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11. |
Recent studies of proton drip-line nuclei using the Berkeley Gas-filled Separator |
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AIP Conference Proceedings,
Volume 518,
Issue 1,
1900,
Page 95-104
M. W. Rowe,
J. C. Batchelder,
V. Ninov,
K. E. Gregorich,
K. S. Toth,
C. R. Bingham,
A. Piechaczek,
X. J. Xu,
J. Powell,
R. Joosten,
Joseph Cerny,
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摘要:
The Berkeley Gas-filled Separator provides new research opportunities at Lawrence Berkeley National Laboratory’s 88-Inch Cyclotron. The use of this apparatus for the study of proton drip-line nuclides is discussed. Preliminary results of78Krbombardments of102Pdtargets at mid-target energies of 360, 375 and 385 MeV are presented. Improvements planned partially as a result of this measurement are also discussed. ©2000 American Institute of Physics.
ISSN:0094-243X
DOI:10.1063/1.1306003
出版商:AIP
年代:1900
数据来源: AIP
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12. |
Two-proton decay experiments at MSU |
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AIP Conference Proceedings,
Volume 518,
Issue 1,
1900,
Page 105-111
M. Thoennessen,
M. J. Chromik,
P. G. Thirolf,
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摘要:
First evidence for direct two-proton radioactivity has been observed in the decay of the first excited state of17Ne.The decay is in competition with the &ggr;-decay back to the ground state of17Neand from the branching ratio the lifetime for the two-proton decay is estimated to be 0.9 ps. The proton-proton angular distribution is statistically not significant to observe any correlations. The first excited state was populated with relativistic Coulomb excitation of the exotic beam of17Ne.This method can also be used to study the inverse reaction (2p, &ggr;). Although the present reaction15O(2p,&ggr;)17Neis not important for astrophysical purposes two-proton capture reactions on heavier proton rich nuclei can have a large impact on the path of the rp-process. ©2000 American Institute of Physics.
ISSN:0094-243X
DOI:10.1063/1.1306004
出版商:AIP
年代:1900
数据来源: AIP
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13. |
In-beam studies of proton emitters using the Recoil-Decay Tagging method |
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AIP Conference Proceedings,
Volume 518,
Issue 1,
1900,
Page 112-124
D. Seweryniak,
P. J. Woods,
J. J. Ressler,
C. N. Davids,
A. Heinz,
A. A. Sonzogni,
J. Uusitalo,
W. B. Walters,
J. A. Caggiano,
M. P. Carpenter,
J. A. Cizewski,
T. Davinson,
K. Y. Ding,
N. Fotiades,
U. Garg,
R. V. F. Janssens,
T.-L. Khoo,
F. G. Kondev,
T. Lauritsen,
C. J. Lister,
P. Reiter,
J. Shergur,
I. Wiedenhoever,
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摘要:
The last five years have witnessed a rapid increase in the volume of data on proton decaying nuclei. The path was led by decay studies with recoil mass separators equipped with double-sided Si strip detectors. The properties of many proton decaying states were deduced, which triggered renewed theoretical interest in the process of proton decay. The decay experiments were closely followed by in-beam &ggr;-ray studies which extended our knowledge of high-spin states of proton emitters. The unparalleled selectivity of the Recoil-Decay Tagging method combined with the high efficiency of large arrays of Ge detectors allowed, despite small cross sections and overwhelming background from strong reaction channels, the observation of excited states in several proton emitters. Recently, in-beam studies of the deformed proton emitters141Hoand131Euhave been performed with the GAMMASPHERE array of Ge detectors and the Fragment Mass Analyzer at ATLAS. Evidence was found for rotational bands in141Hoand131Eu.The deformations and the single-particle configurations proposed for the proton emitting states from the earlier proton-decay studies were confronted with the assignments deduced based on the in-beam data. It should be noted that the cross section for populating131Euis only about 50 nb, and it represents the weakest channel ever studied in an in-beam experiment. ©2000 American Institute of Physics.
ISSN:0094-243X
DOI:10.1063/1.1306005
出版商:AIP
年代:1900
数据来源: AIP
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14. |
Spherical proton emitters and spectroscopic factors |
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AIP Conference Proceedings,
Volume 518,
Issue 1,
1900,
Page 125-131
Paul B. Semmes,
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摘要:
The most commonly used implementation of the WKB method for calculating spherical decay rates is shown to be unsatisfactory, and some improvements are suggested. Also, the smaller than expected experimental spectroscopic factor for the1d3/2state in151Lucan be explained in a particle-core coupling calculation. ©2000 American Institute of Physics.
ISSN:0094-243X
DOI:10.1063/1.1306964
出版商:AIP
年代:1900
数据来源: AIP
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15. |
Ground-state properties of deformed and transitional proton emitters in the relativistic Hartree-Bogoliubov model |
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AIP Conference Proceedings,
Volume 518,
Issue 1,
1900,
Page 132-143
G. A. Lalazissis,
D. Vretenar,
P. Ring,
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摘要:
The Relativistic Hartree Bogoliubov (RHB) model is applied in the description of ground-state properties of proton-rich odd-Z nuclei in the region53⩽Z⩽73.For nuclei close to the drip-lines the RHB framework provides a unified and self-consistent description of mean-field and pairing correlations. The location of the proton drip-line, the ground-state quadrupole deformations and one-proton separation energies at and beyond the drip-line, the deformed single-particle orbitals occupied by the odd valence proton, and the corresponding spectroscopic factors are compared with available experimental data, and with predictions of the macroscopic-microscopic mass model. ©2000 American Institute of Physics.
