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348 results on '"Tveten G."'

51. Analysis of possible systematic errors in the Oslo method

Author

Larsen, A. C., Guttormsen, M., Krticka, M., Betak, E., Bürger, A., Görgen, A., Nyhus, H. T., Rekstad, J., Schiller, A., Siem, S., Toft, H. K., Tveten, G. M., Voinov, A. V., and Wikan, K.

Subjects
Nuclear Experiment
Abstract

In this work, we have reviewed the Oslo method, which enables the simultaneous extraction of level density and gamma-ray transmission coefficient from a set of particle-gamma coincidence data. Possible errors and uncertainties have been investigated. Typical data sets from various mass regions as well as simulated data have been tested against the assumptions behind the data analysis., Comment: 23 pages, 33 figures. As published in Phys. Rev. C

Published
2012
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52. Primary gamma-ray spectra in 44Ti of astrophysical interest

Author

Larsen, A. C., Goriely, S., Bürger, A., Guttormsen, M., Görgen, A., Harrisopulos, S., Kmiecik, M., Konstantinopoulos, T., Lagoyannis, A., Lönnroth, T., Mazurek, K., Norrby, M., Nyhus, H. T., Perdikakis, G., Schiller, A., Siem, S., Spyrou, A., Syed, N. U. H., Toft, H. K., Tveten, G. M., and Voinov, A.

Subjects
Nuclear Experiment
Abstract

Primary gamma-ray spectra for a wide excitation-energy range have been extracted for 44Ti from particle-gamma coincidence data of the 46Ti(p,t gamma)44Ti reaction. These spectra reveal information on the gamma-decay pattern of the nucleus, and may be used to extract the level density and radiative strength function applying the Oslo method. Models of the level density and radiative strength function are used as input for cross-section calculations of the 40Ca(alpha,gamma)44Ti reaction. Acceptable models should reproduce data on the 40Ca(alpha,gamma)44Ti reaction cross section as well as the measured primary gamma-ray spectra. This is only achieved when a coherent normalization of the slope of the level density and radiative strength function is performed. Thus, the overall shape of the experimental primary gamma-ray spectra puts a constraint on the input models for the rate calculations., Comment: 14 pages, 13 figures

Published
2012
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53. Evolution of the pygmy dipole resonance in Sn isotopes

Author

Toft, H. K., Larsen, A. C., Bürger, A., Guttormsen, M., Görgen, A., Nyhus, H. T., Renstrøm, T., Siem, S., Tveten, G. M., and Voinov, A.

Subjects
Nuclear Experiment
Abstract

Nuclear level density and $\gamma$-ray strength functions of $^{121,122}$Sn below the neutron separation energy are extracted with the Oslo method using the ($^3$He,$^3$He$^\prime\gamma$) and ($^3$He,$\alpha \gamma$) reactions. The level densities of $^{121,122}$Sn display step-like structures, interpreted as signatures of neutron pair breaking. An enhancement in both strength functions, compared to standard models for radiative strength, is observed in our measurements for $E_\gamma \gtrsim 5.2 $ MeV. This enhancement is compatible with pygmy resonances centered at $\approx 8.4(1)$ and $\approx 8.6(2)$ MeV, respectively, and with integrated strengths corresponding to $\approx1.8^{+1}_{-5}%$ of the classical Thomas-Reiche-Kuhn sum rule. Similar resonances were also seen in $^{116-119}$Sn. Experimental neutron-capture cross reactions are well reproduced by our pygmy resonance predictions, while standard strength models are less successful. The evolution as a function of neutron number of the pygmy resonance in $^{116-122}$Sn is described as a clear increase of centroid energy from 8.0(1) to 8.6(2) MeV, but with no observable difference in integrated strengths.

Published
2011
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54. Fermi's golden rule applied to the gamma decay in the quasicontinuum of 46Ti

Author

Guttormsen, M., Larsen, A. C., Buerger, A., Goergen, A., Harissopulos, S., Kmiecik, M., Konstantinopoulos, T., Krticka, M., Lagoyannis, A., Loennroth, T., Mazurek, K., Norrby, M., Nyhus, H. T., Schiller, G. Perdikakis A., Siem, S., Spyrou, A., Syed, N. U. H., Toft, H. K., Tveten, G. M., and Voinov, A.

Subjects
Nuclear Experiment
Abstract

Particle-gamma coincidences from the 46Ti(p,p' gamma)46Ti inelastic scattering reaction with 15-MeV protons are utilized to obtain gamma-ray spectra as a function of excitation energy. The rich data set allows analyzing the coincidence data with various gates on excitation energy. This enables, for many independent data sets, a simultaneous extraction of level density and radiative strength function (RSF). The results are consistent with one common level density. The data seem to exhibit a universal RSF as the deduced RSFs from different excitation energies show only small fluctuations provided that only excitation energies above 3 MeV are taken into account. If transitions to well-separated low-energy levels are included, the deduced RSF may change by a factor of 2-3, which might be expected due to the involved Porter-Thomas fluctuations., Comment: 11 pages and 12 figures

Published
2010
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55. Radiative strength functions in 163,164Dy

Author

Nyhus, H. T., Siem, S., Guttormsen, M., Larsen, A. C., Bürger, A., Syed, N. U. H., Tveten, G. M., and Voinov, A.

Subjects
Nuclear Experiment
Abstract

The nuclei 163,164Dy have been investigated using the Oslo method on data from the pick-up reaction 164Dy(3He,alpha gamma)163Dy and the inelastic scattering 164Dy(3He,3He' gamma)164Dy, respectively. The radiative strength functions for both nuclei have been extracted, and a small resonance centered around Eg ?3 MeV is observed in both cases. The parameters of this so-called pygmy M1 resonance (the scissors mode) are compared to previous results on 160,161,162Dy using the Oslo method, and to data on 163Dy measured by the Prague group using the two-step cascade method. In particular, the integrated reduced transition probability B(M1) of the pygmy resonance is compared with neighboring dysprosium isotopes. We also observe an enhanced strength in the region above gamma energy around 5 MeV in 164Dy. Possible origins of this feature are discussed.

Published
2010
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56. Spectroscopy of Neutron-Rich 168,170Dy: Yrast Band Evolution Close to the NpNn Valence Maximum

Author

Söderström, P. -A., Nyberg, J., Regan, P. H., Algora, A., de Angelis, G., Ashley, S. F., Aydin, S., Bazzacco, D., Casperson, R. J., Catford, W. N., Cederkäll, J., Chapman, R., Corradi, L., Fahlander, C., Farnea, E., Fioretto, E., Freeman, S. J., Gadea, A., Gelletly, W., Gottardo, A., Grodner, E., He, C. Y., Jones, G. A., Keyes, K., Labiche, M., Liang, X., Liu, Z., Lunardi, S., Mărginean, N., Mason, P., Menegazzo, R., Mengoni, D., Montagnoli, G., Napoli, D., Ollier, J., Pietri, S., Podolyák, Zs., Pollarolo, G., Recchia, F., Şahin, E., Scarlassara, F., Silvestri, R., Smith, J. F., Spohr, K. -M., Steer, S. J., Stefanini, A. M., Szilner, S., Thompson, N. J., Tveten, G. M., Ur, C. A., Valiente-Dobón, J. J., Werner, V., Williams, S. J., Xu, F. R., and Zhu, J. Y.

