摘要:

In (n,n′&ggr;) experiments performed at the University of Kentucky 7.0 MV accelerator facility, the low‐lying, low‐spin level structures of several even‐A stable Cd nuclei have been systematically studied. Level lifetimes have been determined with the Doppler‐shift attenuation method. Initial results from110–116Cd generally support the interpretation of these nuclei as anharmonic quadrupole vibrators with low‐lying intruder structures, although the details of the low‐spin levels of114Cd and116Cd remain puzzling. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1517940

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

The paper discusses the concept ofQ‐phonons and its connection to the concept ofQ‐invariants and the shape parameters of nuclei. It will also discuss some useful relations betweenQ‐invariants and observables. These relations allow one to determine crucial nuclear observables such as the square of the quadrupole moment of the first 2+state from lifetime data of the gamma‐ and ground band which may have applications, in future measurements with rare isotopes beams. These concepts are discussed for the Barium, Xenon and Cerium nuclei with mass numbers aroundA= 130, because some of these concepts were either introduced or at least heavily used in the discussion of the nuclear structure of these nuclei. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1517941

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

New data is presented on K&pgr;= 0+bands in156,158Gd and178Hf. Each of these nuclei exhibit a different aspect of the nature of K&pgr;= 0+bands in deformed nuclei. In156Gd, there is evidence of a K&pgr;= 0+band with significant two‐phonon &ggr;&ggr; component whereas in178Hf results are shown for a K&pgr;= 0+band whose members exhibit two‐phonon &bgr;&bgr; character. New (p,t) reaction results point to the existence of thirteen excited 0+states in158Gd below an excitation energy of 3.1 MeV. All the results combine to provide a challenge to our present understanding of the nature of these excitations. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1517942

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

To obtain the highest possible resolution has always been a major challenge in high resolution &ggr;‐ray spectroscopy, using crystal diffraction at the Institut Laue Langevin (ILL), Grenoble. About a quarter of a century ago the very first measurements at ILL started with a resolution already sensibly better than the one which could be obtained with solid state detectors. To date &ggr;‐rays emitted after neutron capture can be recorded with unprecedented and unequaled resolving power. In the context of this meeting some key experiments, carried out in the last 25 years, will be discussed. Finally we will try to evaluate where the emphasis might be in the upcoming years. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1517943

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

We identified &ggr; transitions in several neutron‐rich nuclei near132Sn produced in the spontaneous fission of252Cf. These are of interest because they can test shell model calculations. These nuclei are139Ba,133,135Te, and121,123Cd. Excited states in neutron‐rich133Te exhibit four types of particle‐hole bands built on the known 334.3 keV isomer in133Te. The yrast and near yrast particle‐hole states observed up to 6.2 MeV in133Te have characteristics quite similar to those in134Te. The band starting at 5.214 MeV is assigned as a neutron particle‐hole excitation of the double magic core nucleus,132Sn and is a candidate for a tilted rotor band. Theoretical shell model calculations show good agreement with the experimental states up to 4.3 MeV. The new level scheme of139Ba includes 11 new transitions and 10 new levels and is compared with the 83‐neutron isotone135Te. In135Te, a tilted rotor band, also, is proposed. Excited states built on the 11/2−isomeric states in neutron‐rich121,123Cd are identified. The new data indicate that the 11/2−isomers in odd‐A Cd isotopes with N>74 have spherical shapes similar to those in Te while the Cd ground states are likely deformed. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1517944

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

Recent results of the Monte Carlo Shell Model and related studies will be presented for some Sn, Te and Ba nuclei. The anomalousB(E2) value of136Te can be explained within the shell model description which describes the spherical‐to‐deformed phase transition in Ba isotopes. The microscopic realization of E(5) and O(6) symmetries are given with a shell model Hamiltonian which describes energy levels andE2 properties. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1517945

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

We describe theab initioNo‐Core Shell Model, in which the effective Hamiltonians are derived microscopically from realistic nucleon‐nucleon potentials, as a function of the finite harmonic‐oscillator basis space. We give results for theA= 3 nucleon system to demonstrate the viability of the technique. Extending our approach top‐shell nuclei, we present some of our latest results. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1517946

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

The Pairing Model hamiltonian was first solved exactly by Richardson in the sixties. We give here the conditions of integrability for a wider variety of pairing hamiltonians for fermion and boson systems, together with the exact solution for their complete sets of eigenstates. The study of the exact solution for interacting boson models with repulsive pairing shows a new and unexpected mechanism forsddominance. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1517947

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

The unique transition probability in chiral twin bands was predicted based on a simplified frozen alignment Particle plus Rotor (PR) model and a full PR model calculation. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1517948

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

Four regularly spaced rotational bands with large dynamical moments of inertia, which are consistent with known superdeformed bands in the Lu/Hf region, have been identified in174Hf. The states were populated in the130Te(48Ca,4n) reaction at a beam energy of 194 MeV. The Gammasphere array detected the emitted gamma radiation. Ultimate cranker calculations predict substantial triaxial deformation (&ggr; ≈ ±17°) for highly deformed174Hf structures. However,174Hf is eight neutrons away from the previously establishedN= 94 triaxial superdeformed shell gap. Shell gaps atN= 100 and 106 with &ggr; ⩾ 15° are observed when &Vegr;2≈ 0.45, which may be responsible for the predicted TSD minima in174Hf. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1517949

出版商:AIP    

年代:1902

数据来源: AIP