利用智能手机磁传感器研究磁阻尼摆运动

基于Phyphox手机App,将圆柱形钕铁硼磁铁构成的单摆放在黄铜或铝板表面不同距离摆动,利用智能手机磁传感器研究磁阻尼摆运动。结果表明,相同距离下,黄铜和铝板阻尼系数基本与电导率成正比。对于铝板,磁阻尼摆离开板距离从50mm减小到18mm时,阻尼系数从1.139×10^-2s^-1增加到1.114×10^-1s^-1,随距离的变化可以用指数函数来拟合。当距离减小到2.5mm时,观察到临界阻尼现象。当磁阻尼摆离开铝板表面距离为18mm,铝板厚度从1.001mm增加到5.615mm时,磁阻尼系数从9.378×10^-2s^-1增加到1.967×10^-1s^-1。实验结果与基于磁偶极子的理论模型基本一致。本文所搭建的磁阻尼摆实验装置结构简单,研究内容丰富,特别是能定量地研究磁阻尼现象,可以作为居家物理实验开设。     

ZBLAN玻璃中Pr3+掺杂离子3P0和1D2能级的发光特性和寿命

对ZBLAN氟锆酸盐玻璃中Pr³⁺掺杂离子³P₀和¹D₂能级的寿命和发光特性进行了较详细的光谱学研究。首先测量了两种掺杂浓度(质量分数分别为1×10^-3,5×10^-3)的Pr³⁺:ZBLAN玻璃的吸收光谱,然后运用时间分辨激光光谱技术测量了³P₀和¹D₂能级在激光单光子共振激发下的荧光发射谱和能级寿命。将不同荧光发射谱带的强度和文献报道的Judd Ofelt理论计算辐射跃迁几率数值做了比较分析,证明了文献中理论计算结果的可靠性。由于浓度猝灭效应,在相同的激发条件下,掺杂浓度为1×10^-3样品的荧光发射强度明显大于5×10^-3样品的荧光发射强度。但是从我们的测量结果看,掺杂浓度对³P₀和¹D₂ 的能级寿命值无显著影响。掺杂浓度为1×10^-3时,Pr³⁺离子³P₀和¹D₂能级的寿命值分别为46,322μ_s。     

Li2Mo2O6多晶材料的结构与电性能的研究

本文用固相反应烧结制备出Li₂Mo₂O₆多晶材料。经X射线分析、红外光谱和电子顺磁共振谱(EPR)的研究,确定了它的结构是Li₂Mo₂O₄和MoO₂两个晶相组成的烧结体。钼离子以四价状态存在于MoO₂晶相结构中。采用交流阻抗谱分析了晶界与温度变化的相关性。测得了样品的ln(σ_总T)-1/T 曲线是由两段直线和一段曲线所组成;总电导率化能σ_27℃=1.36×10^-3(Ω·cm)^-1,σ_115℃=1.49×10^-3(Ω·cm)^-1,σ_300℃=9.71×10^-3(Ω·cm)^-1,σ_370℃=2.42×10^-3(Ω·cm)^-1;电导活化能E₁=0.043eV,E₂=0.235eV,E_平均=0.76eV。采用维格纳极化电池法测得电子电导率σ_e,σ_e27℃=2.240×10^-5(Ω·cm)^-1,σ_e300℃=4.476×10^-3(Ω·cm)^-1。实验证明,室温下材料为固体电解质,300℃附近为良好的离子与电子混合导体。 关键词：     

电子的原子散射因子解析表达式的拟合

本文用阻尼最小二乘法将国际X射线结晶学手册中全部中性原子的电子散射因子数据,从(sinθ)/λ等于0.0到2.0的范围内,拟合成包含九个参数的解析式 f(s)=sumfrom i=1to4 (a_ie^{-b_is2))+c.用相对偏离因子R=sumfrom k=1toN (f_ok+f_ok)/sumfrom k=1toN (f_ok)作为估计原子散射因子计算值与观测值之间相对偏离程度的判据。计算结果表明,各种原子散射因子的相对偏离因子R约为10-3。文中除列出参数表外,还给出了相对偏离因子、最大误差、平均误差、均方差以及偏差方和。 关键词：}     

