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83 results on '"Kheswa B. V."'

51. 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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52. 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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53. 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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54. 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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55. Photoneutron cross sections for Ni isotopes: Toward understanding (n,γ) cross sections relevant to weak s -process nucleosynthesis

Author

Utsunomiya, H., primary, Renstrøm, T., additional, Tveten, G. M., additional, Goriely, S., additional, Katayama, S., additional, Ari-izumi, T., additional, Takenaka, D., additional, Symochko, D., additional, Kheswa, B. V., additional, Ingeberg, V. W., additional, Glodariu, T., additional, Lui, Y.-W., additional, Miyamoto, S., additional, Larsen, A. C., additional, Midtbø, J. E., additional, Görgen, A., additional, Siem, S., additional, Campo, L. Crespo, additional, Guttormsen, M., additional, Hilaire, S., additional, Péru, S., additional, and Koning, A. J., additional

Published
2018
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56. Low-energy enhancement in the γ-ray strength functions of 73,74Ge

Author

Renstrøm, Therese, Nyhus, H.-T., Utsunomiya, Hiroaki, Schwengner, R., Goriely, S., Larsen, Ann-Cecilie, Filipescu, D. M., Gheorghe, I., Bernstein, L. A., Bleuel, D. L., Glodariu, T., Görgen, A., Guttormsen, Magne, Hagen, Trine Wiborg, Kheswa, B. V., Lui, Y. W., Negi, D., Ruud, I. E., Shima, T., Siem, Sunniva, Takahisa, K., Tesileanu, O., Tornyi, T. G., Tveten, Gry M., and Wiedeking, M.

Published
2016

57. Low-energy enhancement in the gamma-ray strength functions of 73,74Ge

Author

Renstrøm, T., Nyhus, H. -T., Utsumoniya, H., Schwengner, R., Goriely, S., Larsen, A. C., Filipescu, D. M., Gheorghe, I., Bernstein, L. A., Bleuel, D. L., Glodariu, T., Görgen, A., Guttormsen, M., Hagen, T. W., Kheswa, B. V., Lui, Y. -W ., Negi, D., Ruud, I. E., Shima, T., Siem, S., Takahisa, K., Tesileanu, O., Tornyi, T. G., Tveten, G. M., and Wiedeking, M.

Subjects
level densities, Astrophysics::High Energy Astrophysical Phenomena, Nuclear structure, Nuclear Experiment, nuclear reactions, strength functiopns
Abstract

The $\gamma$-ray strength functions and level densities of $^{73,74}$Ge have been extracted up to the neutron separation energy S$_n$ from particle-$\gamma$ coincidence data using the Oslo method. Moreover, the $\gamma$-ray strength function of $^{74}$Ge above S$_n$ has been determined from photo-neutron measurements, hence these two experiments cover the range of E$_\gamma \approx$ 1-13 MeV for $^{74}$Ge. The obtained data show that both $^{73,74}$Ge display an increase in strength at low $\gamma$ energies. The experimental $\gamma$-ray strength functions are compared with $M1$ strength functions deduced from average $B(M1)$ values calculated within the shell model for a large number of transitions. The observed low-energy enhancements in $^{73,74}$Ge are adopted in the calculations of the $^{72,73}$Ge(n,$\gamma$) cross sections, where there are no direct experimental data. Calculated reaction rates for more neutron-rich germanium isotopes are shown to be strongly dependent on the presence of the low-energy enhancement.

Published
2016

58. Low-energy enhancement and fluctuations ofγ-ray strength functions in56,57Fe: test of the Brink–Axel hypothesis

Author

Larsen, A C, primary, Guttormsen, M, additional, Blasi, N, additional, Bracco, A, additional, Camera, F, additional, Campo, L Crespo, additional, Eriksen, T K, additional, Görgen, A, additional, Hagen, T W, additional, Ingeberg, V W, additional, Kheswa, B V, additional, Leoni, S, additional, Midtbø, J E, additional, Million, B, additional, Nyhus, H T, additional, Renstrøm, T, additional, Rose, S J, additional, Ruud, I E, additional, Siem, S, additional, Tornyi, T G, additional, Tveten, G M, additional, Voinov, A V, additional, Wiedeking, M, additional, and Zeiser, F, additional

Published
2017
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59. La137,138,139(n,γ) cross sections constrained with statistical decay properties of La138,139,140 nuclei