ISSN:0094-243X
DOI:10.1063/1.1306006
出版商:AIP
年代:1900
数据来源: AIP
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16. |
Two-proton emission in the hyperharmonics approach |
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AIP Conference Proceedings,
Volume 518,
Issue 1,
1900,
Page 144-153
Ivan G. Mukha,
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摘要:
Nuclear decays into three-particle channels are considered in a few-body approach of hyperspherical harmonics with emphasis on simultaneous, or direct, emission of two protons. General conditions of direct decays are described and their main features, being experimentally established in decays of light nuclei, are reported. The analysis method based on an expansion of decay amplitude into a series of hyperspherical harmonics is reviewed. This basis is a generalisation of the spherical function basis in three-body systems. The method is tested on analysis of the direct decay6Be→&agr;+p+pwhere the three-body components in the nuclear structure of6Behave been studied. In particular, the observed strong proton-proton correlations are treated as a manifestation of a specific three-body quantum effect: the kinematic focusing of fragments over momenta and in space. The method is applied for the predictions of proton-proton correlations and life-time estimates of the nuclei19Mg,34Caand48Ni-candidates for two-proton radioactivity. Each direct 2p-decay should result in a set of peaks in theEp−pspectrum whose number and positions depend on the structure of initial nucleus, opposite to the diproton model, predicting the2Heemission with one peak atEp−p≈0in all cases. ©2000 American Institute of Physics.
ISSN:0094-243X
DOI:10.1063/1.1306007
出版商:AIP
年代:1900
数据来源: AIP
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17. |
Exact calculations for deformed proton emitters |
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AIP Conference Proceedings,
Volume 518,
Issue 1,
1900,
Page 154-163
E. Maglione,
L. S. Ferreira,
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摘要:
Proton decay from deformed nuclei is analyzed and the half-livesT1/2are evaluated exactly, assuming that the emitted proton moves in a deformed single particle Nilsson level. The angular momenta and deformations that reproduce the experimental half-lives are determined. All experimental values currently known for decay from the ground state, recently found isomeric states and fine structure, have a perfect and consistent description within our model, with deformations that are soundly established in this mass region. ©2000 American Institute of Physics.
ISSN:0094-243X
DOI:10.1063/1.1306008
出版商:AIP
年代:1900
数据来源: AIP
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18. |
Theoretical predictions for beta-delayed one- and two-proton emission |
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AIP Conference Proceedings,
Volume 518,
Issue 1,
1900,
Page 164-172
T. Siiskonen,
P. O. Lipas,
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摘要:
Theoretical estimates for isospin-forbidden beta-delayed proton and two-proton emission are calculated in a shell-model framework. The parent nuclei studied are23Aland31Ar.The results are compared to new experimental data. The reliability of the shell-model estimates is discussed. ©2000 American Institute of Physics.
ISSN:0094-243X
DOI:10.1063/1.1306009
出版商:AIP
年代:1900
数据来源: AIP
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19. |
Resonances in deformed nuclei: R-matrix theory and oscillator expansion |
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AIP Conference Proceedings,
Volume 518,
Issue 1,
1900,
Page 173-183
A. T. Kruppa,
W. Nazarewicz,
P. B. Semmes,
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摘要:
Single-particle resonances in deformed nuclei are considered using the coupled-channel Schro¨dinger equation method with the outgoing boundary conditions. Two variants of this method are investigated: the non-adiabatic one (based on the weak-coupling scheme) and the adiabatic one (based on the strong coupling). The R-matrix theory and the Gamow state approach are discussed and compared with each other. It is shown that the widths of very narrow proton resonances can be calculated by combining the harmonic oscillator expansion method with the R-matrix approach. ©2000 American Institute of Physics.
ISSN:0094-243X
DOI:10.1063/1.1306010
出版商:AIP
年代:1900
数据来源: AIP
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20. |
Proton emission from Gamow resonance |
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AIP Conference Proceedings,
Volume 518,
Issue 1,
1900,
Page 184-193
T. Vertse,
A. T. Kruppa,
B. Barmore,
W. Nazarewicz,
L. Gr. Ixaru,
M. Rizea,
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摘要:
We developed two computer codes: CCGAMOW and NONADI for calculating the complex energy eigenvalues and eigenfunctions of deformed Gamow resonances with high accuracy by using the piecewise perturbation method. The code CCGAMOW calculates resonant Nilsson orbitals using the adiabatic approximation in which the energies of the ground and excited rotational states of the daughter nucleus are degenerate. In the code NONADI this approximation and the rotational degree of freedom of the core and the Coriolis coupling in the parent nucleus are taken into account. The difference between adiabatic and non-adiabatic approaches is found to be non-negligible for the proton emission from the ground state of141Ho.©2000 American Institute of Physics.
ISSN:0094-243X
DOI:10.1063/1.1306011
出版商:AIP
年代:1900
数据来源: AIP
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