Subjects
Nuclear Experiment
Abstract

The yrast sequence of the neutron-rich dysprosium isotope 168Dy has been studied using multi-nucleon transfer reactions following collisions between a 460-MeV 82Se beam and a 170Er target. The reaction products were identified using the PRISMA magnetic spectrometer and the gamma rays detected using the CLARA HPGe-detector array. The 2+ and 4+ members of the previously measured ground state rotational band of 168Dy have been confirmed and the yrast band extended up to 10+. A tentative candidate for the 4+ to 2+ transition in 170Dy was also identified. The data on these nuclei and on the lighter even-even dysprosium isotopes are interpreted in terms of Total Routhian Surface calculations and the evolution of collectivity in the vicinity of the proton-neutron valence product maximum is discussed., Comment: 15 pages, 7 figures, submitted to Phys. Rev. C

Published
2009
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57. Spectroscopic studies of Dy-168,170 using CLARA and PRISMA

Author

Söderström, P. -A., Nyberg, J., Regan, P. H., Algora, A., de Angelis, G., Ashley, S. F., Aydin, S., Bazzacco, D., Casperson, R. J., Catford, W. N., Cederkäll, J., Chapman, R., Corradi, L., Fahlander, C., Farnea, E., Freeman, S. J., Gadea, A., Gelletly, W., Grodner, E., He, C. Y., Jones, G. A., Keyes, K., Labiche, M., Liang, X., Liu, Z., Lunardi, S., Marginean, N., Menegazzo, R., Mengoni, D., Napoli, D., Ollier, J., Pietri, S., Podolyàk, Zs., Recchia, F., Sahin, E., Smith, J. F., Spohr, K. M., Steer, S. J., Stefanini, A., Thompson, N. J., Tveten, G., Ur, C. A., Valiente-Dóbon, J. J., Werner, V., and Williams, S. J.

Subjects
Nuclear Experiment
Abstract

Preliminary results from an experiment aiming at Dy-170. Submitted to the LNL Annual Report 2008., Comment: 2 pages, 4 figures, Submitted to the LNL Annual Report 2008

Published
2009

58. Photoneutron emission cross sections for C13

Author

Utsunomiya, H., primary, Goriely, S., additional, Kimura, M., additional, Shimizu, N., additional, Utsuno, Y., additional, Tveten, G. M., additional, Renstrøm, T., additional, Ari-izumi, T., additional, and Miyamoto, S., additional

Published
2024
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59. Erratum: Nuclear level densities and γ−ray strength functions in Sn120,124 isotopes: Impact of Porter-Thomas fluctuations [Phys. Rev. C 106 , 034322 (2022)]

Author

Markova, M., primary, Larsen, A. C., additional, von Neumann-Cosel, P., additional, Bassauer, S., additional, Görgen, A., additional, Guttormsen, M., additional, Bello Garrote, F. L., additional, Berg, H. C., additional, Bjørøen, M. M., additional, Eriksen, T. K., additional, Gjestvang, D., additional, Isaak, J., additional, Mbabane, M., additional, Paulsen, W., additional, Pedersen, L. G., additional, Pettersen, N. I. J., additional, Richter, A., additional, Sahin, E., additional, Scholz, P., additional, Siem, S., additional, Tveten, G. M., additional, Valsdottir, V. M., additional, and Wiedeking, M., additional

Published
2024
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60. γ-Ray Strength Functions and GDR Cross Sections in the IAEA Photonuclear Data Project

Author

Utsunomiya, H., primary, Gheorghe, I., additional, Filipescu, D. M., additional, Stopani, K., additional, Belyshev, S., additional, Renstrøm, T., additional, Tveten, G. M., additional, Fan, G., additional, Wang, H., additional, Goriely, S., additional, Lui, Y.-W., additional, Ari-izumi, T., additional, Miyamoto, S., additional, Varlamov, V., additional, Ishkhanov, B., additional, Larsen, A. C., additional, and Siem, S., additional

Published
2021
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61. Impact of Restricted Spin-Ranges in the Oslo Method: The Example of (d,p)240Pu

Author

Zeiser, F., primary, Potel, G., additional, Tveten, G. M., additional, Larsen, A. C., additional, Guttormsen, M., additional, Laplace, T. A., additional, Siem, S., additional, Bleuel, D. L., additional, Goldblum, B. L., additional, Bernstein, L. A., additional, Garrote, F.  L. Bello, additional, Campo, L. Crespo, additional, Eriksen, T. K., additional, Görgen, A., additional, Hadynska-Klek, K., additional, Midtbø, J. E., additional, Renstrøm, T., additional, Sahin, E., additional, Tornyi, T., additional, Voinov, A., additional, and Wiedeking, M., additional

Published
2020
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62. New experimental constraint on the W185(n,γ)W186 cross section

Author

Larsen, A. C., primary, Tveten, G. M., additional, Renstrøm, T., additional, Utsunomiya, H., additional, Algin, E., additional, Ari-izumi, T., additional, Ay, K. O., additional, Bello Garrote, F. L., additional, Crespo Campo, L., additional, Furmyr, F., additional, Goriely, S., additional, Görgen, A., additional, Guttormsen, M., additional, Ingeberg, V. W., additional, Kheswa, B. V., additional, Kullmann, I. K. B., additional, Laplace, T., additional, Lima, E., additional, Markova, M., additional, Midtbø, J. E., additional, Miyamoto, S., additional, Mjøs, A. H., additional, Modamio, V., additional, Ozgur, M., additional, Pogliano, F., additional, Riemer-Sørensen, S., additional, Sahin, E., additional, Shen, S., additional, Siem, S., additional, Spyrou, A., additional, and Wiedeking, M., additional

Published
2023
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63. Electromagnetic properties of low-lying states in neutron-deficient Hg isotopes: Coulomb excitation of 182Hg, 184Hg, 186Hg and 188Hg

Author

Wrzosek-Lipska, K., Rezynkina, K., Bree, N., Zielińska, M., Gaffney, L. P., Petts, A., Andreyev, A., Bastin, B., Bender, M., Blazhev, A., Bruyneel, B., Butler, P. A., Carpenter, M. P., Cederkäll, J., Clément, E., Cocolios, T. E., Deacon, A. N., Diriken, J., Ekström, A., Fitzpatrick, C., Fraile, L. M., Fransen, Ch., Freeman, S. J., García-Ramos, J. E., Geibel, K., Gernhäuser, R., Grahn, T., Guttormsen, M., Hadinia, B., Hadyńska-Klȩk, K., Hass, M., Heenen, P. -H., Herzberg, R. -D., Hess, H., Heyde, K., Huyse, M., Ivanov, O., Jenkins, D. G., Julin, R., Kesteloot, N., Kröll, Th., Krücken, R., Larsen, A. C., Lutter, R., Marley, P., Napiorkowski, P. J., Orlandi, R., Page, R. D., Pakarinen, J., Patronis, N., Peura, P. J., Piselli, E., Próchniak, L., Rahkila, P., Rapisarda, E., Reiter, P., Robinson, A. P., Scheck, M., Siem, S., Singh Chakkal, K., Smith, J. F., Srebrny, J., Stefanescu, I., Tveten, G. M., Van Duppen, P., Van de Walle, J., Voulot, D., Warr, N., Wiens, A., and Wood, J. L.

Published
2019
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64. Nuclear level densities and γ -ray strength functions in Sn120,124 isotopes: Impact of Porter-Thomas fluctuations

Author

Markova, M., primary, Larsen, A. C., additional, von Neumann-Cosel, P., additional, Bassauer, S., additional, Görgen, A., additional, Guttormsen, M., additional, Garrote, F. L. Bello, additional, Berg, H. C., additional, Bjørøen, M. M., additional, Eriksen, T. K., additional, Gjestvang, D., additional, Isaak, J., additional, Mbabane, M., additional, Paulsen, W., additional, Pedersen, L. G., additional, Pettersen, N. I. J., additional, Richter, A., additional, Sahin, E., additional, Scholz, P., additional, Siem, S., additional, Tveten, G. M., additional, Valsdottir, V. M., additional, and Wiedeking, M., additional

Published
2022
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65. Evolution of the γ -ray strength function in neodymium isotopes

Author

Guttormsen, M., primary, Ay, K. O., additional, Ozgur, M., additional, Algin, E., additional, Larsen, A. C., additional, Bello Garrote, F. L., additional, Berg, H. C., additional, Crespo Campo, L., additional, Dahl-Jacobsen, T., additional, Furmyr, F. W., additional, Gjestvang, D., additional, Görgen, A., additional, Hagen, T. W., additional, Ingeberg, V. W., additional, Kheswa, B. V., additional, Kullmann, I. K. B., additional, Klintefjord, M., additional, Markova, M., additional, Midtbø, J. E., additional, Modamio, V., additional, Paulsen, W., additional, Pedersen, L. G., additional, Renstrøm, T., additional, Sahin, E., additional, Siem, S., additional, Tveten, G. M., additional, and Wiedeking, M., additional

