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14 results on '"Atac Nyberg, Ayse"'

1. Evidence for pseudospin-chiral quartet bands in the presence of octupole correlations

Author

Guo, S., Petrache, C. M., Mengoni, D., Qiang, Y. H., Wang, Y. P., Wang, Y. Y., Meng, J., Wang, Y. K., Zhang, S. Q., Zhao, P. W., Astier, A., Wang, J. G., Fan, H. L., Dupont, E., Lv, B. F., Bazzacco, D., Boso, A., Goasduff, A., Recchia, F., Testov, D., Galtarossa, F., Jaworski, G., Napoli, D. R., Riccetto, S., Siciliano, M., Valiente-Dobon, J. J., Liu, M. L., Li, G. S., Zhou, X. H., Zhang, Y. H., Andreoiu, C., Garcia, F. H., Ortner, K., Whitmore, K., Atac Nyberg, Ayse, Bäck, Torbjörn, Cederwall, Bo, Lawrie, E. A., Kuti, I, Sohler, D., Marchlewski, T., Srebrny, J., Tucholski, A., Guo, S., Petrache, C. M., Mengoni, D., Qiang, Y. H., Wang, Y. P., Wang, Y. Y., Meng, J., Wang, Y. K., Zhang, S. Q., Zhao, P. W., Astier, A., Wang, J. G., Fan, H. L., Dupont, E., Lv, B. F., Bazzacco, D., Boso, A., Goasduff, A., Recchia, F., Testov, D., Galtarossa, F., Jaworski, G., Napoli, D. R., Riccetto, S., Siciliano, M., Valiente-Dobon, J. J., Liu, M. L., Li, G. S., Zhou, X. H., Zhang, Y. H., Andreoiu, C., Garcia, F. H., Ortner, K., Whitmore, K., Atac Nyberg, Ayse, Bäck, Torbjörn, Cederwall, Bo, Lawrie, E. A., Kuti, I, Sohler, D., Marchlewski, T., Srebrny, J., and Tucholski, A.

Abstract

Three nearly degenerate pairs of doublet bands are identified in Ba-131. Two of them, with positive-parity, are interpreted as pseudospin-chiral quartet bands. This is the first time that a complete set of chiral doublet bands built on the pseudospin partners pi(d(5/2), g(7/2)) is observed. The chiral bands with opposite parity built on 3-quasiparticle configurations are directly connected by many E1 transitions, without involving an intermediary non-chiral configuration. The observed band structures in Ba-131 have been investigated by using the reflection-asymmetric particle rotor model. The energies and the electromagnetic transition ratios of the three pairs of doublet bands observed in Ba-131 are reproduced and they are interpreted as chiral doublet bands with three-quasiparticle configurations. It is the first time that multiple chiral bands are observed in the presence of enhanced octupole correlations and pseudospin symmetry., QC 20201020

Published
2020
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2. Testing ab initio nuclear structure in neutron-rich nuclei : Lifetime measurements of second 2(+) state in C-16 and O-20

Author

Ciemala, M., Atac Nyberg, Ayse, Cederwall, Bo, Simonis, J., Ciemala, M., Atac Nyberg, Ayse, Cederwall, Bo, and Simonis, J.

Abstract

To test the predictive power of ab initio nuclear structure theory, the lifetime of the second 2(+) state in neutron-rich O-20, tau(2(2)(+)) = 150(-30)(+80) fs, and an estimate for the lifetime of the second 2(+) state in C-16 have been obtained for the first time. The results were achieved via a novel Monte Carlo technique that allowed us to measure nuclear state lifetimes in the tens-to-hundreds of femtoseconds range by analyzing the Doppler-shifted gamma-transition line shapes of products of low-energy transfer and deep-inelastic processes in the reaction O-18 (7.0 MeV/u) + Ta-181. The requested sensitivity could only be reached owing to the excellent performances of the Advanced gamma-Tracking Array AGATA, coupled to the PARIS scintillator array and to the VAMOS++ magnetic spectrometer. The experimental lifetimes agree with predictions of ab initio calculations using two- and three-nucleon interactions, obtained with the valence-space in-medium similarity renormalization group for O-20 and with the no-core shell model for C-16. The present measurement shows the power of electromagnetic observables, determined with high-precision gamma spectroscopy, to assess the quality of first-principles nuclear structure calculations, complementing common benchmarks based on nuclear energies. The proposed experimental approach will be essential for short lifetime measurements in unexplored regions of the nuclear chart, including r-process nuclei, when intense beams, produced by Isotope Separation On-Line (ISOL) techniques, become available., QC 20200331

Published
2020
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3. Lifetime measurements in Ti-52,Ti-54 to study shell evolution toward N=32

Author

Goldkuhle, A., Atac Nyberg, Ayse, Cederwall, Bo, Zielinska, M., et al., Goldkuhle, A., Atac Nyberg, Ayse, Cederwall, Bo, Zielinska, M., and et al.

