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本文报导了合成109号元素的实验。用能量为4.95,5.05和5.15MeV/u 的~(58)Fe 束轰击~(209)Bi 靶,研究了全熔合产物衰变模式的特性。总辐照剂量为7×10~(17)粒子。所用的实验方法是:用静电场速度过滤器在飞行过程中分离向前方向成峰的反应产物,经过飞行时间装置后注入到位置灵敏固态探测器中,测量其动能,估算出质量、入射的时间和位置。以所有的出射粒子的能量和时间来记录很有限的反应产物发生级联α粒子和(或)自发裂变的继发衰变。在5.15 MeV/u 时的一个特别的衰变过程是:在5ms 和22ms 先分别发射两个α粒子,最后,在13s 后发生自发裂变。第一个α粒子的动能为11.10±0.04MeV。对各种可能的解释进行了详细的分析,例如纯属偶然的信号相关,转移反应产物的衰变和从能量上看允许的余核蒸发等。最后表明质量数为266的109号元素的同位素、即全熔合后的单中子蒸发道、从统计的观点看是最好的指定。本文同时也讨论了合成新元素的前景。 相似文献
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液体表面分子间的吸引力、液体表面的分子有一种使其面积缩成最小的力,或称一种抵抗表面积扩张的力,此力称“表面张力”.液体表面是指液体与空气或其他液体相接触的自由面.若不指明,即可认为相对于空气而言.表面张力的大小与接触面的物质有密切关系.此外,表面张力还与温度有关,温度越高,表面张力越小.表面张力的方向总是与液面相切,与分界线相垂直.若在液面作一长为L的直线,将液面分成两部分,这两部分之间的相互牵引力为F,即表面张力F=σL.其中σ为液体表面张力系数.单位为N/m.由于表面张力的作用,液滴表面有收缩到最小的趋势,而使液滴成近似球形的状态. 相似文献
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主要对上海光源(SSRF)束流位置监视器(BPM)支撑的机械稳定性进行了研究.受有限元计算与初始设计方案的振动测试结果不一致的启发,对BPM支撑与地面的连接考虑了三种方案:膨胀螺母、半灌浆与全灌浆连接.通过采用改进的全灌浆连接来代替初始设计的膨胀螺母连接,BPM支撑的横向最低共振频率由20.2Hz增加到50.2Hz,支撑顶部与地面的横向均方根位移(4-50Hz)之比由4.36降低到1.32,机械稳定性能得到大大的提高. 相似文献
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穿孔板结构在水下有着非常广阔的应用前景,但是目前相关的研究报道非常少.基于空气中穿孔板吸声理论,综合考虑小孔的末端修正,给出了较为准确的水下穿孔板声阻抗表达式.利用传递矩阵法分析了水下穿孔板结构的声压透射特性,得到了垂直入射声压透射公式.对影响穿孔板结构透声性能的主要因素进行了详细的仿真分析,得到了一些重要的结论.采用四传感器测量方法在驻波管中对自制的穿孔板结构进行了测试,实验结果与理论分析基本一致,从而验证了理论分析的正确性.本文为水下穿孔板结构的设计提供了详细的理论和实验依据. 相似文献
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在对物理规律(定理、定律、法则)的基本内容、表述形式、适用条件及范围,有了清楚认识的前提下,对规律的运用进行一些基础的规范化的训练,是必不可少的一步.但要达到"灵活应用"的程度,还必须在解题的过程中反复体会,几经磨砺.习题教学中若能在"活"字上做文章,便能取得事半功倍的效果.为此,应注重做好以下"四个一". 相似文献
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用于中国散裂中子源CSNS的环射频铁氧体同轴谐振腔,工作频率在1.02MHz至2.42MHz.论文对决定腔性能的铁氧体环材料进行了性能测试研究.通过改变铁氧体环的偏置磁场来改变铁氧体的磁导率,使腔的等效电感发生变化,从而使得LC并联谐振回路的谐振频率改变,进而获得铁氧体环在不同频率,不同高频磁场强度下的μrqf、品质因数和功率密度值.本文比较了几种不同铁氧体环的测量结果,选择适合于CSNS的环射频铁氧体谐振腔的材料为4M2. 相似文献
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非典型耦合下二价原子能级的精细结构 总被引:1,自引:1,他引:0
在典型耦合理论基础上,给出了在非典型耦合下计算二价原子精细结构能级的理论公式,并将理论应用到若干具体问题,结果与实验数据相符,且直观地显示出典型耦合只是非典型耦合的特例。 相似文献
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The electron attachment properties of cyanoacetylene HCCCN are
investigated with particular emphasis on the coupling between
dipole-bound and valence states. As an initial step both the
dipole-bound and the valence state of HCCCN- are studied separately
using high level ab initio methods. Predictions for the geometry of
the valence anion, the electron binding energy of the dipole-bound
state, the energy of the temporary anion associated with vertical
attachment into the valence state, the vertical detachment energy of
the valence anion, and the adiabatic electron affinity of HCCCN are
given. Our results indicate that the electron affinity found in the
NIST web-book is not that of HCCCN but of some other C3HN
species. The two anionic states interact with each other, and we study
their electronic coupling by computing the two electron binding
energies along one- and two-dimensional cuts through the potential
energy surfaces, and fitting a diabatic model potential to the ab
initio data. In particular, the two-dimensional cuts allow us to
examine the geometry dependence of the electronic coupling, and to ask
the question whether the coupling elements inferred from
one-dimensional cuts represent typical values. Moreover, the influence
of the theoretical method on the computed coupling elements is
investigated, and the possibility of employing the diabatic model
potential as a mean to extrapolate bound state binding energies into
the metastable domain is pointed out. 相似文献