Published
2022
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66. Nuclear level densities and ?-ray strength functions in 120,124Sn isotopes: Impact of Porter-Thomas fluctuations

Author

Markova, M., Larsen, A. C., Von Neumann-Cosel, P., Bassauer, S., Goergen, A., Guttormsen, M., Garrote, F. L. Bello, Berg, H. C., Bjoroen, M. M., Eriksen, T. K., Gjestvang, D., Isaak, J., Mbabane, M., Paulsen, W., Pedersen, L. G., Pettersen, N. I. J., Richter, A., Sahin, E., Scholz, P., Siem, S., Tveten, G. M., Valsdottir, V. M., Wiedeking, M., Markova, M., Larsen, A. C., Von Neumann-Cosel, P., Bassauer, S., Goergen, A., Guttormsen, M., Garrote, F. L. Bello, Berg, H. C., Bjoroen, M. M., Eriksen, T. K., Gjestvang, D., Isaak, J., Mbabane, M., Paulsen, W., Pedersen, L. G., Pettersen, N. I. J., Richter, A., Sahin, E., Scholz, P., Siem, S., Tveten, G. M., Valsdottir, V. M., and Wiedeking, M.

Abstract

Nuclear level densities (NLDs) and gamma -ray strength functions (GSFs) of 120,124Sn have been extracted with the Oslo method from proton-gamma coincidences in the (p, p'gamma ) reaction. The functional forms of the GSFs and NLDs have been further constrained with the Shape method by studying primary gamma -transitions to the ground and first excited states. The NLDs demonstrate good agreement with the NLDs of 116,118,122Sn isotopes measured previously. Moreover, the extracted partial NLD of 1- levels in 124Sn is shown to be in fair agreement with those deduced from spectra of relativistic Coulomb excitation in forward-angle inelastic proton scattering. The experimental NLDs have been applied to estimate the magnitude of the Porter-Thomas (PT) fluctuations. Within the PT fluctuations, we conclude that the GSFs for both isotopes can be considered to be independent of initial and final excitation energies, in accordance with the generalized Brink-Axel hypothesis. Particularly large fluctuations observed in the Shape-method GSFs present a considerable contribution to the uncertainty of the method and may be one of the reasons for deviations from the Oslo-method strength at low gamma -ray energies and low values of the NLD (below eta 1 x 103-2 x 103 MeV-1).

Published
2022

67. Comprehensive Test of the Brink-Axel Hypothesis in the Energy Region of the Pygmy Dipole Resonance

Author

Markova, M., primary, von Neumann-Cosel, P., additional, Larsen, A. C., additional, Bassauer, S., additional, Görgen, A., additional, Guttormsen, M., additional, Bello Garrote, F. L., additional, Berg, H. C., additional, Bjørøen, M. M., additional, Dahl-Jacobsen, T., additional, Eriksen, T. K., additional, Gjestvang, D., additional, Isaak, J., additional, Mbabane, M., additional, Paulsen, W., additional, Pedersen, L. G., additional, Pettersen, N. I. J., additional, Richter, A., additional, Sahin, E., additional, Scholz, P., additional, Siem, S., additional, Tveten, G. M., additional, Valsdottir, V. M., additional, Wiedeking, M., additional, and Zeiser, F., additional

Published
2021
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68. Coulomb excitation of 107Sn

Author

DiJulio, D. D., Cederkall, J., Fahlander, C., Ekström, A., Hjorth-Jensen, M., Albers, M., Bildstein, V., Blazhev, A., Darby, I., Davinson, T., De Witte, H., Diriken, J., Fransen, Ch., Geibel, K., Gernhäuser, R., Görgen, A., Hess, H., Iwanicki, J., Lutter, R., Reiter, P., Scheck, M., Seidlitz, M., Siem, S., Taprogge, J., Tveten, G. M., Van de Walle, J., Voulot, D., Warr, N., Wenander, F., and Wimmer, K.

Published
2012
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69. Electromagnetic properties of vibrational bands in 170Er

Author

DiJulio, D. D., Cederkall, J., Fahlander, C., Ekström, A., Golubev, P., Mattsson, K., Rudolph, D., de Angelis, G., Aydin, S., Y. Deo, A., Farnea, E., Farrelly, G., Geibel, K., He, C., Iwanicki, J., Kempley, R., Marginean, N., Menegazzo, R., Mengoni, D., Orlandi, R., Podolyak, Z., Recchia, F., Reiter, P., Sahin, E., Smith, J., Söderström, P. A., Torres, D. A., Tveten, G. M., Ur, C. A., Valiente-Dobón, J. J., Wendt, A., and Zielińska, M.

Published
2011
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70. Coulomb excitation of the odd-odd isotopes 106, 108In

Author

Ekström, A., Cederkäll, J., Fahlander, C., Hjorth-Jensen, M., Engeland, T., Blazhev, A., Butler, P. A., Davinson, T., Eberth, J., Finke, F., Görgen, A., Górska, M., Hurst, A. M., Ivanov, O., Iwanicki, J., Köster, U., Marsh, B. A., Mierzejewski, J., Reiter, P., Siem, S., Sletten, G., Stefanescu, I., Tveten, G. M., Van de Walle, J., Voulot, D., Warr, N., Weisshaar, D., Wenander, F., and Zielińska, M.

Published
2010
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71. Statistical properties of the well deformed 153,155Sm nuclei and the scissors resonance

Author

Malatji, K. L., Beckmann, K. S., Wiedeking, M., Siem, S., Goriely, S., Larsen, A. C., Ay, K. O., Garrote, F. L. Bello, Campo, L. Crespo, G��rgen, A., Guttormsen, M., Ingeberg, V. W., Jones, P., Kheswa, B. V., von Neumann-Cosel, P., Ozgur, M., Potel, G., Pellegri, L., Renstr��m, T., Tveten, G. M., and Zeiser, F.

Subjects
FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

The Nuclear Level Densities (NLDs) and the $\gamma$-ray Strength Functions ($\gamma$SFs) of $^{153,155}$Sm have been extracted from (d,p$\gamma$) coincidences using the Oslo method. The experimental NLD of $^{153}$Sm is higher than the NLD of $^{155}$Sm, in accordance with microscopic calculations. The $\gamma$SFs of $^{153,155}$Sm are in fair agreement with QRPA calculations based on the D1M Gogny interaction. An enhancement is observed in the $\gamma$SF for both $^{153,155}$Sm nuclei around 3 MeV in excitation energy and is attributed to the M1 Scissors Resonance (SR). Their integrated strengths were found to be in the range 1.3 - 2.1 and 4.4 - 6.4 $\mu^{2}_{N}$ for $^{153}$Sm and $^{155}$Sm, respectively. The strength of the SR for $^{155}$Sm is comparable to those for deformed even-even Sm isotopes from nuclear resonance fluorescence measurements, while that of $^{153}$Sm is lower than expected.

Published
2021

72. Comprehensive Test of the Brink-Axel Hypothesis in the Energy Region of the Pygmy Dipole Resonance

Author

Markova, M., Von Neumann-Cosel, P., Larsen, A. C., Bassauer, S., Goergen, A., Guttormsen, M., Garrote, F. L. Bello, Berg, H. C., Bjoroen, M. M., Dahl-Jacobsen, T., Eriksen, T. K., Gjestvang, D., Isaak, J., Mbabane, M., Paulsen, W., Pedersen, L. G., Pettersen, N. I. J., Richter, A., Sahin, E., Scholz, P., Siem, S., Tveten, G. M., Valsdottir, V. M., Wiedeking, M., Zeiser, F., Markova, M., Von Neumann-Cosel, P., Larsen, A. C., Bassauer, S., Goergen, A., Guttormsen, M., Garrote, F. L. Bello, Berg, H. C., Bjoroen, M. M., Dahl-Jacobsen, T., Eriksen, T. K., Gjestvang, D., Isaak, J., Mbabane, M., Paulsen, W., Pedersen, L. G., Pettersen, N. I. J., Richter, A., Sahin, E., Scholz, P., Siem, S., Tveten, G. M., Valsdottir, V. M., Wiedeking, M., and Zeiser, F.