Abstract

Lifetimes of the excited states in the neutron-rich Ti-52,Ti-54 nuclei, produced in a multinucleon-transfer reaction, were measured by employing the Cologne plunger device and the recoil-distance Doppler-shift method. The experiment was performed at the Grand Accelerateur National d'Ions Lourds facility by using the Advanced Gamma Tracking Array for the gamma-ray detection, coupled to the large-acceptance variable mode spectrometer for an event-by-event particle identification. A comparison between the transition probabilities obtained from the measured lifetimes of the 2(1)(+) to 8(1)(+) yrast states in Ti-52,Ti-54 and that from the shell-model calculations based on the well-established GXPF1A, GXPF1B, and KB3G fp shell interactions support the N = 32 subshell closure. The B(E2) values for Ti-52 determined in this work are in disagreement with the known data, but are consistent with the predictions of the shell-model calculations and reduce the previously observed pronounced staggering across the even-even titanium isotopes., QC 20191219

Published
2019
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4. M1 and E2 transition rates from core-excited states in semi-magic Ru-94

Author

Ertoprak, Aysegul, Cederwall, Bo, Qi, Chong, Doncel, Maria, Jakobsson, U., Nyako, B. M., Jaworski, G., Davies, P., de France, G., Kuti, I., Napoli, D. R., Wadsworth, R., Ghugre, S. S., Raut, R., Akkus, B., Al Azri, H., Algora, A., de Angelis, G., Atac Nyberg, Ayse, Bäck, Torbjörn, Boso, A., Clement, E., Debenham, D. M., Dombradi, Zs., Erturk, S., Gadea, A., Moradi, F. Ghazi, Gottardo, A., Huyuk, T., Ideguchi, E., Li, H., Michelagnoli, C., Modamio, V., Nyberg, J., Palacz, M., Petrache, C. M., Recchia, F., Sandzelius, M., Siciliano, M., Timar, J., Valiente-Dobon, J. J., Xiao, Z. G., Ertoprak, Aysegul, Cederwall, Bo, Qi, Chong, Doncel, Maria, Jakobsson, U., Nyako, B. M., Jaworski, G., Davies, P., de France, G., Kuti, I., Napoli, D. R., Wadsworth, R., Ghugre, S. S., Raut, R., Akkus, B., Al Azri, H., Algora, A., de Angelis, G., Atac Nyberg, Ayse, Bäck, Torbjörn, Boso, A., Clement, E., Debenham, D. M., Dombradi, Zs., Erturk, S., Gadea, A., Moradi, F. Ghazi, Gottardo, A., Huyuk, T., Ideguchi, E., Li, H., Michelagnoli, C., Modamio, V., Nyberg, J., Palacz, M., Petrache, C. M., Recchia, F., Sandzelius, M., Siciliano, M., Timar, J., Valiente-Dobon, J. J., and Xiao, Z. G.

Abstract

Lifetimes of high-spin states have been measured in the semi-magic (N = 50) nucleus Ru-94. Excited states in Ru-94 were populated in the Ni-58(Ca-40, 4p)Ru-94* fusion-evaporation reaction at the Grand Accelerateur National d'Ions Lourds (GANIL) accelerator complex. DSAM lifetime analysis was performed on the Doppler broadened line shapes in energy spectra obtained from gamma-rays emitted while the residual nuclei were slowing down in a thick 6 mg/cm(2) metallic Ni-58 target. In total eight excited-state lifetimes in the angular momentum range I = (13-20)h have been measured, five of which were determined for the first time. The corresponding B(M1) and B(E2) reduced transition strengths are discussed within the framework of large-scale shell model calculations to study the contribution of different particle-hole configurations, in particular for analyzing contributions from core-excited configurations., QC 20180917

Published
2018
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5. Superallowed Gamow-Teller decay of the doubly magic nucleus 100Sn

Author

Hinke, C. B., Atac Nyberg, Ayse, Strmeň, P., et al., Hinke, C. B., Atac Nyberg, Ayse, Strmeň, P., and et al.

Abstract

The shell structure of atomic nuclei is associated with 'magic numbers' and originates in the nearly independent motion of neutrons and protons in a mean potential generated by all nucleons. During β +-decay, a proton transforms into a neutron in a previously not fully occupied orbital, emitting a positron-neutrino pair with either parallel or antiparallel spins, in a Gamow-Teller or Fermi transition, respectively. The transition probability, or strength, of a Gamow-Teller transition depends sensitively on the underlying shell structure and is usually distributed among many states in the neighbouring nucleus. Here we report measurements of the half-life and decay energy for the decay of 100 Sn, the heaviest doubly magic nucleus with equal numbers of protons and neutrons. In the β-decay of 100Sn, a large fraction of the strength is observable because of the large decay energy. We determine the largest Gamow-Teller strength so far measured in allowed nuclear β-decay, establishing the superallowed nature of this Gamow-Teller transition. The large strength and the low-energy states in the daughter nucleus, 100In, are well reproduced by modern, large-scale shell model calculations., QC 20200229

Published
2012
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6. AGATA-Advanced GAmma Tracking Array

