Probing the density dependence of the symmetry energy with central heavy ion collisions

An improved isospin dependent Boltzmann Langevin model, in which the inelastic channels and momentum dependent interactions are incorporated, is used to investigate the high-density behavior of nuclear symmetry energy. By taking several forms of nuclear symmetry energy, we calculate the time evolutions of neutron over proton ratio, π ultiplicity and π-/π＋ ratio, and the kinetic energy and transverse momentum spectra of π-/π＋ ratio in the heavy ion collisions at 400A MeV. It is found that the neutron over proton ratio and π-/π＋ ratio are very sensitive to the nuclear symmetry energy, and the π- is more sensitive to the nuclear symmetry energy than the π＋. A supersoft symmetry energy results in a larger π-/π＋ ratio.     

新型充Ar靶丸设计

从惯性约束聚变实验物理诊断需求出发,提出并分析了利用聚碳硅烷空心微球作为DT燃料容器实现扩散法充氩的可行性。初步实验研究表明,聚碳硅烷微球有望替代玻璃微球作为DT燃料容器用于内爆物理研究。     

Photoactivation of Rare Earth Elements with 20 MeV Bremsstrahlung

The oxides of scandium, yttrium and all elements from lanthanum through lutetium, except promethium, were irradiated for 1hr with bremsstrahlung γ-rays converted from a 20MeV electron beam, and the radioactive species produced as a result have been examined on the basis of photonuclear reactions, their yields, and their applicability to activation analyses. The sensitivity and selectivity of the proposed method are discussed from the data thus obtained.

The (γ,n) reaction was predominant for most elements, and at least 28 product nuclides have been identified. A number of other (γ,2n) reactions have also been observed.

The yields of the (γn) reactions have been estimated for the lanthanide rare earths through measurement of the resultant activity to be about 10⁷mole·R and somewhat more than 10% smaller for the corresponding (γ,2n) reaction. Reactions with charged particle emission contributed only a small fraction in the observed radioactivity.

Extraneous activity arising from neutron capture was also measured; these activities could be reduced considerably by encasing the sample in boron.

The lower limits of detection averaged about 1 μg for most of the rare earth elements.     

Probing nucleon effective mass splitting with light particle emission

The main objective of this study was to investigate the impact of effective mass splitting on heavy-ion-collision observables.We first analyzed correlations between different nuclear matter parameters obtained from 119 effective Skyrme interaction sets.The values of the correlation coefficients illustrate that the magnitude of effective mass splitting is crucial for tight constraints on the symmetry energy via heavy-ion collisions.The ⁸⁶ Kr+²⁰⁸ Pb system at beam energies ra...     

氧化钆中稀土和非稀土杂质元素的ICP－AES法测定

本文介绍了电感耦合等离子体原子发射光谱法测定氧化钆中１８种元素。经对元素光谱干扰和基体效应的探讨发现：当溶液中氧化钆浓度为５ｍｇ·ｍＬ－１时，本法测定下限在６×１０－５～１×１０－３μｇ（ｇ·Ｇｄ２Ｏ３）－１之间，加入回收率在８２％～１０９％之间；相对标准偏差优于±６．９％。     

Crystalline Phase in Surface Layers of Glass Waste Form

An integral test of γ-ray production data of iron in the latest version of Japanese Evaluated Nuclear Data Library (JENDL-3.2) has been performed by means of a shielding benchmark analysis of KfK leakage neutron and γ-ray spectrum measurements from iron spheres with a ²⁵²Cf source in the center. Two comprehensive systems which consist of a continuous-energy Monte Carlo method and a multi-group Sn transport method have been adopted in this benchmark analysis. For comparison, analyses with JENDL-3.1, FENDL-1 and ENDF/B-IV have been also carried out. The calculation using JENDL-3.2 showed a good agreement with the experiment. It has been concluded that the γ-ray production data of iron in JENDL-3.2 were applicable for use of shielding designs and analyses of the fission neutron source problem.     

A Particle-in-Cell Simulation of Double Layers and Ion-Acoustic Waves

Double layers and ion-acoustic waves are investigated by using a one-dimensional electrostatic particle-in-cell simulation code. Our results show that double layers can be formed even when the drift velocity between electrons and ions is less than the electron thermal velocity. Electron and ion density depressions were clearly seen. Electrons gradually developed a distribu- tion comprising both background and beam components. In fact, as the initial electron-ion drift velocity was less than the electron thermal velocity, intense ion-acoustic waves could be found only at the places where the electron beam was located, suggesting that they are excited by the self-consistently developed electron beam. Besides the Langmuir waves and ion-acoustic waves, the beam mode excited by electron beams produced in our simulation has been clearly found.     