Abstract

The validity of the Brink-Axel hypothesis, which is especially important for numerous astrophysical calculations, is addressed for 116,120,124Sn below the neutron separation energy by means of three independent experimental methods. The gamma-ray strength functions (GSFs) extracted from primary gamma-decay spectra following charged-particle reactions with the Oslo method and with the shape method demonstrate excellent agreement with those deduced from forward-angle inelastic proton scattering at relativistic beam energies. In addition, the GSFs are shown to be independent of excitation energies and spins of the initial and final states. The results provide a critical test of the generalized Brink-Axel hypothesis in heavy nuclei, demonstrating its applicability in the energy region of the pygmy dipole resonance.

Published
2021

73. Strong enhancement of level densities in the crossover from spherical to deformed neodymium isotopes

Author

Guttormsen, Magne, Alhassid, Yoram, Ryssens, Wouter, Ay, K.O., Ozgur, Mustafa, Algin, E, Larsen, A.C., Bello Garrote, F.L., Crespo Campo, L., Dahl-Jacobsen, T., Görgen, Andreas, Hagen, T.W., Ingeberg, V. W., Kheswa, B.V., Klintefjord, M., Midtbø, J.E., Modamio, V, Renstrøm, T., Sahin, E., Siem, Sunniva, Tveten, G. M., Zeiser, F., Guttormsen, Magne, Alhassid, Yoram, Ryssens, Wouter, Ay, K.O., Ozgur, Mustafa, Algin, E, Larsen, A.C., Bello Garrote, F.L., Crespo Campo, L., Dahl-Jacobsen, T., Görgen, Andreas, Hagen, T.W., Ingeberg, V. W., Kheswa, B.V., Klintefjord, M., Midtbø, J.E., Modamio, V, Renstrøm, T., Sahin, E., Siem, Sunniva, Tveten, G. M., and Zeiser, F.

Abstract

info:eu-repo/semantics/published

Published
2021

74. Excitation energy dependence of prompt fission γ -ray emission from Pu241*

Author

Gjestvang, D., primary, Siem, S., additional, Zeiser, F., additional, Randrup, J., additional, Vogt, R., additional, Wilson, J. N., additional, Bello-Garrote, F., additional, Bernstein, L. A., additional, Bleuel, D. L., additional, Guttormsen, M., additional, Görgen, A., additional, Larsen, A. C., additional, Malatji, K. L., additional, Matthews, E. F., additional, Oberstedt, A., additional, Oberstedt, S., additional, Tornyi, T., additional, Tveten, G. M., additional, and Voyles, A. S., additional

Published
2021
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75. Statistical properties of the well deformed Sm153,155 nuclei and the scissors resonance

Author

Malatji, K. L., primary, Beckmann, K. S., additional, Wiedeking, M., additional, Siem, S., additional, Goriely, S., additional, Larsen, A. C., additional, Ay, K. O., additional, Bello Garrote, F. L., additional, Campo, L. Crespo, additional, Görgen, A., additional, Guttormsen, M., additional, Ingeberg, V. W., additional, Jones, P., additional, Kheswa, B. V., additional, von Neumann-Cosel, P., additional, Ozgur, M., additional, Potel, G., additional, Pellegri, L., additional, Renstrøm, T., additional, Tveten, G. M., additional, and Zeiser, F., additional

Published
2021
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76. Radiative Width of the Hoyle State from γ -Ray Spectroscopy

Author

Kibédi, T., primary, Alshahrani, B., additional, Stuchbery, A. E., additional, Larsen, A. C., additional, Görgen, A., additional, Siem, S., additional, Guttormsen, M., additional, Giacoppo, F., additional, Morales, A. I., additional, Sahin, E., additional, Tveten, G. M., additional, Garrote, F. L. Bello, additional, Campo, L. Crespo, additional, Eriksen, T. K., additional, Klintefjord, M., additional, Maharramova, S., additional, Nyhus, H.-T., additional, Tornyi, T. G., additional, Renstrøm, T., additional, and Paulsen, W., additional

Published
2020
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77. High-Statistics Sub-Barrier Coulomb Excitation of 106,108,110Sn

Author

Park, J., primary, Knyazev, A., additional, Rickert, E., additional, Golubev, P., additional, Cederkäll, J., additional, Andreyev, A. N., additional, de Angelis, G., additional, Arnswald, K., additional, Barber, L., additional, Berger, C., additional, Berner, C., additional, Berry, T., additional, Borge, M. J. G., additional, Boukhari, A., additional, Cox, D., additional, Cubiss, J., additional, Cullen, D. M., additional, Ovejas, J. Díaz, additional, Fahlander, C., additional, Gaffney, L. P., additional, Gawlik, A., additional, Gernhäuser, R., additional, Görgen, A., additional, Habermann, T., additional, Henrich, C., additional, Illana, A., additional, Iwanicki, J., additional, Johansen, T. W., additional, Konki, J., additional, Kröll, T., additional, Nara Singh, B. S., additional, Rainovski, G., additional, Raison, C., additional, Reiter, P., additional, Rosiak, D., additional, Saha, S., additional, Saxena, M., additional, Schilling, M., additional, Seidlitz, M., additional, Snäll, J., additional, Stahl, C., additional, Stryjczyk, M., additional, Tengblad, O., additional, Tveten, G. M., additional, Valiente-Dobón, J. J., additional, Van Duppen, P., additional, Viñals, S., additional, Warr, N., additional, Welker, A., additional, Werner, L., additional, De Witte, H., additional, and Zidarova, R., additional

Published
2020
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79. The radiative width of the Hoyle state from $��$-ray spectroscopy

Author

Kib��di, T., Alshahrani, B., Stuchbery, A. E., Larsen, A. C., G��rgen, A., Siem, S., Guttormsen, M., Giacoppo, F., Morales, A. I., Sahin, E., Tveten, G. M., Garrote, F. L. Bello, Campo, L. Crespo, Eriksen, T. K., Klintefjord, M., Maharramova, S., Nyhus, H. -T., Tornyi, T. G., Renstr��m, T., and Paulsen, W.

Subjects
Physics::Accelerator Physics, FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

The cascading 3.21 MeV and 4.44 MeV electric quadrupole transitions have been observed from the Hoyle state at 7.65 MeV excitation energy in $^{12}$C, excited by the $^{12}$C(p,p$^{\prime}$) reaction at 10.7 MeV proton energy. From the proton-$��$-$��$ triple coincidence data, a value of ${��_{\rm rad}}/��=6.2(6) \times 10^{-4}$ was obtained for the radiative branching ratio. Using our results, together with ${��_��^{E0}}/��$ from Eriksen et al., Phys. Rev. C 102, 024320 and the currently adopted $��_��(E0)$ values, the radiative width of the Hoyle state is determined as $��_{\rm rad}=5.1(6) \times 10^{-3}$ eV. This value is about 34% higher than the currently adopted value and will impact on models of stellar evolution and nucleosynthesis., 6 pages, 6 figures

Published
2020
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80. First application of the Oslo method in inverse kinematics - Nuclear level densities and gamma-ray strength functions of 87Kr

Author

Ingeberg, V. W., Siem, S., Wiedeking, M., Sieja, K., Zeiser, F., Bleuel, D. L., Brits, C. P., Bucher, D. T., Dinoko, T. S., Easton, J. L., Görgen, A., Jones, P., Kheswa, B. V., Khumalo, N. A., Larsen, A. C., Lawrie, E. A., Lawrie, J. J., Majola, S. N. T., Malatji, K. L., Makhathini, L., Maqabuka, B., Negi, D., Noncolela, S. P., Papka, P., Sahin, E., Schwengner, R., Tveten, G. M., and Zikhali, B. R.