Author

Akkoyun, S., Algora, A., Alikhani, B., Ameil, F., de Angelis, G., Arnold, L., Astier, A., Atac Nyberg, Ayse, Aubert, Y., Aufranc, C., Austin, A., Aydin, S., Azaiez, F., Badoer, S., Balabanski, D. L., Barrientos, D., Baulieu, G., Baumann, R., Bazzacco, D., Beck, F. A., Beck, T., Bednarczyk, P., Bellato, M., Bentley, M. A., Benzoni, G., Berthier, R., Berti, L., Beunard, R., Lo Bianco, G., Birkenbach, B., Bizzeti, P. G., Bizzeti-Sona, A. M., Le Blanc, F., Blasco, J. M., Blasi, N., Bloor, D., Boiano, C., Borsato, M., Bortolato, D., Boston, A. J., Boston, H. C., Bourgault, P., Boutachkov, P., Bouty, A., Bracco, A., Brambilla, S., Brawn, I. P., Brondi, A., Broussard, S., Bruyneel, B., Bucurescu, D., Burrows, I., Buerger, A., Cabaret, S., Cahan, B., Calore, E., Camera, F., Capsoni, A., Carrio, F., Casati, G., Castoldi, M., Cederwall, Bo, Cercus, J. -L, Chambert, V., El Chambit, M., Chapman, R., Charles, L., Chavas, J., Clement, E., Cocconi, P., Coelli, S., Coleman-Smith, P. J., Colombo, A., Colosimo, S., Commeaux, C., Conventi, D., Cooper, R. J., Corsi, A., Cortesi, A., Costa, L., Crespi, F. C. L., Cresswell, J. R., Cullen, D. M., Curien, D., Czermak, A., Delbourg, D., Depalo, R., Descombes, T., Desesquelles, P., Detistov, P., Diarra, C., Didierjean, F., Dimmock, M. R., Doan, Q. T., Domingo-Pardo, C., Doncel, M., Dorangeville, F., Dosme, N., Drouen, Y., Duchene, G., Dulny, B., Eberth, J., Edelbruck, P., Egea, J., Engert, T., Erduran, M. N., Erturk, S., Fanin, C., Fantinel, S., Farnea, E., Faul, T., Filliger, M., Filmer, F., Finck, Ch., de France, G., Gadea, A., Gast, W., Geraci, A., Gerl, J., Gernhaeuser, R., Giannatiempo, A., Giaz, A., Gibelin, L., Givechev, A., Goel, N., Gonzalez, V., Gottardo, A., Grave, X., Grebosz, J., Griffiths, R., Grint, A. N., Gros, P., Guevara, L., Gulmini, M., Goergen, A., Ha, H. T. M., Habermann, T., Harkness, L. J., Harroch, H., Hauschild, K., He, C., Hernandez-Prieto, A., Hervieu, B., Hess, H., Hueyuek, T., Ince, E., Isocrate, R., Jaworski, G., Johnson, Arne, Jolie, J., Jones, P., Jonson, B., Joshi, P., Judson, D. S., Jungclaus, A., Kaci, M., Karkour, N., Karolak, M., Kaskas, A., Kebbiri, M., Kempley, R. S., Khaplanov, Anton, Klupp, S., Kogimtzis, M., Kojouharov, I., Korichi, A., Korten, W., Kroell, Th., Kruecken, R., Kurz, N., Ky, B. Y., Labiche, M., Lafay, X., Lavergne, L., Lazarus, I. H., Leboutelier, S., Lefebvre, F., Legay, E., Legeard, L., Lelli, F., Lenzi, S. M., Leoni, S., Lermitage, A., Lersch, D., Leske, J., Letts, S. C., Lhenoret, S., Lieder, R. M., Linget, D., Ljungvall, J., Lopez-Martens, A., Lotode, A., Lunardi, S., Maj, A., van der Marel, J., Mariette, Y., Marginean, N., Marginean, R., Maron, G., Mather, A. R., Meczynski, W., Mendez, V., Medina, P., Melon, B., Menegazzo, R., Mengoni, D., Merchan, E., Mihailescu, L., Michelagnoli, C., Mierzejewski, J., Milechina, Larissa, Million, B., Mitev, K., Molini, P., Montanari, D., Moon, S., Morbiducci, F., Moro, R., Morrall, P. S., Moeller, O., Nannini, A., Napoli, D. R., Nelson, L., Nespolo, M., Ngo, V. L., Nicoletto, M., Nicolini, R., Le Noa, Y., Nolan, P. J., Norman, M., Nyberg, J., Obertelli, A., Olariu, A., Orlandi, R., Oxley, D. C., Ozben, C., Ozille, M., Oziol, C., Pachoud, E., Palacz, M., Palin, J., Pancin, J., Parisel, C., Pariset, P., Pascovici, G., Peghin, R., Pellegri, L., Perego, A., Perrier, S., Petcu, M., Petkov, P., Petrache, C., Pierre, E., Pietralla, N., Pietri, S., Pignanelli, M., Piqueras, I., Podolyak, Z., Le Pouhalec, P., Pouthas, J., Pugnere, D., Pucknell, V. F. E., Pullia, A., Quintana, B., Raine, R., Rainovski, G., Ramina, L., Rampazzo, G., La Rana, G., Rebeschini, M., Recchia, F., Redon, N., Reese, M., Reiter, P., Regan, P. H., Riboldi, S., Richer, M., Rigato, M., Rigby, S., Ripamonti, G., Robinson, A. P., Robin, J., Roccaz, J., Ropert, J. -A, Rosse, B., Rossi Alvarez, C., Rosso, D., Rubio, B., Rudolph, D., Saillant, F., Sahin, E., Salomon, F., Salsac, M. -D, Salt, J., Salvato, G., Sampson, J., Sanchis, E., Santos, C., Schaffner, H., Schlarb, M., Scraggs, D. P., Seddon, D., Senyigit, M., Sigward, M. -H, Simpson, G., Simpson, J., Slee, M., Smith, J. F., Sona, P., Sowicki, B., Spolaore, P., Stahl, C., Stanios, T., Stefanova, E., Stezowski, O., Strachan, J., Suliman, G., Soderstrom, P. -A, Tain, J. L., Tanguy, S., Tashenov, Stanislav, Theisen, Ch., Thornhill, J., Tomasi, F., Toniolo, N., Touzery, R., Travers, B., Triossi, A., Tripon, M., Tun-Lanoe, K. M. M., Turcato, M., Unsworth, C., Ur, C. A., Valiente-Dobon, J. J., Vandone, V., Vardaci, E., Venturelli, R., Veronese, F., Veyssiere, Ch., Viscione, E., Wadsworth, R., Walker, P. M., Warr, N., Weber, C., Weisshaar, D., Wells, D., Wieland, O., Wiens, A., Wittwer, G., Wollersheim, H. J., Zocca, F., Zamfir, N. V., Zieblinski, M., Zucchiatti, A., Akkoyun, S., Algora, A., Alikhani, B., Ameil, F., de