Author

Kheswa, B. V., primary, Wiedeking, M., additional, Brown, J. A., additional, Larsen, A. C., additional, Goriely, S., additional, Guttormsen, M., additional, Bello Garrote, F. L., additional, Bernstein, L. A., additional, Bleuel, D. L., additional, Eriksen, T. K., additional, Giacoppo, F., additional, Görgen, A., additional, Goldblum, B. L., additional, Hagen, T. W., additional, Koehler, P. E., additional, Klintefjord, M., additional, Malatji, K. L., additional, Midtbø, J. E., additional, Nyhus, H. T., additional, Papka, P., additional, Renstrøm, T., additional, Rose, S. J., additional, Sahin, E., additional, Siem, S., additional, and Tornyi, T. G., additional

Published
2017
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60. Low-energy enhancement and fluctuations of gamma-ray strength functions in Fe-56,Fe-57: test of the Brink-Axel hypothesis

Author

Larsen, A C, Guttormsen, M, Blasi, N, Bracco, A, Camera, F, Campo, L Crespo, Eriksen, Tomas, Görgen, A, Hagen, T W, Ingeberg, V W, Kheswa, B V, Larsen, A C, Guttormsen, M, Blasi, N, Bracco, A, Camera, F, Campo, L Crespo, Eriksen, Tomas, Görgen, A, Hagen, T W, Ingeberg, V W, and Kheswa, B V

Abstract

Nuclear level densities and gamma-ray strength functions of Fe-56,Fe-57 have been extracted from proton-gamma coincidences. A low-energy enhancement in the gamma-ray strength functions up to a factor of 30 over common theoretical E1 models is confirmed. Angular distributions of the low-energy enhancement in 57Fe indicate its dipole nature, in agreement with findings for Fe-56. The high statistics and the excellent energy resolution of the large-volume LaBr3(Ce) detectors allowed for a thorough analysis of. strength as function of excitation energy. Taking into account the presence of strong Porter-Thomas fluctuations, there is no indication of any significant excitation energy dependence in the gamma-ray strength function, in support of the generalized Brink-Axel hypothesis.

Published
2017

61. Enhanced low-energy γ-decay probability - implications for r-process (n,γ) reaction rates

Author

Larsen, A. C., Guttormsen, M., Bello-Garrotte, F. L., Bernstein, L. A., Bleuel, D. L., Bracco, A., Brown, B. A., Camera, F., Crespo-Campo, L., Frauendorf, S., Goldblum, B. L., Goriely, S., Görgen, A., Hadynska-Klek, K., Hagen, T. W., Harissopulos, S., Kheswa, B. V., Klintefjord, M., Leoni, S., Liddick, S. N., Moretto, L. G., Naqvi, F., Perdikakis, G., Renstrøm, T., Rogers, A. M., Rose, S. J., Sahin, E., Schwengner, R., Siem, S., Simon, A., Spyrou, A., Tveten, G. M., Voinov, A., Wiedeking, M., and Utsunomiya, H.

Subjects
gamma strength function, reaction rates, Nuclear Theory, Nuclear structure, nuclear reactions, neutron capture
Abstract

An unexpected enhancement in the average, reduced γ-decay strength at very low -transition energies has been observed in in f p-shell nuclei as well as in the Mo region. Very recently, it has showed up in 138 La, which is, so far, the heaviest nucleus to display this feature. In this work, we present an experimental and theoretical overview of the low-energy enhancement. In particular, experimental evidence for the dipole nature of the enhancement, and shell-model calculations indicating strong, low-energy M 1 transitions are shown. Possible implications of this low-energy enhancement on astrophysical (n,γ ) reaction rates of relevance for the r-process nucleosynthesis are discussed.

Published
2015

62. Low-energy enhancement in the ��-ray strength functions of $^{73,74}$Ge

Author

Renstr��m, T., Nyhus, H. -T., Utsumoniya, H., Schwengner, R., Goriely, S., Larsen, A. C., Filipescu, D. M., Gheorghe, I., Bernstein, L. A., Bleuel, D. L., Glodariu, T., G��rgen, A., Guttormsen, M., Hagen, T. W., Kheswa, B. V., Lui, Y. -W ., Negi, D., Ruud, I. E., Shima, T., Siem, S., Takahisa, K., Tesileanu, O., Tornyi, T. G., Tveten, G. M., and Wiedeking, M.

