A new assignment for the 9/2+[624] state in 181Hf from the 179Hf(t, p)181Hf reaction

1984 ◽  
Vol 62 (2) ◽  
pp. 192-197 ◽  
Author(s):  
D. G. Burke ◽  
J. C. Waddington ◽  
G. Løvhøiden ◽  
T. F. Thorsteinsen
Keyword(s):  
Ground State ◽  
Half Life ◽  
Low Energy ◽  
Angular Distributions ◽  
Level Spacing ◽  
Reaction Products ◽  
Negative Results ◽  
Energy Formula ◽  
Gamma Transitions ◽  
Irregular Spacing

Angular distributions of protons from the 179Hf(t, p)181Hf reaction were studied using 15-MeV tritons from the McMaster University tandem Van de Graaff accelerator. The reaction products were analyzed with a magnetic spectrograph and detected with nuclear emulsions. Since the 179Hf target ground state is the 9/2+[624] orbital, a strong L = 0 transition was expected to the 9/2+[624] bandhead in 181Hf, which was previously assigned at 68 keV. However, the only L = 0 transition observed was to a level at an excitation energy of 600 ± 5 keV, requiring that this new level be assigned as the 9/2+[624] state. An attempt to observe gamma transitions deexciting this level in a (t, pγ) coincidence experiment yielded negative results. This implies that the 600 ± 5 keV level either has a half-life of [Formula: see text] or decays to an isomeric level by means of a low energy [Formula: see text] unobserved transition. The irregular spacing of possible 9/2+[624] band members suggests that the 11/2+[615] orbital is located near the 9/2+[624] state and perturbs the level spacing by Coriolis mixing.

Study of Delayed States in 94Nb, 108Ag, and 110Ag

1971 ◽  
Vol 49 (6) ◽  
pp. 747-755 ◽  
Author(s):  
S. C. Gujrathi ◽  
J. M. d'Auria ◽  
R. G. Korteling
Keyword(s):  
High Resolution ◽  
Level Scheme ◽  
Half Life ◽  
Gamma Transition ◽  
Low Energy ◽  
X Ray ◽  
Upper Limits ◽  
Energy Gamma ◽  
Gamma Transitions ◽  
First Time

The lifetimes and energies associated with low-energy gamma transitions from the 93Nb(n,γ)94Nb, 107Ag(n,γ)108Ag, and 109Ag(n,γ)110Ag reactions have been studied using a high-resolution Ge(Li) X-ray spectrometer. New weak transitions are observed in the decay of 110Ag at 30.84, 38.19, 41.78, and 136.65 keV, while intense gamma transitions at 105.6, 235.8, and 266.95 keV are resolved into doublets. The half-life of the state involving the intense 117.47 keV transition in 110Ag and the 215 keV transition in 108Ag is confirmed as 36.5 ± 2.0 ns and 54 ± 8 ns, respectively, while a new delayed state associated with the gamma transition of 99.404 keV (T1/2 = 30 ± 5 ns) in 94Nb is observed for the first time. The upper limits for the half-lives involving most of the intense transitions in all the three isotopes are also reported. A level scheme is proposed and discussed for 108Ag.

A study of levels in 147Nd using the (d,t) reaction

1977 ◽  
Vol 55 (19) ◽  
pp. 1687-1696 ◽  
Author(s):  
O. Straume ◽  
D. G. Burke
Keyword(s):  
Ground State ◽  
State Transition ◽  
Energy Levels ◽  
Striking Similarity ◽  
Angular Distributions ◽  
Reaction Products ◽  
Proton Group ◽  
Energy Proton ◽  
Photographic Emulsions ◽  
Peak Widths

The 148Nd(d,t)147Nd reaction has been studied using 12 MeV deuterons. The reaction products were analyzed with an Enge-type magnetic spectrograph and detected with photographic emulsions, giving peak widths (FWHM) of approximately 8 keV. The present results confirm previous indications that the highest energy proton group found in an early 146Nd(d,p) investigation does not correspond to the ground state transition, but to the level at an excitation energy of 50 keV. The (d,t) angular distributions were used to determine l-values for a number of transitions. A striking similarity is noted with the energy levels and spectroscopic strengths previously found in the isotones 149Sm and 151Gd. With the exception of the h11/2 state, it is possible to explain the observed strengths in terms of the spherical shell model, although there is fragmentation of the spherical states.

