682 results on '"J. H. Hamilton"'
Search Results
52. Triaxiality in Neutron-Rich Nuclei with A ˜ 100-126, Z Beyond and Below Ru (Z=44)
- Author
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Sutao Zhu, A. V. Ramayya, Yu Sun, S. Frauendorf, H. J. Li, W. Y. Liang, Y. X. Liu, A. V. Daniel, W. C. Ma, Chang-Feng Jiao, S. H. Liu, Y. X. Luo, G. M. Ter-Akopian, E. Y. Yeoh, J. K. Hwang, Raul Donangelo, Jianchun Wang, Yue Shi, Yu. Oganessian, N. T. Brewer, M. A. Stoyer, I. Y. Lee, J. H. Hamilton, Furong Xu, J. O. Rasmussen, and E. H. Wang
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Physics ,Nuclear physics ,Neutron - Published
- 2017
53. Chiral Vibrations and Collective Bands in 104Mo
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E. H. Wang, B. M. Musangu, J. M. Eldridge, J. O. Rasmussen, A. V. Ramayya, Yu. Ts. Oganessian, W. H. Brantley, Y. X. Luo, J. H. Hamilton, G. M. Ter-Akopian, S. Frauendorf, S. J. Zhu, and C. J. Zachary
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Physics ,Molecular physics - Published
- 2017
54. Multipole Mixing Ratios of Gamma Band to Ground Band Transitions in 102,104,106,108Mo, 108,110,112Ru, and 112,114,116Pd
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J. M. Eldridge, B. Fenker, C. Goodin, C. J. Zachary, J. H. Hamilton, E. Wang, A. V. Ramayya, A. V. Daniel, G. M. Ter-Akopian, and Yu. Ts. Oganesson
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Physics ,Classical mechanics ,Multipole expansion ,Gamma band ,Mixing (physics) ,Computational physics - Published
- 2017
55. Outstanding problems in the band structures of Sm152
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J. H. Hamilton and J. B. Gupta
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Physics ,Spin states ,010308 nuclear & particles physics ,Nuclear structure ,01 natural sciences ,symbols.namesake ,Critical point (thermodynamics) ,Excited state ,0103 physical sciences ,Quadrupole ,symbols ,Anomaly (physics) ,Interacting boson model ,Atomic physics ,010306 general physics ,Hamiltonian (quantum mechanics) - Abstract
The recent data on $B(E2)$ values, deduced from the multi-Coulex excitation of the low spin states in the decay of $^{152}\mathrm{Sm}$, and other experimental findings in the last two decades are compared with the predictions from the microscopic dynamic pairing plus quadrupole model of Kumar and Baranger. The 1292.8 keV ${2}^{+}$ state is assigned to the ${{0}_{3}}^{+}$ band, and the $K=2$ assignment of the 1769 keV ${2}^{+}$ state is confirmed. The anomaly of the shape coexistence of the assumed spherical \ensuremath{\beta} band versus the deformed ground band is resolved. The values from the critical point symmetry X(5) support the collective character of the \ensuremath{\beta} band. The problem with the two-term interacting boson model Hamiltonian in predicting \ensuremath{\beta} and \ensuremath{\gamma} bands in $^{152}\mathrm{Sm}$ leads to interesting consequences. The collective features of the second excited ${K}^{\ensuremath{\pi}}=\phantom{\rule{0.16em}{0ex}}{{0}_{3}}^{+}$ band are preferred over the ``pairing isomer'' view. Also the multiphonon nature of the higher lying ${K}^{\ensuremath{\pi}}={{2}_{2}}^{+}\phantom{\rule{0.16em}{0ex}}\ensuremath{\beta}\ensuremath{\gamma}$ band and ${K}^{\ensuremath{\pi}}={4}^{+}$ band are illustrated vis-\`a-vis the new data and the nuclear structure theory.
- Published
- 2017
56. One- and two-phonon γ -vibrational bands in neutron-rich Mo107
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W. Y. Liang, C. J. Zachary, E. H. Wang, G. H. Bhat, J. A. Sheikh, A. C. Dai, Yu. Ts. Oganessian, A. V. Ramayya, J. K. Hwang, J. O. Rasmussen, Y. X. Luo, N. T. Brewer, J. H. Hamilton, Furong Xu, S. J. Zhu, J. Marcellino, and G. M. Ter-Akopian
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Physics ,010308 nuclear & particles physics ,Phonon ,0103 physical sciences ,Vibrational bands ,Neutron ,010306 general physics ,01 natural sciences ,Molecular physics ,Hot band - Published
- 2017
57. Impact of Modular Total Absorption Spectrometer measurements ofβdecay of fission products on the decay heat and reactorν¯eflux calculation
- Author
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K.C. Goetz, J.W. Johnson, B. C. Rasco, K. Miernik, S. V. Paulauskas, K. P. Rykaczewski, C. Jost, J. H. Hamilton, D. W. Stracener, Marzena Wolinska-Cichocka, Robert Grzywacz, M. Karny, M. Madurga, E. F. Zganjar, David Miller, W. Bielewski, S. Padgett, A. V. Ramayya, Carl J Gross, A. Fijałkowska, and R. Goans
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Physics ,Fission products ,010308 nuclear & particles physics ,Fission ,Xenon-135 ,Analytical chemistry ,General Physics and Astronomy ,01 natural sciences ,Ion ,Nuclear physics ,Excited state ,0103 physical sciences ,Absorption (logic) ,Decay heat ,010306 general physics ,Energy (signal processing) - Abstract
We report the results of a β-decay study of fission products ^{86}Br, ^{89}Kr, ^{89}Rb, ^{90gs}Rb, ^{90m}Rb, ^{90}Kr, ^{92}Rb, ^{139}Xe, and ^{142}Cs performed with the Modular Total Absorption Spectrometer (MTAS) and on-line mass-separated ion beams. These radioactivities were assessed by the Nuclear Energy Agency as having high priority for decay heat analysis during a nuclear fuel cycle. We observe a substantial increase in β feeding to high excited states in all daughter isotopes in comparison to earlier data. This increases the average γ-ray energy emitted by the decay of fission fragments during the first 10 000 s after fission of ^{235}U and ^{239}Pu by approximately 2% and 1%, respectively, improving agreement between results of calculations and direct observations. New MTAS results reduce the reference reactor ν[over ¯]_{e} flux used to analyze reactor ν[over ¯]_{e} interaction with detector matter. The reduction determined by the ab initio method for the four nuclear fuel components, ^{235}U, ^{238}U, ^{239}Pu, and ^{241}Pu, amounts to 0.976, 0.986, 0.983, and 0.984, respectively.
- Published
- 2017
58. EXPERIMENTS ON SYNTHESIS OF SUPERHEAVY NUCLEI 284Fl AND 285Fl IN THE 239,240Pu + 48Ca REACTIONS
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Robert Grzywacz, V. K. Utyonkov, K. Miernik, A. N. Polyakov, Grigory K. Vostokin, K. P. Rykaczewski, M. G. Itkis, V. G. Subbotin, A. A. Voinov, N. T. Brewer, J. H. Hamilton, M. A. Stoyer, Yu. S. Tsyganov, James B. Roberto, M. V. Shumeiko, I. V. Shirokovsky, F. Sh. Abdullin, S. Y. Strauss, S. N. Dmitriev, A. V. Sabelnikov, Yu. Ts. Oganessian, R. N. Sagaidak, and A. M. Sukhov
- Published
- 2017
59. RESULTS FROM THE RECENT STUDY OF THE 249-251Cf + 48Ca REACTIONS
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Grigory K. Vostokin, M. G. Itkis, James B. Roberto, R. N. Sagaidak, A. M. Sukhov, V. G. Subbotin, K. P. Rykaczewski, M. V. Shumeiko, Yu. Ts. Oganessian, A. V. Sabelnikov, J. H. Hamilton, A. A. Voinov, K. Miernik, F. Sh. Abdullin, N. T. Brewer, A. N. Polyakov, Robert Grzywacz, M. A. Stoyer, Yu. S. Tsyganov, V. K. Utyonkov, I. V. Shirokovsky, and S. N. Dmitriev
- Published
- 2017
60. MULTI-PHONON γ VIBRATIONAL BANDS IN 103-108Mo AND 103,105Nb, CHIRAL VIBRATIONS IN 104,106Mo AND OCTUPOLE CORRELATIONS IN 146,147La
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A. V. Ramayya, Yu. Ts. Oganessian, E. H. Wang, J. H. Hamilton, B. M. Musangu, A. A. Wani, W. Y. Liang, G. M. Ter-Akopian, G. H. Bhat, J. O. Rasmussen, A. C. Dai, S. J. Zhu, J. A. Sheikh, J. M. Eldridge, W. Lewis, J. Marcellino, Furong Xu, C. J. Zachary, R. N. Ali, Y. X. Luo, J. K. Hwang, and H. Fryman-Sinkhorn
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Vibration ,Physics ,Phonon ,Vibrational bands ,Molecular physics - Published
- 2017
61. Oblate deformation in neutron-rich Ag118,119
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A. V. Ramayya, Y. X. Liu, J. K. Hwang, Yang Sun, J. O. Rasmussen, G. M. Ter-Akopian, S. J. Zhu, A. C. Dai, Yu. Ts. Oganessian, S. H. Liu, E. H. Wang, N. T. Brewer, W. Y. Liang, J. H. Hamilton, Furong Xu, H. J. Li, and Y. X. Luo
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Physics ,Routhian ,SHELL model ,Oblate spheroid ,Neutron ,Gammasphere ,Atomic physics ,Deformation (engineering) ,Spontaneous fission - Abstract
High-spin-level schemes of $^{118,119}\mathrm{Ag}$ are established for the first time by analyzing the high statistics $\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}$ and $\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}$ coincidence data from the spontaneous fission of $^{252}\mathrm{Cf}$ at Gammasphere. Two bands with 12 new levels in $^{118}\mathrm{Ag}$ and three bands with 14 new levels in $^{119}\mathrm{Ag}$ have been identified. A total Routhian surface calculation and projected shell model calculation have been performed to understand the behavior of these two nuclei. The calculations indicate oblate shape in $^{118,119}\mathrm{Ag}$.