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

The $��$-ray strength functions and level densities of $^{73,74}$Ge have been extracted up to the neutron separation energy S$_n$ from particle-$��$ coincidence data using the Oslo method. Moreover, the $��$-ray strength function of $^{74}$Ge above S$_n$ has been determined from photo-neutron measurements, hence these two experiments cover the range of E$_��\approx$ 1-13 MeV for $^{74}$Ge. The obtained data show that both $^{73,74}$Ge display an increase in strength at low $��$ energies. The experimental $��$-ray strength functions are compared with $M1$ strength functions deduced from average $B(M1)$ values calculated within the shell model for a large number of transitions. The observed low-energy enhancements in $^{73,74}$Ge are adopted in the calculations of the $^{72,73}$Ge(n,$��$) cross sections, where there are no direct experimental data. Calculated reaction rates for more neutron-rich germanium isotopes are shown to be strongly dependent on the presence of the low-energy enhancement.

Published
2015
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63. Nuclear level densities and gamma-ray strength functions of145,149,151Nd isotopes

Author

Ay, K O, primary, Ozgur, M, additional, Algin, E, additional, Guttormsen, M, additional, Garrote, F L Bello, additional, Campo, L Crespo, additional, Görgen, A, additional, Hagen, T W, additional, Ingeberg, V W, additional, Kheswa, B V, additional, Klintefjord, M, additional, Larsen, A C, additional, Midtbo, J E, additional, Modamio, V, additional, Renstrom, T, additional, Rose, S J, additional, Sahin, E, additional, Siem, S, additional, Tveten, G M, additional, and Zeiser, F, additional

Published
2016
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64. Spectroscopy ofYb155: Structure evolution in theN=85isotones

Author

Li, X. Q., primary, Xu, C., additional, Zhang, S. Q., additional, Hua, H., additional, Meng, J., additional, Bark, R. A., additional, Chen, Q. B., additional, Niu, C. Y., additional, Han, R., additional, Wyngaardt, S. M., additional, Wang, S. Y., additional, Wang, S., additional, Qi, B., additional, Liu, L., additional, Zhu, L. H., additional, Shi, Z., additional, Zhang, G. L., additional, Sun, B. H., additional, Le, X. Y., additional, Song, C. Y., additional, Ye, Y. L., additional, Jiang, D. X., additional, Xu, F. R., additional, Li, Z. H., additional, Sun, J. J., additional, Shi, Y., additional, Zhao, P. W., additional, Liang, W. Y., additional, Li, C. G., additional, Wang, C. G., additional, Chen, X. C., additional, Sun, D. P., additional, Liu, C., additional, Li, Z. Q., additional, Jones, P., additional, Lawrie, E. A., additional, Lawrie, J. J., additional, Wiedeking, M., additional, Bucher, T. D., additional, Dinoko, T., additional, Kheswa, B. V., additional, Makhathini, L., additional, Majola, S. N. T., additional, Ndayishimye, J., additional, Noncolela, S. P., additional, Shirinda, O., additional, Gál, J., additional, Kalinka, G., additional, Molnár, J., additional, Nyakó, B. M., additional, Timár, J., additional, Juhász, K., additional, and Arogunjo, M., additional

Published
2016
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65. Nature of low-lying electric dipole resonance excitations inGe74

Author

Negi, D., primary, Wiedeking, M., additional, Lanza, E. G., additional, Litvinova, E., additional, Vitturi, A., additional, Bark, R. A., additional, Bernstein, L. A., additional, Bleuel, D. L., additional, Bvumbi, S., additional, Bucher, T. D., additional, Daub, B. H., 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, Masiteng, L. P., additional, Nchodu, M. R., additional, Ndayishimye, J., additional, Newman, R. T., additional, Noncolela, S. P., additional, Orce, J. N., additional, Papka, P., additional, Pellegri, L., additional, Renstrøm, T., additional, Roux, D. G., additional, Schwengner, R., additional, Shirinda, O., additional, and Siem, S., additional

Published
2016
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66. Low-energy enhancement in theγ-ray strength functions ofGe73,74

Author

Renstrøm, T., primary, Nyhus, H.-T., additional, Utsunomiya, H., additional, Schwengner, R., additional, Goriely, S., additional, Larsen, A. C., additional, Filipescu, D. M., additional, Gheorghe, I., additional, Bernstein, L. A., additional, Bleuel, D. L., additional, Glodariu, T., additional, Görgen, A., additional, Guttormsen, M., additional, Hagen, T. W., additional, Kheswa, B. V., additional, Lui, Y.-W., additional, Negi, D., additional, Ruud, I. E., additional, Shima, T., additional, Siem, S., additional, Takahisa, K., additional, Tesileanu, O., additional, Tornyi, T. G., additional, Tveten, G. M., additional, and Wiedeking, M., additional

Published
2016
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67. Nuclear level densities and γ-ray strength functions of 180,181Ta and neutron capture cross sections.