Angelis, G., Arnold, L., Astier, A., Atac Nyberg, Ayse, Aubert, Y., Aufranc, C., Austin, A., Aydin, S., Azaiez, F., Badoer, S., Balabanski, D. L., Barrientos, D., Baulieu, G., Baumann, R., Bazzacco, D., Beck, F. A., Beck, T., Bednarczyk, P., Bellato, M., Bentley, M. A., Benzoni, G., Berthier, R., Berti, L., Beunard, R., Lo Bianco, G., Birkenbach, B., Bizzeti, P. G., Bizzeti-Sona, A. M., Le Blanc, F., Blasco, J. M., Blasi, N., Bloor, D., Boiano, C., Borsato, M., Bortolato, D., Boston, A. J., Boston, H. C., Bourgault, P., Boutachkov, P., Bouty, A., Bracco, A., Brambilla, S., Brawn, I. P., Brondi, A., Broussard, S., Bruyneel, B., Bucurescu, D., Burrows, I., Buerger, A., Cabaret, S., Cahan, B., Calore, E., Camera, F., Capsoni, A., Carrio, F., Casati, G., Castoldi, M., Cederwall, Bo, Cercus, J. -L, Chambert, V., El Chambit, M., Chapman, R., Charles, L., Chavas, J., Clement, E., Cocconi, P., Coelli, S., Coleman-Smith, P. J., Colombo, A., Colosimo, S., Commeaux, C., Conventi, D., Cooper, R. J., Corsi, A., Cortesi, A., Costa, L., Crespi, F. C. L., Cresswell, J. R., Cullen, D. M., Curien, D., Czermak, A., Delbourg, D., Depalo, R., Descombes, T., Desesquelles, P., Detistov, P., Diarra, C., Didierjean, F., Dimmock, M. R., Doan, Q. T., Domingo-Pardo, C., Doncel, M., Dorangeville, F., Dosme, N., Drouen, Y., Duchene, G., Dulny, B., Eberth, J., Edelbruck, P., Egea, J., Engert, T., Erduran, M. N., Erturk, S., Fanin, C., Fantinel, S., Farnea, E., Faul, T., Filliger, M., Filmer, F., Finck, Ch., de France, G., Gadea, A., Gast, W., Geraci, A., Gerl, J., Gernhaeuser, R., Giannatiempo, A., Giaz, A., Gibelin, L., Givechev, A., Goel, N., Gonzalez, V., Gottardo, A., Grave, X., Grebosz, J., Griffiths, R., Grint, A. N., Gros, P., Guevara, L., Gulmini, M., Goergen, A., Ha, H. T. M., Habermann, T., Harkness, L. J., Harroch, H., Hauschild, K., He, C., Hernandez-Prieto, A., Hervieu, B., Hess, H., Hueyuek, T., Ince, E., Isocrate, R., Jaworski, G., Johnson, Arne, Jolie, J., Jones, P., Jonson, B., Joshi, P., Judson, D. S., Jungclaus, A., Kaci, M., Karkour, N., Karolak, M., Kaskas, A., Kebbiri, M., Kempley, R. S., Khaplanov, Anton, Klupp, S., Kogimtzis, M., Kojouharov, I., Korichi, A., Korten, W., Kroell, Th., Kruecken, R., Kurz, N., Ky, B. Y., Labiche, M., Lafay, X., Lavergne, L., Lazarus, I. H., Leboutelier, S., Lefebvre, F., Legay, E., Legeard, L., Lelli, F., Lenzi, S. M., Leoni, S., Lermitage, A., Lersch, D., Leske, J., Letts, S. C., Lhenoret, S., Lieder, R. M., Linget, D., Ljungvall, J., Lopez-Martens, A., Lotode, A., Lunardi, S., Maj, A., van der Marel, J., Mariette, Y., Marginean, N., Marginean, R., Maron, G., Mather, A. R., Meczynski, W., Mendez, V., Medina, P., Melon, B., Menegazzo, R., Mengoni, D., Merchan, E., Mihailescu, L., Michelagnoli, C., Mierzejewski, J., Milechina, Larissa, Million, B., Mitev, K., Molini, P., Montanari, D., Moon, S., Morbiducci, F., Moro, R., Morrall, P. S., Moeller, O., Nannini, A., Napoli, D. R., Nelson, L., Nespolo, M., Ngo, V. L., Nicoletto, M., Nicolini, R., Le Noa, Y., Nolan, P. J., Norman, M., Nyberg, J., Obertelli, A., Olariu, A., Orlandi, R., Oxley, D. C., Ozben, C., Ozille, M., Oziol, C., Pachoud, E., Palacz, M., Palin, J., Pancin, J., Parisel, C., Pariset, P., Pascovici, G., Peghin, R., Pellegri, L., Perego, A., Perrier, S., Petcu, M., Petkov, P., Petrache, C., Pierre, E., Pietralla, N., Pietri, S., Pignanelli, M., Piqueras, I., Podolyak, Z., Le Pouhalec, P., Pouthas, J., Pugnere, D., Pucknell, V. F. E., Pullia, A., Quintana, B., Raine, R., Rainovski, G., Ramina, L., Rampazzo, G., La Rana, G., Rebeschini, M., Recchia, F., Redon, N., Reese, M., Reiter, P., Regan, P. H., Riboldi, S., Richer, M., Rigato, M., Rigby, S., Ripamonti, G., Robinson, A. P., Robin, J., Roccaz, J., Ropert, J. -A, Rosse, B., Rossi Alvarez, C., Rosso, D., Rubio, B., Rudolph, D., Saillant, F., Sahin, E., Salomon, F., Salsac, M. -D, Salt, J., Salvato, G., Sampson, J., Sanchis, E., Santos, C., Schaffner, H., Schlarb, M., Scraggs, D. P., Seddon, D., Senyigit, M., Sigward, M. -H, Simpson, G., Simpson, J., Slee, M., Smith, J. F., Sona, P., Sowicki, B., Spolaore, P., Stahl, C., Stanios, T., Stefanova, E., Stezowski, O., Strachan, J., Suliman, G., Soderstrom, P. -A, Tain, J. L., Tanguy, S., Tashenov, Stanislav, Theisen, Ch., Thornhill, J., Tomasi, F., Toniolo, N., Touzery, R., Travers, B., Triossi, A., Tripon, M., Tun-Lanoe, K. M. M., Turcato, M., Unsworth, C., Ur, C. A., Valiente-Dobon, J. J., Vandone, V., Vardaci, E., Venturelli, R., Veronese, F., Veyssiere, Ch., Viscione, E., Wadsworth, R., Walker, P. M., Warr, N., Weber, C., Weisshaar, D., Wells, D., Wieland, O., Wiens, A., Wittwer, G., Wollersheim, H. J., Zocca, F., Zamfir, N. V., Zieblinski, M., and Zucchiatti, A.