锐钛矿金红石的高温原位X射线衍射研究

对TiO₂粉末进行了空气和真空条件下从室温到1200℃的加热原位X射线衍射实验, 得到了空气和真空条件下微米级锐钛矿颗粒转变为金红石的起始温度分别为850℃ 和855℃; 分别修正了空气条件下锐钛矿在(27–850℃)范围和金红石在(900–1200℃) 范围内的晶胞参数和真空条件下锐钛矿在(27–850℃)范围和金红石在(950–1200℃) 范围的晶胞参数, 从而得到了晶胞参数随温度变化的关系, 得到了锐钛矿和金红石在空气中和真空中的热膨胀系数, 并总结了热膨胀系数随温度变化的规律. 室温下锐钛矿在空气条件下的热膨胀系数为 α_a=4.55063×10^-6/℃, α_c=7.7543×10^-6/℃, β=16.85836×10^-6/℃; 真空下为 α_a=4.69429×10^-6/℃, α_c=9.02850×10^-6/℃, β=18.69688×10^-6/℃. 室温下, 金红石在空气条件下的热膨胀系数为 α_a=6.81243×10^-6/℃, α_c=8.71644×10^-6/℃, β=22.22178×10^-6/℃; 真空条件下为 α_a=6.05834×10^-6/℃, α_c= 8.39280×10^-6/℃, β=20.52362×10^-6/℃. 关键词： 2')" href="#">TiO₂ 原位X射线衍射 相转变 热膨胀     

Exploring hidden-charm and hidden-strange hexaquark states from lattice QCD

Based on five different ensembles of newly generated (2+1)-flavor configurations with pion mass of approximately m_π■(140-310) MeV, we present a lattice analysis of hidden-charm and hidden-strange hexaquarks with the quark content ■. The correlation matrices of two types of operators with J^PC=0⁺⁺, 0^-+, 1⁺⁺ and 1^-- are simulated to extract the masses of the hexaquark candidates, which are subsequently extrapolated to the physical pi...     

变换参考系解二体问题

【题目】真空中质量分别为m₁和m₂的两个小球,只受万有引力作用,某个时刻两个小球相距l₀,小球1的速度为v₀,方向指向小球2,小球2的速度为v₀,速度方向垂直两球球心的连线,问若m₁=m₂=m₀,当速度v₀满足什么条件时,两小球的间距可以为无穷远?解法1:惯性参考系法（质心参考系）解题思路:寻找惯性参考系,分析两小球相对于惯性参考系的受力,确定两小球在惯性参考系的运动特点,直接运用牛顿运动定律或能量守恒求两小     

H2（V=3）+H2（He）碰撞中的转动能量转移

激发态Na₂与H₂碰撞,使H₂（V=3,J=3）得到布居,在H₂和He总气压为800 Pa及温度为700 K的条件下,利用相干反斯托克斯拉曼散射（CARS）光谱技术研究了H₂（3,3）与H₂（He）间转动能量转移过程.改变CARS激光束与激发Na₂的激光之间的延迟时间,测量He不同摩尔配比时H₂（3,J）态CARS谱强度的时间演化,得到H₂（3,3）的总弛豫速率系数分别为k_3,3^H₂=（21士5）×10^-3cm³·s^-1和k_3,3^H_e=（5.6士1.6）×10^-13cm³·s^-1.测量H₂（3,J）各转动态的相对CARS谱强度,由速率方程分析,得到H₂（3,3）+H₂→H₂（3,J）+H₂中,对于J=2,4,转移速率系数分别为（11±4）×10^-13cm³·s^-1和（8.2±3.1）×10^-13cm³·s_<sup>-1.在H₂（3,3）+He→H₂（3,J）+He中,对于J=2,4,转移速率系数分别为（3.1±1.2）×10^-13cm³·s^-1和（2.1士0.7）×10¹³cm³·s^-1.对于H₂（3,3）,单量子弛豫|△J|=1约占该态总弛豫率的90%.     