Author

Malatji, K. L., Kheswa, B. V., Wiedeking, M., Garrote, F. L. Bello, Brits, C. P., Bleue, D. L., Giacoppo, F., Görgen, A., Guttormsen, M., Hadynska-Klek, K., Hagen, T. W., Ingeberg, V. W., Klintefjord, M., Larsen, A. C., Nyhus, H. T., Renstrøm, T., Rose, S., Sahin, E., Siem, S., and Tveten, G. M.

Subjects
*GAMMA rays, *ENERGY level densities, *NEUTRON capture, *NUCLEAR cross sections, *NUCLEOSYNTHESIS, TANTALUM isotopes
Abstract

The γ-ray strength functions and nuclear level densities in the quasi-continuum of 180,181Ta are extracted from particle-γcoincidence events with the OsloMethod, below the Sn. The data were used as input in the TALYS reaction code for calculations of the astrophysical Maxwellian-averaged (n, γ) cross-sections to investigate nucleosynthesis of nature's rarest stable isotope 180Ta. [ABSTRACT FROM AUTHOR]

Published
2017
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68. Resonances in odd-odd 182Ta.

Author

Brits, C. P., Wiedeking, M., Garrote, F. L. Bello, Bleuel, D. L., Giacoppo, F., Görgen, A., Guttormsen, M., Hadynska-Klek, K., Hagen, T. W., Ingeberg, V. W., Kheswa, B. V., Klintefjord, M., Larsen, A. C., Malatji, K. L., Nyhus, H. T., Papka, P., Renstrøm, T., Rose, S., Sahin, E., and Siem, S.

Subjects
GAMMA rays, RADIOACTIVE decay, TANTALUM, PHOTONS, ACTINIDE elements
Abstract

Enhanced γ -decay on the tail of the giant electric dipole resonance, such as the scissors or pygmy resonances, can have significant impact on (n,γ) reaction rates. These rates are important input for modeling processes that take place in astrophysical environments and nuclear reactors. Recent results from the University of Oslo indicate the existence of a significant enhancement in the photon strength function for nuclei in the actinide region due to the scissors resonance. Further, the M1 strength distribution of the scissors resonances in rare earth nuclei has been studied extensively over the years. To investigate the evolution and persistence of the scissor resonance in other mass regions, an experiment was performed utilizing the NaI(Tl) γ -ray detector array (CACTUS) and silicon particle telescopes (SiRi) at the University of Oslo Cyclotron laboratory. Particle-γ coincidences from the 181Ta(d,p)182Ta and 181Ta(d,d')181Ta reactions were used to measure the nuclear level density and photon strength function of the well-deformed 181Ta and 182Ta systems, to investigate the existence of resonances below the neutron separation energy. [ABSTRACT FROM AUTHOR]

Published
2017
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69. Statistical gamma-ray decay studies at iThemba LABS.

Author

Wiedeking, M., Bernstein, L. A., Bleuel, D. L., Brits, C. P., Sowazi, K., Görgen, A., Goldblum, B. L., Guttormsen, M., Kheswa, B. V., Larsen, A. C., Majola, S. N. T., Malatji, K. L., Negi, D., Nogwanya, T., Siem, S., and Zikhali, B. R.

Subjects
RADIOACTIVE decay, GAMMA ray detectors, PARTICLE telescopes, SILICON, ISOBARIC spin, NEUTRONS
Abstract

A program to study the γ -ray decay from the region of high-level density has been established at iThemba LABS, where a high-resolution gamma-ray detector array is used in conjunction with silicon particle-telescopes. Results from two recent projects are presented: 1) The 74Ge(α, α ' γ) reaction was used to investigate the Pygmy Dipole Resonance. The results were compared to (γ, γ ') data and indicate that the dipole states split into mixed isospin and relatively pure isovector excitations. 2) Data from the 95Mo(d,p) reaction were used to develop a novel method for the determination of spins for low-lying discrete levels utilizing statistical γ -ray decay in the vicinity of the neutron separation energy. These results provide insight into the competition of (γ, n) and (γ, γ ') reactions and highlights the need to correct for angular momentum barrier effects. [ABSTRACT FROM AUTHOR]