- Published
- 2017
62. Complete β -decay pattern for the high-priority decay-heat isotopes I137 and Xe137 determined using total absorption spectroscopy
- Author
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K. P. Rykaczewski, A. V. Ramayya, Carl J Gross, Robert Grzywacz, J. H. Hamilton, David Miller, Bertis Rasco, M. Karny, S. Padgett, D. W. Stracener, K. Miernik, A. Fijałkowska, M. Madurga, K.C. Goetz, E. F. Zganjar, E. H. Spejewski, J. C. Blackmon, C. U. Jost, J.W. Johnson, Marzena Wolinska-Cichocka, S. V. Paulauskas, and N. T. Brewer
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Physics ,Total absorption spectroscopy ,010308 nuclear & particles physics ,Neutron emission ,Branching fraction ,01 natural sciences ,Nuclear magnetic resonance ,0103 physical sciences ,Neutron ,Absorption (logic) ,Atomic physics ,Nuclear Experiment ,010306 general physics ,Ground state ,Energy (signal processing) ,Intensity (heat transfer) - Abstract
Background: An assessment done under the auspices of the Nuclear Energy Agency in 2007 suggested that the $\ensuremath{\beta}$ decays of abundant fission products in nuclear reactors may be incomplete. Many of the nuclei are potentially affected by the so called pandemonium effect and their $\ensuremath{\beta}\text{\ensuremath{-}}\ensuremath{\gamma}$ decay heat should be restudied using the total absorption technique. The fission products $^{137}\mathrm{I}$ and $^{137}\mathrm{Xe}$ were assigned highest priority for restudy due to their large cumulative fission branching fractions. In addition, measuring $\ensuremath{\beta}$-delayed neutron emission probabilities is challenging and any new technique for measuring the $\ensuremath{\beta}$-neutron spectrum and the $\ensuremath{\beta}$-delayed neutron emission probabilities is an important addition to nuclear physics experimental techniques.Purpose: To obtain the complete $\ensuremath{\beta}$-decay pattern of $^{137}\mathrm{I}$ and $^{137}\mathrm{Xe}$ and determine their consequences for reactor decay heat and ${\overline{\ensuremath{\nu}}}_{e}$ emission. Complete $\ensuremath{\beta}$-decay feeding includes ground state to ground state $\ensuremath{\beta}$ feeding with no associated $\ensuremath{\gamma}$ rays, ground state to excited states $\ensuremath{\beta}$ transitions followed by $\ensuremath{\gamma}$ transitions to the daughter nucleus ground state, and $\ensuremath{\beta}$-delayed neutron emission from the daughter nucleus in the case of $^{137}\mathrm{I}$.Method: We measured the complete $\ensuremath{\beta}$-decay intensities of $^{137}\mathrm{I}$ and $^{137}\mathrm{Xe}$ with the Modular Total Absorption Spectrometer at Oak Ridge National Laboratory. We describe a technique for measuring the $\ensuremath{\beta}$-delayed neutron energy spectrum, which also provides a measurement of the $\ensuremath{\beta}$-neutron branching ratio, ${P}_{n}$.Results: We validate the current Evaluated Nuclear Structure Data File (ENSDF) evaluation of $^{137}\mathrm{Xe}\phantom{\rule{4pt}{0ex}}\ensuremath{\beta}$ decay. We find that major changes to the current ENSDF assessment of $^{137}\mathrm{I}\ensuremath{\beta}$-decay intensity are required. The average $\ensuremath{\gamma}$ energy per $\ensuremath{\beta}$ decay for $^{137}\mathrm{I}\ensuremath{\beta}$ decay ($\ensuremath{\gamma}$ decay heat) increases by 19%, from 1050--1250 keV, which increases the average $\ensuremath{\gamma}$ energy per $^{235}\mathrm{U}$ fission by $0.11%$. We measure a $\ensuremath{\beta}$-delayed neutron branching fraction for $^{137}\mathrm{I}\ensuremath{\beta}$ decay of $7.9\ifmmode\pm\else\textpm\fi{}0.2(\mathrm{fit})\ifmmode\pm\else\textpm\fi{}0.4(\mathrm{sys})%$ and we provide a $\ensuremath{\beta}$-neutron energy spectrum.Conclusions: The Modular Total Absorption Spectrometer measurements of $^{137}\mathrm{I}$ and $^{137}\mathrm{Xe}$ demonstrate the importance of revisiting and remeasuring complex $\ensuremath{\beta}$-decaying fission products with total absorption spectroscopy. We demonstrate the ability of the Modular Total Absorption Spectrometer to measure $\ensuremath{\beta}$-delayed neutron energy spectra.
- Published
- 2017
63. Reexamining the nuclear structure of Gd154 in the dynamic pairing plus quadrupole model
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J. B. Gupta and J. H. Hamilton
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Physics ,Decay scheme ,010308 nuclear & particles physics ,Nuclear structure ,01 natural sciences ,Symmetry (physics) ,Nuclear physics ,Excited state ,Pairing ,0103 physical sciences ,Quadrupole ,Atomic physics ,Interacting boson model ,010306 general physics ,Intensity (heat transfer) - Abstract
In a previous study of the collective multiphonon bands in $^{154}\mathrm{Gd}$, using the microscopic dynamic pairing plus quadrupole model, data for eight $K$ bands were analyzed. In the last four decades, its decay scheme is significantly revised and the nuclear theory has undergone a significant change. Special focus is on new weak intensity transitions in several bands and on the reassigned levels in its decay scheme. The present study represents a detailed revised analysis of the collective even parity bands below 2.1 MeV. Also, a discussion is given on the nature of the ${K}^{\ensuremath{\pi}}={0}^{+}$ excited bands, validity of band mixing approach, and of the assumption of shape coexistence of \ensuremath{\beta} band with ground band. Comparison is made with the $X$(5) analytical symmetry and the algebraic interacting boson model predictions. Discussion of the $2n$ transfer reactions is given. The validity of the multiphonon view of the ${K}^{\ensuremath{\pi}}={4}^{+}$ and ${2}_{2}^{+}$ bands is also studied.
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- 2017
64. Impact of Modular Total Absorption Spectrometer measurements of β decay of fission products on the decay heat and reactor ν[over ¯]_{e} flux calculation
- Author
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A, Fijałkowska, M, Karny, K P, Rykaczewski, B C, Rasco, R, Grzywacz, C J, Gross, M, Wolińska-Cichocka, K C, Goetz, D W, Stracener, W, Bielewski, R, Goans, J H, Hamilton, J W, Johnson, C, Jost, M, Madurga, K, Miernik, D, Miller, S W, Padgett, S V, Paulauskas, A V, Ramayya, and E F, Zganjar
- Abstract
We report the results of a β-decay study of fission products ^{86}Br, ^{89}Kr, ^{89}Rb, ^{90gs}Rb, ^{90m}Rb, ^{90}Kr, ^{92}Rb, ^{139}Xe, and ^{142}Cs performed with the Modular Total Absorption Spectrometer (MTAS) and on-line mass-separated ion beams. These radioactivities were assessed by the Nuclear Energy Agency as having high priority for decay heat analysis during a nuclear fuel cycle. We observe a substantial increase in β feeding to high excited states in all daughter isotopes in comparison to earlier data. This increases the average γ-ray energy emitted by the decay of fission fragments during the first 10 000 s after fission of ^{235}U and ^{239}Pu by approximately 2% and 1%, respectively, improving agreement between results of calculations and direct observations. New MTAS results reduce the reference reactor ν[over ¯]_{e} flux used to analyze reactor ν[over ¯]_{e} interaction with detector matter. The reduction determined by the ab initio method for the four nuclear fuel components, ^{235}U, ^{238}U, ^{239}Pu, and ^{241}Pu, amounts to 0.976, 0.986, 0.983, and 0.984, respectively.
