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1.
高激发213Fr核的形变研究 总被引:1,自引:0,他引:1
对132MeV^16O ^197Au反应产生的断变碎片和巨偶极共振γ射线进行了符合测量,得到了E^*=92MeV的高发^213Fr的γ衰变谱和γ角关联谱,观测到复合核巨偶极共振γ角关联谱存在很大的各向异性,利用改进的统计模型程序分析了实验数据,不考虑裂变延迟时,统计模型计算可以很好拟合地实验结果,通过对γ角关联谱的理论计算与实验结果的比较,可以得出高激发^213Fr核(E^*=92MeV)的形状从长集体长椭球向非集体扁椭球变化。 相似文献
2.
在微观Vlasov方程的框架下,研究了11Li核的巨偶极共振.正常的及软巨偶极共振的计算结果都与实验值较好地符合.这两种模式对平均场自旋-轨道耦合力的依赖都十分敏感.而11Li中子晕的分布仅对软巨偶极共振有着十分重要的效应.同时也讨论了中子分离能的影响. 相似文献
3.
本文讨论了高激发核中的同位旋标量表面巨共振和偶极巨共振.利用能量权重求和规则的概念在一个简化的模型中计算了208Pb的巨共振能量,而有限温度下的推广的Thomas-Fermi近似则被用于描写有限温度平衡态.结果表明,能量权重求和规则和巨共振能量对体系温度的依赖都很弱.这一微弱的温度依赖可以归因于由温度引起的剩余相互作用的减弱以及参与跃迁的组态数增加这两个效应之间的相互抵消. 相似文献
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利用q变形转动惯量的转子模型,系统地计算了148Gd核6个超形变带的E2r跃迁能谱以及相应的动力学转动惯量随转动频率的变化关系.计算结果表明,q变形转动惯量的转子模型不仅能较精确地描述超形变晕带,而且可以描述超形变激发带. 相似文献
6.
本文介绍了第四次核核碰撞国际会议的主要报告内容,包括核结构、核反应机制、超相对论重离子碰撞、放射性核束及其核物理研究、核天体物理学及核技术应用.同时,也介绍了各个领域已经取得的最新进展及今后研究的热门课题. In this paper the main reports given on Nucleus—Nucleus Collisions International Con-ference Ⅳ are briefly introduced.It includes nuclear stracture,nuclear reaction mechanism,super rela-tivistic HIC,redioactive nuclear beams and its nuclear physics research,nuclear astrophysics and appli-cations of nuclear technigue.The Latest developments in every fields and the top research point in thenear future are introduced. 相似文献
7.
简要叙述了高温转动核电偶极巨共振实验研究的历史和现状,并着重介绍了现存的一些问题及新的探索. The history and current status of the experimental study of giant dipole resonance in hot rotating nuclei has been reviewed.Some open problems and new development are stressed. 相似文献
8.
用sdg IBM的内禀态,解析计算了稀土区的152—164Dy、154—168)Er、170—186W、168—194Os等偶偶同位素的基态形变,与其它理论及实验结果进行系统比较,表明sdg IBM能对核的形变作出很好的描述. 相似文献
9.
利用我们最近提出的Hill-Wheeler方程的一种数值解法,考虑动力学效应计算了172Os核转晕态的形状随转动频率的变化.所得结果比通常的总罗斯量面(TRS)计算的形变值更符合于实验测量值.这表明,至少对于像172Os这样的过渡核,核形变的动力学效应是不能忽略的. 相似文献
10.
朱凌燕 朱胜江 李明 J.H.Hamilton A.V.Ramaya B.R.S.Babu W.C.Ma J.O.Rasmussen M.A.Stoyer I.Y.Lee 《中国物理 C》1998,22(10):885-890
通过对252Cf自发裂变所产生的瞬发γ谱的实验研究,建立并扩展了丰中子核144,146Ce的高自旋和八极形变集体带,最高自旋态可达15-.对这两个核的八极形变特性进行了讨论. 相似文献
11.