Published
2017
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70. Observation of low-lying resonances in the quasicontinuum of195,196Pt and enhanced astrophysical reaction rates

Author

Giacoppo, F., primary, Bello Garrote, F. L., additional, Eriksen, T. K., additional, Görgen, A., additional, Guttormsen, M., additional, Hagen, T. W., additional, Larsen, A. C., additional, Kheswa, B. V., additional, Klintefjord, M., additional, Koehler, P. E., additional, Moretto, L. G., additional, Nyhus, H. T., additional, Renstrøm, T., additional, Sahin, E., additional, Siem, S., additional, and Tornyi, T. G., additional

Published
2015
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71. Level densities and thermodynamical properties of Pt and Au isotopes

Author

Giacoppo, F., primary, Bello Garrote, F. L., additional, Bernstein, L. A., additional, Bleuel, D. L., additional, Eriksen, T. K., additional, Firestone, R. B., additional, Görgen, A., additional, Guttormsen, M., additional, Hagen, T. W., additional, Kheswa, B. V., additional, Klintefjord, M., additional, Koehler, P. E., additional, Larsen, A. C., additional, Nyhus, H. T., additional, Renstrøm, T., additional, Sahin, E., additional, Siem, S., additional, and Tornyi, T., additional

Published
2014
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72. Observation of low-lying resonances in the quasicontinuum of 195,196Pt and enhanced astrophysical reaction rates.

Author

Giacoppo, F., Bello Garrote, F. L., Eriksen, T. K., Görgen, A., Guttormsen, M., Hagen, T. W., Larsen, A. C., Kheswa, B. V., Klintefjord, M., Koehler, P. E., Moretto, L. G., Nyhus, H. T., Renstrøm, T., Sahin, E., Siem, S., and Tornyi, T. G.

Subjects
DIPOLE interactions, NEUTRONS, ISOTOPES, NEUTRON capture, NUCLEOSYNTHESIS
Abstract

An excess of strength on the low-energy tail of the giant dipole resonance recently has been observed in the γ-decay from the quasicontinuum of 195,196Pt. The nature of this phenomenon is not yet fully investigated. If this feature is present also in the γ-ray strength of the neutron-rich isotopes, it can affect the neutron-capture reactions involved in the formation of heavy-elements in stellar nucleosynthesis. The experimental level density and γ-ray strength function of 195,196 Pt are presented together with preliminary calculations of the corresponding neutron-capture cross sections. [ABSTRACT FROM AUTHOR]

Published
2015
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73. High resolution148Nd(3He,nγ) two proton stripping reaction and the structure of the 02+state in150Sm

Author

Sharpey-Schafer, J. F., primary, Papka, P., additional, Bvumbi, S. P., additional, Jones, P. M, additional, Vymers, P., additional, Bucher, T. D., additional, Dinoko, T. S., additional, Easton, J. L., additional, Herbert, M. S., additional, Kheswa, B. V., additional, Khumalo, N., additional, Lawrie, E. A., additional, Lawrie, J. J., additional, Majola, S. N. T., additional, Ndayishimye, J., additional, Negi, D., additional, Noncolela, S. P., additional, Orce, J. N., additional, Shirinda, O., additional, Sithole, P., additional, Standkiewicz, M.A., additional, and Wiedeking, M., additional

Published
2014
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74. Study of 0+States at iThemba LABS

Author

Jones, P., primary, Papka, P., additional, Sharpey-Shafer, J.F., additional, Vymers, P., additional, Bvumbi, S. P., additional, Bucher, T. D., additional, Dinoko, T. S., additional, Easton, J. L., additional, Herbert, M. S., additional, Kheswa, B. V., additional, Khumalo, N., additional, Lawrie, E. A., additional, Lawrie, J. J., additional, Majola, S. N. T., additional, Ndayishimye, J., additional, Negi, D., additional, Noncolela, S. P., additional, Orce, J. N., additional, Shirinda, O., additional, Sithole, P., additional, Stankiewicz, M. A., additional, and Wiedeking, M., additional

Published
2013
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75. Study of 0+ States at iThemba LABS.