Abstract

The Advanced GAmma Tracking Array (AGATA) is a European project to develop and operate the next generation gamma-ray spectrometer. AGATA is based on the technique of gamma-ray energy tracking in electrically segmented high-purity germanium crystals. This technique requires the accurate determination of the energy, time and position of every interaction as a gamma ray deposits its energy within the detector volume. Reconstruction of the full interaction path results in a detector with very high efficiency and excellent spectral response. The realisation of gamma-ray tracking and AGATA is a result of many technical advances. These include the development of encapsulated highly segmented germanium detectors assembled in a triple cluster detector cryostat, an electronics system with fast digital sampling and a data acquisition system to process the data at a high rate. The full characterisation of the crystals was measured and compared with detector-response simulations. This enabled pulse-shape analysis algorithms, to extract energy, time and position, to be employed. In addition, tracking algorithms for event reconstruction were developed. The first phase of AGATA is now complete and operational in its first physics campaign. In the future AGATA will be moved between laboratories in Europe and operated in a series of campaigns to take advantage of the different beams and facilities available to maximise its science output. The paper reviews all the achievements made in the AGATA project including all the necessary infrastructure to operate and support the spectrometer., QC 20120327

Published
2012
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7. Evidence for a spin-aligned neutron-proton paired phase from the level structure of 92Pd

Author

Cederwall, Bo, Ghazi Moradi, Farnaz, Bäck, Torbjörn, Johnson, Arne, Blomqvist, Jan-Erik, Clément, E., de France, G., Wadsworth, R., Andgren, Karin, Lagergren, Karin, Dijon, A., Jaworski, G., Liotta, Roberto, Qi, Chong, Nyakó, B. M., Nyberg, J., Palacz, M., Al-Azri, H., Algora, A., de Angelis, G., Atac Nyberg, Ayse, Bhattacharyya, S., Brock, T., Brown, J. R., Davies, P., Di Nitto, A., Dombrádi, Zs., Gadea, A., Gál, J., Hadinia, Baharak, Johnston-Theasby, F., Joshi, P., Juhász, K., Julin, R., Jungclaus, A., Kalinka, G., Kara, S. O., Khaplanov, Anton, Kownacki, J., La Rana, G., Lenzi, S. M., Molnár, J., Moro, R., Napoli, D. R., Nara Singh, B. S., Persson, Andreas, Recchia, F., Sandzelius, Mikael, Scheurer, J. -N, Sletten, G., Sohler, D., Söderström, P. -A, Taylor, M. J., Timár, J., Valiente-Dobón, J. J., Vardaci, E., Williams, S., Cederwall, Bo, Ghazi Moradi, Farnaz, Bäck, Torbjörn, Johnson, Arne, Blomqvist, Jan-Erik, Clément, E., de France, G., Wadsworth, R., Andgren, Karin, Lagergren, Karin, Dijon, A., Jaworski, G., Liotta, Roberto, Qi, Chong, Nyakó, B. M., Nyberg, J., Palacz, M., Al-Azri, H., Algora, A., de Angelis, G., Atac Nyberg, Ayse, Bhattacharyya, S., Brock, T., Brown, J. R., Davies, P., Di Nitto, A., Dombrádi, Zs., Gadea, A., Gál, J., Hadinia, Baharak, Johnston-Theasby, F., Joshi, P., Juhász, K., Julin, R., Jungclaus, A., Kalinka, G., Kara, S. O., Khaplanov, Anton, Kownacki, J., La Rana, G., Lenzi, S. M., Molnár, J., Moro, R., Napoli, D. R., Nara Singh, B. S., Persson, Andreas, Recchia, F., Sandzelius, Mikael, Scheurer, J. -N, Sletten, G., Sohler, D., Söderström, P. -A, Taylor, M. J., Timár, J., Valiente-Dobón, J. J., Vardaci, E., and Williams, S.