It is shown that the lifetime of a nuclear excited state in the region of femtoseconds could be accurately measured by a precision measurement facility of a flat crystal spectrometer, if the angular correlation of two successive γ-rays in cascade decay is taken into account in the Doppler shift attenuation method. 相似文献
12.
高激发核物质液-气相变与核温度 总被引:6,自引:3,他引:3
评述了高激发核的激发能及核温度的测量方法,以及这些测量方法的可靠性.同时还根椐理论模拟的结果讨论了当前得到的核物质量热曲线中可能存在的问题,提出了进一步开展核物质量热曲线研究中温度测量的一些措施.The methods measuring excitation energies and temperature of highly excited nuclear matter and their reliability have been summarized. According to the research and simulation the measured caloric curve has been discussed and some suggestions for further investigation of nuclear temperature were pointed out. 相似文献
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利用转移反应11B(d,p)12B和12C(d,p)13C抽取12B<—>11B+n和13C<—>12C+n重叠函数的核渐近归一化常数,计算了12B和13C核中价中子密度分布的均方根半径及其在核外的几率.实验结果表明,12B的第二(Jπ=2-),第三(Jπ=1-)激发态和13C的第一(Jπ=1/2+)激发态为中子晕态,而13C的第三(Jπ=5/2+)激发态是中子皮态.考察了库仑势和角动量对晕形成的阻碍效应.提出了均方根半径对于有效核子分离能的统一的标度定律. 相似文献
14.
简要叙述了该课题研究的现状,并从核裂变和巨形变结合的观点上,对中重核和重核中的巨形变态研究提出一些看法,以推动对这个课题的探讨 . The recent development on investigation of hyperdeformation is outlined. From point of view of combining hyperdeformation with nuclear fission, a discussion on approaches for studying hyperdeformation is given for pushing ahead with this research. 相似文献
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Experimental and theoretical investigations towards a better understanding of the radiation mechanisms in WO2Br2-discharges, so-called “cluster lamps” are presented. The main purpose of the investigation is to find out whether a major part of the continuum emitted from these discharges, which in the past has been interpreted as thermal cluster radiation, could also originate from molecular band radiation, in particular from triatomic molecules in colder discharge regions. Comparing emission spectra of WO2Br2-discharges from different plasma regions, using lamps operated at different vapor pressures and power levels (i.e. non-LTE and LTE-discharges), we conclude that by far the major part of the strong continuum radiation emitted from WO2Br2 lamps is indeed thermal radiation of hot tungsten cluster particles. WO— (below 550 nm) and WO2-molecular radiation (above 650 nm), which is superimposed on the cluster continuum, also contribute to the total radiation output, but to a lesser degree. A crude model for WO2 molecular emission is presented. Unfortunately, the WO2 emission component greatly impedes proper fitting of the measured cluster continuum to a thermal cluster model. 相似文献
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We investigate the effects of the nuclear hexadecapole deformations on the interaction potentials between nuclei, the driving potentials and the fusion probabilities for some cold fusion reactions leading to super-heavy elements. It is found that nuclear hexadecapole deformations change significantly the structure of the driving potentials and the fusion probabilities for some reaction channels. 相似文献
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基于量子分子动力学模型,系统地研究了从48Ca到298114一系列核素在不同温度下的最大Lyapunov指数、密度涨落以及体系多重碎裂之间的关系.发现最大Lyapunov指数随温度变化有一峰值出现(该峰值所对应的温度为"临界温度"),在该临界温度时体系的密度涨落达到最大,碎块的质量分布能够给出较好的PowerLaw指数.通过对最大Lyapunov指数与密度涨落随时间变化行为的研究,发现密度涨落的时间尺度要大于混沌的时间尺度,意味着混沌的概念可以用来研究体系的多重碎裂过程.最后还给出了有限体系相变的临界温度随体系大小变化的规律. Within a quantum molecular dynamics model we calculate the largest Lyapunov exponent (LLE), the density fluctuation, and the mass distribution of fragments for a series of nuclear systems at different initial temperatures. It is found that the LLE peaks at the temperature ("critical temperature") where the density fluctuation reaches a maximal value and the mass distribution fragments is fitted best by the Fisher s power law from which the critical exponents for mass and charge distribution are obtain... 相似文献
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概要介绍了超形变核态的相互作用玻色子模型研究的现状、理论框架及一些应用.The present status, the framework and some applications of the investigation on the superdeformed nuclear states in the scheme of the interacting boson model are described. 相似文献
19.
