中微子质量与宇宙超大尺度结构

由>10²Mpc的宇宙超大尺度结构推知我们的宇宙委可能主要是由热暗物质(中微子)所组成,其质量m_v～10^－1eV(0.16eV).     

银河宇宙线的统计模型

假设能量低于3×10^l8eV的宇宙线主要起源于银河系超新星爆发,用各向同性弥散传播模型详细研究了铁核的非定态空间密度分布,考虑到原初宇宙线的成份和河外宇宙线的影响,以及银河系超新星在空间和时间上的一个合理分布,该统计模型能很好解释10¹²—10²⁰eV宇宙线的观测谱.     

锗的正电子表面态的测量研究

通过测量低能正电子入射到锗(Ge)靶的电子偶素产额随靶温度的变化,测定了在真空度为1.33×10^－4Pa时锗的正电子表面态的束缚能E_b=2.2eV;Ps形成的激活能E_a=0.2±0.01eV.讨论了高真空与超高真空条件下E_b,E_a的变化.     

90Mo电磁跃迁几率的测量

利用束流能量为116MeV的⁵⁹Co(³⁵Cl,2p2n)⁹⁰Mo反应布居⁹⁰Mo的高自旋态.用10台反康普顿HPGe探测器组成的探测阵列进行γγ符合测量.通过多普勒展宽峰的形状分析测定⁹⁰Mo高自旋态的寿命.在正宇称衰变系观察到增强的M1跃迁,推断I=13以上是扁椭形变.负宇称高自旋态具有大的B(E2)值,并随自旋增大而起伏变化.正、负宇称态之间的跃迁显示增大的E1跃迁,似有八极关联的可能.但是,⁹⁰Mo并不处在理论预言的存在八极形变的核区内.     

133Sm和149Yb的β缓发质子衰变

利用⁴⁰Ca+⁹⁶Ru融合蒸发反应产生了近质子滴线核¹³³Sm, 配合氦喷嘴带传输系统采用“质子-γ”符合方法观测了它们的β缓发质子衰变, 其中包括半衰期、质子能谱、第二代子核低位态之间的γ跃迁, 并估计出衰变到第二代子核不同低位态的分支比. 通过统计理论拟合上述实验数据, 指认了¹³³Sm的自旋宇称的可能范围. 并用Woods-Saxon Strutinsky方法计算了限制组态的¹³³Sm的核势能面, 通过对比发现¹³³Sm的自旋宇称可能有两种成分:5/2⁺和1/2^－. 这一结果与2001年发表的¹³³Sm(EC+β⁺)衰变的简单衰变纲图是相容的. 此外用同一方法分析了2001年Eur. Phys.J.A12:1—4中发表的有关¹⁴⁹Yb的β缓发质子衰变实验数据, 由此指认了¹⁴⁹Yb的基态自旋宇称为1/2^－.     

B-X and C-X Band Systems of CuCl Revisited: Laser-induced Fluorescence Study in 465−490 nm

通过20400～21800 cm^-1的激光诱导荧光激发谱,重新研究了CuCl的B～X和C～X带系,洪特情形(a)的转动分析揭示出明显的单重态到单重态的跃迁特征. 测量的寿命(分别为4.670和4.667 μs)对于纯的单重态明显太长, 表明CuCl的B态和C态应该位于单重态(¹П和¹∑⁺)和三重态(³П_0,1,2)的混合区,光谱所观测到的这两个激发态可能是被临近三重态严重微扰的单重态.     

