RIBLL粒子鉴别气体电离室

描述了一种用于兰州放射性束流线粒子鉴别的阳极分别在x,y方向分条共阴极纵向场双叠层电离室.对其性能进行初步测试,得到了坪曲线和能量分辨.在10kPa的P10工作气体(10%CH₄+90%Ar)时,阴极电压为–650V,阳极电压为+120V是较佳的工作点.当工作气压为25kPa时,阴极电压为–1650V,阳极电压为+240V的工作条件较好,此时,对²³⁹Pu α源相对能量分辨约为4.7%.     

一套用于重离子耗散反应测量的电离室望远镜

重离子耗散反应需要鉴别产物的电荷数Z,为此,研制了一套ΔE-E望远镜.ΔE由两个串接在一起的气体电离室ΔE₁和ΔE₂组成,位置灵敏硅半导体测量粒子的剩余能量E.被探测粒子的轨迹与电离室的电场方向平行.该望远镜具有很低的能量探测阈,较小的外尺寸和强的抗电磁干扰能力.重离子耗散反应¹⁹F+²⁷Al产物的激发函数实验测量表明,该望远镜的电荷分辨Z/ΔZ约为30.     

气体比分对RPC在流光模式下工作性能的影响

对不同比分气体对RPC性能的影响进行了大量的实验研究,主要是进行了基于氩、异丁烷和绿色氟利昂F134A(C₂H₂F₄)的实验,保持氩气的比分为20%,30%,40%,改变异丁烷和F134A的比分进行实验,分别测量了探测效率、单计数率、暗电流、信号幅度和多重计数随高压的变化曲线,结果发现,减少氩气的比分,增加异丁烷和F134A的比分可以增加RPC的坪长,探测效率也有所提高,在效率坪区的暗电流也有所减小,但工作高压也需要相应地增加。     

一种多阳极横向场电离室

描述了一种将用于兰州放射性束流线较重离子鉴别的多阳极横向场电离室.对其性能进行了初步测试,得到该电离室有较长的坪区和较好的能量分辨.在10⁴Pa的P10工作气体(10%CH₄+90%Ar)下,坪区长度为700V.对²⁴⁴Cm α放射源,在第4片阳极对应的灵敏区域能量损失为1.30MeV,能量分辨41.1keV,相对能量分辨约3.16%。     

高分辨率初始光电子能谱由真空紫外激光速度——映射图像的方法

通过采用真空紫外(VUV)激光速度-地图成像-TPE(真空紫外VMI-TPE)方法获得了高分辨率初始光电子(TPE)氯苯(C₆H₅Cl(X¹A₁))的光谱,炔丙基自由基(C₃H₃(X²B₁))和烯丙基(C₃H₅(X²A₁)). 观察到的真空紫外VMI-TPE方法的光电子能量分辨率在1~2 cm^-1,可以和在真空紫外激光脉冲场电离光电子(VUV-PFI-PE)的测量媲美. 类似真空紫外PFI-PE测量,真空紫外VMI-光电子(真空紫外VMI-PE)和真空紫外VMI-TPE测量能量分辨率依赖于直流电场在光电离区加速电子. C₆H₅Cl和C₃H₃的电离初始值的降低为F的函数表示Stark偏移校正为VUV-VMI-TPE测量由-3.1√F管辖,这是半经典预测值-6.1√F的一半. 我们还测量C₆H₅Cl和C₃H₅的真空紫外光能量的真空紫外VMI-PE谱接近其电离初始值. 在VUV-VMI-PE测量中观察到的C₃H₅⁺阳离子振动谱和振动级数,nv₇⁺(n=0~3). 真空紫外VMI-TPE可以实现更高的实验灵敏度和类似真空紫外PFI-PE测量的能量分辨率,使真空紫外VMI-TPE法成为高分辨率真空紫外PFI-PE测量一个很好的替代.     

OH+C2H3F的反应机理及产物支化比反应的理论研究

本文对HOC₂H₃F可能解离通道的势能面进行从头算CCSD(T)/CBS//B3LYP/6-311G(d，p)计算，同时对速率常数进行Rice-Ramsperger-Kassel-Marcus计算. 生成主要产物CH₂CHO+HF最有利的反应途径是OHC₂H₃F→i2→TS14→i6→TS9→i3→TS3→CH₂CHO+HF，其中速率决定步骤是HF通过TS11从CO桥接位置解离，能量比反应物高3.8 kcal/mol. 借助中间态TS14，F原子从C_α迁移到C_β位置生成CH₂O+CH₂F，然后通过中间态TS16，H从O迁移到C_α位置；通过中间态TS5，C-C键断裂生成产物，其能量比反应物低1.8 kcal/mol，比TS11低4.0 kcal/mol.     

