摘要:

Penning trap mass measurements on radioactive isotopes are performed with the ISOLTRAP mass spectrometer at ISOLDE/CERN. In the last years the applicability of the spectrometer has been considerably extended. The most recent measurements were carried out on isotopes of rare earth elements and on isotopes withZ=80–85.An accuracy of&dgr;m/m≈1⋅10−7was achieved. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57389

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Beams of relativistic exotic nuclei were produced, separated and investigated with the combination of the fragment separator FRS and the storage ring ESR. The following experiments are presented: 1) Direct mass measurements of relativistic nickel and bismuth projectile fragments were performed using Schottky spectrometry. Applying electron cooling, the relative velocity spread of the circulating secondary nuclear beams of low intensity was reduced to below10−6.The achieved mass resolving power ofm/&Dgr;m=6.5⋅105(FWHM) in recent measurements represents an improvement by a factor of two compared to our previous experiments. The previously unknown masses of more than 100 proton-rich isotopes have been measured in the range of54⩽Z⩽84.The results are compared with mass models and estimated values based on extrapolations of experimental values. 2) Exotic nuclei with half-lives shorter than the time required for electron cooling can be investigated by time-of-flight measurements with the ESR being operated in the isochronous mode. This novel experimental technique has been successfully applied in a first measurement with nickel fragments. A mass resolving power ofm/&Dgr;m=1.5⋅105(FWHM) was achieved in this mode of operation. 3) Nuclear half-lives of stored and cooled bare projectile fragments have been measured to study the influence of the ionic charge state on the beta-decay probability. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57307

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

In this talk we present the status of self-consistent theoretical methods, to describe the ground state properties and in particular nuclear masses over the entire range of the periodic table. We discuss their advantages and their shortcomings for the description of nuclear masses as compared to earlier more phenomenological methods based on the macroscopic-microscopic approach. In particular we emphasize, that in regions close to the drip-lines one expects a softening of the nuclear surface and a reduction of the spin-orbit splitting, which leads the quenching of some shell effects. This has to be described self-consistently. As compared the non-relativistic methods, relativistic models have the advantage, that they are assumed to be more reliable in taking into account the proper isospin dependence of the spin-orbit splitting. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57216

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

An overview is given of developments of interest for the determination of atomic masses of atomic around nuclear ground-states. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57225

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Short of proposing a full microscopic mass formula, we outline the steps that should make it possible. The construction rests on defining the nuclear monopole Hamiltonian,Hmthat has to be extracted phenomenologically because of the bad saturation properties of the realistic forces. We propose a preliminary form ofHmthat makes clear the origin of shell effects, and with only three paraters, reproduces the known spectra of particle and hole states on doubly magic cores to within 300 keV. Predictions are made for the yet unobserved levels around132Sn,and those associated to22O,34,42Si,68,78Ni,100Snand for the particle-hole gaps in these nuclei. Finally we analyze the single particle gaps for theN=50and 82 isotones, to conclude that the major closures are likely to persist away from stability. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57308

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The masses of 16 neutron-rich nuclei in the mass range from 35 to 45 have been measured using a direct time of flight technique following the fragmentation of a48Cabeam at 60 MeV/nucleon. The masses of35,36Mg,38Al,39,40Si,42,43Pand43,44Sare reported for the first time. Preliminary analysis shows that theN=28shell closure persists, even if weakened by the large neutron excess. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57309

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Measurements of nuclear moments far from stability have been performed mainly applying laser spectroscopy and &bgr;-NMR spectroscopy. A short overview of the experimental techniques are given. The &bgr;-NMR experiments on the quadrupole moments of sodium isotopes and of the magnetic moment of11Be,both using optically pumped radioactive beams, are discussed in more detail. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57250

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Different applications of the nuclear level mixing principle have been used to study nuclear moments of nuclei far from stability and of high-spin isomers. The basic principles are explained and an overview of results obtained over the last years is given. We discuss in particular the first application of this technique to projectile fragmentation products, as well as the results obtained on quadrupole moments of high-spin isomers in the Pb-region and in the massA=180region. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57310

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The ground state magnetic dipole moment of9Chas been remeasured using the &bgr;-NMR technique and our new value of1.396(3)&mgr;Nis in agreement with the previously measured value for this nuclide. The quenched magnetic moment of9Cand the anomalously large isoscalar spin expectation value for the9C−9LiT=3/2mirror pair compare favorably with the results of shell model calculations employing isospin nonconserving (INC) interactions. The ground state magnetic moment of21Mgwas also investigated to determine the significance of INC effects in the heavierA=21T=3/2mirror system. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57269

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

A major objective of the laser-IGISOL program has been realized with the first ever on-line observation of collinear laser induced fluorescence from an ion of a refractory element. The measurements demonstrate that the IGISOL can be operated in a mode that produces ion beams of good emittance with reasonable extraction efficiency. The technique has been used to study the neutron-deficient Hf isotopes. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57276

出版商:AIP    

年代:1998

数据来源: AIP