Anomaly in the charge radii and nuclear structure

The axially deformed relativistic mean field theory is applied to study the isotope shift of charge distributions of odd-Z Pr isotope chain. The nuclear structure associated with the shell and the isotope effect is investigated. The mechanism of link in the isotope shift at the neutron magic number N = 82 is revealed to be dependent on the neutron energy level structure at the Fermi energy, demonstrating that the spin-orbit coupling interaction and p-n attraction are well described by the relativistic mean field theory.

Microscopic examination of NpNn dominance in the evolution of nuclear structure

The proton-neutron interaction in determining the evolution of nuclear structure has been studied by using the Brillouin-Wigner perturbation expansion. The particle-hole and particle-particle p-n interactions are unifiedly described in the theory. The obtained formulas of level energies and excitation energies scaled in the small- and large-NpNn limits can well explain the linearity of the extracted proton-neutron interaction energies and the attenuation of the 2(1)(+) excitation energies against the valence nucleon product NpNn for five mass regions from A = 100-200.

Penning trap mass measurements on nobelium isotopes

The Penning trap mass spectrometer SHIPTRAP at GSI Darmstadt allows accurate mass measurements of radionuclides, produced in fusion-evaporation reactions and separated by the velocity filter SHIP from the primary beam. Recently, the masses of the three nobelium isotopes No252-254 were determined. These are the first direct mass measurements of transuranium elements, which provide new anchor points in this region. The heavy nuclides were produced in cold-fusion reactions by irradiating a PbS target with a Ca-48 beam, resulting in production rates of the nuclei of interest of about one atom per second. In combination with data from decay spectroscopy our results are used to perform a new atomic-mass evaluation in this region.

Probing the symmetrical potential in nuclear reaction iinduced by neutron-halo nuclei

In terms of the isospin-dependent quantum molecular dynamics model (IQMD), important isospin effect in the halo-neutron nucleus induced reaction mechanism is. investigated, and consequently, the symmetrical potential form is extracted in the intermediate energy heavy ion collision. Because the interactive potential and in-medium nucleon-nucleon (N-N) cross section in the IQMD model sensitively depend on the density distribution of the colliding system, this type of study is much more based on the extended density distribution with a looser inner nuclear structure of the halo-neutron nucleus. Such a density distribution includes averaged characteristics of the isospin effect of the reaction mechanism and the looser inner nuclear structure. In order to understand clearly the isospin effect of the halo-neutron nucleus induced reaction mechanism, the effects caused by the neutron-halo nucleus and by the stable nucleus with the same mass are compared under the same condition of the incident channel. It is found that in the concerned beam energy region, the ratio of the emitted neutrons and protons and the ratio of the isospin fractionations in the neutron-halo nucleus case are considerably larger than those in the stable nucleus case. Therefore, the information of the symmetry potential in the heavy ion collision can be extracted through such a procedure.

Lamins and their genes

The nuclear lamina is an important nuclear structure. The studies on its peptides lamins and genes have made substantial progress in recent years. In this paper, the new achievements in studies of new lamin members and their functions, lamin genes and their origin and differentiation, are reviewed and discussed. Some research areas that deserve to be investigated further are put forward.

HIRFL today

HIRFL was upgraded from beginning 2000. Besides of researches on nuclear physics, atomic physics, irradiative material and biology, the cancer therapy by heavy ion and hadron physics are being developing. The injector system of SFC+SSC can provide all ions from proton to uranium with higher intensity. The Cooling Storage Ring (CSR) has accelerated beams successful. The ions C-12(6+), Ar-36(18+), Xe-129(27+) have been accelerated up 1000MeV/u, 235MeV/u with about 10(9)similar to 10(8) ions per spill respectively. The beam momentum dispersion was measured from 4x10(-3) to 2x10(-4) after cooling by the electron cooler or similar to 4x10(-4) after accelerated to 1000MeV/u without cooling. In order to improve the nuclear structure and heavy isotope research in SFC+SSC energy domain, A Wien filter was added in front of RIBLL and gas was filled in first section of RIBLL; a new spectrometry SHANS has being installed. Presently, there are two starting version experimental setups at CSR.

Systematic study on alpha decay half-lives of superheavy nuclei

The a-decay half-lives of a set of superheavy nuclear isotope chain from Z = 105 to 120 have been analyzed systematically within the WKB method, and some nuclear structure features are found. The decay barriers have been determined in the quasi-molecular shape path within the Generalized Liquid Drop Model (GLDM) including the proximity effects between nucleons in a neck and the mass and charge asymmetry. The results are in reasonable agreement with the published experimental data for the alpha decay half-lives of isotopes of charge 112, 114, and 116, of the element 294118 and of some decay products. A comparison of present calculations with the results by the DDM3Y effective interaction and by the Viola-Seaborg Sobiczewski (VSS) formulae is also made. The experimental a decay half lives all stand in between the GLDM calculations and VSS formula results. This demonstrates the possibility of these models to provide reasonable estimates for the half-lives of nuclear decays by a emissions for the domain of SHN. The half-lives of these new nuclei are thus well tested from the reasonable consistence of the macroscopic, the microscopic, the empirical formulae and the experimental data. This also shows that the present data of SHN themselves are consistent. It could suggest that the present experimental claims on the existence of new elements Z = 110 similar to 118 are reliable. It is expected that greater deviations of a few SHN between the data and the model may be eliminated by further improvements on the precision of the measurements.