利用动力学加统计模型对200Pb 系统的断前中子的发射进行了模拟。计算结果表明,在核耗散的形变关系(DDND) 确定的情况下,断前中子多重性会随着能级密度坐标关系(DDLDP) 的增强而减少,且该规律主要由第一阶段内断前中子的发射决定。此外,选定DDLDP 而采用核耗散的不同形变关系也都很好地重现了实验数据。为了解释上述现象,提出了研究热核退激的路径分析方法,其主要内容是把核耗散看成是实验粒子在拉伸维度上的阻尼力,而核裂变的动力学过程是该阻尼力和自由能产生的驱动力之间相互竞争的结果。利用该方法对200Pb 系统的断前中子多重性进行了分析,并指出在确定DDND时应考虑DDLDP。Within a certain deformation dependence of nuclear dissipation (DDND), the simulation results about the deexcitation process of 200Pb show that the prescission neutron multiplicities decrease with increasing deformation dependence of level density parameter (DDLDP). Moreover, this pattern is determined by the emission of prescission neutron in the first period of nuclear fission. On the other hand, all of the results from two kinds of different DDNDs can reproduce the experiment data perfectly with a certain DDLDP. In order to illustrate those phenomena, the pathwise analysis method (PAM) is presented in this paper. In the PAM, nuclear dissipation is treated as the damping force on the elongation dimension, whereas the fission dynamics process results from the competition between damping force and the driving force stemming from the nuclear free energy. The prescission neutron multiplicity in the deexcitation process of 200Pb is analyzed, and the results point out that the DDLDP needs to be taken into account in studying the DDND. 相似文献
20.
Gui-Fang Shan Wei Yang Ming-Bo Yang Bang-Hu Xie Qiang Fu Yiu-Wing Mai 《Journal of Macromolecular Science: Physics》2013,52(4):799-811
The strain rate, temperature, and microstructure-dependent, tensile-yielding behavior of three semi-crystalline polymers, namely high-density polyethylene (HDPE), polyamide 6 (PA6) and low-density polyethylene (LDPE), was investigated. It is found that, depending on the strain rate and temperature, the three polymers exhibit markedly different tensile deformation behavior, especially the shape of the stress-strain curves. LDPE exhibits a uniform extension and shows no obvious geometrically unstable effect, such as necking, during the overall tensile process. HDPE and PA6, on the other hand, show clear necking and cold-drawing phenomena during the uniaxial tensile process. When considering the effect of strain temperature on necking, significant differences between HDPE and PA6 emerge. For both, the heterogeneous necking disappears and homogeneous deformation occurs with increasing temperature. For HDPE, the homogeneous deformation takes place in the vicinity of the melting temperature, while for PA6, it takes place close to the glass transition temperature instead. The conventional yield point, corresponding to the force maximum in stress-strain curves, becomes less defined as the testing temperature is increased. It is applicable, to some extent, to combine the Brereton analysis and Considère construction to predict such a point quantitatively. However, this combination can only be suitable for homogeneously deformed material. In addition, it is found that the special, double yielding behavior will take place under certain deformation conditions for all three semi-crystalline polymers. With respect to judging the appearance of the double yielding of polymers, it seems that it can be estimated qualitatively by plotting the compression residual strain-applied strain curves of the samples. 相似文献