Probing Density Dependence of Symmetry Energy with Angular Distribution of Light Particles in HICs

正The nuclear symmetry energy plays a crucial role for understanding not only nuclear structure and reaction but also astrophysics phenomena.However,theoretical predictions on the density dependence of symmetry energy of nuclear matter show large uncertainties away from the normal density.Lot of efforts have been devoted to     

Measurements of the Thermal Neutron Macroscopic Absorption Cross Section for Neutron Absorbing Layers

Objective of this study is measuring the macroscopic cross section of a neutron absorbing layer for thermal neutrons. For this purpose a neutron source and BF ₃ detector have been applied. For measuring macroscopic cross section of thermal neutrons by the \( I = BI_{0} e^{{ - \sum\nolimits_{tot} t}} \) Formula, it is necessary to provide suitable geometric conditions in order to assume the production and build-up coefficient to be the unit value (=1). To fulfill required conditions for this assumption, surface of the detector is covered with a 2 mm thick layer of cadmium. Radiation window of the detector has a 3 cm diameter, situated directly in front of the source. By placing the cadmium cover over the detector, variation of \( Ln{\frac{{I_{0}^{{}} }}{I}} \) values verses thickness of absorbent layer, renders linear function behavior, making it possible to measure the macroscopic cross section. The next stage is applying the MCNP code by simulating F1 tally and cosine-cards for calculating Total Macroscopic Cross-Section. Validation of this study is achieved through comparison of simulation by the MCNP code and results rendered by experiment measurements.     

钍资源的核能利用问题探讨

分析了钍/铀燃料循环特点,评估了国际上钍资源利用研究开发现状和发展趋势,并试图按照科学发展观提出了我国钍资源核能利用的战略思考和钍/铀燃料循环前瞻性研究开发课题.     

模型泵内部流场的数值模拟

采用雷诺时均N-S方程和标准k-ε湍流模型,应用三维非结构四面体网格建模,选用旋转流体机械模型中的多重参考坐标系模型(MRF),对设计工况下反应堆主冷却剂泵模型泵的三维不可压缩湍流流场进行了数值模拟,模拟结果较好地揭示了内部流场的特点.本文分析了流场内总的压力分布和速度分布,描述了叶轮、导叶和球壳各个部分的内部流场特征,并探讨了造成这些特征的原因.研究结果可用于反应堆主冷却剂泵的性能预测,并为其水力优化设计提供有益参考.     

Superfluidity in the Solar Interior: Implications for Solar Eruptions and Climate

Efforts to understand unusual weather or abrupt changes in climate have been plagued by deficiencies of the standard solar model (SSM) [1]. Although it assumes that our primary source of energy began as a homogeneous ball of hydrogen (H) with a steady, well-behaved H-fusion reactor at its core, observations instead reveal a very heterogeneous, dynamic Sun. As examples, the upward acceleration and departure of H⁺ ions from the surface of the quiet Sun and abrupt climatic changes, including geomagnetic reversals and periodic magnetic storms that eject material from the solar surface are not explained by the SSM. The present magnetic fields are probably deep-seated remnants of very ancient origin. These could have been generated from two mechanisms. These are (1) Bose-Einstein condensation [2] of iron-rich, zero-spin material into a rotating, superfluid, superconductor surrounding the solar core and/or (2) superfluidity and quantized vortices in nucleon-paired Fermions at the core [3].     

废放射源整备用封装管的设计与检测

研制废放射源整备封装管,使整备后废放射源满足处置或者长期贮存要求,是废放射源管理的重要组成部分。本文针对不同活度、不同核素的废放射源,设计制造了不同的封装管,并对其中的螺纹封装管进行了跌落性、抗冲击性、耐热性等一系列检测。检测结果表明,本研究设计的封装管,满足封装废放射源的要求。     

Calculation of Distribution Ratios of Rare Earth Elements in Multistage Counter Current Extraction with HDEHP

Extraction of rare earth elements with di (2-ethylhexyl) phosphoric acid (HDEHP) - tributyl-phosphate (TBP)-n-paraffin system was studied as functions of concentrations of the quantity of H⁺ released into aqueous phase. The ratio of rare earth elements extracted into organic phase was found to depend on the initial composition of the aqueous solution. The ratios determined for various concentrations of rare earth elements and acid were shown as a linear function of the concentrations of acid in aqueous phase and that of rare earth elements in organic phase after extraction. The acid concentration in aqueous phase after extraction can be estimated from any initial concentrations of acid and rare earth elements in aqueous solution by this equation. Also a graphic process of experimental results could give approximate values of distribution ratio for various initial concentrations of rare earth elements and nitric acid. For calculation of the distribution ratio of each stage in multi-stage counter current extraction, a computation code was programmed on the basis of the graphical process. The calculated values agreed well with those obtained experimentally in multistage extraction.     

