~3He正比计数器探测效率模拟及灵敏度刻度

利用Monte Carlo程序研究了3He正比计数器慢化体厚度与探测效率的关系,单能中子及Hess谱中子模拟给出5 cm的聚乙烯慢化体优化厚度。利用天然中子本底对探测器装置进行测试,并对探测器灵敏度进行了刻度。     

河南铝土矿生态环境现状及治理恢复对策研究

河南省铝土矿资源总量较大,但分布不均衡,多为露天开采,平均铝硅比为5.54.对于历史遗留的铝土矿民采破坏状况,根据不同的破坏类型提出了相应的治理恢复方案;对于露天开采及地下开采的铝土矿生态影响,也提出了相应的治理恢复措施;探讨了矿山的生态治理责任归属问题,并提出了相关建议,供决策者参考.     

On Larkin-Imry-Ma State of 3He-A in Aerogel

Superfluid ³He-A shares the properties of spin nematic and chiral orbital ferromagnet. Its order parameter is characterized by two vectors and . This doubly anisotropic superfluid, when it is confined in aerogel, represents the most interesting example of a system with continuous symmetry in the presence of random anisotropy disorder. We discuss the Larkin-Imry-Ma state, which is characterized by the short-range orientational order of the vector , while the long-range orientational order is destroyed by the collective action of the randomly oriented aerogel strings. On the other hand, sufficiently large regular anisotropy produced either by the deformation of the aerogel or by applied superflow suppresses the Larkin-Imry-Ma effect leading to the uniform orientation of   . The interplay of regular and random anisotropy allows us to study many different effects.      

Long-Range Order in the A-like Phase of Superfluid 3He in Aerogel

A mutual action of the random anisotropy brought in the superfluid ³He by aerogel and of the global anisotropy caused by its deformation is considered. Strong global anisotropy tends to suppress fluctuations of orientation of the order parameter and stabilizes ABM order parameter. In a limit of vanishing anisotropy fluctuations of ABM order parameter became critical. It is argued that still in a region of small fluctuations the order parameter changes its form to be less sensitive to the random anisotropy. For a favorable landscape of the free energy of superfluid ³He the fluctuations remain small even in a limit of vanishing global anisotropy and the long-range order is maintained.      

Quantum Fingering of the Inverted Liquid-Crystal 4He Interface in the Field of Gravity

The simplest example of fingering occurs when a heavier liquid occupies the half-space above a lighter one. The fingers of the heavier liquid driven by gravity grow down, displacing the lighter liquid upward. The fingering of the superfluid phase into the ⁴He crystal facet below its roughening transition temperature can provide us an example of macroscopic quantum nucleation phenomena. Due to cusp-like singularity in the surface tension as a function of the facet orientation the crystal facet has a relative stability and its fingering is accompanied by overcoming some critical nucleation barrier. The barrier height is proportional to the square of the facet step energy and depends on a ratio of the facet size to the capillary length. At sufficiently low temperatures the thermal activation mechanism for the interface fingering is replaced with the quantum one associated with the penetration through the nucleation barrier.      

A spin polarized He metastable beam investigation of the adsorption of l-cysteine on magnetic surfaces

We report first results on the deposition of l-cysteine (Cys), a fundamental amino-acid, on a magnetic substrate. Molecules have been deposited under ultra-high vacuum conditions on Fe(1 0 0) films. Electronic and magnetic properties of adsorbed molecules have been investigated by spin polarized metastable deexcitation spectroscopy (SPMDS). The spectra show a growth dynamics apparently similar to the one already reported on coinage metal surfaces with the formation of a strongly-bound thiolate species (SFe bond) and weakly-bound second-layer molecules. SPMDS revealed the spin-polarized character of an Auger (Penning) deexcitation peak related to a Cys molecular orbital. Interestingly, these spin-polarization effects, ascribed to the interaction with the magnetized substrate, vanish before the first layer completion, suggesting a possible correlation with the SAM assembly properties.     

氦气和氖气中大气压均匀介质阻挡放电特性比较

均匀介质阻挡放电（HDBD）相对于丝状模式具有更为广阔的应用前景,为研究其机理特性,在8mm气隙距离的氦气和氖气中分别实现了大气压HDBD;通过电压电流波形和Lissajous图形测量以及发光图像拍摄比较了两者放电特性的区别;研究了不同电压幅值下两者各放电参量的变化规律,并结合放电机理分析对实验结果进行了讨论。研究结果...     

Analysis of the Variability of the L-H Transition Power Threshold in a Helium-4 Discharge

In this paper, a mechanism about the variability of the L-H transition power thresh- old PL-H is proposed which is based on the ion orbit losses. Only in the edge where there are enough ion orbit losses and the negative radial electric field Er is high enough can the H-mode be triggered. The ion orbit losses are determined by the ion in the loss region under certain edge conditions. For different mass A and different charge Z, the critical loss energy E Z2/A in the loss region. In H and D charges, because the D＋ loss region is larger than H＋, it can be deduced that the PL-H of H is larger than that of D. In a 4He discharge, experiment finds there exist a considerable number of 4He1＋ in the plasma edge. The actual ion orbit losses are determined by the mixing ratio of a He1＋ and 4He2＋. The 4He1＋ loss region is larger than that of 4He2＋, and the loss region of D＋ interposes between 4He1＋ and 4He2＋. Different 4He1＋ content can cause the edge ion losses in a 4He discharge to be greater than, less than or equal to that in a D discharge. So a 4He discharge can exhibit multiple experimental phenomena in the PL-H.     

磷灰石(U-Th)/He热年代学方法及其在地貌演化研究中的应用

文章描述了磷灰石(U-Th)/He热年代学方法的基本测年原理、校正模型、封闭温度和实践验证,及此方法在古地形演化、山体剥露历史和剥蚀速率研究中的应用。     

降低电磁纯铁冷轧薄板矫顽力的研究

就铝合量和冷轧变形量对电磁纯铁冷轧板矫顽力(Hc)的影响结合生产实际进行了研究并在生产实残中取得较好效果。