Nd3+螯合物的含氢有机溶液光谱性能研究

研究了Nd(TTA)₃螯合物溶于二甲基甲酰胺溶剂的光谱性质，溶液中所有氢未置换为氘.测量了这种溶液体系的吸收谱、荧光谱和荧光寿命.在898和1058 nm波长处观察到明显的Nd³⁺荧光特征峰.用Judd-Ofelt理论对吸收谱进行分析计算，得到了三个强度参数Ω_t(t=2,4,6)分别为Ω₂=4.9×10^-20 cm², Ω₄=5.1×10^-20 cm²和Ω₆=2.5×10^-20 cm².利用强度参数计算了⁴F_3/2能级与⁴I_9/2和⁴I_11/2之间的跃迁强度S_ed、自发辐射系数A_ed以及荧光分支比β等，估算了⁴F_3/2能级的辐射跃迁寿命τ_r＝682 μs.实测1058和898 nm波长处荧光寿命τ大约为460和505 μs，因此荧光量子效率分别高达0.67和0.74.荧光量子效率高表明Nd³⁺在这种溶液中无辐射跃迁比较弱；强度参数Ω₂比较大，表明Nd³⁺在溶液中具有不对称配位场环境，不对称的配位场环境可大大促进Nd³⁺吸收激发能量.光谱质量因子Ω₄/Ω₆>1，使得898 nm的辐射强于1058 nm的辐射. 关键词： Nd 有机溶液 光谱性能 Judd-Ofelt理论     

吸附在活性炭、三氧化二铝和硅胶上分子的核弛豫研究

本文提出核与电子偶极相互作用和自旋扩散两种作用在被吸附到固体多电子表面上的分子弛豫起着重要作用,给出了自旋晶格弛豫时间(T_1e)和相关时间(τ_c)的关系:T_1e,-kτ_c/1+ω₀²τ_c²)^1/2,式中k对给定固体是常数。吸附在硅胶上甲苯的弛豫数据可用此式描述。得到了甲苯中甲基在不同温度下的τ_c。,它们在374K到240K间的相关时间在3.56×10^-9 s到5.76×10^-8 s范围。由此计算出其活化能为15.0kJ/mol。     

Zero value of the Schwarzschildian mass of asymptotically euclidian time-symmetrical gravitational waves

It is shown that a coordinate system with simple coordinate conditions can be chosen such that one can explicitly see that the Schwarzschildian mass of an asymptotically Euclidian time-symmetrical system of gravitational waves is equal to zero. It is explicitly seen in the coordinate system with coordinate conditions ? _i (?gg ^ik)=0 and in the set of coordinate systems with the coordinate condition ? _i (?gg ⁰ⁱ )=0. In this set of coordinate systems one of the field equations can be written in the form \( - 8\pi \surd ( - g)(T_0^0 - \tfrac{1}{2}T) = \partial _\alpha L_0^{0\alpha } \) where \(L_i^{kn} = \tfrac{1}{2}\surd ( - g)(g^{mn} \Gamma _{im}^k - g^{km} \Gamma _{im}^k )\) , α=1, 2, 3. From this equation it follows that \(m = 2\smallint ({\rm T}_0^0 - \tfrac{1}{2}T)\surd ( - g) dV\) , andm=0 atT _i ^k =0.     

