Rotational Bands of Some Neutron Deficient Odd-A Pt Isotopes in Particle-Triaxial-Rotor Model

Theoretical calculations are performed for neutron deficient Pt isotopes ^177pt and ^175,173,171 Pt in the particletriaxial-rotor model with variable moment of inertia. The obtained energy spectra agree with experimental data quite well. The calculated results indicate that all these nuclei are in triaxial rotation with ^177pt; being in prolate and ^175,173,171pt in oblate. Several levels are predicted for the 13/2^＋ band in ^169pt.     

磷钨磷钼钨Dawson型杂多化合物的合成

Dawson型磷钨杂多化合物(HPC)作为多相或均相催化剂,对烯烃环氧化反应极为有效[1]。在HPC中引入钼原子可以提高它的氧化能力;引入过渡元素如铜可以改善其氧化还原反应的可逆性[2]。目前已合成出Nb、Ti、Mn、Fe、Co等多种过渡元素取代的Dawson型HPC[3],并且证明其具有良好的氧化还原催化性能。本文以Na2WO4·2H2O和Na2HPO4·12H2O为原料合成了K10Na2H2P2W16O60,再以其为反应物合成了过渡元素镍、铜取代的磷钨、磷钼钨共三种Dawson型杂多化合物:K14[Ni2P2W16O62]·24H2O、K15H5[Ni(P2W16MoO61)2]·26H2O和K15H3[Cu(…     

MULTI-LAMBDA MATTER IN A CHIRAL HADRONIC MODEL

Multi-lambda matter is investigated in the framework of a chiral hadronic model. It is shown that multi-lambda matter consisting of {N,Λ} is a metastable state as the strangeness per baryon and the density of hadronic matter are varied. The effective lambda mass decreases as the baryon density increases, and remains larger than that of the nucleon.     

高自旋超形变带的代数模型研究

介绍高自旋超形变带的研究现状,提出一种可以统一描述超形变带的ΔI=4分岔现象、全同带现象等的代数模型,计算结果表明ΔI=4分岔现象可能起因于具有SO(5)(或SU(5))对称的微扰,全同带现象可能是产生超形变态的平均场具有超对称性的结果.     

Rotational Property of~(249)Cm in Particle-Triaxial-Rotor Model

We study the rotational energy spectrum and deformation feature of very heavy nucleus 249Cm in the particle-triaxial-rotor model with variable moment of inertia.Such a nucleus is the unique one involving both multiband structure and high spin states and locating very near the superheavy region.By calculating the energy spectrum,we determine the configurations and quadrupole and triaxial deformation parameters β and γ of the nucleus.The calculated results indicate that the high spin band of 249Cm is built upon the ν[620] 12+configuration with deformation parameters β = 0.296 and γ = 7.5 and the bands based on the ν[622] 32+,ν[613] 72+,ν[750] 12 configuration respectively are also the ones with quite large axial deformation but small triaxial deformation.     

Proton Fraction in Hot Neutron Star Matter with a Chiral Hadronic Model

In the framework of a chiral hadronic model it has been numerically proven that the parabolic expansion with respect to δ^2 at finite density and temperature is a good approximation in the relativistic mean field theory,It is also shown that the proton fraction in the modified Urca process is considerably restrained in comparison with that of the direct Urca process.Then,we discuss the influences of the density-dependent and temperature-dependent asymmetry energy on the proton fraction in hot neutron star matter.     

Description of Superdeformed Bands of the Nuclei in A ～60 Mass Region

Using the supersymmetry scheme including many-body interactions, we investigate the superdeformed (SD) bands of the nuclei in A ～ 60 mass region systematically. Quantitatively good results of the γ-ray energy spectra and the dynamical moments of inertia are obtained. It shows that the supersymmetry approach is powerful to describe the generic rotational property of SD states of light nuclei.     

北京大学物理学本科人才培养模式改革的探索

基于社会发展和学生素质的新特点,探讨了新的历史条件下人才培养的思路和模式：以人为本,尊重人才素质和发展目标的多样性与自主性,更加突出优秀创造性人才的培养;在确保高水准的基本知识传授和基本训练的同时,给学生以多样化的选择自由.对课程体系进行了模块化、结构化的改造,以适应多样化的需要.加强了学生选课指导和专业发展指导,以保障新的教学计划的实施.课外科技活动的范围逐步扩大,研究型学习成为培养学生创新能力的重要环节.     

原子核形状相变的壳模型研究

利用玻色映射方法, 我们在壳模型中计算了原子核低激发态性质的一些特征量, 并与这些量在相互作用玻色子模型的动力学对称性中的数值进行比较, 得到原子核的集体运动形状相在壳模型中的对应, 分析了壳模型中的单极对、四极对和 四极-四极相互作用对形状相的影响, 还在壳模型中研究了U(5)—O(6)相变过程, 得到的结果与在相互作用玻色子模型中得到的结果一致.     

GSR型金选择树脂对氰化液中Ag（Ⅰ）的吸附性能研究

本文研究了GSR金选择树脂对氰化液中Ag（Ⅰ）的交换量和选择性。结果表明，该类树脂对Ag（Ⅰ）的交换量明显大于活性炭。该树脂的选择系数[Ag（Ⅰ）／Fe（Ⅱ）]是普通阴树脂的80倍。采用GSR－05树脂的RIP工艺试验表明，金银的吸附率超过99％，其浸出回收率比锌置换工艺分别提高5．7和13．8个百分点。