Subjects
(d, level density, Hauser-Feshbach model, shell model, inverse kinematics, Nuclear structure, gamma-ray strength function, Nuclear Experiment, nuclear reactions, p) recation, s-process
Abstract

A novel technique for extracting the gamma-ray strength function (SF) and nuclear level density (NLD) from inverse kinematics experiments is presented, which allows for measurements of these properties, across a vast range of previously inaccessible nuclei. Proton-gamma coincidence events from the d(86Kr, p)87Kr reaction were measured at iThemba LABS and the SF and NLD in 87 Kr obtained with the Oslo Method.The SF and NLD are important parameters in Hauser-Feshbach calculations to constrain (n,gamma) cross sections of nuclei for which these cannot be measured directly. The extracted SF and NLD are used as input in Hauser-Feshbach calculations to constrain the 86Kr(n,gamma)87Kr cross section which is important for the 87Rb production in the s-process. The nature of the low-energy region of the SF is explored through comparison to shell model calculations with the LNPS-SDG interaction.

Published
2020

81. IAEA Photonuclear Data Library 2019

Author

Kawano, T., Cho, Y. S., Dimitriou, P., Filipescu, D., Iwamoto, N., Plujko, V., Tao, X., Utsunomiya, H., Varlamov, V., Xu, R., Capote, R., Gheorghe, I., Gorbachenko, O., Jin, Y. L., Renström, T., Stopani, K., Tian, Y., Tveten, G. M., Wang, J. M., Belgya, T., Firestone, R., Goriely, S., Kopecky, J., Krticka, M., (0000-0002-7620-8882) Schwengner, R., Siem, S., Wiedeking, M., Kawano, T., Cho, Y. S., Dimitriou, P., Filipescu, D., Iwamoto, N., Plujko, V., Tao, X., Utsunomiya, H., Varlamov, V., Xu, R., Capote, R., Gheorghe, I., Gorbachenko, O., Jin, Y. L., Renström, T., Stopani, K., Tian, Y., Tveten, G. M., Wang, J. M., Belgya, T., Firestone, R., Goriely, S., Kopecky, J., Krticka, M., (0000-0002-7620-8882) Schwengner, R., Siem, S., and Wiedeking, M.

Abstract

Photo-induced reaction cross section data are of importance for a variety of current or emerging applications, such as radiation shielding design and radiation transport analyses, calculations of absorbed dose in the human body during radiotherapy, physics and technology of fission reactors (influence of photo-reactions on neutron balance) and fusion reactors (plasma diagnostics and shielding), activation analyses, safeguards and inspection technologies, nuclear waste transmutation, medical isotope production and astrophysical applications. To address these data needs the IAEA Photonuclear Data library was produced in 2000, containing evaluated photo-induced cross sections and neutron spectra for 164 nuclides which were deemed relevant for the applications. Since the release of the IAEA Photonuclear Data Library however, new experimental data as well as new methods to assess the reliability of experimental cross sections have become available. Theoretical models and input parameters used to evaluate photo-induced reactions have improved significantly over the years. In addition, new measurements of partial photoneutron cross sections using mono-energetic photon beams and advanced neutron detection systems have been performed allowing for the validation of the evaluations and assessments of the experimental data. Furthermore, technological advances have led to the construction of new and more powerful gamma-beam facilities, therefore new data needs are emerging. We report our coordinated efforts to address these data needs and present the results of the new evaluations of more than 200 nuclides included in the new updated IAEA Photonuclear Data Library, where the photon energy goes up to 200 MeV. We discuss the new assessment method and make recommendations to the user community in cases where the experimental data are discrepant and the assessments disagree. In addition, in the absence of experimental data, we present model predictions for photo-induced reaction cro

Published
2020

82. Primary gamma-ray intensities and gamma-strength functions from discrete two-step gamma-ray cascades in radiative proton-capture experiments

Author

Scholz, P., Guttormsen, M., Heim, F., Larsen, A. C., Mayer, J., Savran, D., Spieker, M., Tveten, G. M., Voinov, A. V., Wilhelmy, J., Zeiser, F., Zilges, A., Scholz, P., Guttormsen, M., Heim, F., Larsen, A. C., Mayer, J., Savran, D., Spieker, M., Tveten, G. M., Voinov, A. V., Wilhelmy, J., Zeiser, F., and Zilges, A.

Abstract

Background: Reaction rates of radiative capture reactions can play a crucial role in the nucleosynthesis of heavy nuclei in explosive stellar environments. These reaction rates depend strongly on gamma-ray decay widths in the reaction products, which are, for nonresonant capture reactions at high excitation energies, derived from the gamma-ray strength function and the nuclear level density. Recently, the ratio method was applied to primary gamma rays observed from (d, p) reactions and nuclear resonance fluorescence measurements to extract the dipole strength in atomic nuclei and to test the generalized Brink-Axel hypothesis. Purpose: The purpose of this work is to apply the ratio method to primary y -ray intensities of the Cu-63,Cu-65(p,gamma) reactions to extract gamma-ray strength information on the nuclei Zn-64,Zn-66. The impact of spin distribution, total gamma-ray decay widths, level densities, and width fluctuations on the application of the ratio method will be discussed. Additionally, by comparing the relative gamma-ray strength at different excitation energies, conclusions on the validity of the generalized Brink-Axel hypothesis can be made. Method: The radiative proton capture reaction measurements have been performed at the HORUS gamma-ray spectrometer of the University of Cologne at one excitation energy for each reaction. Primary gamma-ray intensities have been determined by normalizing secondary gamma-ray transitions in two-step cascades using their absolute branching ratio. The ratio method was applied to the measured primary gamma-ray intensities as well as to previous measurements by Erlandsson et al. at different excitation energies. Results: The relative strength function curve for Zn-64 from our measurement shows no significant deviation from the previous measurement at a different excitation energy. The same is true for Zn-66 where both measurements were at almost the same excitation energy. Absolute gamma-strength function values have been obt

Published
2020

83. In-beam γ-ray spectroscopy of Te 136 at relativistic energies

Author

Vaquero, V., Jungclaus, A., Doornenbal, P., Wimmer, K., Moro, A. M., Ogata, K., Furumoto, T., Chen, S., Nácher, E., Sahin, E., Shiga, Y., Steppenbeck, D., Taniuchi, R., Xu, Z. Y., Ando, T., Baba, H., Bello Garrote, F. L., Franchoo, S., Hadynska-Klek, K., Kusoglu, A., Liu, J., Lokotko, T., Momiyama, S., Motobayashi, T., Nagamine, S., Nakatsuka, N., Niikura, M., Orlandi, R., Saito, T. Y., Sakurai, H., Söderström, P. A., Tveten, G. M., Vajta, Zs, and Yalcinkaya, M.

Subjects
Nuclear Experiment
Abstract

The reduced transition probability B(E2;01+→21+) to the first excited 2+ state of the neutron-rich nucleus Te136, with two protons and two neutrons outside the doubly magic Sn132 core, was measured via Coulomb excitation at relativistic energies at the RIKEN Radioactive Isotope Beam Factory. A value of B(E2)=0.191(26) e2b2 was extracted from the measured inelastic scattering cross section on an Au target taking into account the contributions from both Coulomb and nuclear excitations. In addition, an upper limit for the transition strength to a 2+ state of mixed-symmetry character in the excitation energy range of 1.5-2.2 MeV was determined and compared to the predictions of various theoretical calculations. Because of the high statistics gathered in the present experiment the error of the deduced B(E2) value is dominated by the systematic uncertainties involved in the analysis of Coulomb excitation experiments at beam energies around 150 MeV/u. Therefore, the latter are for the first time assessed in detail in the present work.