- Published
- 2017
65. Remarks on the Fission Barriers of SHN and Search for Element 120
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L. Dahl, S. Heinz, I. Kojouharov, Ken Moody, H. G. Burkhard, Katsuhisa Nishio, S. Antalic, Klaus Eberhardt, Jörg Runke, G. Münzenberg, Roger Henderson, K. P. Rykaczewski, Norbert Trautmann, H. J. Schött, Petra Thörle-Pospiech, D. A. Shaughnessy, R. Lang, W. Barth, C. Scheidenberger, Birgit Kindler, J. M. Kenneally, J. H. Hamilton, J. Maurer, S. Hofmann, A. V. Yeremin, D. Miller, James B. Roberto, R. Mann, Juha Uusitalo, M. A. Stoyer, K. Tinschert, A. G. Popeko, S. Saro, K. Miernik, Bettina Lommel, R. Grzywacz, and K. Morita
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Nuclear physics ,Physics ,fissio ,ydinreaktiot ,ta114 ,fission barriers ,Fission ,super-heavy nuclei ,Element (category theory) ,fysiikka ,cross-sections - Published
- 2017
66. First Results from the Modular Total Absorption Spectrometer at the HRIBF
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A. V. Ramayya, Carl J Gross, R. Goans, Lucia Cartegni, E. H. Spejewski, K. P. Rykaczewski, K. Miernik, M. Karny, S. V. Paulauskas, Bertis Rasco, David Miller, Robert Grzywacz, E.F. Zganjar, J. H. Hamilton, Marzena Wolinska-Cichocka, C. Jost, D. W. Stracener, M. Madurga, Mohammad Alshudifat, Aleksandra Fijałkowska, S. Padgett, K.C. Goetz, and J.W. Johnson
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Nuclear physics ,Physics ,Nuclear and High Energy Physics ,Fission products ,Uranium-238 ,Ion beam ,Nuclear transmutation ,Spectrometer ,Nuclear data ,Decay heat ,Nuclear Experiment ,Isotopes of caesium - Abstract
A Modular Total Absorption Spectrometer constructed at the Holifield Radioactive Ion Beam Facility has been applied to decay studies of over 20 238 U fission products. The measurements were focused on nuclei identified as important for decay heat analysis during a nuclear fuel cycle. Preliminary results on the average electromagnetic (EM) energy release in the β decay of 89 Kr and 139 Xe isotopes yielded values of 2446 keV and 1126 keV, respectively. It represents an increase of over 35% and 20%, respectively, when compared to the average EM energies deduced using the ENSDF database.
- Published
- 2014
67. Intertwining of Greiner’s Theoretical Works and Our Experimental Studies
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J. H. Hamilton, A. V. Ramayya, and E. H. Wang
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Nuclear physics ,Physics ,Phonon ,Neutron emission ,Cluster (physics) ,Zero (complex analysis) ,Ternary fission ,Island of stability ,Spontaneous fission ,Cold fusion - Abstract
The one phonon \(\gamma \)-vibrational bands in \(^{154}\)Gd are compared with the theories existing at the time (1960) showing the best agreement with the rotation vibration model of Faessler and Greiner. In recent years experimental evidences have been found for both one, two, and possibly three phonon \(\gamma \) bands in the A \(=\) 103–110 region including the first such bands in odd N-even Z and even N-odd Z nuclei. Nuclear shape coexistence was discovered in both \(^{72}\)Se and \(^{184-188}\)Hg with the Frankfurt Generalized Collective Model reproducing the two different shapes. Cluster radioactivity predicted by Sandulescu, Poenaru and Greiner has been observed. Maximum cluster radioactivity is seen in the zero neutron emission in cold binary and ternary fission of \(^{252}\)Cf. Finally, recent super heavy discoveries of the new elements 115, 117 and 118 are described. The half lives in 117 which is closest in N to N \(=\) 184 on the Island of Stability support the theoretical predictions of the long-lived island.
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- 2016
68. New insights into the nuclear structure in neutron-rich 112,114,115,116,117,118Pd
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A. V. Ramayya, W. C. Ma, S. H. Liu, Yue Shi, J. D. Cole, N. J. Stone, I. Y. Lee, J. K. Hwang, N. T. Brewer, Raul Donangelo, Yu. Ts. Oganessian, Y. X. Luo, M. A. Stoyer, A. V. Daniel, G. M. Ter-Akopian, E. H. Wang, S. J. Zhu, John O. Rasmussen, J. H. Hamilton, S. Frauendorf, and Furong Xu
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Physics ,Nuclear and High Energy Physics ,Isotope ,Spins ,Fission ,Isotone ,Nuclear structure ,Neutron ,Gammasphere ,Chiral symmetry breaking ,Molecular physics - Abstract
New level schemes of 112,114,115,116,117,118Pd are established by means of γ – γ – γ , γ – γ – γ – γ and γ – γ ( θ ) measurements of prompt fission γ rays from 252Cf using the Gammasphere multi-detector array. Spins/parities were assigned to levels based on γ – γ angular correlation measurements, level systematics and decay patterns. In the even-N isotopes 112,114,116Pd, two sets of odd-parity bands were identified and extended with spins measured in each band. The odd-parity bands with large level staggerings were interpreted as disturbed chirality with less pronounced triaxial deformations in the Pd isotopes than observed in the chiral symmetry breaking 110,112Ru with maximum triaxiality. Onset of wobbling motion was identified from the sign of the signature splitting in the γ band of even–even 114Pd, and probably also in 116Pd, as first seen in the N = 68 isotone 112Ru. Maximal triaxiality in Ru and Pd isotopes is found to be reached for N = 68 , 112Ru and 114Pd, 4 neutrons more than predicted in the theoretical calculations. The new data and TRS calculations allowed a systematic study of the band crossings in the even-N 112,114,116Pd and odd-N 115,117Pd isotopes. Now we find a new overall, more complex shape evolution than previously proposed from triaxial prolate in 110Pd via triaxial oblate in 112Pd to nearly oblate in 114,116Pd with a large change of the triaxial deformation parameter γ toward nearly oblate in the ( π g 9 / 2 ) 2 alignment in 114,115,116,117,118Pd, and triaxial-prolate–triaxial-oblate shape coexisting bands in 115Pd.
- Published
- 2013
69. In124levels populated in theβdecay ofCd124
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K. P. Rykaczewski, J. C. Batchelder, Marzena Wolinska-Cichocka, S. W. Padgett, D. W. Stracener, J. H. Hamilton, N. T. Brewer, Robert Grzywacz, A. V. Ramayya, S. H. Liu, Carl J Gross, A. Fijałkowska, K. Miernik, Stan Paulauskas, and M. Karny
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Physics ,Nuclear physics ,010308 nuclear & particles physics ,0103 physical sciences ,010306 general physics ,01 natural sciences - Published
- 2016
70. Proposeds=±1octupole bands inXe140
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H. J. Li, E. H. Wang, A. V. Ramayya, Yu. Ts. Oganessian, G. M. Ter-Akopian, S. J. Zhu, J. O. Rasmussen, Y. X. Luo, Y. Huang, Zhigang Xiao, and J. H. Hamilton
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Physics ,010308 nuclear & particles physics ,0103 physical sciences ,Astrophysics ,010306 general physics ,01 natural sciences - Published
- 2016
71. Review of even element super-heavy nuclei and search for element 120
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Robert Grzywacz, D. A. Shaughnessy, Roger Henderson, Jörg Runke, W. Barth, L. Dahl, Julien Maurer, Kosuke Morita, G. Münzenberg, R. Mann, M. A. Stoyer, J. M. Kenneally, Bettina Lommel, K. P. Rykaczewski, Norbert Trautmann, Sigurd Hofmann, Katsuhisa Nishio, K. Miernik, R. Lang, K. Tinschert, James B. Roberto, J. H. Hamilton, S. Antalic, Juha Uusitalo, Klaus Eberhardt, S. Heinz, A. V. Yeremin, S. Saro, Christoph Scheidenberger, Petra Thörle-Pospiech, Birgit Kindler, Kenton J. Moody, A. G. Popeko, I. Kojouharov, H. J. Schött, H. G. Burkhard, and David Miller
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Physics ,Nuclear and High Energy Physics ,Sequence ,Period (periodic table) ,Field (physics) ,Isotope ,010308 nuclear & particles physics ,Hadron ,01 natural sciences ,Nuclear physics ,0103 physical sciences ,Nuclear fusion ,Decay chain ,010306 general physics ,Event (probability theory) - Abstract
The reaction 54Cr$ + $248Cm was investigated at the velocity filter SHIP at GSI, Darmstadt, with the intention to study production and decay properties of isotopes of element 120. Three correlated signals were measured, which occurred within a period of 279ms. The heights of the signals correspond with the expectations for a decay sequence starting with an isotope of element 120. However, a complete decay chain cannot be established, since a signal from the implantation of the evaporation residue cannot be identified unambiguously. Measured properties of the event chain are discussed in detail. The result is compared with theoretical predictions. Previously measured decay properties of even element super-heavy nuclei were compiled in order to find arguments for an assignment from the systematics of experimental data. In the course of this review, a few tentatively assigned data could be corrected. New interpretations are given for results which could not be assigned definitely in previous studies. The discussion revealed that the cross-section for production of element 120 could be high enough so that a successful experiment seems possible with presently available techniques. However, a continuation of the experiment at SHIP for a necessary confirmation of the results obtained in a relatively short irradiation of five weeks is not possible at GSI presently. Therefore, we decided to publish the results of the measurement and of the review as they exist now. In the summary and outlook section we also present concepts for the continuation of research in the field of super-heavy nuclei.
