M., Stefanova E.A., Vedia V., and Yordanov O.

Subjects
Physics, QC1-999
Abstract

A fast-timing experiment was performed at the Argonne National Laboratory to measure the lifetimes of the lowest lying states of nuclei belonging to the deformed regions around mass number A≃110 and A≃150. These regions were populated via spontaneous fission of 252Cf and the gamma radiation following the decay of excited states in the fission fragments was measured using 51 Gammasphere detectors coupled with 25 LaBr3:Ce detectors. A brief description of the acquisition system and some preliminary results from the fast-timing analysis of the fission fragment 100Zr are presented. The lifetime value of τ = 840(65) ps was found for the 2+ state in 100Zr consistent within one standard deviation of the adopted value with 791 +26 -35ps. This is associated with a quadrupole deformation parameter of 0.36(2) which is within one standard deviation of the literature value of 0.3556+82 -57.

Published
2018
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3. Fast-timing measurements in the ground-state band of Pd 114

Author

Rohrer, J., Regan, P.H., Ayangeakaa, A.D., Gurgi, L.A., Berry, T.A., Sethi, J., Carpenter, M.P., Bruce, A.M., Carmona Gallardo, M., Vedia, V., Lauritsen, T., Greene, J.P., Shand, C.M., Anderson, J.T., Rudigier, M., Ilieva, S., Copp, P., Lazarus, I., Smoleń, M., Simpson, J., Kondev, F.G., Pucknell, V., Gamba, E.R., Kröll, T., Yordanov, O., Niţǎ, C.R., Stefanova, E.A., Reed, M., Lalkovski, S., Fernández Martínez, G., Seweryniak, D., Ilieva, R., Hartley, D.J., Daniel, T., Lotay, G., Bottoni, S., Cullen, D.M., Burrows, I., Zhu, S., Lane, G.J., Carroll, R.J., and Podolyák, Z.

Abstract

Using a hybrid Gammasphere array coupled to 25 LaBr3(Ce) detectors, the lifetimes of the first three levels of the yrast band in Pd114, populated via Cf252 decay, have been measured. The measured lifetimes are τ2+=103(10)ps, τ4+=22(13)ps, and τ6+≤10ps for the 21+, 41+, and 61+ levels, respectively. Palladium-114 was predicted to be the most deformed isotope of its isotopic chain, and spectroscopic studies have suggested it might also be a candidate nucleus for low-spin stable triaxiality. From the lifetimes measured in this work, reduced transition probabilities B(E2;J→J-2) are calculated and compared with interacting boson model, projected shell model, and collective model calculations from the literature. The experimental ratio RB(E2)=B(E2;41+→21+)/B(E2;21+→01+)=0.80(42) is measured for the first time in Pd114 and compared with the known values RB(E2) in the palladium isotopic chain: the systematics suggest that, for N=68, a transition from γ-unstable to a more rigid γ-deformed nuclear shape occurs.

Published
2019
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4. New yrast and non-yrast states in $^{136}$I and medium-spin structure of $^{136}$I and $^{136}$Xe : Roles of the proton d$_{5/2}$ and the neutron h$_{9/2}$ orbitals beyond $^{132}$Sn

Author

Lozeva, R., Stefanova, E.A., Naïdja, H., Nowacki, F., Rząca-Urban, T., Wisniewski, J., Urban, W., Ahmad, I., Blanc, A., De France, G., Didierjean, F., Duchêne, G., Faust, H., Greene, J.P., Köster, U., Mutti, P., Simpson, G., Smith, A.G., Soldner, T., Ur, C.A., Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg (UNISTRA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut Laue-Langevin (ILL), ILL, Grand Accélérateur National d'Ions Lourds (GANIL), Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Université de Strasbourg (UNISTRA)-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 Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), 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), and Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])

Subjects
[PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Structure
Abstract

International audience; In this article we report on the observation of new yrast and non-yrast states in 136I, populated in the prompt-γ spectroscopy EXILL campaign at the ILL using both 235U(n,f) and 241Pu(n,f) reactions. We propose an extension of the level scheme and interpretation of the new spectroscopic results in comparison to state-of-the-art shell-model calculations. We discuss the role of the proton d5/2 orbital in the structure of this nucleus with Z=53 and the energy split between the πd5/2andπg7/2 orbitals. We also provide a complete overview of all experimental information about this nucleus and include new data from 252Cf,248Cm fission and β decay of 136Te to 136I. We give a new interpretation of 136I and its decay to 136Xe in terms of the influence of the neutron h9/2 orbital and the Gamow-Teller strength for N=83.