Abstract

Shell structure and magic numbers in atomic nuclei were generally explained by pioneering work(1) that introduced a strong spin-orbit interaction to the nuclear shell model potential. However, knowledge of nuclear forces and the mechanisms governing the structure of nuclei, in particular far from stability, is still incomplete. In nuclei with equal neutron and proton numbers (N = Z), enhanced correlations arise between neutrons and protons (two distinct types of fermions) that occupy orbitals with the same quantum numbers. Such correlations have been predicted to favour an unusual type of nuclear superfluidity, termed isoscalar neutron-proton pairing(2-6), in addition to normal isovector pairing. Despite many experimental efforts, these predictions have not been confirmed. Here we report the experimental observation of excited states in the N = Z = 46 nucleus Pd-92. Gamma rays emitted following the Ni-58(Ar-36,2n)Pd-92 fusion-evaporation reaction were identified using a combination of state-of-the-art high-resolution c-ray, charged-particle and neutron detector systems. Our results reveal evidence for a spin-aligned, isoscalar neutron-proton coupling scheme, different from the previous prediction(2-6). We suggest that this coupling scheme replaces normal superfluidity (characterized by seniority coupling(7,8)) in the ground and low-lying excited states of the heaviest N = Z nuclei. Such strong, isoscalar neutron-proton correlations would have a considerable impact on the nuclear level structure and possibly influence the dynamics of rapid proton capture in stellar nucleosynthesis., QC 20110501

Published
2011
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8. High-spin study of 162Ta

Author

Ghazi Moradi, Farnaz, Bäck, Torbjörn, Cederwall, Bo, Sandzelius, Mikael, Atac Nyberg, Ayse, Johnson, Arne, Qi, Chong, Liotta, Roberto, Hadinia, Baharak, Andgren, Karin, Khaplanov, Anton, Wyss, Ramon, Eeckhaudt, S., Grahn, T., Greenlees, P. T., Jones, P. M., Julin, R., Juutinen, S., Ketelhut, S., Leino, M., Nyman, M., Rahkila, P., Sarén, J., Scholey, C., Sorri, J., Uusitalo, J., Ganioglu, E., Thomson, J., Joss, D. T., Page, R. D., Ertürk, S., Simpson, J., Gomez Hornillos, M. B., Bianco, L., Ghazi Moradi, Farnaz, Bäck, Torbjörn, Cederwall, Bo, Sandzelius, Mikael, Atac Nyberg, Ayse, Johnson, Arne, Qi, Chong, Liotta, Roberto, Hadinia, Baharak, Andgren, Karin, Khaplanov, Anton, Wyss, Ramon, Eeckhaudt, S., Grahn, T., Greenlees, P. T., Jones, P. M., Julin, R., Juutinen, S., Ketelhut, S., Leino, M., Nyman, M., Rahkila, P., Sarén, J., Scholey, C., Sorri, J., Uusitalo, J., Ganioglu, E., Thomson, J., Joss, D. T., Page, R. D., Ertürk, S., Simpson, J., Gomez Hornillos, M. B., and Bianco, L.

Abstract

Excited states in the odd-odd neutron deficient nucleus (162)Ta (Z = 73, N = 89) have been studied for the first time. The gamma spectroscopy analysis using gamma - gamma - gamma coincidences revealed a strongly coupled rotational structure that was established up to large angular momentum states. The rotational band was assigned to the configuration pi h(11/2)[514]9/2 circle times nu i(13/2)[660]1/2 based on its rotational and electromagnetic properties. The data are interpreted within the framework of total Routhian surface calculations, which suggests an axially symmetric shape with a gamma-softminimum at beta(2) approximate to 0.16 and gamma approximate to 6 degrees. The crossing of the signature partners observed in heavier (N >= 91) odd-odd nuclides in this mass region is found to be absent at N = 89. This might be correlated with a change in S-band structure above the paired band crossing at these neutron numbers., QC 20120210

Published
2011
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9. High-spin isomers in 96Ag : excitations across the Z=38 and Z=50, N=50 closed shells

Author

Boutachkov, P., Górska, M., Grawe, H., Blazhev, A., Braun, N., Brock, T.S., Liu, Z., Nara Singh, B.S., Wadsworth, R., Pietri, S., Domingo-Pardo, C., Kojouharov, I., Cáceres, L., Engert, T., Farinon, F., Gerl, J., Goel, N., Grebosz, J., Hoischen, R., Kurz, N., Nociforo, C., Prochazka, A., Schaffner, H., Steer, S. J., Weick, H., Wollersheim, H-J., Faestermann, T., Podolyák, Zs., Rudolph, D., Atac Nyberg, Ayse, Bettermann, L., Eppinger, K., Finke, F., Geibel, K., Gottardo, A., Hinke, C., Ilie, G., Iwasaki, H., Jolie, J., Krücken, R., Merchán, E., Nyberg, Johan, Pfützner, M., Regan, P. H., Reiter, P., Rinta-Antila, S., Scholl, C., Söderström, P.-A., Warr, N., Woods, P. J., Nowacki, F., Sieja, K., Boutachkov, P., Górska, M., Grawe, H., Blazhev, A., Braun, N., Brock, T.S., Liu, Z., Nara Singh, B.S., Wadsworth, R., Pietri, S., Domingo-Pardo, C., Kojouharov, I., Cáceres, L., Engert, T., Farinon, F., Gerl, J., Goel, N., Grebosz, J., Hoischen, R., Kurz, N., Nociforo, C., Prochazka, A., Schaffner, H., Steer, S. J., Weick, H., Wollersheim, H-J., Faestermann, T., Podolyák, Zs., Rudolph, D., Atac Nyberg, Ayse, Bettermann, L., Eppinger, K., Finke, F., Geibel, K., Gottardo, A., Hinke, C., Ilie, G., Iwasaki, H., Jolie, J., Krücken, R., Merchán, E., Nyberg, Johan, Pfützner, M., Regan, P. H., Reiter, P., Rinta-Antila, S., Scholl, C., Söderström, P.-A., Warr, N., Woods, P. J., Nowacki, F., and Sieja, K.