- Published
- 2016
72. Publisher's Note: Reexamining Gamow-Teller decays nearNi78[Phys. Rev. C93, 044325 (2016)]
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N. T. Brewer, Ivan Borzov, C. Jost, E. F. Zganjar, D. W. Stracener, J. A. Winger, S. W. Padgett, S. H. Liu, J. K. Hwang, A. Fijałkowska, A. Korgul, A. V. Ramayya, W. Krolas, Carl J Gross, A. J. Mendez, D.W. Miller, Robert Grzywacz, Stan Paulauskas, Marzena Wolinska-Cichocka, M. Karny, Lucia Cartegni, K. P. Rykaczewski, K. Miernik, J. H. Hamilton, C. Mazzocchi, M. Al-Shudifat, C. R. Bingham, Rebecca Surman, J. C. Batchelder, S. V. Ilyushkin, and M. Madurga
- Subjects
Nuclear physics ,Physics - Published
- 2016
73. Reexamining Gamow-Teller decays nearNi78
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A. V. Ramayya, Robert Grzywacz, Carl J Gross, C. Jost, K. P. Rykaczewski, D. W. Stracener, Lucia Cartegni, J. K. Hwang, S. Padgett, E. F. Zganjar, S. H. Liu, J. H. Hamilton, S. V. Ilyushkin, A. Fijałkowska, Ivan Borzov, Stan Paulauskas, J. A. Winger, D.W. Miller, M. Karny, M. Madurga, K. Miernik, C. Mazzocchi, M. Al-Shudifat, A. J. Mendez, Rebecca Surman, A. Korgul, N. T. Brewer, W. Krolas, Marzena Wolinska-Cichocka, C. R. Bingham, and J. C. Batchelder
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Physics ,010308 nuclear & particles physics ,Fission ,Branching fraction ,Nuclear Theory ,0103 physical sciences ,Neutron ,Atomic physics ,010306 general physics ,Spectroscopy ,01 natural sciences ,Mass separation ,Excitation - Abstract
Decays of neutron-rich nuclei $^{82,83}\mathrm{Zn}$ and $^{82,83}\mathrm{Ga}$ produced in proton-induced fission of $^{238}\mathrm{U}$ were studied at the Holifield Radioactive Ion Beam Facility using on-line mass separation and $\ensuremath{\beta}\text{\ensuremath{-}}\ensuremath{\gamma}$ spectroscopy techniques. New $\ensuremath{\gamma}$-ray transitions were identified and level schemes, which include states at high excitation energies in the range between 3--7 MeV were constructed. These high-energy levels were identified to be populated through allowed Gamow-Teller $\ensuremath{\beta}$ transitions, and their structure was interpreted with new shell-model calculations. A $\ensuremath{\beta}$-delayed neutron branching ratio of $69\ifmmode\pm\else\textpm\fi{}7%$ was deduced for $^{82}\mathrm{Zn}$ and revised $\ensuremath{\beta}$-decay half-life values of $^{82}\mathrm{Zn}$ [155(17)(20) ms] and $^{83}\mathrm{Zn}$ [122(28) ms] were determined.
- Published
- 2016
74. Remarks on the fission barriers of super-heavy nuclei
- Author
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Katsuhisa Nishio, Kenton J. Moody, D. A. Shaughnessy, Petra Thörle-Pospiech, L. Dahl, R. Mann, A. G. Popeko, M. A. Stoyer, K. P. Rykaczewski, J. H. Hamilton, R. Lang, Kosuke Morita, J. Maurer, K. Miernik, Klaus Eberhardt, Bettina Lommel, I. Kojouharov, W. Barth, Robert Grzywacz, K. Tinschert, Roger Henderson, David Miller, James B. Roberto, G. Münzenberg, Christoph Scheidenberger, Norbert Trautmann, Birgit Kindler, Sigurd Hofmann, Juha Uusitalo, S. Heinz, S. Antalic, A. V. Yeremin, J. M. Kenneally, and Jörg Runke
- Subjects
Physics ,Nuclear and High Energy Physics ,Isotope ,010308 nuclear & particles physics ,Fission ,Nuclear Theory ,Hadron ,01 natural sciences ,Entrance channel ,Nuclear physics ,medicine.anatomical_structure ,0103 physical sciences ,medicine ,Nuclear fusion ,Decay chain ,Atomic physics ,Nuclear Experiment ,010306 general physics ,Nucleus - Abstract
Shell-correction energies of super-heavy nuclei are approximated by using $ Q_{\alpha}$ values of measured decay chains. Five decay chains were analyzed, which start at the isotopes 285Fl, 294118, 291Lv, 292Lv and 293Lv. The data are compared with predictions of macroscopic-microscopic models. Fission barriers are estimated that can be used to eliminate uncertainties in partial fission half-lives and in calculations of evaporation-residue cross-sections. In that calculations, fission probability of the compound nucleus is a major factor contributing to the total cross-section. The data also provide constraints on the cross-sections of capture and quasi-fission in the entrance channel of the fusion reaction. Arguments are presented that fusion reactions for synthesis of isotopes of elements 118 and 120 may have higher cross-sections than assumed so far.
- Published
- 2016
75. New high-spin level schemes and excitation modes of 117,118,119,120,122Cd
- Author
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J. K. Hwang, Raul Donangelo, G. M. Ter-Akopian, C. Nelson, S. J. Zhu, I. Y. Lee, A. V. Ramayya, W. C. Ma, J. H. Hamilton, K. Li, S. H. Liu, A. V. Daniel, N. T. Brewer, C. T. Goodin, John O. Rasmussen, M. A. Stoyer, J. D. Cole, N. J. Stone, and Y. X. Luo
- Subjects
Physics ,Nuclear and High Energy Physics ,Spins ,Isotope ,Fission ,Parity (physics) ,Neutron ,Gammasphere ,Atomic physics ,Excitation ,Coincidence - Abstract
High-spin level schemes of 117,118,119,120,122 Cd are expanded by analyzing our high-statistics triple- and higher-fold coincidence events of prompt fission γ rays from 252 Cf at Gammasphere. Spin/parity assignments were made based on new γ – γ angular correlation measurements and level systematics in the neighboring isotopes. Stretch-aligned band structures observed in low-lying levels in 117,119,121 Cd are seen to weaken with increasing spins, with a quasi-rotational degree of freedom manifested at higher spins. The 5 − levels in even- N 118,120 Cd were tentatively interpreted as candidates of quadrupole–octupole (QOC) coupling. The model-independent spin versus ℏω curves for even- N and odd- N Cd isotopes imply quasi-rotational alignment of an h 11 / 2 neutron pair in the even- N Cd isotopes. The relative energies of the lowest 11 / 2 − , 9 / 2 − , 7 / 2 − , and 15 / 2 − levels in 117 Cd and 119 Cd suggest triaxial shapes based on Meyer-Ter-Vehn theory for these odd- N Cd nuclei. For the even- N Cd isotopes evidence of triaxiality may also be provided by the Shell Correction version of the Tilted Axis Cranking model (SCTAC).
