摘要:

An effective relativistic field theory is used to investigate nuclei along the proton drip line together with proton emission in heavy deformed nuclei. Nucleons are described as Dirac particles moving in self‐consistent relativistic scalar and time‐like vector fields. Pairing correlations are treated within the relativistic Hartree‐Bogoliubov (RHB) approximation using a finite range Gogny interaction. This method provides a fully microscopic and universal description of nuclei in the vicinity and far from the valley of stability. It allows the determination of the proton drip line and the investigation of proton emitters, in particular the calculation of the proton separation energies, the quantum numbers of the corresponding proton levels and their spectroscopic factors. We find good agreement for experimentally known proton emitters in medium heavy nuclei and we predict new possible proton emitters below Z=50. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1615161

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

A new model for the effective two‐body nucleon‐nucleon interaction has been recently successful in calculation of ground state properties of spherical, doubly closed shell nuclei from16O to208Pb [1] and nuclear matter and neutron star properties [2]. The application of the density dependent finite range separable monopole (SMO) interaction has been now extended to axially symmetrical deformed nuclei [3]. In the present paper we report on HF+BCS calculation of ground‐state properties of even‐even spherical and deformedN = Zand proton‐rich nuclei between theN = Zand the proton‐drip line for 28⩽Z⩽50. The SMO results shown include total energy surfaces and deduced shapes, single‐particle energies, two‐dimensional distribution of nucleon densities, charge radii and two‐proton separation energies. A comparison is made with results obtained using the SkO Skyrme interaction and some other theoretical models as well as with experimental data, where available. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1615162

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

In an experiment performed at the GSI Fragment Separator the decay of45Fe has been investigated. Five45Fe atoms were implanted in a silicon telescope mounted inside a high‐efficiency NaI detector. The implantation events were correlated with radioactive decay signals. One of them was consistent with the &bgr; decay of45Fe accompanied by the emission of a 10 MeV proton. In each of the four other decay events, a signal corresponding to the emission of 1.1 ± 0.1 MeV particle(s) was recorded with no coincident signals in the NaI detector. This observation represents the first evidence for the two‐proton ground state decay of45Fe. The time distribution of the observed decay events corresponds to a half‐life of3.2−1.0+2.6 ms. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1615163

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

According to most mass models, several of the best candidates for two‐proton radioactivity lie in theA= 50 mass region, at the proton drip‐line. Recent experiments using the fragmentation of a58Nibeam allowed us to reach this region and observe some of these candidates, like45Feand48Ni. During an experiment at the GANIL / LISE3 facility helded in 2000, we could identify 22 events of implantation of45Fenuclei. The energy distribution of the corresponding decay events shows a clear peak at (1.14 ± 0.04)MeVthat could be assigned to the direct 2‐proton emission from the ground state. This energy is in very good agreement with several theoretical predictions, and no coincident &bgr; particle has been observed experimentally. A half‐life of(4.7−1.4+3.4) mshas been measured for the decay of45Fe. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1615164

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

R‐matrix formulas are used to calculate di‐proton decay widths of18Ne,45Fe and48Ni. This formulation allows one to relate the decay amplitude to the correlated many‐body wave functions for these nuclei. The role of pairing correlations is discussed. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1615165

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Theoretical studies of several prospective 2pemitters are performed in a three‐body core+p+pmodel. Lifetime dependencies on the decay energy are calculated for19Mg,30Ar,34Ca,45Fe,48Ni,54Zn,62Se and compared to the quasiclassical estimates. An observation of products from the in‐flight decay of 2pemitting nuclei is discussed as an important technique supplementing a standard implantation method for a broad range of lifetimes of prospective 2pemitters. The sensitivity of the model to various aspects of nuclear dynamics is demonstrated on the45Fe example. Momentum correlations for emitted protons are discussed with the emphasis on19Mg and45Fe. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1615166

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

We measured for the first time the &agr; decay of114Ba. The &agr; decay of the daughter and granddaughter nuclei110Xe and106Te was also observed and the hitherto unknown half‐life of110Xe was determined. The resulting &agr;‐decay Q‐values and reduced widths as well as the Q‐value for12C cluster decay of114Ba are discussed in comparison with theoretical predictions. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1615167

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

With the use of the Berkeley Gas‐filled Separator, the &agr; decay of178Pb was identified in78Kr irradiations of102Pd. Following their separation from the incident beam particles, reaction products were implanted in a position‐sensitive silicon detector. Two events with E&agr;of 7602 and 7629 keV were observed and assigned to178Pb because they were position‐correlated with known descendants in the174Hg &agr;‐decay chain. The half‐life of178Pb was calculated with the maximum likelihood method to be122−50+290 &mgr;s. A mass excess of 3608(39) keV and a proton separation energy of 362(48) keV were deduced for178Pb based on the known masses of174Hg and177Tl. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1615168

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

A microscopic description of the alpha decay of the odd mass nuclei will be presented for axially deformed nuclei. Realistic mean field + pairing residual interaction in a very large single particle basis has been used. Systematics for At and Rn isotopes, as well as for221Fr,241Am and Pa ‐ isotopes. It is found that the approach gives predictions in good agreement with experimental data for well deformed nuclei. New recent calculations for241–243Am,253–255Es and255–257Fm isotopes will be discussed. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1615169

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

The anomalous proton‐decay rates in131Eu and141Ho have been explained by the presence of large quadrupole deformation. Consistent with this hypothesis was the discovery of the decay branch in131Eu to the 2+state in the daughter nucleus. Direct evidence that141Ho and131Eu are deformed came from the observation of rotational bands. From the dynamic moment of inertia the deformation of &bgr;2=0.25(4) was deduced for the141Ho ground state. The large signature splitting in the ground‐state band in141Ho indicates that Coriolis mixing plays an important role in this nucleus. The comparison between the Particle‐Rotor Model and the data indicates that141Ho has significant hexadecapole deformation and/or might be triaxial. The comparison between theory and experiment constrains other parameters used in the proton decay rate calculations from deformed nuclei such as the Coriolis interaction and pairing strength. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1615170

出版商:AIP    

年代:1903

数据来源: AIP