14C激发态中子晕

利用¹³C(d,p)¹⁴C反应实验数据,抽取转移反应重叠函数渐近归一化常数,计算了¹⁴C的1^－和0^－激发态的最后一个中子的密度分布的均方根半径和在核外的几率.研究结果表明,¹⁴C的1^－和0^－激发态为中子晕态.     

e+e－实验中ψ(2S)能区连续态单光子湮没过程的贡献

研究了e⁺e^－实验中ψ(2S)能区连续态单光子湮没过程的截面对观测总截面的贡献.针对ψ(2S)质量处ωπ⁰和π⁺π^－两个观测末态,利用唯象模型估计了单光子湮没过程贡献的大小.分析表明,对于ψ(2S)→ωπ⁰和ψ(2S)→π⁺π^－,以及其他电磁末态分支比的确定,单光子湮没过程的贡献必须认真考虑.通过研究,我们认为对于BES实验来说,为了获得共振态电磁末态分支比的正确结果,至少需要在低于ψ(2S)共振峰的能量点采集10pb^－1的数据.     

ZnO压敏陶瓷缺陷结构表征及冲击老化机理研究

对多元ZnO压敏陶瓷电阻片进行了多达14000次的大电流冲击老化试验, 通过显微结构、电气性能及介电特性的测量对其缺陷结构进行了表征, 并研究了缺陷结构与大电流冲击老化之间的关系. 试验表明多次大电流冲击老化导致试样的电气性能明显下降, 发现ZnO压敏陶瓷的几何效应不仅受控于晶粒还与晶界密切相关. 另外, 通过介电谱分析观察到ZnO压敏陶瓷存在四种缺陷弛豫过程, 低温-60 ℃下的两个缺陷弛豫峰激活能约为0.24 eV和0.35 eV, 认为它们分别对应着本征的锌填隙缺陷L(Zn_i^··)和氧空位缺陷L(V_O^·)并且不受冲击老化的影响. 高温80℃以上两个松弛峰的活化能约为0.71 eV和0.84 eV, 认为它们分别对应着非本征的晶间相电子陷阱L(ingr)和晶界处界面态陷阱L(gb). 发现大电流冲击后, 仅界面态陷阱激活能从0.84 eV降低到0.76 eV, 认为界面态陷阱主要控制着ZnO压敏陶瓷的电气性能和稳定性.     

Υ(3S)→Υ(1S)π＋π－衰变及一个可能的bbqq态

利用手征幺正方法研究了衰变\Upsilon(3S)→\Upsilon(1S)π^＋π^－.通过引入一个J^P=1^＋, I=1的中间态, 该衰变的π^＋π^－不变质量谱和cosθπ角分布都能够得到很好的解释. 同时,其他\Upsilon(nS)各态之间的π^＋π^－跃迁也能得到很好的描述. 通过拟合CLEO的数据,对这个态的质量和宽度作了预言. 该态的夸克组成应该是bbqq.     

A CoGeNT confirmation of the DAMA signal

The CoGeNT Collaboration has recently reported a rising low energy spectrum in their ultra low noise Germanium detector. This is particularly interesting as the energy range probed by CoGeNT overlaps with the energy region in which DAMA has observed their annual modulation signal. We show that the mirror dark matter candidate can simultaneously explain both the DAMA annual modulation signal and the rising low energy spectrum observed by CoGeNT. This constitutes a model dependent confirmation of the DAMA signal and adds weight to the mirror dark matter paradigm.     

Heterotic string dark matter from the graviton multiplet

In the string theory framework for physics beyond the standard model the hidden sector of E₈×E₈ heterotic string theory and the graviton multiplet provide compelling sources for the dark matter in the universe.

In the present investigation I consider the graviton multiplet as one particular dark matter source in heterotic string theory. In particular, it is pointed out that an appreciable fraction of dark matter from the graviton multiplet requires a mass generating phase transition around T_c10⁸ GeV, where the symmetry partners of the graviton would evolve from an ultrahard fluid to pressureless dark matter. This indicates m10 MeV for the massive components of the graviton multiplet, and it is reassuring that the corresponding dilaton lifetime τ10¹⁷ s is compatible with a dark matter interpretation.     