- Published
- 2012
76. Nature of $K^{\pi}=0_{2}^{+}$ bands in A=140-180 region, a global analysis
- Author
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Juhi Gupta and J. H. Hamilton
- Subjects
Physics ,Nuclear and High Energy Physics ,Amplitude ,Pairing ,Hadron ,Quadrupole ,Beta (velocity) ,Atomic physics ,Interacting boson model ,Ground state ,Energy (signal processing) - Abstract
The nature of $K^{\pi}=0_{2}^{+}$ band is analyzed in the light of the variation of the $ E(0_{2}^{+})$ and $B(E2)$ values, with N and Z, for the $A=140-180$ region. The absolute $B(E2)$ strengths for the excitation of $2_{\gamma}$ and $ 2_{K=02}$ states are studied. Also the roles of $B(E2,0_{2}^{+}-2_{g})$ and $ B(E2,0_{2}^{+}-2_{\gamma})$ are discussed. Comparison with the dynamic pairing plus quadrupole model, for all the nuclei studied here, are made on a global basis. The lack of overlap in the wave function amplitudes $A_{200}(\beta,\gamma)$ of $0_{2}^{+}$ and $A_{100}(\beta,\gamma)$ of the ground state also explains the reduced $B(E2,\beta -g)$ strength. The $ B(E2,2_{\beta}\rightarrow 0_{\beta})$ is a good measure of the rotational collectivity (deformation) of the band. Shape coexistence at N = 88, 90 nuclei is reviewed. The possibility of $ K^{\pi}=0_{2}^{+}$ as a $ \gamma\gamma$ -vibration, when allowed by energy, in expected cases is examined. The interacting boson model predictions are also considered as required.
- Published
- 2015
77. IDENTIFICATION OF HIGH-SPIN STATES IN NEUTRON-RICH 88,90,92<font>Kr</font> AND 86<font>Se</font>
- Author
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X. Q. Zhang, S. C. Wu, A. V. Ramayya, S. H. Liu, J. K. Hwang, I. Y. Lee, Raul Donangelo, J. O. Rasmussen, Yu. Ts. Oganessian, J. D. Cole, K. Li, Y. X. Luo, G. M. Ter-Akopian, A. V. Daniel, S. J. Zhu, A. Unzhakova, M. A. Stoyer, J. H. Hamilton, C. T. Goodin, W. C. Ma, and N. T. Brewer
- Subjects
Physics ,Nuclear physics ,Nuclear and High Energy Physics ,Spin states ,Spins ,Angular correlation ,Excited state ,General Physics and Astronomy ,Neutron ,Gammasphere ,Atomic physics ,Coincidence ,Spontaneous fission - Abstract
Level schemes of even–even neutron-rich 88-92 Kr and 86 Se have been investigated by measuring triple-γ coincidence data from the spontaneous fission of 252 Cf with the Gammasphere detector array. The level scheme of 88 Kr has been extended up to 7169 keV state. Several new excited states with new transitions have been identified in 90,92 Kr and 86 Se . Spins and parities have been assigned to levels in these nuclei by following regional systematics and angular correlation measurements. The level structures of the N = 52, 54, Se , Kr , and Sr isotones are discussed.
- Published
- 2011
78. New multi-phonon gamma vibrational bands in A∼110 neutron-rich nuclei
- Author
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E. Y. Yeoh, J. K. Hwang, Y. X. Luo, A. V. Ramayya, H. B. Ding, J. O. Rasmussen, Qiang Xu, K. Li, Jian-Guo Wang, Long Gu, J. H. Hamilton, S. H. Liu, Zhigang Xiao, and Shengjiang Zhu
- Subjects
Physics ,Spin states ,Coincident ,Phonon ,Excited state ,Vibrational bands ,General Physics and Astronomy ,Condensed Matter::Strongly Correlated Electrons ,Neutron ,Gammasphere ,Atomic physics ,Spontaneous fission - Abstract
The high spin states of neutron-rich 103Nb, 107Tc and 109Tc nuclei in A∼110 region have been investigated by measuring prompt γ-γ-γ coincident measurements populated with the spontaneous fission of 252Cf with the Gammasphere detector array. In 103Nb, one-phonon K = 9/2 and two-phonon K = 13/2 γ-vibrational bands have been identified. In 107Tc and 109Tc, one-phonon K = 11/2 and two-phonon K = 15/2 γ-vibrational bands, in which the zero-phonon bands are based on K=7/2 excited states, have also been identified. The two-phonon bands are first observed in odd-Z nuclei. The characteristics for these band structures have been discussed.
- Published
- 2011
79. NUCLEAR STRUCTURE OF 150<font>Sm</font> IN THE DPPQ MODEL AND IBM
- Author
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J. B. Gupta, J. H. Hamilton, and Kishlay Kumar
- Subjects
Physics ,Nuclear and High Energy Physics ,Excited state ,Pairing ,Anharmonicity ,Potential energy surface ,Nuclear structure ,General Physics and Astronomy ,Atomic physics ,Microscopic theory ,Interacting boson model ,Wave function - Abstract
The decay pattern of the low lying levels in the shape transitional nucleus 150 Sm is analyzed in terms of the quasi-vibrational and quasi-rotational collective model. The Dynamic Pairing plus quadrupole Model in the microscopic theory of the collective model is employed to predict extensive structure characteristics. The potential energy surface (PES), the spectroscopic factors and the E2, E0 transition rates from the DPPQ model are illustrated. Comparison is made with the predictions in the Interacting Boson Model (IBM-1). A correspondence is demonstrated of the effect of the control parameter in the two models on the calculated nuclear structure. The study of the wave functions of the two spin I = 2 excited states in IBM is carried out. The alternative view of an anharmonic vibrator and a soft rotor is discussed in terms of the E2 transition rates and other structural characteristics.
- Published
- 2010
80. Octupole excitations in 141,144Cs and the pronounced decrease of dipole moments with neutron number in odd-Z neutron-rich 141,143,144Cs
- Author
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A. V. Ramayya, J. K. Hwang, Raul Donangelo, C. T. Goodin, E. F. Jones, S. H. Liu, M. A. Stoyer, J. D. Cole, N. J. Stone, W. C. Ma, Y. X. Luo, K. Li, H. L. Crowell, A. V. Daniel, I. Y. Lee, J. H. Hamilton, G. M. Ter-Akopian, P. M. Gore, J. O. Rasmussen, and S. J. Zhu
- Subjects
Physics ,Nuclear and High Energy Physics ,Dipole ,Neutron number ,Yrast ,Transition dipole moment ,Neutron ,Gammasphere ,Atomic physics ,Quantum number ,Spontaneous fission - Abstract
The level scheme of odd-Z neutron-rich 141Cs (Z=55, N=86) was extended and expanded and that of 144Cs (N=89) was identified for the first time by means of γ–γ–γ coincidence measurements of prompt γ rays in the spontaneous fission of 252Cf with Gammasphere. Spin/parity was assigned to the levels based on angular correlations and level systematics in 141,143Cs. Parity doublets characteristic of both simplex quantum number s=+i and s=−i were proposed in 141Cs. The tests by using rotational frequency ratio ω−(I)/ω+(I) imply octupole vibrations in 141Cs and 143Cs. B(E1)/B(E2) values and electric dipole moments D0 were calculated for 141Cs, and re-determined for 143Cs. It was found that B(E1)/B(E2) values of 141Cs are simplex-dependent and the average value is one order of magnitude larger than that of 143Cs, and the deduced dipole moment D0 of 141Cs is considerably larger than that of 143Cs, and comparable to the N=86 isotone 142Ba. For 144Cs the yrast sequence looks like a well-deformed rotational band, but no octupole band structure was identified in this nucleus. The overall variations of D0 in 141,143,144Cs exhibit a pronounced drop of dipole moment with increasing neutron number in this odd-Z isotopic chain, which may be analogous in nature to the quenching of D0 observed in even–even 146Ba (Z=56, N=90) and 224Ra (Z=88, N=136), and to the drop of D0 in the odd-Z neutron-rich 147La (Z=57, N=90) reported by our collaboration.
- Published
- 2010
81. New levels in spherical 96Y
- Author
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A. V. Ramayya, C. J. Zachary, G. M. Ter-Akopian, J. H. Hamilton, Rui Han, Y. X. Luo, S. J. Zhu, J. K. Hwang, J. O. Rasmussen, E. H. Wang, Yu. Ts. Oganessian, N. T. Brewer, and J. M. Eldridge
- Subjects
Physics ,Nuclear and High Energy Physics ,010308 nuclear & particles physics ,Computer Science::Information Retrieval ,Astrophysics::Instrumentation and Methods for Astrophysics ,General Physics and Astronomy ,Computer Science::Computation and Language (Computational Linguistics and Natural Language and Speech Processing) ,01 natural sciences ,Coincidence ,Nuclear physics ,0103 physical sciences ,Computer Science::General Literature ,Neutron ,Gammasphere ,Detector array ,010306 general physics ,Spontaneous fission - Abstract
New transitions in neutron rich [Formula: see text]Y have been identified by analyzing the high statistics [Formula: see text]-[Formula: see text]-[Formula: see text] and [Formula: see text]-[Formula: see text]-[Formula: see text]-[Formula: see text] coincidence data from the spontaneous fission of [Formula: see text]Cf at the Gammasphere detector array. Shell model calculations were performed and are found in good agreement with experimental data. The ground state is nearly spherical but a new excited band has large deformation.