Published
2018

5. Structure of the neutron mid-shell nuclei 111,11347Ag64,66

Author

Lalkovski, S., Stefanova, E.A., Kisyov, S., Korichi, A., Bazzacco, D., Bergstrom, M., Gorgen, A., Herskind, B., Hubel, H., Jansen, A., Khoo, T.L., Kutsarova, T., Lopez-Martens, A., Minkova, A., Podolyak, Zsolt, Schonwasser, G., and Yordanov, O.

Subjects
Condensed Matter::Quantum Gases, Nuclear Theory, Nuclear Experiment
Abstract

111Ag and 113Ag were produced in induced fission reaction, where yrast and near-yrast states were populated. To interpret the new data the Interacting Boson-Fermion model was used. A good agreement with the experimental data is achieved, suggesting that the two Ag nuclei have a well developed collectivity, superimposed on \pi g9/2-3 excitations previously observed throughout the entire isotopic chain.

Published
2017

6. High-spin states and lifetimes in $^{33}$S and shell-model interpretation in the $sd-fp$ space

Author

Aydin, S., Ionescu-Bujor, M., Gavrilov, G. Tz., Dimitrov, B.I., Lenzi, S.M., Recchia, F., Tonev, D., Bouhelal, M., Kavillioglu, F., Pavlov, P., Bazzacco, D., Bizzeti, P.G., Bizzeti-Sona, A.M., De Angelis, G., Deloncle, I., Farnea, E., Gadea, A., Gottardo, A., Goutev, N., Haas, F., Huyuk, T., Laftchiev, H., Lunardi, S., Marinov, Tz. K., Mengoni, D., Menegazzo, R., Michelagnoli, C., Napoli, D.R., Petkov, P., Sahin, E., Singh, P.P., Stefanova, E.A., Ur, C.A., Valiente-Dobón, J.J., Yavahchova, M.S., Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg (UNISTRA)-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), 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
[PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], Nuclear Theory, Nuclear Experiment
Abstract

International audience; The structure of the S33 nucleus was investigated in the Mg24(N14,αp) fusion-evaporation reaction using a 40-MeV N14 beam. The level scheme was extended up to an excitation energy of 11.7 MeV and spin 19/2+. Lifetimes of the intermediate- and high-spin states have been investigated by the Doppler shift attenuation method. Data were compared with different shell-model calculations where effective interactions involving two main shells, the sd and the fp, are used.

Published
2017

7. High-spin states of 8838Sr50: breaking of the neutron core

Author

Stefanova, E.A, Kutsarova, T, Deloncle, I, Porquet, M.-G, Grinberg, M, Gueorguieva, E, Venkova, Ts, Minkova, A, Azaiez, F, Bouneau, S, Bourgeois, C, Duprat, J, Gall, B.J.P, Gautherin, C, Hoellinger, F, Lucas, R, Sergolle, H, Schulz, N, Wilson, A, and Stoyanov, Ch

Published
2000
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8. Fast-timing Measurements in $^{100}$Zr Using LaBr$_{3}$(Ce) Detectors Coupled with Gammasphere

Author

Gamba, E.R., primary, Bruce, A.M., additional, Rudigier, M., additional, Lalkovski, S., additional, Bottoni, S., additional, Carpenter, M.P., additional, Zhu, S., additional, Ayangeakaa, A.D., additional, Anderson, J.T., additional, Berry, T.A., additional, Burrows, I., additional, Carrol, R.J., additional, Copp, P., additional, Carmona Gallardo, M., additional, Cullen, D.M., additional, Daniel, T., additional, Fernández Martínez, G., additional, Greene, J.P., additional, Gurgi, L.A., additional, Hartley, D.J., additional, Ilieva, R., additional, Ilieva, S., additional, Janssens, R.V.F., additional, Kondev, F.G., additional, Kröll, T., additional, Lane, G.J., additional, Lauritsen, T., additional, Lazarus, I., additional, Lotay, G., additional, Niţă, C.R., additional, Podolyák, Zs., additional, Pucknell, V., additional, Reed, M., additional, Regan, P.H., additional, Rohrer, J., additional, Sethi, J., additional, Seweryniak, D., additional, Shand, C.M., additional, Simpson, J., additional, Smoleń, M., additional, Vedia, V., additional, Stefanova, E.A., additional, and Yordanov, O., additional