Influence of the weakly interacting light U boson on the properties of massive protoneutron stars

Considering the octet baryons in relativistic mean field theory and selecting entropy per baryon S=l,we calculate and discuss the influence of U bosons on the equation of state,mass-radius,moment of inertia and gravitational redshift of massive protoneutron stars(PNSs).The effective coupling constant gu of U bosons and nucleons is selected from 0 to 70 GeV~(-2).The results indicate that U bosons will stiffen the equation of state(EOS).The influence of U bosons on the pressure is more obvious at low density than high density,while the influence of U bosons on the energy density is more obvious at high density than low density.The U bosons play a significant role in increasing the maximum mass and radius of PNS.When the value of gu changes from 0 to 70 GeV~(-2),the maximum mass of a massive PNS increases from 2.11M_⊙ to 2.58M_⊙,and the radius of a PNS corresponding to PSR J0348+0432 increases from 13.71 km to 24.35 km.The U bosons will increase the moment of inertia and decrease the gravitational redshift of a PNS.For the PNS of the massive PSR J0348+0432,the radius and moment of inertia vary directly with gu,and the gravitational redshift varies approximately inversely with gu.     

Charged axially symmetric solution and energy in teleparallel theory equivalent to general relativity

An exact charged solution with axial symmetry is obtained in the teleparallel equivalent of general relativity. The associated metric has the structure function G(ξ)=1-ξ²-2mAξ³-q²A²ξ⁴. The fourth order nature of the structure function can make calculations cumbersome. Using a coordinate transformation we get a tetrad whose metric has the structure function in a factorizable form (1-ξ²)(1+r₊Aξ)(1+r_-Aξ) with r_± as the horizons of Reissner–Nordström space-time. This new form has the advantage that its roots are now trivial to write down. Then, we study the singularities of this space-time. Using another coordinate transformation, we obtain a tetrad field. Its associated metric yields the Reissner–Nordström black hole. In calculating the energy content of this tetrad field using the gravitational energy-momentum, we find that the resulting form depends on the radial coordinate! Using the regularized expression of the gravitational energy-momentum in the teleparallel equivalent of general relativity we get a consistent value for the energy.     

Topological and physical effects of rotation and spin in the general relativistic theory of gravitation

Interrelations of the intrinsic momentum (spin), rotation of material distributions, and intrinsic momentum of the gravitational field are investigated in the context of the general relativistic theory of gravitation involving the general relativity theory (GRT) and the Einstein-Cartan theory. It is demonstrated that the spin density vector of the gravitational field s _g ⁱ is equal to the rotor of the tetrad reference point ωⁱ=ɛ^iklm e _k ^(a) e_(a)l,m/2 to within the factor 1/κ (s _g ⁱ =ω/κc). It is demonstrated that the vector s _g ⁱ is proportional to the spin density vector of the gravitating field sⁱ (ω)=jc(Ψγⁱγ₅Ψ)/2 as well as the pseudovector of space-time torsion Qⁱ in the Einstein-Cartan theory, which in both cases induces a cubic nonlinearity of the spinor field. An expression for the energy-momentum density tensor of the eddy gravitational field is derived. It is also demonstrated that the free eddy gravitational field with polarized spin can form “mole holes.” An ideal fast-rotating self-gravitating fluid can cause a similar effect. The corresponding exact solutions of joint systems of the Einstein and rotating ideal fluid equations are presented. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 57–60, October, 2007.     

Search for strong gravitational lensing effect in the current GRB data of BATSE

Because gamma-ray bursts(GRBs)trace the high-z universe,there is an appreciable probability for a GRB to be gravitational lensed by galaxies in the universe.Herein we consider the gravitational lensing effect of GRBs contributed by the dark matter halos in galaxies.Assuming that all halos have the singular isothermal sphere(SIS)mass profile in the mass range 1010h?1M?M2×1013h?1M?and all GRB samples follow the intrinsic redshift distribution and luminosity function derived from the Swift LGRBs sample,we calculated the gravitational lensing probability in BATSE,Swift/BAT and Fermi/GBM GRBs,respectively.With an derived probability result in BATSE GRBs,we searched for lensed GRB pairs in the BATSE5B GRB Spectral catalog.The search did not find any convincing gravitationally lensed events.We discuss our result and future observations for GRB lensing observation.     