- Published
- 2018
82. Super deformation to maximum triaxiality in ; superdeformation, chiral bands and wobbling motion
- Author
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G. M. Ter-Akopian, A. V. Ramayya, J. K. Hwang, J. H. Hamilton, S. J. Zhu, J. O. Rasmussen, S. Frauendorf, Yuri Oganessian, S. H. Liu, Y. X. Luo, and A. V. Daniel
- Subjects
Physics ,Superdeformation ,Nuclear and High Energy Physics ,Classical mechanics ,Quantum mechanics ,Motion (geometry) ,Deformation (meteorology) - Published
- 2010
83. Study of the 249-251Cf + 48Ca reactions: recent results and outlook
- Author
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Robert Grzywacz, F. Sh. Abdullin, Yu. S. Tsyganov, Yu. Ts. Oganessian, Grigory K. Vostokin, S. N. Dmitriev, K. Miernik, A. N. Polyakov, R. N. Sagaidak, A. A. Voinov, A. V. Sabelnikov, A. M. Sukhov, N. T. Brewer, M. V. Shumeiko, V. G. Subbotin, I. V. Shirokovsky, James B. Roberto, V. K. Utyonkov, K. P. Rykaczewski, J. H. Hamilton, M. A. Stoyer, and M. G. Itkis
- Subjects
Physics ,History ,Computer Science Applications ,Education - Published
- 2018
84. EVEN-PARITY BANDS OF 108, 110, 112<font>Ru</font>
- Author
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X. L. Che, J. O. Rasmussen, J. L. Wood, J. D. Cole, M. A. Stoyer, C. T. Goodin, Y. X. Luo, J. K. Hwang, Raul Donangelo, Z. Jiang, S. J. Zhu, J. H. Hamilton, and A. V. Ramayya
- Subjects
Physics ,Nuclear and High Energy Physics ,General Physics and Astronomy ,Gammasphere ,Spectral bands ,Band crossing ,Atomic physics ,Electronic band structure ,Coincidence ,Parity bit ,Spontaneous fission - Abstract
High-spin, even-parity bands in neutron-rich 108, 110, 112 Ru nuclei were reinvestigated and considerably expanded by measuring many-fold prompt γ-ray coincidence events following the spontaneous fission of 252 Cf with Gammasphere. Our high statistics data allow us to detect weaker transitions and bands not previously published. Also, gamma branching ratios, which are important for theory, are carefully measured from all levels. In 110 Ru , we find a doubling of levels for both ground and quasi-gamma bands above the 8+ levels. There are likely two-phonon quasi-gamma bands in 110, 112 Ru , as well as a bandhead level in 108 Ru . The odd–even spin energy band staggering observed in the quasi-gamma bands in 108, 110, 112 Ru and the doubling of levels in 110 Ru present a challenge to theory.
- Published
- 2009
85. ODD-PARITY BANDS OF 108, 110, 112<font>Ru</font>
- Author
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X. L. Che, A. V. Ramayya, Z. Jiang, G. M. Ter-Akopian, C. T. Goodin, Jing-ye Zhang, S. Frauendorf, I. Y. Lee, M. A. Stoyer, V. I. Dimitrov, A. V. Daniel, S. J. Zhu, K. Li, J. O. Rasmussen, Y. X. Luo, J. K. Hwang, Raul Donangelo, J. D. Cole, N. J. Stone, and J. H. Hamilton
- Subjects
Nuclear physics ,Physics ,Nuclear and High Energy Physics ,Gamma ray ,General Physics and Astronomy ,Gammasphere ,Spontaneous fission ,Parity bit - Abstract
Two similar sets of odd-parity bands are observed in each of three even–even neighbors, 108, 110, 112 Ru , from a study of prompt spontaneous-fission gamma rays at Gammasphere. A careful study of the odd-parity levels of these nuclei shows evidence for the features of chiral doubling. Comparisons are made with reported other candidates for chiral doubling.
- Published
- 2009
86. The first observation of a deformed ground-state band in 100Nb and the high-spin level scheme of its 4n fission partner 148La
- Author
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D. Fong, J. D. Cole, W. C. Ma, A. V. Ramayya, A. V. Daniel, S. J. Zhu, Y. X. Luo, K. Li, I. Y. Lee, C. T. Goodin, M. A. Stoyer, J. H. Hamilton, I. Stefanescu, G. M. Ter-Akopian, J. O. Rasmussen, J. K. Hwang, and Raul Donangelo
- Subjects
Physics ,Nuclear and High Energy Physics ,Isotope ,Fission ,Gammasphere ,Parity (physics) ,Atomic physics ,Ground state ,Internal conversion coefficient ,Coincidence ,Spontaneous fission - Abstract
The high-spin level schemes of odd–odd 100Nb ( Z = 41 , N = 59 ) and 148La ( Z = 57 , N = 91 ) were identified from γ – γ – γ coincidence studies of prompt γ rays in the spontaneous fission of 252Cf with Gammasphere. Spin/parity assignments for the levels in these two nuclei were made based on the low-lying levels assigned in decay work, on the internal conversion coefficient (ICC) measurements and the level systematics of the neighboring isotopes. A K π = 1 + deformed ground-state band was identified in 100Nb. The onset of ground-state deformation in Nb isotopes is found to take place at N = 59 , in contrast to N = 60 for Sr ( Z = 38 ), Y ( Z = 39 ) and Zr ( Z = 40 ) isotopes. Unlike the observation in 99Nb, the N = 56 subshell closure seems to be no longer dominant in 100Nb. The bands observed in 148La are interpreted as aligned coupling of [ π h 11 / 2 υ h 9 / 2 ] low J to the deformed core rotor.
- Published
- 2009
87. Identification of one-phonon and two-phonon γ-vibrational bands in odd-Z 103Nb nucleus
- Author
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W. C. Ma, H. B. Ding, E. Y. Yeoh, J. K. Hwang, A. V. Ramayya, J. O. Rasmussen, Qiang Xu, Long Gu, Y. X. Luo, Jian-Guo Wang, I. Y. Lee, Zhigang Xiao, K. Li, J. H. Hamilton, Sheng-Jiang Zhu, and S. H. Liu
- Subjects
Physics ,Nuclear and High Energy Physics ,C band ,Phonon ,Astrophysics::High Energy Astrophysical Phenomena ,Spontaneous fission ,Two-phonon γ-vibrational band ,High-spin states ,medicine.anatomical_structure ,medicine ,Vibrational bands ,Neutron ,Atomic physics ,Nucleus - Abstract
Collective bands in the neutron-rich 103 Nb nucleus have been investigated by measuring prompt γ -rays following spontaneous fission of 252 Cf. Three new bands have been identified. The band based on the 716.8 keV level is proposed as a candidate for the K π = 9 / 2 + one-phonon γ -vibrational band, and the band built on the 1282.1 keV level is proposed as a candidate for the K π = 13 / 2 + two-phonon γ -vibrational band. The two-phonon γ -vibrational band is the first such band identified in odd- Z nuclei.
- Published
- 2009
- Full Text
- View/download PDF
88. New level schemes and octupole correlations of light neutron-rich lanthanum isotopes 143,144La
- Author
-
Y. X. Luo, A. V. Ramayya, J. O. Rasmussen, S. J. Zhu, J. D. Cole, J. H. Hamilton, C. T. Goodin, M. A. Stoyer, I. Y. Lee, I. Stefanescu, W. C. Ma, J. K. Hwang, D. Fong, Raul Donangelo, A. V. Daniel, K. Li, and G. M. Ter-Akopian
- Subjects
Physics ,Nuclear reaction ,Nuclear and High Energy Physics ,Internal conversion ,Branching fraction ,Yrast ,Neutron ,Gammasphere ,Atomic physics ,Radioactive decay ,Spontaneous fission - Abstract
The yrast and near-yrast level scheme of light neutron-rich 143La ( Z = 57 , N = 86 ) is reinvestigated and expanded and that of 144La ( N = 87 ) is proposed for the first time by measuring prompt γ rays from the spontaneous fission of 252Cf at Gammasphere. Spins/parities are assigned to the lowest-lying levels of 143,144La based on the early studies of β − decay, and the assignments for high-spin levels of 143,144La are made by measuring internal conversion coefficients and following the level systematics of the neighboring heavier La isotopes and even–even Ba and Ce nuclei. The B ( E 1 ) / B ( E 2 ) ratios, energy displacements δ E ( I ) and rotational frequency ratios ω − ( I ) / ω + ( I ) of the new parity-doublets of 143,144La indicate that octupole deformations/correlations also develop in these nuclei. The band-crossings observed in a rotational frequency range of 0.31 to 0.34 MeV for the two even-parity bands in 143La but being absent in 144La are interpreted as due to alignment of a pair of i 13 / 2 neutrons in 143La.