OVERVIEW ON THE HIRFL-CSR FACILITY

The status of the HIRFL (Heavy Ion Facility in Lanzhou) - Cooler Storage Ring (CSR) at the IMP is reported. The main physics goals at the HIRFL-CSR are the researches on nuclear structure and decay property, EOS of nuclear matter, hadron physics, highly charged atomic physics, high energy density physics, nuclear astrophysics, and applications for cancer therapy, space industries, materials and biology sciences. The HIRFL-CSR is the first ion cooler-storage-ring system in China, which consists of a main ring (CSRm), an experimental ring (CSRe) and a radioactive beamline (RIBLL2). The two existing cyclotrons SFC (K=70) and SSC (K=450) are used as its injectors. The 7MeV/u12C6+ ions were stored successfully in CSRm with the stripping injection in January 2006. After that, realized were the accelerations of C-12(6+), Ar-36(18+), Kr-78(28+) and Xe-129(27+) ions with energies of 1GeV/u, 1GeV/u, 450 MeV/u and 235 MeV/u, respectively, including accumulation, electron cooling and acceleration. In 2008, the first two isochronous mass measurement experiments with the primary beams of Ar-36(18+) and Kr-78(28+) were performed at CSRe with the Delta p/p similar to 10(-5).

Isospin symmetry breaking at high spins in the mirror pair Se-67 and As-67

Recent experimental data have revealed large mirror energy differences (MED) between high-spin states in the mirror nuclei Se-67 and As-67, the heaviest pair where MED have been determined so far. The MED are generally attributed to the isospin symmetry breaking caused by the Coulomb force and by the isospin-nonconserving part of the nucleon-nucleon residual interaction. The different contributions of the various terms have been extensively studied in the fp shell. By employing large-scale shell-model calculations, we show that the inclusion of the g(9/2) orbit causes interference between the electromagnetic spin-orbit and the Coulomb monopole radial terms at high spin. The large MED are attributed to the aligned proton pair excitations from the p(3/2) and f(5/2) orbits to the g(9/2) orbit. The relation of the MED to deformation is discussed.

Isobaric yield ratios and the symmetry energy in heavy-ion reactions near the Fermi energy

The relative isobaric yields of fragments produced in a series of heavy-ion-induced multifragmentation reactions have been analyzed in the framework of a modified Fisher model, primarily to determine the ratio of the symmetry energy coefficient to the temperature, a(sym)/T, as a function of fragment mass A. The extracted values increase from 5 to similar to 16 as A increases from 9 to 37. These values have been compared to the results of calculations using the antisymmetrized molecular dynamics (AMD) model together with the statistical decay code GEMINI. The calculated ratios are in good agreement with those extracted from the experiment. In contrast, the values extracted from the ratios of the primary isobars from the AMD model calculation are similar to 4 to 5 and show little variation with A. This observation indicates that the value of the symmetry energy coefficient derived from final fragment observables may be significantly different than the actual value at the time of fragment formation. The experimentally observed pairing effect is also studied within the same simulations. The Coulomb coefficient is also discussed.

Experimental study of the two-proton correlated emission from the excited states of Ne-17,Ne-18 and S-28,S-29

A series of experiments have been performed by complete kinematics measurements to study two-proton (2p) correlated emission from the excited states of Ne-17,Ne-18 and S-28,S-29 via the Coulomb excitation by bombarding on Au-197 target. 2p and residua coincident events were picked Out under strict conditions. Visible p-p correlations were observed. It is shown that 2p can be emitted from the high-lying excited states. 2p halo may lead to 2p emission with large spectroscopy factor for the states close to or beyond the threshold.

A novel approach to isoscaling: The role of the order parameter m = N-f-Z(f)/A(f)

Isoscaling is derived within a recently proposed modified Fisher model where the free energy near the critical point is described by the Landau O(m(6)) theory. In this model m = N-f-Z(f)/A(f) is the order parameter, a consequence of (one of) the symmetries of the nuclear Hamiltonian. Within this framework we show that isoscaling depends mainly on this order parameter through the 'external (conjugate) field' H. The external field is just given by the difference in chemical potentials of the neutrons and protons of the two sources. To distinguish from previously employed isoscaling relationships, this approach is dubbed: m-scaling. We discuss the relationship between this framework and the standard isoscaling formalism and point out some substantial differences in interpretation of experimental results which might result. These should be investigated further both theoretically and experimentally. (C) 2010 Elsevier B.V. All rights reserved.

RFQ冷却聚束器RFQ1L的研制

SHANS (Spectrometer of Heavy Atoms and Nuclear Structure，重原子和核结构研究谱议)正在建设中，它不但可以直接鉴别离子的电荷数Z和质量数A，而且还将在核结构和核衰变的精细研究方面发挥重要作用。RFQ冷却聚束器RFQ1L和彭宁离子阱LPT是其中的两个重要组成部分。 RFQ冷却聚束器RFQ1L的主要目的是收集经过充气反冲谱议分离后的反应产物，然后经过冷却、聚束，使原来品质很差的束流转化为能量单一、发射度小、束斑很小的高品质束流。现在已经顺利完成了模拟、设计、机械加工和机械安装等工作，其中机械安装部分是本论文的主要工作之一。经过近半年的时间，我们克服了种种困难，高质量地完成了RFQ1L的机械安装工作。各种测量综合显示：各部件间的位置精度达到了±0.5 mm；真空系统的真空度达到了1.7×10-4 Pa，系统压升率为(0.04±0.02) Pa/h；各电极间的绝缘效果和导电效果良好。彭宁离子阱LPT的主要目的是直接高精度测量原子核的质量。质量是原子核的一个最基本属性，对检验和拓广现有核理论、研究核天体物理中的核反应过程和基本常数具有非常重要的作用。控制系统在LPT中起着至关重要的作用。控制系统的设计和实现也是本论文的另一个主要工作。本论文详细论述了LPT的控制系统LPTCtrlSys的基本要求、硬件和软件布局情况