The properties of neutron-rich boron isotopes are studied in the relativistic continuum Hartree-Bogoliubov theory in coordinate space with NL-SH,PK1 and TM2 effective interactions.Pairing corrections are taken into account by a density dependent force of zero range.The binding energies calculated for these nuclei agree with the experimental data quite well.The neutron-rich nucleus 17 B has been predicted to have a two-neutron halo structure in its ground state.The halo structure of 17 B is reproduced in a self-consistent way,and this halo is shown to be formed by the valence neutron level 2s 1/2.
Ji Juan-XiaLI Jia-XingHAN RuiWANG Jian-SongHU Qiang
In this paper we present a timing detector which has low detection threshold and is radiation-resistant.The photons induced by radioactive beam ions passing through a thin plastic-scintillator foil BC422,emit from the foil center corresponding to one focal point of an aluminum ellipsoidal mirror and are reflected to another focus point at which the cathode of a photomultiplier tube locates.A time resolution of about 115 ps can be achieved for1 2N of 58.5 MeV/u and 130 ps for1 7B of 43.7 MeV/u.The counting rate up to 10 8packets per second(pps) is allowed.
The ground-state properties of N=3 isotones and mirror nuclei have been investigated in the Rrelativistic Continuum Hartree-Bogoliubov theory with the NLSH effective interaction. Pairing correlations are taken into account by a density-dependent 5-force. The calculations show that the proton density distributions of SB and 9C have a long tail, the core has an increasing tendency of 9C and the paired off valence protons make the halo distribution shrink. The cross sections for the 8B（gC）＋12C reaction which are consistent with the experimental data are calculated using the Glauber model. On the whole, we think that SB is a one-proton halo nucleus and 9C is a two-proton halo nucleus.
The mirror nuclei ^12N and ^12B are separated by the Radioactive Ion Beam Line in Lanzhou （RIBLL） at HIRFL from the breakup of 78.6 MeV/u 14N on a Be target. The total reaction cross-sections of ^12N at 34.9 MeV/u and ^12B at 54.4 MeV/u on a Si target have been measured by using the transmission method. Assuming ^12N consists of a ^11C core plus one halo proton, the excitation function of ^12N and ^12B on a Si target and a C target were calculated with the Glanber model. It can fit the experimental data very well. The characteristic halo structure for ^12N was found with a large diffusion of the protons density distribution.
Deformed even–even nuclei Barium isotopes with quadrupole–octupole deformations are investigated on the basis of a collective model.The model describes energy levels of the yrast band with alternating parity in the neutron-rich^(140;142;144;146;148)Ba.The structure of the alternating parity bands is examined by odd–even (△I=1) staggering diagrams.An analytical method of the collective model is proposed for the calculation of E2 transition probabilities in alternating spectra of the nuclei^(140;142;144;146)Ba.
The potential energy surfaces and density distributions of ground states in even-mass Be isotopes are studied by using the point-coupling covariant density functional theory with the PC-F1 effective interaction.The clustering structure is exhibited automatically in most of the Be isotopes.The results indicate that ^(6)Be has an α+2p clustering structure,while ^(8,10,14)Be have the 2αclustering structure.Theα–αdistances and the corresponding quadrupole deformation parameters have a similar evolution trend against the neutron number.