- Published
- 2009
89. Extended collective bands in neutron-rich 109 Ru
- Author
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J. H. Hamilton, Gu Long, A. V. Ramayya, Ding Huai-Bo, K. Li, C. T. Goodin, J. K. Hwang, J. O. Rasmussen, Wang Jian-Guo, Che Xing-Lai, I. Y. Lee, Y. X. Luo, S. H. Liu, and Zhu Sheng-Jiang
- Subjects
Physics ,Nuclear and High Energy Physics ,Astrophysics::High Energy Astrophysical Phenomena ,Nuclear Theory ,Astronomy and Astrophysics ,Parity (physics) ,Nuclear physics ,Neutron ,Atomic physics ,Nuclear Experiment ,Ground state ,Instrumentation ,Excitation ,Spontaneous fission - Abstract
Levels in the neutron-rich 109Ru have been studied by observing the prompt γ-rays following the spontaneous fission fragments of 252Cf. The ground state band and the negative parity bands have been confirmed and extended. A positive parity band with the band head level at 332.5 keV is newly identified and suggested as a single-neutron excitation band built on the 7/2+[404] Nilsson orbital. Some structural characteristics of these bands are discussed.
- Published
- 2009
90. Evolution of chirality from γ soft 108Ru to triaxial 110,112Ru
- Author
-
Y. X. Luo, A. V. Ramayya, Z. Jang, V. Dimitrov, D. Almehed, M. A. Stoyer, Jing-ye Zhang, J. D. Cole, N. J. Stone, J. O. Rasmussen, G. M. Ter-Akopian, X. L. Che, I. Stefanescu, A. V. Daniel, J. H. Hamilton, A. Gelberg, C. T. Goodin, J. K. Hwang, Raul Donangelo, S. J. Zhu, K. Li, and S. Frauendorf
- Subjects
Physics ,Nuclear and High Energy Physics ,Random field ,medicine.anatomical_structure ,medicine ,Parity (physics) ,Atomic physics ,Random phase approximation ,Chirality (chemistry) ,Nucleus ,Spontaneous fission - Abstract
Rotational bands in 108,110,112Ru have been investigated by means of γ – γ – γ and γ – γ ( θ ) coincidences of prompt γ rays emitted in the spontaneous fission of 252Cf. The positive parity bands are described by different versions of IBA, where 108Ru is best described as a γ-soft nucleus whereas 110,112Ru are more like rigid triaxial rotors. New Δ I = 1 negative parity doublet bands are found. In case of 110,112Ru, these are interpreted as soft chiral vibrations. Many of the experimental findings can be explained by microscopic calculations that combine the TAC mean-field with random phase approximation but a simple geometrical explanation is not apparent.
- Published
- 2009
91. Identification of the 109Xe and 105Te α-decay chain
- Author
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G. Drafta, Sean Liddick, J. Thomson, K. Li, J. C. Batchelder, D. T. Joss, Iain Darby, Robert Grzywacz, Carl J Gross, C. Mazzocchi, J. A. Winger, Mohammed N. Tantawy, A. Korgul, K. P. Rykaczewski, K. Lagergren, A. A. Hecht, J. H. Hamilton, J. K. Hwang, W. Krolas, C. R. Bingham, C. Goodin, R. D. Page, and S. V. Ilyushkin
- Subjects
Physics ,Ion beam ,Isotope ,Branching fraction ,General Physics and Astronomy ,Nuclear physics ,Isotopes of tin ,General Materials Science ,Decay chain ,Alpha decay ,Physical and Theoretical Chemistry ,Atomic physics ,Radioactive decay ,Dimensionless quantity - Abstract
The α-decay chain 109Xe → 105Te → 101Sn was identified at the Holifield Radioactive Ion Beam Facility. Advances in digital electronics have made possible the identification of both alpha emitters in the same experiment despite the disparate half-lives of 13 ±2 ms and 620 ±70 ns for 109Xe and 105Te, respectively. Two α-decay transitions were observed from 109Xe with Qα values of 4067 ±10 and 4217 ±8 keV. One transition between the ground states of 105Te and 101Sn was observed with a Qα value of 4889 ±6 keV. Using the measured half-lives, branching ratios, and Qα values the reduced α-decay widths, δ2, were determined. Comparison of the δ2 value for 105Te with 213Po indicates a “superallowed" character in the α emission of 105Te.
- Published
- 2007
92. Triaxiality, chiral bands and gamma vibrations in A=99–114 nuclei
- Author
-
J. K. Hwang, V. I. Dimitrov, A. Gelberg, X. L. Che, A. V. Ramayya, I. Y. Lee, J. O. Rasmussen, J. H. Hamilton, P. M. Gore, Jing-ye Zhang, Y. X. Luo, Z. Jiang, H. B. Ding, A. V. Daniel, S. J. Zhu, K. Li, S. Frauendorf, J. D. Cole, W. C. Ma, E. F. Jones, I. Stefancescu, and G. M. Ter-Akopian
- Subjects
Physics ,Nuclear and High Energy Physics ,Spins ,Gammasphere ,Moment of inertia ,Atomic physics ,Spin (physics) ,Axial symmetry ,Kinetic energy ,Symmetry (physics) ,Spontaneous fission - Abstract
Prompt γ – γ – γ coincidence measurements of A = 99 –114 neutron-rich nuclei populated in the spontaneous fission of 252 Cf were made with Gammasphere. The high statistics data, 5.7×10 11 triples and higher folds, opened up discoveries of new band structures and significant extensions of previously known bands. The new data for ground bands in 99,101 Y, 101,105 Nb, 105,107,109,111 Tc and 111,113 Rh when compared with one quasi-particle plus triaxial rotor calculation, revealed a smooth transition from axial symmetry in 99,101 Y to maximize triaxiality in 111,113 Rh. In 106 Mo, 110,112 Ru, pairs of Δ I = 1 doublet bands are established to high spins. Their constant and equal kinetic moments of inertia, small energy differences between states of the same spin and very similar B(E2)/B(M1) ratios for each band in these nuclei suggest that these are chiral doublet bands. If they are not chiral, then a new symmetry is indicted. Extended one- and new two-phonon γ -vibrational bands are observed in 110,112 Ru. The extended one-phonon bands in 104-108 Mo, and 108-112 Ru exhibit an unexpected reversal in the energy level staggering pattern with spin. The first one- and two-phonon γ -bands in an odd- A nucleus are seen in 105 Mo with level energies almost identical to these same bands known in 104 Mo.
- Published
- 2007
93. Study of fission process and neutron-rich nuclei
- Author
-
J. K. Hwang, J. O. Rasmussen, A. V. Ramayya, Y. X. Luo, G. M. Ter-Akopian, A. Gelberg, S. J. Zhu, J. H. Hamilton, and C. T. Goodin
- Subjects
Physics ,Nuclear and High Energy Physics ,Fission ,Nuclear Theory ,Particle ,Neutron ,Gammasphere ,Atomic physics ,Nuclear Experiment ,Axial symmetry ,Ternary operation ,Coincidence ,Spontaneous fission - Abstract
Prompt triple γ coincidence studies of the nuclei produced in the spontaneous fission of 252Cf were carried out at Gammasphere. The relative yield matrix for the Ba-Mo and Ba-α-Zr charge splits was determined using an improved analysis. An upper limit for the second mode of 0.5 % is found for the binary case, while the ternary case shows evidence of a strong second mode. Half-lives of several states in neutron-rich nuclei were measured by using a new time-gated γ − γ − γ coincidence technique. A large deformation of β = 0.47 was observed in 104Zr using this method. New band structures were found in several odd-A Y, Nb, Tc, and Rh nuclei. These nuclei show a smooth evolution from axial symmetry in Y to maximum triaxiality in Rh. Particle plus triaxial rotor calculations have been made for these odd-A nuclei. The gamma band staggering in 108,110,112Ru will be discussed.