Abstract

Excited states in (96)Ag were populated in fragmentation of an 850-MeV/u (124)Xe beam on a 4-g/cm(2) Be target. Three new high-spin isomers were identified and the structure of the populated states was investigated. The level scheme of (96)Ag was established, and a spin parity of (13(-)), (15(+)), and (19(+)) was assigned to the new isomeric states. Shell-model calculations were performed in various model spaces, including pi nu(p(1/2), g(9/2), f(5/2), p(3/2)) and the large-scale shell-model space pi nu(gds), to account for the observed parity changing M2 and E3 transitions from the (13(-)) isomer and the E2 and E4 transitions from the (19(+)) core-excited isomer, respectively. The calculated level schemes and reduced transition strengths are found to be in very good agreement with the experiment., QC 20120220

Published
2011
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10. Discrimination of gamma rays due to inelastic neutron scattering in AGATA

Author

Atac Nyberg, Ayse, Kaşkaş, Ayşe, Akkoyun, Serkan, Şenyiğit, Menekse, Hüyük, Tayfun, Kara, S. Okan, Nyberg, Johan, Atac Nyberg, Ayse, Kaşkaş, Ayşe, Akkoyun, Serkan, Şenyiğit, Menekse, Hüyük, Tayfun, Kara, S. Okan, and Nyberg, Johan

Abstract

Possibilities of discriminating neutrons and γ rays in the AGATA γ-ray tracking spectrometer have been investigated with the aim of reducing the background due toinelastic scattering of neutrons in the high-purity germanium crystals. This background may become a serious problem especially in experiments with neutron-rich radioactive ion beams. Simulations using the Geant4 toolkit and a tracking program based on the forward tracking algorithm were carried out by emitting neutrons and γ rays from the center of AGATA. Three different methods were developed and tested in order to find "fingerprints" of the neutron interaction points in the detectors. In a simulation with simultaneous emission of six neutrons with energies in the range 1-5 MeV and 10 γ rayswith energies between 150 and 1450 keV, the peak-to-background ratio at a γ-ray energy of 1.0 MeV was improved by a factor of 2.4 after neutron rejection with a reduction of the photopeak efficiency at 1.0 MeV of only a factor of 1.25., QC 20120214

Published
2009
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11. THE NORTHWEST FRONTIER : SPECTROSCOPY OF N similar to Z NUCLEI BELOW MASS 100

Author

Wadsworth, R., Singh, B. S. Nara, Steer, A. N., Jenkins, D. C., Bentley, M. A., Brock, T., Davies, P., Glover, R., Pattabiraman, N. S., Scholey, C., Grahn, T., Greenlees, P. T., Jones, P., Jakobsson, U., Julin, R., Juutinen, S., Ketelhut, S., Leino, M., Nyman, M., Perua, P., Pakarinen, J., Rahkila, P., Ruotslainen, P., Sorri, J., Uusitalo, J., Lister, C. J., Butler, P. A., Dimmock, M., Joss, D. T., Thomson, J., Rinta-Antila, S., Cederwall, Bo, Hadinia, Baharak, Sandzelius, Mikael, Atac Nyberg, Ayse, Betterman, L., Blazhev, A., Braun, N., Finke, F., Geibel, K., Ilie, G., Iwasaki, H., Jolie, J., Reiter, P., Scholl, C., Warr, N., Boutachkov, P., Caceres, L., Domingo, C., Engert, T., Farinon, F., Gerl, J., Goel, N., Gorska, M., Grawe, H., Kurz, N., Kojuharov, I., Pietri, S., Nociforo, C., Prochazka, A., Wollersheim, H-J, Eppinger, K., Faestermann, T., Hinke, C., Hoischen, R., Kruecken, R., Gottardo, A., Liu, Z., Woods, P., Grebosz, J., Merchant, E., Nyberg, J., Soderstrom, P-A, Podolyak, Z., Regan, P., Steer, S., Pfutzner, M., Rudolph, D., Wadsworth, R., Singh, B. S. Nara, Steer, A. N., Jenkins, D. C., Bentley, M. A., Brock, T., Davies, P., Glover, R., Pattabiraman, N. S., Scholey, C., Grahn, T., Greenlees, P. T., Jones, P., Jakobsson, U., Julin, R., Juutinen, S., Ketelhut, S., Leino, M., Nyman, M., Perua, P., Pakarinen, J., Rahkila, P., Ruotslainen, P., Sorri, J., Uusitalo, J., Lister, C. J., Butler, P. A., Dimmock, M., Joss, D. T., Thomson, J., Rinta-Antila, S., Cederwall, Bo, Hadinia, Baharak, Sandzelius, Mikael, Atac Nyberg, Ayse, Betterman, L., Blazhev, A., Braun, N., Finke, F., Geibel, K., Ilie, G., Iwasaki, H., Jolie, J., Reiter, P., Scholl, C., Warr, N., Boutachkov, P., Caceres, L., Domingo, C., Engert, T., Farinon, F., Gerl, J., Goel, N., Gorska, M., Grawe, H., Kurz, N., Kojuharov, I., Pietri, S., Nociforo, C., Prochazka, A., Wollersheim, H-J, Eppinger, K., Faestermann, T., Hinke, C., Hoischen, R., Kruecken, R., Gottardo, A., Liu, Z., Woods, P., Grebosz, J., Merchant, E., Nyberg, J., Soderstrom, P-A, Podolyak, Z., Regan, P., Steer, S., Pfutzner, M., and Rudolph, D.