高浓度氩气稀释对C2H2-2.5O2气体直接起爆临界能量影响的实验研究

 采用高压电点火进行直接起爆,通过放电过程中电流的输出信号确定起爆能量,实验测定了C₂H₂-2.5O₂气体和加入摩尔浓度为70%氩气的C₂H₂-2.5O₂混合气体直接起爆的临界起爆能量,研究了高浓度氩气稀释对C₂H₂-2.5O₂混合物临界起爆能量的影响。实验测得的混合物临界起爆能量实验值与Lee等人的表面积能量理论值基本吻合。研究表明：C₂H₂-2.5O₂气体和加入摩尔浓度为70%氩气的C₂H₂-2.5O₂混合气体的临界起爆能量均依赖于初始压力,并呈反相关指数关系;在相同实验条件下,高浓度氩气稀释极大提高了混合气体直接起爆的临界起爆能量。分析认为,由于临界起爆能量正比于诱导区长度的3次方,因此在相同初始压力下,高浓度氩气的稀释增加了C₂H₂-2.5O₂混合气体爆轰诱导区长度,并最终导致其临界起爆能量的显著上升。     

紧凑的非链式脉冲HF激光器

研究了气体组分和峰化电容对紫外光预电离脉冲HF激光器性能的影响.实验发现最佳气体混合比为SF₆/C₂H₆=20:1,峰化电容和主放电电容的最佳比为C_p/C_s=0.3,在最佳气体混合比时,最大激光脉冲峰值功率和对应的总气压随充电电压的提高而增大.同时得到了E/P值和激光能量的关系.整个器件的最大激光输出为400mJ,脉冲峰值功率为1.5MW,最大电光转换效率约为2.2%.     

多丝室工作于自猝灭流光模式下定位特性的研究

对多丝室运行于自猝灭流光(SQS)模式下的定位性能进行了实验研究.用两种不同的丝室结构,以Ar和CO₂的混合气体作为工作气体,在不同的CO₂含量比例及高压下测试了感应电荷信号在阳极丝周围电极上的分布.以阳极丝相邻电极上感应电荷的比来确定入射粒子在垂直阳极丝方向上的位置,分辨率σ_x好于350μm.由阴极面上感应电荷的分布,用重心法确定入射粒子在沿阳极丝方向上的位置,分辨率好于250μm.     

环戊酮光电离解离的实验和理论研究

本文介绍了真空紫外光电离质谱结合理论计算研究环戊酮单分子的光电离解离过程. 在9.0∽15.5 eV能量范围内,测量了环戊酮离子及其碎片离子的光电离效率曲线. 通过光电离效率曲线,将环戊酮分子的电离能确定为9.23±0.03 eV,并确认碎片离子为：C₅H₇O⁺,C₄H₅O⁺,C₄H₈⁺,C₃H₃O⁺,C₄H₆⁺,C₂H₄O⁺,C₃H₆⁺,C₃H₅⁺,C₃H₄⁺,C₃H₃⁺,C₂H₅⁺, C₂H₄⁺. 利用量子化学计算方法,在ωB97X-D/6-31+G(d,p)理论水平基础上,提出了C₅H₈O⁺的解离机制. 通过对环戊酮解离路径的分析,发现开环和氢迁移过程为环戊酮离子解离的主要路径.     

Self-organization of five species in a cyclic competition game

Cyclic competition game models, particularly the “rock–paper–scissors” model, play important roles in exploring the problem of multi-species coexistence in spatially ecological systems. We propose an extended “rock–paper–scissors” game to model cyclic interactions among five species, and find that two of the five can coexistent when biodiversity disappears, which is different from the “rock–paper–scissors” game. As the number of fingers is five, we named the new model the “fingers” game, where the thumb, forefinger, middle finger, ring finger, and little finger cyclically dominate their subsequent species and are dominated by their former species. We investigate the “fingers” model in two ways: direct simulations and nonlinear partial differential equations. An important finding is that the number of species in a cyclic competition game has an influence on the emergence of biodiversity. To be specific, the “rock–paper–scissors” model is in favor of maintaining biodiversity in comparison with the “fingers” model when the variables (population size, reproduction rate, selection rate, and migration rate) are the same. It is also shown that the mobility and reproduction rate can promote or jeopardize biodiversity.     