- Published
- 2007
94. Identification of new transitions and mass assignments of levels inPr143–153
- Author
-
E. H. Wang, A. Lemasson, J. H. Hamilton, A. V. Ramayya, J. K. Hwang, J. M. Eldridge, A. Navin, M. Rejmund, S. Bhattacharyya, S. H. Liu, N. T. Brewer, Y. X. Luo, J. O. Rasmussen, H. L. Liu, H. Zhou, Y. X. Liu, H. J. Li, Y. Sun, F. R. Xu, S. J. Zhu, G. M. Ter-Akopian, Yu. Ts. Oganessian, M. Caamaño, E. Clément, O. Delaune, F. Farget, G. de France, and B. Jacquot
- Subjects
Physics ,Nuclear and High Energy Physics ,Isotope ,Fission ,Coulomb barrier ,Gammasphere ,Atomic physics ,Coincidence ,Spectral line ,Spontaneous fission - Abstract
The previously reported levels assigned to 151,152,153Pr have recently been called into question regarding their mass assignment. The above questioned level assignments are clarified by measuring g-transitions tagged with A and Z in an in-beam experiment in addition to the measurements from 252Cf spontaneous fission (SF) and establish new spectroscopic information from $N=84$ to $N=94$ in the Pr isotopic chain. The isotopic chain 143-153Pr has been studied from the spontaneous fission of 252Cf by using Gammasphere and also from the measurement of the prompt g-rays in coincidence with isotopically-identified fission fragments using VAMOS++ and EXOGAM at GANIL. The latter were produced using 238U beams on a 9Be target at energies around the Coulomb barrier. The g-g-g-g data from 252Cf (SF) and those from the GANIL in-beam A- and Z-gated spectra were combined to unambiguously assign the various transitions and levels in 151,152,153Pr and other isotopes. New transitions and bands in 145,147,148,149,150Pr were identified by using g-g-g and g-g-g-g coincidences and A and Z gated g-g spectra. The transitions and levels previously assigned to 151,153Pr have been confirmed by the (A,Z) gated spectra. The transitions previously assigned to 152Pr are now assigned to 151Pr on the basis of the (A,Z) gated spectra. Two new bands with 20 new transitions in 152Pr and one new band with 7 new transitions in 153Pr are identified from the g-g-g-g coincidence spectra and the (A,Z) gated spectrum. In addition, new g-rays are also reported in 143-146Pr. New levels of 145,147-153Pr have been established, reliable mass assignments of the levels in 151,152,153Pr have been reported and new transitions have been identified in 143-146Pr showing the new avenues that are opened by combining the two experimental approaches.
- Published
- 2015
95. Experiments on the synthesis of superheavy nucleiFl284andFl285in thePu239,240+Ca48reactions
- Author
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Robert Grzywacz, James B. Roberto, A. A. Voinov, Grigory K. Vostokin, V. G. Subbotin, N. T. Brewer, M. V. Shumeiko, A. V. Sabelnikov, R. N. Sagaidak, Yu. S. Tsyganov, Yuri Oganessian, V. K. Utyonkov, A. M. Sukhov, I. V. Shirokovsky, F. Sh. Abdullin, S. Y. Strauss, K. Miernik, A. N. Polyakov, K. P. Rykaczewski, J. H. Hamilton, S. N. Dmitriev, M. A. Stoyer, and M. G. Itkis
- Subjects
Physics ,Nuclear and High Energy Physics ,Order (ring theory) ,chemistry.chemical_element ,Flerovium ,chemistry ,Neutron number ,Production (computer science) ,Decay chain ,Alpha decay ,Atomic physics ,Nuclear Experiment ,Energy (signal processing) ,Spontaneous fission - Abstract
Irradiations of $^{239}\mathrm{Pu}$ and $^{240}\mathrm{Pu}$ targets with $^{48}\mathrm{Ca}$ beams aimed at the synthesis of $Z=114$ flerovium isotopes were performed at the Dubna Gas Filled Recoil Separator. A new spontaneously fissioning (SF) isotope $^{284}\mathrm{Fl}$ was produced for the first time in the $^{240}\mathrm{Pu}+^{48}\mathrm{Ca}$ (250 MeV) and $^{239}\mathrm{Pu}+^{48}\mathrm{Ca}$ (245 MeV) reactions. The cross section of the $^{239}\mathrm{Pu}(^{48}\mathrm{Ca},3n)^{284}\mathrm{Fl}$ reaction channel was about 20 times lower than predicted by theoretical models and about 50 times lower than the maximum fusion-evaporation cross section for the $3n$ and $4n$ channels measured in the $^{244}\mathrm{Pu}+^{48}\mathrm{Ca}$ reaction. In the $^{240}\mathrm{Pu}+^{48}\mathrm{Ca}$ experiment, performed at 245 MeV in order to maximize the $3n$-evaporation channel, three decay chains of $^{285}\mathrm{Fl}$ were detected. The $\ensuremath{\alpha}$-decay energy of $^{285}\mathrm{Fl}$ was measured for the first time and decay properties of its descendants $^{281}\mathrm{Cn}, ^{277}\mathrm{Ds}, ^{273}\mathrm{Hs}, ^{269}\mathrm{Sg}$, and $^{265}\mathrm{Rf}$ were determined with higher accuracy. The assignment of SF events observed during the irradiation of the $^{240}\mathrm{Pu}$ target with a 250 MeV $^{48}\mathrm{Ca}$ beam to $^{284}\mathrm{Fl}$ decay is presented and discussed. The cross sections at both $^{48}\mathrm{Ca}$ energies are similar and exceed that observed in the reaction with the lighter isotope $^{239}\mathrm{Pu}$ by a factor of 10. The decay properties of the synthesized nuclei and their production cross sections indicate a rapid decrease of stability of superheavy nuclei as the neutron number decreases from the predicted magic neutron number $N=184$.
- Published
- 2015
96. Stretched Weak Coupling States of an Octupole Phonon in Spherical Semi-Magic Nuclei
- Author
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J. H. Hamilton, A. V. Ramayya, and J. K. Hwang
- Subjects
Physics ,Condensed matter physics ,Phonon ,Magic (programming) - Published
- 2015
97. Triaxial Deformations and the Proton Intruder Orbital π1/2+[431] in Very Neutron-Rich Odd–Odd Nb Isotopes
- Author
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Furong Xu, Yu. Oganessian, J. O. Rasmussen, E. H. Wang, Sutao Zhu, A. V. Ramayya, Y. X. Luo, J. K. Hwang, Raul Donangelo, S. Frauendorf, S. H. Liu, G. M. Ter-Akopian, W. C. Ma, J. H. Hamilton, N. T. Brewer, Yu Sun, W. Y. Liang, Y. X. Liu, I. Y. Lee, Chang-Feng Jiao, and Jianchun Wang
- Subjects
Physics ,Proton ,Isotope ,Neutron ,Atomic physics - Published
- 2015
98. Connecting the 'Hot Fusion Island' to the Nuclear Mainland: Search for 283,284,285Fl Decay Chains
- Author
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Yu. Ts. Oganessian, A. A. Voinov, N. T. Brewer, F. Sh. Abdullin, Yu. S. Tsyganov, M. V. Shumeiko, K. P. Rykaczewski, Grigory K. Vostokin, A. V. Sabelnikov, James B. Roberto, V. K. Utyonkov, R. N. Sagaidak, V. G. Subbotin, I. V. Shirokovsky, A. M. Sukhov, J. H. Hamilton, Robert Grzywacz, Roger Henderson, K. Miernik, A. N. Polyakov, M. A. Stoyer, M. G. Itkis, and S. N. Dmitriev
- Subjects
Nuclear physics ,Physics ,Fusion ,Oceanography ,Mainland ,Decay chain - Published
- 2015
99. RECENT EXPERIMENT ON SYNTHESIZING FLEROVIUM ISOTOPES IN THE REACTION 239Pu + 48Ca
- Author
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Roger Henderson, K. P. Rykaczewski, S. N. Dmitriev, Grigory K. Vostokin, Yu. Ts. Oganessian, K. Miernik, A. N. Polyakov, James B. Roberto, J. H. Hamilton, R. N. Sagaidak, A. M. Sukhov, Robert Grzywacz, M. G. Itkis, V. K. Utyonkov, M. A. Stoyer, Yu. S. Tsyganov, A. A. Voinov, N. T. Brewer, A. V. Sabelnikov, F. Sh. Abdullin, M. V. Shumeiko, I. V. Shirokovsky, and V. G. Subbotin
- Subjects
Physics ,Flerovium ,chemistry ,Isotope ,Radiochemistry ,chemistry.chemical_element - Published
- 2015
100. Search for Double γ-Vibrational Bands in Neutron-Rich 105 Mo Nucleus
- Author
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J. K. Hwang, LI Ming-Liang, Zhu Sheng-Jiang, Y. X. Luo, A. V. Ramayya, Che Xing-Lai, J. H. Hamilton, Ding Huai-Bo, I. Y. Lee, J. O. Rasmussen, and Chen Yong-Jing
- Subjects
Physics ,medicine.anatomical_structure ,Yrast ,medicine ,Vibrational bands ,General Physics and Astronomy ,Head (vessel) ,Neutron ,Gammasphere ,Detector array ,Atomic physics ,Nucleus ,Spontaneous fission - Abstract
Levels in the neutron-rich 105Mo nucleus have been investigated by observing prompt γ-rays following the spontaneous fission fragments of 252Cf with the Gammasphere detector array. The yrast band has been confirmed and updated. The other two collective bands with the band head levels at 870.5 and 1534.6 keV are newly observed, and they are suggested as the candidates for one-phonon K = 9/2 and two-phonon K = 13/2 double γ-vibrational bands, respectively. Systematic characteristics of these bands have been discussed.
- Published
- 2006
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