Properties and structure of N = Z nuclei within relativistic mean field theory

The axially deformed relativistic mean field theory with the force NLSH has been performed in the blocked BCS approximation to investigate the proper-ties and structure of N=Z nuclei from Z=20 to Z=48. Some ground state quantities such as binding energies, quadrupole deformations, one/two-nucleon separation energies, root-mean-squaxe (rms) radii of charge and neutron, and shell gaps have been calculated. The results suggest that large deformations can be found in medium-heavy nuclei with N=Z=38-42. The charge and neutron rms radii increase rapidly beyond the magic number N=Z=28 until Z=42 with increasing nucleon number, which is similar to isotope shift, yet beyond Z=42, they decrease dramatically as the structure changes greatly from Z=42 to Z=43. The evolution of shell gaps with proton number Z can be clearly observed. Besides the appearance of possible new shell closures, some conventional shell closures have been found to disappear in some region. In addition, we found that the Coulomb interaction is not strong enough to breakdown the shell structure of protons in the current region.

DIRECT MASS MEASUREMENTS OF EXOTIC NUCLEI IN STORAGE RINGS

Mass measurements of exotic nuclei is a fast, developing field which is essential for basic nuclear physics and a wide range of applications. The method of storage ring mass spectrometry has many advantages: (1) a large amount of nuclides can be simultaneously measured; (2) very short-lived (T-1/2 greater than or similar to 50 mu s) and very rare species (yields down to single ions) can be accessed; (3) nuclides in several atomic charge states can be investigated, (4) half-life measurements can be performed with time-resolved mass spectrometry. In this contribution we concentrate on some recent achievements and future perspectives of the storage ring mass spectrometry.

Probing the Structure of Unstable Nuclei Through the Recoiled Proton Tagged Knockout Reaction

Recoiled proton tagged knockout reaction experiments were carried-out for He-8 at 82.5 MeV/u in RIKEN and for He-6 at 65 MeV/u in Lanzhou. The very preliminary results for the distinguish of the reaction mechanism are presented and compared to the kinematics calculation.

Fine structure of alpha decay to rotational states of heavy nuclei

To gain a better insight into alpha-decay fine structure, we calculate the relative intensities of alpha decay to 2(+) and 4(+) rotational states in the framework of the generalized liquid drop model (GLDM) and improved Royer's formula. The calculated relative intensities of a decay to 2(+) states are in good agreement with the experimental data. For the relative intensities of alpha decay to 4(+) states, a good agreement with experimental data is achieved for Th and U isotopes. The formula we obtain is useful for the analysis of experimental data of alpha-decay fine structure. In addition, some predicted relative intensities which are still not measured are provided for future experiments.

Multi-phonon gamma-vibrational bands in odd-mass nuclei studied by triaxial projected shell model approach

Inspired by the recent experimental data [J.-G. Wang, et al., Phys. Lett. B 675 (2009) 420], we extend the triaxial projected shell model approach to study the gamma-band structure in odd-mass nuclei. As a first application of the new development, the gamma-vibrational structure of Nb-103 is investigated. It is demonstrated that the model describes the ground-state band and multi-phonon gamma-vibrations quite satisfactorily, supporting the interpretation of the data as one of the few experimentally-known examples of simultaneous occurrence of one- and two-gamma-phonon vibrational bands. This generalizes the well-known concept of the surface gamma-oscillation in deformed nuclei built on the ground-state in even-even systems to gamma-bands based on quasiparticle configurations in odd-mass systems. (c) 2010 Elsevier BM. All rights reserved.

High-spin states of odd-odd nuclei in the A similar to 170 mass region

Efforts have been made in our group to study the band structure of odd-odd nuclei in the A similar to 170 mass region. We aimed at providing new data of high-spin states and searching for the low-spin signature inversion in the 2-qp bands built on the pi h(9/2) circle times nu i(13/2) and pi i(13/2)circle times nu i(13/2) configurations. In this talk, main results of our work will be summarized, and some systematic features of signature inversion discussed. The spin and parity assignments for the pi i(13/2) circle times nu i(13/2) band in (184)An could be regarded as firm providing a good example for systematic and theoretical investigations.

Measurement of the total reaction cross section for the mirror nuclei N-12 and B-12

The mirror nuclei N-12 and B-12 are separated by the Radioactive Ion Beam Line in Lanzhou (RIBLL) at HIRFL from the breakup of 78.6 MeV/u N-14 on a Be target. The total reaction cross-sections of N-12 at 34.9 MeV/u and B-12 at 54.4 MeV/u on a Si target have been measured by using the transmission method. Assuming N-12 consists of a C-11 core plus one halo proton, the excitation function of N-12 and B-12 on a Si target and a C target were calculated with the Glauber model. It can fit the experimental data very well. The characteristic halo structure for N-12 was found with a large diffusion of the protons density distribution.