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本文以原子结构的拉卡方法为基础,从三价原子的拉卡基出发,反复利用三个角动量耦合的基本关系以及3j、6j、9j符号的性质,具体推导了(n1 l1)(n2 l2)(n3l3)和(n1 l1)2(n3l3)组态下三价原子非相对论哈密顿矩阵元的计算式,除径向部分用Slater-Condon径向积分表示以外,完成了所有的角向积分与自旋求和;简要举例说明了如何利用该矩阵元计算式推导三价原子非相对论谱项能量表达式以及利用变分原理确定其中的Slater-Condon径向积分,从而求出具体的谱项能量数值.可以说,本文已建立起三价原子非相对论性能级结构的一般理论. 相似文献
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Qin Wang Zhiguo Lü Hang Zheng 《The European Physical Journal B - Condensed Matter and Complex Systems》2016,89(4):109
The coupling effects on the optical absorption spectrum of semiconductor quantum dots arestudied by using the standard model with valence and conduction band levels coupled todispersive quantum phonons of infinite modes. By deducing the analytical expression of theoptical absorption coefficient, the relationship between the measurable quantities and theintrinsic properties of the semiconductor quantum dot is established. By this expression,the peak position, the line shape, the linewidth, and the energy shift of the absorptionspectrum of semiconductor quantum dot can be calculated precisely for a wide range ofparameters. The role of coupling strength as a mechanism of absorption line asymmetry isinvestigated, and the calculation results clearly show the coupling-induced asymmetry inthe absorption line. This analytical approach is applied to GaAs quantum dot, and theresults are consistent with those of experiment observations. 相似文献
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Harmonic and anharmonic symmetry force constants matrices have been calculated using a stepwise coupling method for the twelve isotopic species of nitrosyl fluoride, chloride and bromide. The valence force fields derived from the above matrices were used to recalculate the normal frequencies and the potential energy distribution among force constants. The valence force fields are compared with others previously reported obtained by different methods. 相似文献
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The exact vibration-rotation quantum mechanical kinetic energy operator (KEO) for centrally-connected penta-atomic molecules such as methane and its isotopomers is derived for two sets of internal valence coordinates: the polyspherical coordinates and the bond-angle valence coordinates. The vibrational KEO including the pseudo-potential term is discussed for two forms of the modified Jacobian. For the rotational and vibration-rotation coupling KEO, results for two schemes of embedding the body-fixed coordinate system are presented: the bond embedding and the bisector embedding. Full expressions for the bisector embedding are too complicated to give in detail, but the working connection between the two embedding schemes is given. The future applications, including the perturbative and variational calculation of the vibrations and/or rotations for centrally connected penta-atomic molecules using the vibration-rotation KEO expressions derived in this work, are discussed. 相似文献
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We calculate the static magnetic susceptibility and specific heat of a model periodic system, with valence fluctuations between two magnetic configurations, intended to describe intermediate valence Tm compounds.These properties are derived from an expression for the free energy obtained using the coherent potential approximation, which properly takes into account the correlation energy and the configurational entropy.The resulting properties are in reasonable agreement with the experimental data. Unlike the results found in the commonly studied Anderson model, we find divergences in the magnetic susceptibility that indicate the onset of ferromagnetic order for some values of the model parameters. 相似文献