Published
2019

84. In-beam γ -ray spectroscopy of Te 136 at relativistic energies

Author

Vaquero, Victor, Jungclaus, Andrea, Doornenbal, P., Wimmer, K., Moro, A.M., Ogata, K., Furumoto, T., Chen, S., Nácher, Enrique, Sahin, E., Shiga, Y., Steppenbeck, D., Taniuchi, R., Xu, Z. Y., Ando, T., Baba, H., Bello Garrote, F.L., Franchoo, S., Hadynska-Klek, K., Kusoglu, A., Liu, J., Lokotko, T., Momiyama, S., Motobayashi, T., Nagamine, S., Nakatsuka, Nathan, Niikura, M., Orlandi, R., Saito, T. Y., Sakurai, H., Söderström, P. A., Tveten, G. M., Vajta, Z., Yalcinkaya, M., RIKEN Nishina Center for Accelerator-Based Science, Ministerio de Economía y Competitividad (España), and Ministerio de Ciencia, Innovación y Universidades (España)

Abstract

14 pags., 11 figs-. 3 tabs., The reduced transition probability B(E2;01+→21+) to the first excited 2+ state of the neutron-rich nucleus Te136, with two protons and two neutrons outside the doubly magic Sn132 core, was measured via Coulomb excitation at relativistic energies at the RIKEN Radioactive Isotope Beam Factory. A value of B(E2)=0.191(26) e2b2 was extracted from the measured inelastic scattering cross section on an Au target taking into account the contributions from both Coulomb and nuclear excitations. In addition, an upper limit for the transition strength to a 2+ state of mixed-symmetry character in the excitation energy range of 1.5-2.2 MeV was determined and compared to the predictions of various theoretical calculations. Because of the high statistics gathered in the present experiment the error of the deduced B(E2) value is dominated by the systematic uncertainties involved in the analysis of Coulomb excitation experiments at beam energies around 150 MeV/u. Therefore, the latter are for the first time assessed in detail in the present work., We thank Dirk Weisshaar for valuable discussions and the staff of the RIKEN Nishina Center accelerator complex for providing high-intensity beams to the experiment. This work was supported by the Spanish Ministerio de Economía y Competitividad under Contracts No. FPA2014-57196-C5-4-P, No. FPA2017-84756-C4-2-P, and No. FIS2014-53448-C2-1-P.

Published
2019

85. First application of the Oslo method in inverse kinematics

Author

Ingeberg, V. W., primary, Siem, S., additional, Wiedeking, M., additional, Sieja, K., additional, Bleuel, D. L., additional, Brits, C. P., additional, Bucher, T. D., additional, Dinoko, T. S., additional, Easton, J. L., additional, Görgen, A., additional, Guttormsen, M., additional, Jones, P., additional, Kheswa, B. V., additional, Khumalo, N. A., additional, Larsen, A. C., additional, Lawrie, E. A., additional, Lawrie, J. J., additional, Majola, S. N. T., additional, Malatji, K. L., additional, Makhathini, L., additional, Maqabuka, B., additional, Negi, D., additional, Noncolela, S. P., additional, Papka, P., additional, Sahin, E., additional, Schwengner, R., additional, Tveten, G. M., additional, Zeiser, F., additional, and Zikhali, B. R., additional

Published
2020
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86. Publisher's Note: Statistical properties of Pu243 , and Pu242(n,γ) cross section calculation [Phys. Rev. C 93 , 014323 (2016)]

Author

Laplace, T. A., primary, Zeiser, F., additional, Guttormsen, M., additional, Larsen, A. C., additional, Bleuel, D. L., additional, Bernstein, L. A., additional, Goldblum, B. L., additional, Siem, S., additional, Bello Garrote, F. L., additional, Brown, J. A., additional, Campo, L. Crespo, additional, Eriksen, T. K., additional, Giacoppo, F., additional, Görgen, A., additional, Hadyńska-Klȩk, K., additional, Henderson, R. A., additional, Klintefjord, M., additional, Lebois, M., additional, Renstrøm, T., additional, Rose, S. J., additional, Sahin, E., additional, Tornyi, T. G., additional, Tveten, G. M., additional, Voinov, A., additional, Wiedeking, M., additional, Wilson, J. N., additional, and Younes, W., additional

Published
2019
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87. γ -ray strength function for barium isotopes

Author

Utsunomiya, H., primary, Renstrøm, T., additional, Tveten, G. M., additional, Goriely, S., additional, Ari-izumi, T., additional, Ingeberg, V. W., additional, Kheswa, B. V., additional, Lui, Y.-W., additional, Miyamoto, S., additional, Hilaire, S., additional, Péru, S., additional, and Koning, A. J., additional

Published
2019
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88. Benchmarking the extraction of statistical neutron capture cross sections on short-lived nuclei for applications using the β -Oslo method

Author

Liddick, S. N., primary, Larsen, A. C., additional, Guttormsen, M., additional, Spyrou, A., additional, Crider, B. P., additional, Naqvi, F., additional, Midtbø, J. E., additional, Bello Garrote, F. L., additional, Bleuel, D. L., additional, Crespo Campo, L., additional, Couture, A., additional, Dombos, A. C., additional, Giacoppo, F., additional, Görgen, A., additional, Hadynska-Klek, K., additional, Hagen, T. W., additional, Ingeberg, V. W., additional, Kheswa, B. V., additional, Lewis, R., additional, Mosby, S., additional, Perdikakis, G., additional, Prokop, C. J., additional, Quinn, S. J., additional, Renstrøm, T., additional, Rose, S. J., additional, Sahin, E., additional, Siem, S., additional, Tveten, G. M., additional, Wiedeking, M., additional, and Zeiser, F., additional

Published
2019
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89. Restricted spin-range correction in the Oslo method: The example of nuclear level density and γ -ray strength function from Pu239(d,pγ)Pu240

Author

Zeiser, F., primary, Tveten, G. M., additional, Potel, G., additional, Larsen, A. C., additional, Guttormsen, M., additional, Laplace, T. A., additional, Siem, S., additional, Bleuel, D. L., additional, Goldblum, B. L., additional, Bernstein, L. A., additional, Bello Garrote, F. L., additional, Crespo Campo, L., additional, Eriksen, T. K., additional, Görgen, A., additional, Hadynska-Klek, K., additional, Ingeberg, V. W., additional, Midtbø, J. E., additional, Sahin, E., additional, Tornyi, T., additional, Voinov, A., additional, Wiedeking, M., additional, and Wilson, J., additional

Published
2019
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90. First experimental constraint on the Os191(n,γ) reaction rate relevant to s -process nucleosynthesis

Author

Kullmann, I. K. B., primary, Larsen, A. C., additional, Renstrøm, T., additional, Beckmann, K. S., additional, Garrote, F. L. Bello, additional, Campo, L. Crespo, additional, Görgen, A., additional, Guttormsen, M., additional, Midtbø, J. E., additional, Sahin, E., additional, Siem, S., additional, Tveten, G. M., additional, and Zeiser, F., additional

Published
2019
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91. Nuclear level densities and γ -ray strength functions of Ta180,181,182

Author

Brits, C. P., primary, Malatji, K. L., additional, Wiedeking, M., additional, Kheswa, B. V., additional, Goriely, S., additional, Garrote, F. L. Bello, additional, Bleuel, D. L., additional, Giacoppo, F., additional, Görgen, A., additional, Guttormsen, M., additional, Hadynska-Klek, K., additional, Hagen, T. W., additional, Hilaire, S., additional, Ingeberg, V. W., additional, Jia, H., additional, Klintefjord, M., additional, Larsen, A. C., additional, Majola, S. N. T., additional, Papka, P., additional, Péru, S., additional, Qi, B., additional, Renstrøm, T., additional, Rose, S. J., additional, Sahin, E., additional, Siem, S., additional, Tveten, G. M., additional, and Zeiser, F., additional

Published
2019
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92. Re-estimation of 180Ta nucleosynthesis in light of newly constrained reaction rates

Author

Malatji, K.L., Wiedeking, M., Goriely, Stéphane, Brits, C.P., Kheswa, B.V., Bello Garrote, F.L., Bleuel, D.L., Giacoppo, F, Görgen, Andreas, Guttormsen, Magne, Hadynska-Klek, K., Hagen, T.W., Ingeberg, V. W., Klintefjord, M., Larsen, Ann-Cecilie, Papka, P., Renstrøm, Therese, Sahin, E, Siem, Sunniva, Siess, Lionel, Tveten, G. M., Zeiser, F., Malatji, K.L., Wiedeking, M., Goriely, Stéphane, Brits, C.P., Kheswa, B.V., Bello Garrote, F.L., Bleuel, D.L., Giacoppo, F, Görgen, Andreas, Guttormsen, Magne, Hadynska-Klek, K., Hagen, T.W., Ingeberg, V. W., Klintefjord, M., Larsen, Ann-Cecilie, Papka, P., Renstrøm, Therese, Sahin, E, Siem, Sunniva, Siess, Lionel, Tveten, G. M., and Zeiser, F.