PROPERTIES OF ALPHA DECAY TO ROTATIONAL BANDS OF HEAVY NUCLEI

In the framework of the generalized liquid drop model (GLDM) and improved Royer's formula, we investigate the branching ratios and half-lives of alpha-decay to the members of the ground-state rotational bands of heavy even-even Fm and No isotopes. The calculated results are in good agreement with the available experimental data and some useful predictions are provided for future experiments.

Radiation-induced crystallization of polyamide-1010 containing heterogeneous nuclei

Radiation-induced crystallization of polyamide-1010 (PA1010) or nylon-1010 containing heterogeneous nuclei (neodymium oxide, Nd2O3) is discussed in this paper by Wide Angle X-ray Diffraction (WAXD) and Differential Scanning Calorimetry (DSC). The results show that at low dosage the crystallinities of the irradiated specimens increase, while crystallite size (L(hkl)) decreases, indicating that some new crystallites are produced in the course of irradiation. The new centers were brought about in the fold surface of the lamellae. Copyright (C) 1997 Elsevier Science Ltd

Investigation of irradiated PA1010 containing heterogeneous nuclei

This paper deals with radiation effects on PA1010 containing heterogeneous nuclei (Nd2O3). With the help of DSC, WAXD and ESR techniques, the change in the crystallinity and the perfection of the crystal of irradiated PA1010 containing heterogeneous nuclei were studied. Copyright (C) 1996 Elsevier Science Ltd.

Influence of the fold surface of the lamellae on radiation effects - Research on irradiated polyamide-1010 containing heterogeneous nuclei

Irradiated polyamide-1010 (PA1010) and PA1010 containing 0.5% (wt) heterogeneous nuclei were studied by ESR, WAXD, DSC and the determination of gel fractions. The fold surface of the lamellae plays an important role in the effects of radiation on crystalline PA1010. The results show that the direct radiation effects on both samples vary, while after being heated to 220 degrees C, the final radiation effects are identical, regardless of the difference in the amount of the fold surface of the lamellae. The post-radiation effects result predominantly from the fold surface.

Nuclear ingredients for cross section calculation of exotic nuclei

The increasing need for cross sections far from the valley of stability, especially for applications such as nuclear astrophysics, poses a challenge for nuclear reaction models. So far, predictions of cross sections have relied on more or less phenomenological approaches, depending on parameters adjusted to available experimental data or deduced from systematic relations. While such predictions are expected to be reliable for nuclei not too far from the experimentally known regions, it is clearly preferable to use more fundamental approaches, based on sound physical bases, when dealing with very exotic nuclei. Thanks to the high computer power available today, all major ingredients required to model a nuclear reaction can now be (and have been) microscopically (or semi-microscopically) determined starting from the information provided by an effective nucleon-nucleon interaction. All these microscopic ingredients have been included in the latest version of the TALYS nuclear reaction code (http://www.talys.eu/).

Platinum nuclei: Concealed configuration mixing and shape coexistence

The role of configuration mixing in the Pt region is investigated. For this chain of isotopes, the nature of the ground state changes smoothly, being spherical around mass A~174 and A~192 and deformed around the midshell N=104 region. This has a dramatic effect on the systematics of the energy spectra as compared to the systematics in the Pb and Hg nuclei. Interacting boson model with configuration mixing calculations are presented for gyromagnetic factors, α-decay hindrance factors, and isotope shifts. The necessity of incorporating intruder configurations to obtain an accurate description of the latter properties becomes evident. © 2011 American Physical Society.

Deformation of stem cell nuclei by nanotopographical cues.

Cells sense cues in their surrounding microenvironment. These cues are converted into intracellular signals and transduced to the nucleus in order for the cell to respond and adapt its function. Within the nucleus, structural changes occur that ultimately lead to changes in the gene expression. In this study, we explore the structural changes of the nucleus of human mesenchymal stem cells as an effect of topographical cues. We use a controlled nanotopography to drive shape changes to the cell nucleus, and measure the changes with both fluorescence microscopy and a novel light scattering technique. The nucleus changes shape dramatically in response to the nanotopography, and in a manner dependent on the mechanical properties of the substrate. The kinetics of the nuclear deformation follows an unexpected trajectory. As opposed to a gradual shape change in response to the topography, once the cytoskeleton attains an aligned and elongation morphology on the time scale of several hours, the nucleus changes shape rapidly and intensely.