摘要:

The ISAC (Isotope Separator and Accelerator) Radioactive Beams laboratory has been in operation for about 4 years. An upgrade in the RB upper energy and mass range will be operational in 2 years and funding for a further upgrade in available number of RB will be submitted this year. There are a number of major experimental facilities now available with physics results produced. A key new facility in the area of nuclear astrophysics, the DRAGON (Detector of Recoils And Gammas Of Nuclear reactions) facility, has finished its first major study, namely a direct measurement for the first time of the21Na(p,&ggr;)22Mg reaction, a reaction believed to play a key role in the production of22Na during novae explosions. This report will provide a review of the experimental facilities now available at ISAC, along with details of this first published result from the DRAGON facility. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1691678

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

Exciting opportunities in the study of nuclei far from stability in both the neutron and proton rich side are opening with the recent availability of radioactive ion beams (RIBs) at energies above the Coulomb barrier at the Holifield Radioactive Ion Beam Facility (HRIBF). These RIBs provide a unique opportunity for a whole class of measurements that could never before be realized. A recent highlight has been the acceleration of “pure” beams of fission fragments such as82Ge (T1/2=4.6s) and132Sn (T1/2=40s). These semi‐magic and doubly‐magic nuclei are important benchmarks within the chart of nuclides, because they are constraints for the shell‐model parameter sets. We are currently developing the required experimental tools and specialized techniques for studies in nuclear astrophysics, reaction spectroscopy, and nuclear structure research with RIBs. I will discuss some of the challenges encountered with examples from selected topical areas with which I have been involved. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1691679

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

Medium polarization effects induce an effective pairing interaction between nucleons which renormalize the nucleon‐nucleon bare potential. We assess the importance of these renormalization processes concerning pairing correlations in both exotic nuclei as well as nuclei lying along the stability valley. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1691680

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

The Coupled Cyclotron Facility at the National Superconducting Cyclotron Laboratory at Michigan State University provides a large variety of new isotopes previously inaccessible and others at rates sufficienct for in‐beam spectroscopy. This talk presents some of our recent results elucidating the structure of exotic nuclei.After a general overview of scientific highlights from the first two years of operation particular results from several in‐beam gamma‐ray spectroscopy experiments in the vicinities of neutron numbersN=16,N=20,N=28 in the &pgr;(sd) shell around56Ni will be discussed. Inelastic scattering experiments with gamma‐ray detection on light and heavy targets have determined specific transition matrix elements and excited state energies. One‐ and two‐particle nucleon knockout reactions were used to investigate the wave functions of specific states and to deduce corresponding spectroscopic factors. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1691681

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

In‐beam gamma‐spectroscopy using fragmentation reactions of both stable and radioactive beams have been performed in order to study the structure of excited states in the neutron‐rich18,20C,21–24O and23,25F isotopes. For the produced fragments, &ggr;‐ray energies, intensities and &ggr;&ggr; coincidences have been measured. Based on this information new level schemes are proposed up to the neutron separation energy for some of these isotopes. The systematics of the 2+energy has been extended up to20C in the C isotopic chain. Level schemes are suggested for21O and22O. The non observation of any &ggr;‐ray from23O and24O suggests that their excited states lie above the neutron decay thresholds. The study of F isotopes provides hint of the possible change in nuclear structure between the F and O isotopic chains. These results, together with the size of the N=14 and N=16 shell gaps in C,O,F isotopes are discussed in the framework of shell model calculations. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1691682

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

We have studied the high spin states in160–162Ho in order to investigate the properties of the rotational bands and their dependence on the single particle orbits involved. The reaction158,160Gd(7Li,xn) at 56 MeV were used to produce the Ho isotopes of interest. In all three Ho isotopes the known rotational bands have been significantly extended. New band‐crossings have been observed for the first time in this work. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1691683

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

The structure of low‐lying states of the carbon isotopes is investigated using the extended version of the Antisymmetrized Molecular Dynamics (AMD) Multi‐Slater Determinant model. We can reproduce reasonably well many experimental data for carbon isotopes12C‐22C. A special approach is adopted for15C to better describe the tail of the wave function. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1691684

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

A new method for calculating the low‐lying states of light nuclei is proposed: Antisymmetrized Molecular Dynamics (AMD) — Superposition of Selected Snapshots (AMD triple‐S). In addition to the cluster features of the core nucleus, the properties of the wave of valence nucleons are well expressed in terms of a superposition of selected AMD wave functions. For6He, the binding energy and the halo nature are reproduced using effective interactions determined from a phase‐shift analysis. For the deformed core cases, in12Be, the newly observedJ= 0 state at 2.24 MeV is analyzed to be the second 0+state. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1691685

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

A new design of magnetic spectrometer, MAGNEX, is under construction for the INFN‐LNS, Catania. It is primarily intended for use with the Tandem‐accelerated radioactive beams from the EXCYT facility. Both projects are expected to be completed by early 2004. Considering the broad choice of both stable and radioactive beams that will be available at the LNS, the spectrometer provides new opportunities for, e.g., spectroscopy of weakly bound nuclei by direct reactions, reaction mechanisms with large isospin and nuclear astrophysics. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1691686

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

Recent results pertaining to nuclear structure from neutron‐induced reactions on90Zr,193Ir,196Pt and238U are presented. The data were taken using the GEANIE spectrometer comprised of 26 high‐purity Ge detectors with 20 BGO escape‐suppression shields. The broad‐spectrum pulsed neutron source of the Los Alamos Neutron Science Center’s WNR facility provided neutrons in the energy range from 0.6 to 200 MeV. The time‐of‐flight technique was used to determine the incident neutron energies. Results from shell model calculations for90Zr and from IBM‐2 calculations for196Pt are generally in good agreement with the observed spectrum of excited states. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1691687

出版商:AIP    

年代:1904

数据来源: AIP