Experimental study on downstep in Chinese intonation

Downstep in pitch contour of Chinese Putonghua is examined using subtly designed sentences by controlling tone combinations. The results show both automatic and nonautomatic downstep phenomena exist in Chinese. In non-automatic downstep, low tones compress downwards the pitch range of the following syllables. and the main influence of downstep is on topline. Low tone not only lower the topline behind it, but also raise the high tones before it, the effects are compatible with each other. In automatic downstep, the topline of pitch contour in intonational phrase is presented as a linear downtrend, but it differs among speakers due to the effect of personal stress practice. In comparison with downstep phenomenon in other tone or non-tone languages, the downstep ratio in Chinese is not constant, and the domain of downstep is not limited within the adjacent tones.     

Contrastive analysis on tone between Putonghua and Taiwan Mandarin

The differences of the pitch and duration of Chinese syllables between Putonghua （PTH） and Taiwan Mandarin （TM） were studied. The speech materials to be used are not only isolated syllables, but also sentences. The results reveal that： For the isolated syllables, T1 and T2 in TM are influenced by Minnan dialect, therefore their pitch are lower than those in PTH. T3 is fall-rise in PTH, while it is fall in TM. Moreover, the syllable duration sequence for different tone is T3〉T2〉T1〉T4 in PTH, while it is T1〉T2〉T3〉T4 in TM. For the syllables in sentences, T2 is mid-rise in PTH, while it is mid-level in TM. And the T3 is longer than T4 but shorter than T1 or T2 in PTH, while it is the shortest in TM. Furthermore the effects of prosodic phrase boundary on duration for different tones are almost the same in PTH, but the lengthening part of T1 or T2 is longer than that of T3 or T4 in TM.     

Abelian-Higgs phase of SU(2) QCD and glueball energy

It is shown that SU(2) QCD admits an dual Abelian-Higgs phase, with a Higgs vacuum of a type-Ⅱ superconductor. This is done by using a connection decomposition for the gluon field and the random-direction approximation. Using a bag picture with soft wall, we presented a calculational procedure for the glueball energy based on the recent proof for wall-vortices [Nucl. Phys. B 741(2006)1].     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Signal generation in an isotropic medium in scanning electron acoustic microscope

Based on the research in Ref. [5][Materials Science and Engineering, 1989; A122： 57 63], an improved model of heat source is set up, the different modes of Lamb wave in an isotropic sample generated by a chopped electron beam at frequency f are obtained with integral transform and normal function expansion method, and the output signal of PZT coupled at the back surface of the sample is found out. The generation mechanism of SEAM （Scanning Electron Acoustic Microscopy） signal is discussed. It shows that the SEAM is a near field imaging technique with high spatial resolution and its best lateral spatial resolution is about 2√2α （α is the radius of the focused electron beam）. Some of experimental results of SEAM images are presented in the paper and it shows that the spatial resolution of SEAM is better than 0.5 μm and smaller than the thermal diffusion length of the sample. Therefore the character of near field imaging in SEAM is also proved experimentally.     

High efficiency filtering using two-dimensional photonic crystal coupled cavity structures

Transmission spectra of coupled cavity structures (CCSs) in two-dimensional (2D) photonic crystals (PCs) are investigated using a coupled mode theory, and an optical filter based on CCS is proposed. The performance of the filter is investigated using finite-difference time-domain (FDTD) method, and the results show that within a very short coupling distance of about 3λ, where λ is the wavelength of signal in vacuum, the incident signals with different frequencies are separated into different channels with a contrast ratio of 20 dB. The advantages of this kind of filter are small size and easily tunable operation frequencies.     

Real-time restoration of rotational blurred image using gradient-loading

The key to the restoration of rotational motion blurred image is how to restore the image under a low cost and to correct the irreversibility of the degradation function matrix.Based on the special qualities of degradation function matrix and precise deduction in space-domain, we present a new approach using gradient-loading for restoration of rotational blurred image.By easily adding a gradient operator, the irreversibility of the original matrix is corrected and can be applied for inverse filtering then.Gradientloading is the optimized approach which combines the advantages of both the approaches using constrained least square filtering and traditional diagonal-loading.Compared with the approach using least square filtering, its peak signal-to-noise ratio (PSNR) is improved from 3.18 to 6.46dB, while the computing time is reduced to 1/2-1/3.Experimental results demonstrate the effectiveness, noise-resistibility, robustness, and low complexity of this approach, which make it more suitable for real-time environment.     

All-Optical Logic Device Using Bent Nonlinear Tapered Y-Junction Waveguide Structure

We propose an all-optical logic device made of a bent tapered Y-junction waveguide with a Kerr-type nonlinear interface. It could provide an AND gate, OR gate, and exclusive-OR (XOR) gate. We could obtain different transmission results by adjusting the bending angle. The numerical simulation results show that the device functions as AND, OR, and XOR gates.