Author

Jones, P., Papka, P., Sharpey-Shafer, J. F., Vymers, P., Bvumbi, S. P., Bucher, T. D., Dinoko, T. S., Easton, J. L., Herbert, M. S., Kheswa, B. V., Khumalo, N., Lawrie, E. A., Lawrie, J. J., Majola, S. N. T., Ndayishimye, J., Negi, D., Noncolela, S. P., Orce, J. N., Shirinda, O., and Sithole, P.

Subjects
MAGNETIC spectrometer, MAGNETIC lens spectrometers, NEUTRONS, LOW energy electron diffraction, GRAVITY assist (Astrodynamics)
Abstract

An initial series of experiments utilising the (³He,n) reactions have been carried out at iThemba LABS. These are complimentary to transfer reactions such as (t,p) stripping or (p,t) pick-up reactions measurements using magnetic spectrometers. However, in the past, (³He,n) measurements have suffered from ambiguities due to the low energy resolution inbuilt into the time-of-flight techniques used. By combining neutron detection techniques with the AFRODITE γ-ray array, it has been shown that very good energy resolutions can be achieved. This enables the relative strengths of two proton stripping to excited states, separated by only a few keV, to be accurately measured. This technique has been applied to first excited 02+ states and, in particular to those uniquely seen in double β-decay. [ABSTRACT FROM AUTHOR]

Published
2013
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76. Statistical nuclear properties and synthesis of 138La.

Author

Kheswa, B. V., Wiedeking, M., Giacoppo, F., Goriely, S., Guttormsen, M., Larsen, A. C., Bello Garrote, F. L., Eriksen, T. K., Görgen, A., Hagen, T. W., Koehler, P. E., Klintefjord, M., Nyhus, H. T., Papka, P., Renstrøm, T., Rose, S., Sahin, E., Siem, S., and Tornyi, T.

Subjects
NEUTRONS, PHOTODISINTEGRATION, PHOTONUCLEAR reactions, NUCLEAR density, NEUTRINOS
Abstract

The synthesis of the neutron deficient 138La nucleus has been a puzzle for a long time. It has not been clear whether it is produced through photodisintegration processes or neutrino induced reactions due to unavailability of experimental data for nuclear level densities and γ strength functions of 138,139La nuclei. In the present work these nuclear properties have been measured and are used to investigate the synthesis of 138La. The results support the neutrino interactions as a dominant production process for 138La. [ABSTRACT FROM AUTHOR]

Published
2015
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77. New collective structures in the 163Yb nucleus.

Author

Sithole, M. A., Sharpey Schafer, J. F., Majola, S. N. T., Bucher, T. D., Dinoko, T. R. S., Ntshangase, S. S., Lawrie, E. A., Khumalo, N. A., Jongile, S., Mdletshe, L., Bark, R. A., Erasmus, N., Jones, P., Kheswa, B. V., Lawrie, J. J., Makhathini, L., Malatji, K. L., Maqabuka, B., Noncolela, S. P., and Ndayishimye, J.

Subjects
EXCITED states, NEUTRONS, SPECTROMETERS
Abstract

The 152Sm(16O, 5n)163Yb reaction at a beam energy of 93 MeV was used to study the excited states of 163Yb with the AFRODITE γ -ray spectrometer at iThemba LABS. The level scheme of 163Yb has been extended and new rotational bands established. The band based on the ground-state has been extended from a spin of 11/2- to spin 43/2-. A high-K band based on the neutron [505]11/2- Nilsson orbital has been observed and is reported for the first time in this work. Additional new states in 163Yb were observed which all decay to the yrast band. Some of these states are placed in a sequence which is conjectured to be a γ band involving a coupling with the i13/2[642]5/2+ neutron orbital. The band structures are discussed with reference to Cranked Shell Model (CSM) calculations and a systematic comparison with the neighbouring nuclei. [ABSTRACT FROM AUTHOR]

Published
2019
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78. Coulomb and Inelastic Excitations of Target Nuclei in (3He,n) Two Proton Stripping Reactions on 27Al, 59Co, 148Nd and 160Gd

Author

Sharpey-Schafer, J. F., Papka, P., Jones, P. M., Vymers, P., Bark, R. A., Bucher, T. D., Bvumbi, S. P., Dinoko, T. S., Easton, J. L., Herbert, M. S., Kheswa, B. V., Khaleel, E. A. M. A., Khumalo, N., Lawrie, E. A., Lawrie, J. J., Majola, S. N. T., Ndayishimye, J., Nchodu, M. R., Negi, D., Noncolela, S. P., J. N. Orce, Shirinda, O., Sithole, P., and Wiedeking, M.

