摘要:

The excitation function for the elastic scattering reaction p(18Ne,p)18Ne was measured with the first radioactive beam from the SPIRAL facility at GANIL. Several resonances have been observed, corresponding to new excited states in the compound nucleus19Na. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1737111

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

A new detector apparatus has been designed and developed to be used in experiments performed with radioactive ion beams. It consists of 16 highly segmented silicon strip detectors arranged in two‐layer telescopes and subtending a large solid angle (about 70&percent; of 4&pgr; sr). An innovative readout system for the position information that uses highly integrated electronics (ASIC chips) has been implemented. A first successful experiment has been performed at the Argonne National Laboratory (USA) to study the17F scattering by a208Pb target at 90.4 MeV of incident energy. The17F angular distribution has been analyzed and the optical model potential best‐fit parameters determined. The same analysis performed on17F data taken at higher incident energy, in completely different experimental conditions, gives consistent results. The comparison with experiments performed with stable beams (19F,16O,17O) indicates a behavior for the17F more similar to that of the Oxygen isotopes than to the19F one. Despite of the short data collection time, also the cross section for the17F →16O + p break‐up process has been estimated. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1737112

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

The subbarrier fusion cross section has been measured in the system11,10Be+209Bi. The data were collected at the RIKEN Ring Cyclotron with a total beam intensity of ∼10+5Hz typical for such radioactive nuclear beams of first generation. The cross section accuracy is around 10 to 15 &percent;. The two excitation functions look, within the statistical uncertainty very similar as well as the9Be+209Bi one at difference with the expectations. This is triggering further theoretical analysis. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1737113

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

In this paper we show how effective parameters such as effective binding energies can be defined for a proton in the combined nuclear‐Coulomb potential, including also the target potential, in the case in which the proton is bound in a nucleus which is partner of a nuclear reaction. Using such effective parameters the proton behaves similarly to a neutron. In this way some unexpected results obtained from dynamical calculations for reactions initiated by very weakly bound proton halo nuclei can be interpreted. Namely the fact that stripping dominates the nuclear breakup cross section which in turn dominates over the Coulomb breakup even when the target is heavy at medium to high incident energies. Our interpretation helps also clarifying why the existence and characteristics of a proton halo extracted from different types of data have sometimes appeared contradictory. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1737114

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

The new radioactive ion beam facility is planned as part of the project of a new international accelerator facility. These new accelerators shall serve several user communities from different fields of physics, namely nuclear structure and nuclear astrophysics, hadron studies with antiprotons, investigations of compressed nuclear matter, compressed macroscopic matter in plasmas, atomic and applied physics. The existing GSI accelerators will be extended by two new synchrotrons SIS 100 and SIS 300 for high intensity and higher energy primary beams of protons and heavy ions. Radioactive ion beams will be produced and separated in‐flight with a new fragment separator called Super‐FRS providing fragments to three experimental areas: fast in flight beams, slowed down or stopped rare isotopes and radioactive ions stored in one of the new storage rings CR and NESR. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1737115

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

Based on the “LINAG Phase 1” conceptual design, a two years detailed study on a ISOL‐type facility for the production of high intensity exotic beams, named SPIRAL2, has been launched. The radioactive isotope beams are produced via the fission process, with the aim of 1013fissions/s at least, induced in a UCxtarget either by fast neutrons from a C converter or by direct bombardment of fissile material. Fusion‐evaporation residues, using heavy ions beams in different targets can also be produced in this facility. The driver, with an acceleration potential of 40 MV will accelerate deuterons (5 mA) and q/A =3 ions (1 mA) Even heavier ions will be possible in a later stage. The driver consists in high‐performance ECR sources, an RFQ cavity and independent phase superconducting resonators. As it is a linear accelerator, further upgrade will be possible in future. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1737116

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

By coupling the Ring Cyclotron and RIPS fragment separator, RIKEN has performed various studies with fast radio‐isotope (RI) beams produced by heavy‐ion projectile fragmentation. Various studies on properties of nuclei far from the stability line have been performed with the RI beams. To provide more extended research opportunities, a project to build a new accelerator complex called “RI Beam Factory (RIBF)” has been started. RIBF in its first phase is already under construction, and the first RI beams should be supplied during the year of 2006. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1737117

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

Tri‐nucleon molecular structures in6He and6Be were investigated by using the6Li(7Li,7Be)6He reaction at 455 MeV and6Li(3He,t)6Be reaction at 450 MeV, respectively. Binary decay into t+t from a broad state atEx= 18.0 ± 1.0 MeV in6He and into3He+3He from one atEx= 18.0 ± 1.2 MeV in6Be, were observed by measuring tri‐nucleon cluster‐decays in coincidence with reaction‐particles. The branching ratios for binary decay were estimated to be about 0.7 for both6He and6Be. From the angular correlations of decay particles, these states are assigned to bePstates. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1737118

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

The isovector giant dipole resonance (GDR) of an &agr;‐cluster in6Li and7Li, and their analogs in6,7He and6,7Be were searched for by using the6,7Li(p,p′),6,7Li(3He,t) and6,7Li(7Li,7Be) reactions at the incident energies of 300, 450 and 455 MeV, respectively. New resonances were found for the first time atEx=27.0±1.5 MeV in6Li and atEx=29.0±1.5 MeV in7Li, both with widths (FWHM) of 12±2 MeV. In6He,6Be,7He and7Be resonances with widths of 12±2 MeV were observed via the charge exchange reactions atEx=24.0±1.5, 23.5±1.5, 18.0±1.5, and 28.0±1.5 MeV, respectively. All of these resonances were assigned to be dipole resonances based on the measured angular distributions of differential cross sections. The resonance shapes were reproduced well with the resonance shape of the GDR of4He reported in the (&ggr;,n) reaction. The averaged ratios of the cross sections for these resonances in A=6 to those in A=7 for each isotope were estimated to be nealy unity, 1.2±0.3. The averaged value of the respective cross section ratios of these resonances to the GDR in their respective target nuclei was 0.44±0.08, which was consistent with the ratios of the cross sections of the GDR in4He to those of the GDR in6,7Li reported in the photo‐nuclear reactions. The excitation energies of these dipole resonances in A=6 and 7 nuclei relative to the separation energies of an &agr;‐particle in6Li and7Li, respectively, agreed well with the excitation energy of the GDR in4He (≈26 MeV). We conclude that the resonances observed in6,7Li are the GDR of the &agr;‐cluster and the resonances in6,7He and6,7Be are their analogs. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1737119

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

The excitation energy of the6Li+208Pb system has been studied at several energies around the Coulomb barrier with a large solid angle detector array. The &agr; +d/6Li*excitation above the breakup threshold (Sd= 1.475 MeV) has been deduced from the invariant mass of the &agr; +dsystem. All the collected data show a similar behaviour: the cross sections are peaked at around 1 MeV above the threshold and they have an exponential decay on the high energy side, suggesting a direct breakup process. A Monte‐Carlo simulation of the whole reaction mechanism has been performed in order to check the validity of data analysis procedure and to study the influence of the set‐up geometry onto the experimental results.Two different theoretical approaches, the former based on fully quantum mechanical Coupled Channel calculations and the latter based on simpler semi‐classical calculations, treating the relative motion of the &agr; +dcluster structure along a classical trajectory, reproduce both in shape and absolute value the experimental excitation energy distributions. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1737120

出版商:AIP    

年代:1904

数据来源: AIP