The nuclear structure of 166Er

1979 ◽  
Vol 57 (11) ◽  
pp. 1999-2025 ◽  
Author(s):  
J. D. Panar ◽  
D. G. Burke
Keyword(s):  
Proton Transfer ◽  
Excitation Energy ◽  
Ground State ◽  
Transfer Reactions ◽  
Angular Distributions ◽  
Neutron Transfer ◽  
Reaction Products ◽  
Proton Transfer Reactions ◽  
Photographic Emulsions ◽  
Transfer Study

Two-quasiparticle states in 166Er have been studied using the 167Er(d,t)166Er, 167Er(3He.α)166Er, 165Ho(3He,d)166Er, and 165Ho(α,t)166Er reactions. Beams of 15 MeV deuterons, 24 MeV 3He2+, and 27 MeV 4He2+ particles were produced by the McMaster University tandem Van de Graaff accelerator. The reaction products were analyzed with an Enge split-pole magnetic spectrograph and detected with photographic emulsions. Angular distributions were obtained for the (d,t) and (3He,d) reactions for levels up to ~2700 keV in excitation energy, although selected peaks were investigated at somewhat higher energies. The interpretation of the data was performed within the framework of the Unified model, incorporating pairing effects. In the neutron transfer study, two-quasiparticle states formed by removing a particle from the predominantly 7/2+[633] 167Er ground state were investigated, whereas the proton transfer study dealt with two-quasiparticle states formed by adding a particle to the 7/2−[523] ground state of 165Ho. Several previous assignments have been supported and many new ones are proposed. Several other assignments proposed in an earlier proton transfer study have been found to be incorrect. Earlier observations that some levels were populated in both the neutron transfer and proton transfer reactions have been confirmed and extended. In addition, the observation in the (d,t) reaction of several states populated by l = 0 neutron transfers has been interpreted in terms of a complex mixing scheme involving the 7/2+[633] ± 1/2+[400] configurations.

A Study of Levels in 149Nd using the (d, t) and (3He, α) Reactions

1973 ◽  
Vol 51 (4) ◽  
pp. 455-464 ◽  
Author(s):  
D. G. Burke ◽  
J. C. Waddington ◽  
D. E. Nelson ◽  
J. Buckley
Keyword(s):  
Cross Sections ◽  
Ground State ◽  
State Transition ◽  
Angular Distributions ◽  
Ground State Transition ◽  
Reaction Products ◽  
Q Value ◽  
Nilsson Model ◽  
Photographic Emulsions ◽  
Peak Widths

Triton spectra from the 150Nd(d, t)149Nd reaction have been measured at 15 angles using beams of 12 MeV deuterons. The 150Nd(3He, α)149Nd reaction was studied at four angles with 24 MeV 3He beams. In all cases the reaction products were analyzed with an Enge-type magnetic spectrograph and detected with photographic emulsions. The peak widths (FWHM) were approximately 8 keV for the (d, t) studies and 25 keV for the (3He, α) spectra. It is now evident that the highest energy triton group ascribed to the 150Nd(d, t)149Nd reaction in previous works does not correspond to the ground state transition. According to the current interpretation the ground state transition has a Q value of −1.122 ± 0.010 MeV. The (d, t) angular distributions and the ratios of (3He, α) and (d, t) cross sections at selected angles were used to determine l values for a number of the transitions. Three states in 149Nd at 481, 813, and 986 keV are definitely populated by l = 0 transitions and thus have Iπ = 1/2+. A strongly perturbed band consisting of a mixture of Nilsson states from the i13/2 shell has been found, with properties similar to the corresponding bands in the isotones 151Sm and 153Gd. The total observed intensity for each of the l values 0, 1, 2, and 6 cannot be explained by the extreme single-particle shell model but is consistent with that predicted by the Nilsson model. However, the splitting of the strength among the observed states cannot be explained by the basic Nilsson model.