Abstract

The spectroscopy and structure of excited states of N similar to Z nuclei in the mass 70-100 region has been investigated using two techniques. In the A similar to 70-80 region fusion evaporation reactions coupled with the recoil-beta-tagging method have been employed at Jyvaskyla to study low-lying states in odd-odd N = Z nuclei. Results from these and other data for known odd-odd nuclei above mass 60 will be discussed. In the heavier mass 90 region a fragmentation experiment has been performed using the RIS-ING/FRS setup at GSI. This experiment was primarily aimed at searching for spin gap isomers in nuclei around A similar to 96. The objectives of the latter experiment will be discussed., QC 20110323 43rd Zakopane Conference on Nuclear Physics, Zakopane, POLAND, SEP 01-07, 2008

Published
2009

12. Band-terminating states in Ag-101

Author

Sohler, D., Cederkäll, Joakim, Atac Nyberg, Ayse, Johnson, Arne, Kerek, Andras, Klamra, Wlodzimierz, Norlin, Lars Olov, Weiszflog, M., et, al, Sohler, D., Cederkäll, Joakim, Atac Nyberg, Ayse, Johnson, Arne, Kerek, Andras, Klamra, Wlodzimierz, Norlin, Lars Olov, Weiszflog, M., and et, al

Abstract

Excited states of the neutron deficient Ag-101 nucleus have been investigated via the Cr-50(Ni-58, 3rho1alpha) heavy-ion induced reaction at 261 meV by use of in-beam spectroscopic methods. On the basis of the measured gammagamma-cincidence relations and angular distribution ratios high-spin bands have been extended up to I-pi = 35/2(+), 45/2((-)) and (49/2(-)). The negative parity states at the highest energy have been interpreted as terminating non-collective oblate states in the framework of the Nilsson-Strutinsky cranking formalism., QC 20100525 QC 20111027 Author count: 32

Published
2004
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13. Coexistence of superdeformed shapes in Er-154

Author

Lagergren, K, Cederwall, Bo, Bäck, Torbjörn, Wyss, Ramon, Ideguchi, E., Johnson, Arne, Atac Nyberg, Ayse, Axelsson, A., Azaiez, F., Bracco, A., Cederkäll, Joakim, Dombradi, Z., Fahlander, C., Gadea, A., Million, B., Petrache, C. M., Rossi-Alvarez, C., Sampson, J. A., Sohler, D., Weiszflog, M., Lagergren, K, Cederwall, Bo, Bäck, Torbjörn, Wyss, Ramon, Ideguchi, E., Johnson, Arne, Atac Nyberg, Ayse, Axelsson, A., Azaiez, F., Bracco, A., Cederkäll, Joakim, Dombradi, Z., Fahlander, C., Gadea, A., Million, B., Petrache, C. M., Rossi-Alvarez, C., Sampson, J. A., Sohler, D., and Weiszflog, M.

Abstract

A new superdeformed rotational band has been observed in Er-154 using the Euroball Ge detector array. The new band and the one previously observed can be understood as based on coexisting superdeformed structures at prolate and triaxial shapes, respectively. The observation resolves long-standing difficulties in the theoretical interpretation of superdeformed states in Er-154., QC 20100525

Published
2001
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14. Lifetime measurements of core-excited states in semi-magic 95Rh

Author

Ertoprak, Aysegul, Qi, Chong, Cederwall, Bo, Doncel, Maria, Jakobsson, U., Nyako, B., Jaworski, G., Davies, P., de France, G., Kuti, I., Napoli, D. R., Wadsworth, R., Ghugre, S. S., Raut, R., Akkus, B., Al-Azri, H., Algora, A., de Angelis, G., Atac Nyberg, Ayse, Bäck, Torbjörn, Boso, A., Clement, E., Debenham, D. M., Dombradi, Zs., Erturk, S., Gadea, A., Ghazi Moradi, Farnaz, Gottardo, A., Huyuk, T, Ideguchi, E., Li, Hongjie J., Michelagnoli, C., Modamio, V., Nyberg, J., Palacz, M., Petrache, C. M., Recchia, F., Sandzelius, M., Siciliano, M., Timar, J., Valiente-Dobon, J. J., Xiao, Z. G., Ertoprak, Aysegul, Qi, Chong, Cederwall, Bo, Doncel, Maria, Jakobsson, U., Nyako, B., Jaworski, G., Davies, P., de France, G., Kuti, I., Napoli, D. R., Wadsworth, R., Ghugre, S. S., Raut, R., Akkus, B., Al-Azri, H., Algora, A., de Angelis, G., Atac Nyberg, Ayse, Bäck, Torbjörn, Boso, A., Clement, E., Debenham, D. M., Dombradi, Zs., Erturk, S., Gadea, A., Ghazi Moradi, Farnaz, Gottardo, A., Huyuk, T, Ideguchi, E., Li, Hongjie J., Michelagnoli, C., Modamio, V., Nyberg, J., Palacz, M., Petrache, C. M., Recchia, F., Sandzelius, M., Siciliano, M., Timar, J., Valiente-Dobon, J. J., and Xiao, Z. G.

Abstract

Lifetimes of negative-parity states have been determined in the semi-magic (N=50) nucleus 95Rh. The fusion-evaporation reaction 58Ni(40Ca, 3p) was used to populate high-spin states in 95Rh at the Grand Accelerateur National d'Ions Lourds (GANIL) accelerator facility. The results were obtained using the Doppler Shift Attenuation Method (DSAM) based on the Doppler broadened line shapes produced during the slowing down process of the residual nuclei in a thick 6~ mg/cm2 metallic target. B(M1) and B(E2) reduced transition strengths are compared with predictions from large-scale shell-model calculations., QC 20200409

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