双单元建筑物的换气速度和内部流动的测量

采用示踪气体稀释法对选定的双单元建筑物的换气速度和内部流动进行了测量,以期建立一种实际测量的方法,同时获得一些有用的数据。测量结果表明,选定的建筑物具有令人满意的换气速度,内部流通良好,可满足室内空气质量的要求,但对污染事故的屏蔽能力较差。本工作可以为研究室内空气质量和建筑物屏蔽因子提供一些借鉴。     

口服二巯基丁二酸治疗慢性汞中毒

应用二巯基丁二酸胶囊对某厂46名接触汞职工进行了驱汞治疗。通过口服、低剂量、间隔用药,并补充必需微量元素,经过2～5个疗程,职工尿汞较驱汞前显著降低,并有28名职工尿汞恢复至2倍正常参考值以下,整个驱汞过程无任何不良反应发生。     

The Oblique Incident Effects of Electromagnetic Wave in Atmospheric Pressure Plasma Layers

The propagating behaviours, i.e. phase shift, transmissivity, reflectivity and absorp- tivity, of an electromagnetic （EM） wave in a two-dimensional atmospheric pressure plasma layer are described by the numerical solutions of integral-differential Maxwell＇s equations through a generalized finite-difference-time-domain （FDTD） algorithm. These propagating behaviours are found to be strongly affected by five factors： two EM wave characteristics relevant to the oblique incident and three dimensionless factors. The two EM wave factors are the polarization mode （TM mode or TE mode） and its incident angle. The three dimensionless factors are： the ratio of the maximum electron density to the critical density no/nor, the ratio of the plasma layer width to the wave length d/λ, and the ratio of the collision frequency between electrons and neutrals to the incident wave frequency veo/f.     

Backscattering of Gamma-Rays from Semi-Infinite Stratified Slabs of Alternating Tin and Aluminum Layers

The backscattering of γ-rays has been investigated from semi-infinite stratified slabs of alternating layers of tin and aluminum. The energy spectrum and the angular distribution of backscattered photons, as well as the number and energy albedos were obtained for ⁶⁰Co and ¹³⁷Cs point isotropic sources. They were compared with the data obtained with single layers of tin and aluminum. The stratified slabs of alternating layers were assumed in this study to be equivalent in property to a homogeneous mixture of tin and aluminum, and the effective atomic numbers were computed on this basis. The resulting values are found to agree with the effective atomic numbers corresponding to the albedo values obtained for the alternating layers.     

弥散燃料板芯体中U-Mo/Al-Si合金基体反应层性质研究

针对弥散型燃料板采用实验方法分析U-Mo燃料相与Al-Si基体反应层的性质。实验结果表明:反应层主要出现在U-Mo燃料颗粒的内部微裂纹处及燃料颗粒与基体界面处,其形貌和厚度均不规则。U-Mo与Al-Si遵循空位扩散机制,扩散过程主要为Al、Si向U-Mo合金的扩散。在反应层中Al含量基本维持不变,Si含量沿基体-燃料相方向递增,并聚集在U-Mo侧的反应层中。当基体中Si含量达到5%时,可明显抑制扩散反应的进行,从而改进燃料板性能。     

The Oxygen to Carbon Ratio in the Solar Interior: Information from Nuclear Reaction Cross-Sections

Mass separation in the Sun may explain a serious difficulty that has plagued nuclear astrophysics for decades: Why the oxygen to carbon ratio in the Suns photosphere is only two, O/C 2. After correcting for mass fractionation, the ratio of these helium-burning products in the Sun is much larger, O/C 9–10. The lower value, O/C 9, is probably more reliable. It is based on measurements of mass separation of stable noble gas isotopes in the solar wind over the mass range of 3–136 amu. The higher value, O/C 10, is based on a comparison of neutron-capture cross-sections and the abundances of s-products in the photosphere over the mass range of 25–207 amu. Both methods indicate that Fe, Ni, O, Si, and S are the most abundant elements in the Sun. These elements are produced in the deep interior of supernovae.