Modeling brain tissue volumes over the lifespan: quantitative analysis of postmortem weights and in vivo MR images

Normative measurements of brain gray matter and white matter tissue volumes across the lifespan have not yet been established. The purpose of this article was to use mathematical modeling and analytical functions to demonstrate the growth trajectory of gray matter and white matter from age 0 to age 90. For each gender, brain weight functions were generated by utilizing existing autopsy data from 4400 subjects. Brain gray matter, white matter and lateral ventricular volumes were measured from 39 MR volumes of normal individuals. These were converted to weight by multiplying the tissue volumes by the specific gravity of that tissue. White matter volumes were described by a saturating exponential function, and the gray matter volume function was calculated by subtracting the white matter weight function from the brain weight function. For each gender, equations were generated for white matter and gray matter volumes as a function of age over the lifespan.     

Strange stars properties calculated in the framework of the Field Correlator Method

We calculate the strange star properties in the framework of the Field Correlator Method. We find that for gluon condensate values G₂$G_2$ in the range 0.006–0.007 GeV⁴$0.006\text{–}0.007{\text{GeV}}^4$, which give a critical temperature Tc∼170 MeV$T_c\sim 170\text{MeV}$ at μc=0${\mu }_c=0$, the sequences of strange stars are compatible with some of the semi-empirical mass–radius relations and data obtained from astrophysical observations.     

Raman spectroscopy for the analysis of coal: a review

The advances in the characterization of amorphous carbons by Raman spectroscopy over the last four decades are of interest to many industries, especially those involving the combustion, gasification and pyrolysis of coal. Many researchers report on the Raman character of the natural organic matter in carbon‐containing compounds, such as coal, and relate the Raman bands to the structural order of the amorphous carbons. The basis of most of these studies evolved around the assignment of the G (graphitic, ∼1580 cm⁻¹) band to crystalline graphite and any other bands, called D bands, (disorder, various from 1100 to 1500 cm⁻¹) to any type of structural disorder in the graphitic structure. Concerning coal analysis, the information gained by Raman investigations has been used to describe char evolution as a function of temperature, the presence of catalysts and different gasification conditions. In addition, researchers looked at maturation, grade, doppleritization and many more aspects of interest. One aspect that has, however, not been addressed by most of the researchers is the natural inorganic matter (NIM) in the carbon‐containing compounds. Micro‐Raman spectroscopy (MRS) has many advantages over other characterization tools, i.e. in situ analysis, nondestructive, no sample preparation, low detection limit, micrometer‐scale characterization, versatility and sensitivity to many amorphous compounds. With the distinct advantages it has over that of other molecular characterization tools, such as powder X‐ray diffraction (PXRD), Fourier‐transform infrared spectrometry (FT‐IR) and scanning electron microscopy with X‐ray detection (SEM/EDS), it is surprising that it has not yet been fully exploited up to this point for the characterization of the NIM in coal and other amorphous carbons. This paper reviews the work published on the Raman characterization of the natural organic matter (NOM) of coals and reports on preliminary results of the NIM character of various South African coals, whereby various inorganic compounds and minerals in the coal have been characterized. Copyright © 2010 John Wiley & Sons, Ltd.     

Magnetized quark and strange quark matter in the spherical symmetric space–time admitting conformal motion

In this paper, we have examined magnetized quark and strange quark matter in the spherical symmetric space–time admitting one-parameter group of conformal motions. For this purpose, we have solved Einstein’s field equations for spherical symmetric space–time via conformal motions. Also, we have discussed the features of the obtained solutions.     

Dark matter in the framework of the shell-universe

We show that the shell-universe model (used to explain the observed expansion rate of the universe without a dark energy component) provides a natural mechanism for local increasing of the brane tension leading to the modified Newtons law alternative to galactic dark matter.     

The development of perturbations in the universe described by the nonstationary equation of state

The growth of the perturbation density in a baryon substance due to a nonstationary character of the equation of state of nonbaryon matter in the Universe is studied. It is shown that the perturbations evolve slower than within the Friedmann cosmological model. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 61–67, March, 2009.