摘要:

The observation of fine structure in proton emission allows one to measure the composition of the parent state’s wavefunction and the deformation of the daughter state. A systematic study of proton‐unbound nuclei in the rare earth region is ongoing at the HRIBF. Newly discovered fine structure in the decays of145Tm and141Ho are discussed, as well as advances in our experimental equipment. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1556626

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

In experiments at the FRS of GSI and at the SISSI‐LISE3 facility of GANIL, the decay of the proton drip‐line nucleus45Fe has been studied after projectile fragmentation of a58Ni primary beam. Fragment‐implantation events have been correlated with radioactive decay events in silicon telescopes on an event‐by‐event basis. The decay‐energy spectrum of45Fe implants shows a distinct peak consistent with a two‐proton ground‐state decay of45Fe. None of the events in the peak were found to be in coincidence with &ggr; radiation or with &bgr; particles which were searched for in the telescope‐surrounding detectors. The decay energy for45Fe agrees nicely with several theoretical predictions for two‐proton emission. These predictions strongly support the observed decay to be a simultaneous two‐proton ground‐state decay. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1556627

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

The systematic study of entry distributions populating proton‐rich Pt and Au isotopes indicates a limit in the excitation energy and angular momentum in the population of173Au, a nucleus beyond the proton drip line. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1556628

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Relationship between quantum shell structure and classical periodic orbits is briefly reviewed on the basis of semi‐classical trace formula. Using the spheroidal cavity model, it is shown that three‐dimensional periodic orbits, which are born out of bifurcation of planar orbits at large prolate deformations, generate the superdeformed shell structure. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1556629

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Average yrast moments of inertia at high spins, where the pairing correlations are expected to be largely absent, were found to deviate from the rigid‐body values. This indicates that shell effects contribute to the moment of inertia. We discuss the gross dependence of moments of inertia and shell energies on the neutron number in terms of the semiclassical periodic orbit theory. We show that the ground‐state shell energies, nuclear deformations and deviations from rigid‐body moments of inertia are all due to the same periodic orbits. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1556630

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

The width of the Giant Dipole Resonance in Sn was studied by means of inelastic scattering. This study allowed for the first measurement of the GDR width at a temperature of 1 MeV. The width was found to be 4±1 MeV, and is consistent with the ground state measurement. This result is in disagreement with adiabatic thermal shape fluctuation calculations, indicating an overestimation of the influence of thermal shape fluctuations at low temperature. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1556631

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

High‐energy &ggr; rays emitted in the symmetric reaction90Zr +89Y have been measured at the Argonne National Laboratory using the LEPPEX array coupled to the Fragment Mass Analyzer (FMA). The high‐energy &ggr;‐ray spectra emitted by the giant dipole resonance built on excited states and associated with the evaporation of 0, 1 and 2 nucleons have been measured. The statistical model analysis indicates that the radiative‐fusion process, namely the 0 particle emission channel, can be well described as a compound nucleus decay channel. In addition, the analysis of the high‐energy &ggr;‐ray spectra associated with the different evaporation channels provides the first evidence that shell effects still play a role in determining the nuclear shapes of179Au in the temperature interval 0.5–1 MeV. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1556632

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Recent analyses of multifragmentation in terms of Fisher’s model and the related construction of a phase diagram brings forth the problem of the true existence of the vapor phase and the meaning of its associated pressure. Our analysis shows that a thermal emission picture is equivalent to a Fisher‐like equilibrium description which avoids the problem of the vapor and explains the recently observed Boltzmann‐like distribution of the emission times. In this picture a simple Fermi gas thermometric relation is naturally justified. Low energy compound nucleus emission of intermediate mass fragments is shown to scale according to Fisher’s formula and can be simultaneously fit with the much higher energy ISiS multifragmentation data. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1556633

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Average nuclear level densities close to the nuclear binding energy in56Fe and57Fe are extracted from primary &ggr;‐ray spectra. A step structure is observed in the level density for both isotopes, and is interpreted as breaking of Cooper pairs. Thermal properties of56Fe are studied within the statistical canonical ensemble. The experimental heat capacity in56Fe is compared with the theoretical heat capacity calculated within the shell model Monte Carlo approach. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1556634

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Recent developments in the description of the structural evolution of nuclei invoke the concepts of phase transitions and phase coexistence. New, analytic, parameter‐free symmetries have been developed that describe nuclei at the “critical points” of phase/shape transition regions. The complete nuclear phase diagram at low energy and low angular momentum can be elegantly described in terms of the Landau theory of second order phase transition points and the lines of first order phase transitions that intersect these points. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1556635

出版商:AIP    

年代:1903

数据来源: AIP