scholarly journals STRONGLY ENHANCED LOW ENERGY α-PARTICLE DECAY IN HEAVY ACTINIDE NUCLEI AND LONG-LIVED SUPERDEFORMED AND HYPERDEFORMED ISOMERIC STATES

2001 ◽  
Vol 10 (03) ◽  
pp. 209-236 ◽  
Author(s):  
A. MARINOV ◽  
S. GELBERG ◽  
D. KOLB ◽  
J. L. WEIL
Keyword(s):  
Cross Sections ◽  
Ground State ◽  
Production Cross ◽  
Heavy Ion ◽  
Evaporation Residue ◽  
Low Energy ◽  
Reaction Products ◽  
Low Energies ◽  
Secondary Reactions ◽  
Isomeric States

Unidentified low energy and very enhanced α-particle groups have been observed in various actinide fractions produced via secondary reactions in a CERN W target which had been irradiated with 24-GeV protons. In particular, 5.14, 5.27 and 5.53 MeV α-particle groups with corresponding half-lives of 3.8±1.0 y, 625±84 d and 26±7d, have been seen in Bk, Es and Lr-No sources, respectively. The measured energies are a few MeV lower than the known ground state to ground state α-decays in the corresponding neutron-deficient actinide nuclei. The half-lives are 104 to 107 shorter than expected from energy versus lifetime relationship for such low-energy α-particles in this region of nuclei. The deduced evaporation residue cross sections are in the mb region, about 104 times higher than expected. Not only is it impossible to identify these α-decays with any known activity in the whole nuclear chart, but they also could not be due to hypothetically unknown isomeric states in various conceivable neutron deficient nuclei, nor due to unknown isomeric states in the rare-earth region. Based on the fact that in other experiments we have found isomeric states in the second and third minima of the potential for other heavy ion reaction products, one can now understand in a quantitative way, both the unusual low energies, the unusual enhanced lifetimes and the unusual large production cross sections, in terms of production of similar isomeric states in appropriate actinide isotopes. Some consequences regarding the production of the long-lived superheavy elements are also discussed.

The Reaction and Microscopic Electron Properties from Dynamic Evolutions of Condensed-Phase RDX Under Shock Loading

2020 ◽  
Vol 75 (4) ◽  
pp. 285-291
Author(s):  
Jiao-Nan Yuan ◽  
Hai-Chao Ren ◽  
Yong-Kai Wei ◽  
Wei-Sen Xu ◽  
Guang-Fu Ji ◽  
...  
Keyword(s):  
Shock Wave ◽  
Ground State ◽  
Shock Loading ◽  
Reaction Rates ◽  
Reaction Products ◽  
Decomposition Rates ◽  
Multi Scale ◽  
Wave Velocities ◽  
Wide Gap ◽  
Reaction Initiation

AbstractMicroscopic electron properties of α-hexahydro-1,3,5-trinitro-1,3,5-triazine (α-RDX) with different shock wave velocities have been investigated based on molecular dynamics together with multi-scale shock technique. The studied shock wave velocities are 8, 9 and 10 km ⋅ s−1. It has been said that the shock sensitivity and reaction initiation of explosives are closely relevant with their microscopic electron properties. The reactions, including the reaction products, which are counted from the trajectory during the simulations are analysed first. The results showed that the number of the products strictly rely on shock wave velocities. The reaction rates and decomposition rates are also studied, which showed the differences between the different shock velocities. The results of electron properties show that α-RDX is a wide-gap insulator in the ground state and the metallisation conditions of shocked RDX are determined, which are lower than under-static high pressure.

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