Published
2018
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9. Coexisting structures in 105Ru

Author

Lalkovski, S., Ivanova, D., Stefanova, E.A., Korichi, A., Petkov, P., Kownacki, J., Kutsarova, T., Minkova, A., Bazzacco, D., Bergstrøm, M., Görgen, A, Herskind, Bent, Hübel, H., Yordanov, O., Lalkovski, S., Ivanova, D., Stefanova, E.A., Korichi, A., Petkov, P., Kownacki, J., Kutsarova, T., Minkova, A., Bazzacco, D., Bergstrøm, M., Görgen, A, Herskind, Bent, Hübel, H., and Yordanov, O.

Published
2014

10. High-spin level scheme of 194Pb

Author

Kutsarova, T., Stefanova, E.A., Minkova, A., Lalkovski, S., Korichi, A., Lopez-Martens, A., Hannachi, F., Huebel, H., Gorgen, A., Jansen, A., Schonwasser, G., Khoo, T.L., Herskind, B., Bergstrom, M., Bazzacco, D., Podolyak, Z., 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 d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), and 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)

Subjects
MODEL, NUCLEI, SHAPE COEXISTENCE, MAGNETIC ROTATION, PB ISOTOPES, SUPERDEFORMED STATES, BANDS, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment, SHEARS MECHANISM, LEAD ISOTOPES, 21.10.Re, 23.20.En, 25.70.Gh, 27.80.+w
Abstract

High-spin states in 194Pb have been populated in the 168Er(30Si,4n) reaction at 142 MeV. The emitted gamma rays were detected by the EUROBALL III multidetector array. The level scheme was considerably extended and many previously observed gamma-ray transitions were reordered. Four new magnetic rotational bands were observed. The energies and spins of the bandheads of all previously observed magnetic rotational bands were corrected based on the observation of new transitions. From nine observed bands, only one could not be connected to the lower lying states. Based on comparison systematics with neighboring Pb isotopes and tilted-axis cranking model calculations previously reported, configuration assignments to the observed bands have been made.

Published
2009

11. High-spin states and band terminations in $^{69}$As

Author

Stefanescu, L., Eberth, J., Gersch, G., Steinhardt, T., Thelen, O., Warr, N., Weisshaar, D., Carlsson, B.G., Ragnarsson, I., De Angelis, G., Martinez, T., Jungclaus, A., Schwengner, R., Lieb, K.P., Stefanova, E.A., Curien, D., Institut de Recherches Subatomiques (IReS), and Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]
Abstract

PACS number(s): 23.20.Lv,21.10.Re, 27.50.+e,21.60.-n

Published
2004

12. Observation of positive-parity bands in 109Pd and 111Pd:Enhanced ¿ softness

Author

Stefanova, E.A., Lalkovski, S., Korichi, A., Bergström, M., Lopez-Martens, A., Xu, F.R., Liu, H.L., Kisyov, S., Minkova, A., Herskind, Bent, Stefanova, E.A., Lalkovski, S., Korichi, A., Bergström, M., Lopez-Martens, A., Xu, F.R., Liu, H.L., Kisyov, S., Minkova, A., and Herskind, Bent

Published
2012

13. High-spin states of $^{88}_{38}$Sr$_{50}$ : breaking of the neutron core

Author

Stefanova, E.A., Kutsarova, T., Deloncle, I., Porquet, M.G., Grinberg, M., Gueorguieva, E., Venkova, Ts., Minkova, A., Azaiez, F., Bouneau, S., Bourgeois, C., Duprat, J., Gall, B.J.P., Gautherin, C., Hoellinger, F., Lucas, R., Sergolle, H., Schulz, N., Wilson, A., Stoyanov, Ch., 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), Institut de Physique Nucléaire d'Orsay (IPNO), Institut de Recherches Subatomiques (IReS), and Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]
Published
2000

14. Study of the high-spin structure in $^{88}$Sr and some neighbouring isotopes produced by heavy-ion induced fission

Author

Stefanova, E.A., Kutsarova, T., Grinberg, M., Venkova, T., Stoyanov, C., Porquet, M.G., Deloncle, I., Wilson, A., Minkova, A., Gall, B.J.P., Hoellinger, F., Schulz, N., Sergolle, H., Duprat, J., Azaiez, F., Bouneau, S., Bourgeois, C., Gautherin, C., Lucas, R., 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), Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Institut de Physique Nucléaire d'Orsay (IPNO), and Lorgeril, Jocelyne