Abstract

Recent measurements of the nuclear level densities and γ-ray strength functions below the neutron thresholds in 180,181,182Ta are used as input in the nuclear reaction code TALYS. These experimental average quantities are utilized in the calculations of the 179,180,181Ta radiative neutron capture cross sections. From the latter, astrophysical Maxwellian-averaged (n,γ) cross sections (MACS) and reaction rates are extracted, which in turn are used in large astrophysical network calculations to probe the production mechanism of 180 Ta. These calculations are performed for two scenarios, the s-process production of 180,181Ta in Asymptotic Giant Branch (AGB) stars and the p-process nucleosynthesis of 180Tam in Type-II supernovae. Based on the results from this work, the s-process in stellar evolution is considered negligible in the production of 180Tam whereas 181Ta is partially produced by AGB stars. The new measurements strongly constrain the production and destruction rates of 180Tam at p-process temperatures and confirm significant production of nature’s rarest stable isotope 180Tam by the p-process., SCOPUS: ar.j, info:eu-repo/semantics/published

Published
2019

93. γ-ray strength function for barium isotopes

Author

Utsunomiya, Hiroaki, Renstrøm, Therese, Tveten, G. M., Goriely, Stéphane, Ari-Izumi, T., Ingeberg, V. W., Kheswa, B.V., Lui, Yiu-Wing, Miyamoto, S., Hilaire, Stéphane, Péru, S., Koning, Arjan J., Utsunomiya, Hiroaki, Renstrøm, Therese, Tveten, G. M., Goriely, Stéphane, Ari-Izumi, T., Ingeberg, V. W., Kheswa, B.V., Lui, Yiu-Wing, Miyamoto, S., Hilaire, Stéphane, Péru, S., and Koning, Arjan J.

Abstract

Photoneutron cross sections were measured for 137Ba and 138Ba at energies below two-neutron threshold using quasimonochromatic γ -ray beams produced in laser Compton scattering at the NewSUBARU synchrotron radiation facility. The photoneutron data are used to constrain the γ -ray strength function on the basis of the Hartree-Fock-Bogolyubov plus quasiparticle random phase approximation using the Gogny D1M interaction. Supplementing the experimentally constrained γ-ray strength function with the zero-limit E1 and M1 contribu- tions, which are unique to the deexcitation mode, we discuss radiative neutron capture cross sections relevant to the s-process nucleosynthesis of barium isotopes in the vicinity of the neutron magic number 82., info:eu-repo/semantics/published

Published
2019

94. Electromagnetic properties of low-lying states in neutron-deficient Hg isotopes: Coulomb excitation of Hg-182, Hg-184, Hg-186 and Hg-188

Author

Wrzosek-Lipska, K., Rezynkina, K., Bree, N., Zielinska, M., Gaffney, L. P., Petts, A., Andreyev, A., Bastin, B., Bender, M., Blazhev, A., Bruyneel, B., Butler, P. A., Carpenter, M. P., Cederkall, J., Clement, E., Cocolios, T. E., Deacon, A. N., Diriken, J., Ekstrom, A., Fitzpatrick, C., Fraile, L. M., Fransen, Ch., Freeman, S. J., Garcia-Ramos, J. E., Geibel, K., Gernhauser, R., Grahn, T., Guttormsen, M., Hadinia, B., Hadynska-Klek, K., Hass, M., Heenen, P. -H., Herzberg, R. -D., Hess, H., Heyde, K., Huyse, M., Ivanov, O., Jenkins, D. G., Julin, R., Kesteloot, N., Kroell, Th., Kruecken, R., Larsen, A. C., Lutter, R., Marley, P., Napiorkowski, P. J., Orlandi, R., Page, R. D., Pakarinen, J., Patronis, N., Peura, P. J., Piselli, E., Prochniak, L., Rahkila, P., Rapisarda, E., Reiter, P., Robinson, A. P., Scheck, M., Siem, S., Chakkal, K. Singh, Smith, J. F., Srebrny, J., Stefanescu, I., Tveten, G. M., Van Duppen, P., Van de Walle, J., Voulot, D., Warr, N., Wiens, A., Wood, J. L., Wrzosek-Lipska, K., Rezynkina, K., Bree, N., Zielinska, M., Gaffney, L. P., Petts, A., Andreyev, A., Bastin, B., Bender, M., Blazhev, A., Bruyneel, B., Butler, P. A., Carpenter, M. P., Cederkall, J., Clement, E., Cocolios, T. E., Deacon, A. N., Diriken, J., Ekstrom, A., Fitzpatrick, C., Fraile, L. M., Fransen, Ch., Freeman, S. J., Garcia-Ramos, J. E., Geibel, K., Gernhauser, R., Grahn, T., Guttormsen, M., Hadinia, B., Hadynska-Klek, K., Hass, M., Heenen, P. -H., Herzberg, R. -D., Hess, H., Heyde, K., Huyse, M., Ivanov, O., Jenkins, D. G., Julin, R., Kesteloot, N., Kroell, Th., Kruecken, R., Larsen, A. C., Lutter, R., Marley, P., Napiorkowski, P. J., Orlandi, R., Page, R. D., Pakarinen, J., Patronis, N., Peura, P. J., Piselli, E., Prochniak, L., Rahkila, P., Rapisarda, E., Reiter, P., Robinson, A. P., Scheck, M., Siem, S., Chakkal, K. Singh, Smith, J. F., Srebrny, J., Stefanescu, I., Tveten, G. M., Van Duppen, P., Van de Walle, J., Voulot, D., Warr, N., Wiens, A., and Wood, J. L.

Abstract

The neutron-deficient mercury isotopes serve as a classical example of shape coexistence, whereby at low energy near-degenerate nuclear states characterized by different shapes appear. The electromagnetic structure of even-mass 182-188 Hg isotopes was studied using safe-energy Coulomb excitation of neutron-deficient mercury beams delivered by the REX-ISOLDE facility at CERN. The population of 0 + 1,2, 2(1,2)(+) and 4(1)(+) states was observed in all nuclei under study. Reduced E2 matrix elements coupling populated yrast and non-yrast states were extracted, including their relative signs. These are a sensitive probe of shape coexistence and may be used to validate nuclear models. The experimental results are discussed in terms of mixing of two different configurations and are compared with three different model calculations: the Beyond Mean Field model, the Interacting Boson Model with configuration mixing and the General Bohr Hamiltonian. Partial agreement with experiment was observed, hinting to missing ingredients in the theoretical descriptions.

Published
2019

95. Experimental $��$-decay strength in $^{59, 60}$Ni compared with microscopic calculations

Author

Renstr��m, T., Tveten, G. M., Midtb��, J. E., Utsunomiya, H., Achakovskiy, O., Kamerdzhiev, S., Brown, B. Alex, Avdeenkov, A., Ari-izumi, T., G��rgen, A., Grimes, S. M., Guttormsen, M., Hagen, T. W., Ingeberg, V. W., Katayama, S., Kheswa, B. V., Larsen, A. C., Lui, Y. -W., Nyhus, H. -T., Siem, S., Symochko, D., Takenaka, D., and Voinov, A. V.

Subjects
Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Nuclear Experiment (nucl-ex)
Abstract

Nuclear level densities and $��$-ray strength functions have been extracted for $^{59, 60}\rm{Ni}$, using the Oslo method on data sets from the $^{60}$Ni($^{3}$He,$^{3}$He$^{\prime}��$)$^{60}$Ni and $^{60}$Ni($^{3}$He,$����$)$^{59}$Ni reactions. Above the neutron separation energy, S$_n$, we have measured the $��$-ray strength functions for $^{61}$Ni and $^{60}$Ni in photoneutron experiments. The low-energy part of the $^{59,60}$Ni $��$-ray strength functions show an increase for decreasing $��$ energies. The experimental $��$-ray strength functions are compared with $M1$ $��$-ray strength functions calculated within the shell model. The $E1$ $��$-ray strength function of $^{60}$Ni has been calculated using the QTBA framework. The QTBA calculations describe the data above $E_��\approx$ 7 MeV, while the shell-model calculations agree qualitatively with the low energy part of the $��$-ray strength function. Hence, we give a plausible explanation of the observed shape of the $��$-decay strength.