三分子反应模型涨落的临界行为

本文讨论了三分子反应模型在1+k₃A²<[1+A((k₃D₁)/D₂)^1/2]²情况下的临界行为。由于在临界点附近不稳定模式是空间均匀的,因此可由总粒子数满足的生-灭方程来讨论。我们引入了涨落波的幅度作为描述涨落分布突变的参数。在利用重整化方法迴避了定态解在临界点上涨落发散所引起的困难后,得到了描述平均密度及涨落分布临界行为的广义Landau-Ginzburg方程。解析及数值分析表明,当B增大越过临界点B_m,平均密度达到周期变化的稳态,这和反应扩散方程结果是一致的,涨落二阶矩一般也达到一周期稳态,振幅很大而且主要由平均密度振动的幅度所决定。因此从涨落分布的突变来看,B_m并不与典型的二类相变类似。 关键词：     

Nonlinear gravitational waves in plasma

An exact solution is obtained for the relativistic collisionless kinetic equations describing a test plasma in the field of a strong plane gravitational wave. The gravitational wave induces in the plasma a longitudinal electric current whose amplitude is maximum at temperatures Te ip m_ec². The interaction of gravitational waves with a system consisting of Boltzmann ions and degenerate electrons is also considered.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 20–24, July 1981.The authors thank G. G. Ivanov for a number of valuable comments.     

Solar neutrino oscillation parameters after KamLAND

We explore the impact of the data from the KamLAND experiment in constraining neutrino mass and mixing angles involved in solar neutrino oscillations. In particular, we discuss the precision with which we can determine the mass squared difference Δm _⊙ ² and the mixing angle θ_⊙ from combined solar and KamLAND data. We show that the precision with which Δm _⊙ ² can be determined improves drastically with the KamLAND data, but the sensitivity of KamLAND to the mixing angle is not as good. We study the effect of enhanced statistics in KamLAND as well as reduced systematics in improving the precision. We also show the effect of the SNO salt data in improving the precision. Finally, we discuss how a dedicated reactor experiment with a baseline of 70 km can improve the θ_⊙ sensitivity by a large amount.     

关于等离子体中的瞬变过程

利用Spitzer的广义欧姆定律分析等离子体中由垂直于磁场的压强梯度所引起的宏观瞬变性质。在垂直于磁场方向的初始流动速度为零的条件下,得出在恒稳磁场中的瞬时扩散系数(当ω_ceτ?1)为 D= (2km_ec²)/e² T/(B²τ)+(kc)/eT/Be^-m_e/(miτ)tsinω_cit,式中τ为电子离子的平均碰撞时间间隔。     

Effective field theory for massive gravitons and gravity in theory space

We introduce a technique for restoring general coordinate invariance into theories where it is explicitly broken. This is the analog for gravity of the Callan-Coleman-Wess-Zumino formalism for gauge theories. We use this to elucidate the properties of interacting massless and massive gravitons. For a single graviton with a Planck scale M_Pl and a mass m_g, we find that there is a sensible effective field theory which is valid up to a high-energy cutoff Λ parametrically above m_g. Our methods allow for a transparent understanding of the many peculiarities associated with massive gravitons, among them the need for the Fierz-Pauli form of the Lagrangian, the presence or absence of the van Dam-Veltman-Zakharov discontinuity in general backgrounds, and the onset of non-linear effects and the breakdown of the effective theory at large distances from heavy sources. The natural sizes of all non-linear corrections beyond the Fierz-Pauli term are easily determined. The cutoff scales as Λ∼(m_g⁴M_Pl)^1/5 for the Fierz-Pauli theory, but can be raised to Λ∼(m_g²M_Pl)^1/3 in certain non-linear extensions. Having established that these models make sense as effective theories, there are a number of new avenues for exploration, including model building with gravity in theory space and constructing gravitational dimensions.