Subjects
[PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]
Published
1998

15. Structure of High-Spin States in 90Sr and 92Sr

Author

Stefanova, E.A., primary, Schwengner, R., additional, Danchev, M., additional, Rainovski, G., additional, Balabanski, D.L., additional, Axiotis, M., additional, de Angelis, G., additional, Djongolov, M., additional, Dönau, F., additional, Gadea, A., additional, Galindo, E., additional, Hartley, D.J., additional, Jungclaus, A., additional, Kröll, Th., additional, Kutsarova, T., additional, Lieb, K.P., additional, Marginean, N., additional, Martinez, T., additional, Mueller, W.F., additional, Napoli, D.R., additional, Reviol, W., additional, Riedinger, L.L., additional, Schilling, K.D., additional, Eberth, J., additional, Thelen, O., additional, Ur, C.A., additional, Wagner, A., additional, and Zeidan, O., additional

Published
2001
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16. Magnetic moments: Study of the interplay between single-particle and collective excitations.

Author

Benczer-Koller, N., Kumbartzki, G.J., Boutachkov, P., Escuderos, A., Sharon, Y.Y., Zamick, L., Stefanova, E.A., Robinson, S.J.Q., and Werner, V.

Subjects
EXCITON theory, NUCLEAR reactions, NUCLEAR physics, NUCLEAR excitation, MAGNETISM
Abstract

Both theoretical descriptions of nuclei and experimental techniques for measuring magnetic moments have become very sophisticated. Yet, in general, good agreement between calculations and measurements still eludes us. Highlights are presented of new measurements of g factors of mixedsymmetry states in 92,94Zr, of the 4 state in 70Ge, and of the 2 states in some S and Ar isotopes. [ABSTRACT FROM AUTHOR]

Published
2007
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17. Observation of negative-parity high-spin states of68As.

Author

Stefanova, E.A., Lieb, K.P., Stefanescu, I., De Angelis, G., Curien, D., Eberth, J., Farnea, E., Gadea, A., Gersch, G., Jungclaus, A., Martinez, T., Schwengner, R., Steinhardt, T., Warr, N., Weisshaar, D., and Wyss, R.

Subjects
*PARTICLES (Nuclear physics), *ELECTROMAGNETIC waves, *GAMMA rays, *DETECTORS, *NUCLEAR physics, *CALCIUM
Abstract

The neutron-deficient nucleus68As was populated at high spin in two experiments using the reaction40Ca(32S, 3pn) at beam energies of 105 and 95 MeV. A self-supporting and a gold-backed, highly enriched40Ca target were used. Gamma rays were detected with the EUROBALL array, combined with the charged-particle detector array EUCLIDES and the Neutron Wall. The68As level scheme was considerably extended, especially at negative parity and many previous spin-parity assignments were confirmed or rejected. The total-Routhian-surface (TRS) calculations find shape coexistence and ? softness for the negative- and positive-parity states, respectively. [ABSTRACT FROM AUTHOR]

Published
2005
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18. High-spin structure of the neutron-rich 107,109 45Rh isotopes: the role of triaxiality.

Author

Venkova, Ts., Porquet, M.-G., Deloncle, I., Gall, B.J.P., De Witte, H., Petkov, P., Bauchet, A., Kutsarova, T., Gueorgieva, E., Duprat, J., Gautherin, C., Hoellinger, F., Lucas, R., Minkova, A., Schulz, N., Sergolle, H., Stefanova, E.A., and Wilson, A.

Abstract

The 107,109Rh nuclei have been produced as fission fragments following the fusion reaction 28Si +176Yb at 145 MeV bombarding energy and studied with the Eurogam2 array. In both nuclei three new rotational bands with the odd proton occupying the πg9/2, πp1/2 and π(g7/2/d5/2) sub-shells have been observed. In 107Rh, two other bands involving strong M1 transitions have been identified at excitation energy larger than 2 MeV. They can be interpreted in terms of three quasiparticle excitations. In addition new structures consisting of four transitions, built on states located at low excitation energy (680 keV in 107Rh and 642 keV in 109Rh), point out the importance of triaxial deformation in these two isotopes. [ABSTRACT FROM AUTHOR]

Published
1999
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