79. Enhanced low-energy γ-decay probability - Implications for r-process (n; γ) reaction rates

Author

Larsen, A. C., Guttormsen, M., Bello Garrotte, F. L., Bernstein, L. A., Bleuel, D. L., Bracco, A., Brown, B. A., Camera, F., Crespo Campo, L., Frauendorf, S., Bethany Goldblum, Goriely, S., G�rgen, A., Hadynska-Klek, K., Hagen, T. W., Harissopulos, S., Kheswa, B. V., Klintefjord, M., Leoni, S., Liddick, S. N., Naqvi, F., Perdikakis, G., Renstr�m, T., Rogers, A. M., Rose, S. J., Sahin, E., Schwengner, R., Siem, S., Simon, A., Spyrou, A., Tveten, G. M., Voinov, A., Wiedeking, M., and Utsunomiya, H.

Subjects
Nuclear Physics - Experiment

80. La 137 , 138 , 139 ( n , γ ) cross sections constrained with statistical decay properties of La 138 , 139 , 140 nuclei

Author

Kheswa, B. V., Wiedeking, M., Brown, J. A., Larsen, A. C., Goriely, S., Guttormsen, M., Bello Garrote, F. L., Bernstein, L. A., Bleuel, D. L., Eriksen, T. K., Giacoppo, F., Görgen, A., Goldblum, B. L., Hagen, T. W., Koehler, P. E., Klintefjord, M., Malatji, K. L., Midtbø, J. E., Nyhus, H. T., Papka, P., Renstrøm, T., Rose, S. J., Sahin, E., Siem, S., and Tornyi, T. G.

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82. Low-lying positive parity bands in 162Yb.

Author

Mdletshe, L., Ntshangase, S. S., Sharpey-Schafer, J. F., Majola, S. N. T., Dinoko, T. R. S., Khumalo, N. A., Lawrie, E. A., Bark, R. A., Bucher, T. D., Erasmus, N., Jones, P., Jongile, S., Kheswa, B. V., Lawrie, J. J., Makhathini, L., Malatji, K. L., Maqabuka, B., Ndayishimye, J., Noncolela, S. P., and Shirinda, O.

Subjects
YTTERBIUM, HEAVY ion fusion reactions, NUCLEAR vibrational states, ELECTRONIC band structure, NUCLEAR spin
Abstract

The structure of the low-lying positive parity bands in 162Yb has been studied at iThemba LABS, using the 150Sm(16O,4n)162Yb fusion-evaporation reaction. A band built on the first excited 02+ state has been identified for the first time. In addition, we report new rotational levels that form the band structures of both the odd and even spin components of the γ-vibrational band. The first excited 02+ band and the even spin members of the γ-vibrational band exhibit a Landau-Zenner crossing. This crossing demonstrates that the significant signature splitting between the odd and even spin members of the γ band is contributed to by band mixing. [ABSTRACT FROM AUTHOR]

Published
2018
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83. 137,138,139La (n, γ) cross sections constrained with statistical decay properties of 138,139,140La nuclei.

Author

Kheswa, B. V., Wiedeking, M., Brown, J. A., Larsen, A. C., Goriely, S., Guttormsen, M., Garrote, F. L. Bello, Bernstein, L. A., Bleuel, D. L., Eriksen, T. K., Giacoppo, F., Görgen, A., Goldblum, B. L., Hagen, T. W., Koehler, P. E., Klintefjord, M., Malatji, K. L., Midtbø, J. E., Nyhus, H. T., and Papka, P.

Subjects
*ATOMIC nucleus, *RADIOACTIVE decay
Abstract

The nuclear level densities and γ-ray strength functions of 138,139,140La were measured using the 139La(³He, α), 139La(³He,' ³He), and 139La(d, p) reactions. The particle-γ coincidences were recorded with the silicon particle telescope (SiRi) and NaI(Tl) (CACTUS) arrays. In the context of these experimental results, the low-energy enhancement in the A ~ 140 region is discussed. The 137,138,139La(n, γ) cross sections were calculated at s- and p-process temperatures using the experimentally measured nuclear level densities and γ-ray strength functions. Good agreement is found between 139La (n, γ) calculated cross sections and previous measurements. [ABSTRACT FROM AUTHOR]

Published
2017
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