Published
2018
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96. Photoneutron cross sections for Ni isotopes: Toward understanding $(n,\gamma)$ cross sections relevant to weak $s$-process nucleosynthesis

Author

Utsunomiya, H., Renstrøm, T., Tveten, G. M., Goriely, S., Katayama, S., Ari-izumi, T., Takenaka, D., Symochko, D., Kheswa, B. V., Ingeberg, V. W., Glodariu, T., Lui, Y. -W., Miyamoto, S., Larsen, A. C., Midtbø, J. E., Görgen, A., Siem, S., Campo, L. Crespo, Guttormsen, M., Hilaire, S., Péru, S., Koning, A. J., Direction des Applications Militaires (DAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Direction des Applications Militaires ( DAM ), and Commissariat à l'énergie atomique et aux énergies alternatives ( CEA )

Subjects
Nuclear Theory, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], Astrophysics::High Energy Astrophysical Phenomena, Nuclear Reactions, [ PHYS.NEXP ] Physics [physics]/Nuclear Experiment [nucl-ex], [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment, [ PHYS.NUCL ] Physics [physics]/Nuclear Theory [nucl-th]
Abstract

Photoneutron cross sections were measured for $^{58}$Ni, $^{60}$Ni, $^{61}$Ni, and $^{64}$Ni at energies between the one-neutron and two-neutron thresholds using quasi-monochromatic $\gamma$-ray beams produced in laser Compton-scattering at the NewSUBARU synchrotron radiation facility. The new photoneutron data are used to extract the $\gamma$-ray strength function above the neutron threshold complementing the information obtained by the Oslo method below the threshold. We discuss radiative neutron capture cross sections and the Maxwellian-averaged cross sections for Ni isotopes including $^{63}$Ni, a branching point nucleus along the weak s-process path. The cross sections are calculated with the experimentally constrained $\gamma$-ray strength functions from the Hartree-Fock-Bogolyubov plus quasi-particle-random phase approximation based on the Gogny D1M interaction for both $E1$ and $M1$ components and supplemented with the $M1$ upbend., Comment: 9 pages, 7 figures, re-submitted to PRC

Published
2018
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97. Energy dependence of the prompt γ -ray emission from the (d,p) -induced fission of U ∗ 234 and Pu ∗ 240

Author

Rose, S. J., Zeiser, F., Wilson, J. N., Oberstedt, A., Oberstedt, S., Siem, S., Tveten, G. M., Bernstein, L. A., Bleuel, D. L., Brown, J. A., Crespo Campo, L., Giacoppo, F., Görgen, A., Guttormsen, M., Hadyńska, K., Hafreager, A., Hagen, T. W., Klintefjord, M., Laplace, T. A., Larsen, A. C., Renstrøm, T., Sahin, E., Schmitt, C., Tornyi, T. G., and Wiedeking, M.

Subjects
Astrophysics::High Energy Astrophysical Phenomena, Nuclear Theory, Nuclear Experiment, nucl-ex
Abstract

© 2017 American Physical Society. Prompt-fission γ rays are responsible for approximately 5% of the total energy released in fission, and therefore important to understand when modeling nuclear reactors. In this work we present prompt γ-ray emission characteristics in fission as a function of the nuclear excitation energy of the fissioning system. Emitted γ-ray spectra were measured, and γ-ray multiplicities and average and total γ energies per fission were determined for the U(d,pf)233 reaction for excitation energies between 4.8 and 10 MeV, and for the Pu(d,pf)239 reaction between 4.5 and 9 MeV. The spectral characteristics show no significant change as a function of excitation energy above the fission barrier, despite the fact that an extra ∼5 MeV of energy is potentially available in the excited fragments for γ decay. The measured results are compared with model calculations made for prompt γ-ray emission with the fission model code gef. Further comparison with previously obtained results from thermal neutron induced fission is made to characterize possible differences arising from using the surrogate (d,p) reaction.

Published
2017
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98. Anomalies in the Charge Yields of Fission Fragments from the U(n,f)238 Reaction

Author

Wilson, J. N., Lebois, M., Qi, L., Amador-Celdran, P., Bleuel, D., Briz, J. A., Carroll, R., Catford, Wilton, De Witte, H., Doherty, D. T., Eloirdi, R., Georgiev, G., Gottardo, A., Goasduff, A., Hadyńska-Klęk, K., Hauschild, K., Hess, H., Ingeberg, V., Konstantinopoulos, T., Ljungvall, J., Lopez-Martens, A., Lorusso, G., Lozeva, R., Lutter, R., Marini, P., Matea, I., Materna, T., Mathieu, L., Oberstedt, A., Oberstedt, S., Panebianco, S., Podolyak, Zsolt, Porta, A., Regan, Patrick, Reiter, P., Rezynkina, K., Rose, S. J., Sahin, E., Seidlitz, M., Serot, O., Shearman, Robert, Siebeck, B., Siem, S., Smith, A. G., Tveten, G. M., Verney, D., Warr, N., Zeiser, F., and Zielinska, M.

Subjects
Nuclear Theory, Physics::Atomic and Molecular Clusters, Nuclear Experiment
Abstract

Fast-neutron-induced fission of 238U at an energy just above the fission threshold is studied with a novel technique which involves the coupling of a high-efficiency γ-ray spectrometer (MINIBALL) to an inverse-kinematics neutron source (LICORNE) to extract charge yields of fission fragments via γ−γ coincidence spectroscopy. Experimental data and fission models are compared and found to be in reasonable agreement for many nuclei; however, significant discrepancies of up to 600% are observed, particularly for isotopes of Sn and Mo. This indicates that these models significantly overestimate the standard 1 fission mode and suggests that spherical shell effects in the nascent fission fragments are less important for low-energy fast-neutron-induced fission than for thermal neutron-induced fission. This has consequences for understanding and modeling the fission process, for experimental nuclear structure studies of the most neutron-rich nuclei, for future energy applications (e.g., Generation IV reactors which use fast-neutron spectra), and for the reactor antineutrino anomaly.

Published
2017

99. In-beam γ -ray spectroscopy of Te136 at relativistic energies

Author

Vaquero, V., primary, Jungclaus, A., additional, Doornenbal, P., additional, Wimmer, K., additional, Moro, A. M., additional, Ogata, K., additional, Furumoto, T., additional, Chen, S., additional, Nácher, E., additional, Sahin, E., additional, Shiga, Y., additional, Steppenbeck, D., additional, Taniuchi, R., additional, Xu, Z. Y., additional, Ando, T., additional, Baba, H., additional, Bello Garrote, F. L., additional, Franchoo, S., additional, Hadynska-Klek, K., additional, Kusoglu, A., additional, Liu, J., additional, Lokotko, T., additional, Momiyama, S., additional, Motobayashi, T., additional, Nagamine, S., additional, Nakatsuka, N., additional, Niikura, M., additional, Orlandi, R., additional, Saito, T. Y., additional, Sakurai, H., additional, Söderström, P. A., additional, Tveten, G. M., additional, Vajta, Zs., additional, and Yalcinkaya, M., additional

Published
2019
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100. γ -ray strength function for thallium isotopes relevant to the Pb205−Tl205 chronometry

Author

Utsunomiya, H., primary, Renstrøm, T., additional, Tveten, G. M., additional, Goriely, S., additional, Ari-izumi, T., additional, Filipescu, D., additional, Kaur, J., additional, Lui, Y.-W., additional, Luo, W., additional, Miyamoto, S., additional, Larsen, A. C., additional, Hilaire, S., additional, Péru, S., additional, and Koning, A. J., additional

Published
2019
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