丰中子核145,147La的八极形变

通过对²⁵²Cf自发裂变产生的瞬发γ谱的实验研究,建立与扩展了丰中子核^145,147La的高自旋态能级图,最高自旋态达到(41/2⁺)与(43/2^－).测得的交叉相联的相反宇称带及带间的强化E1跃迁说明在^145,147La中形成强的八极形变.对¹⁴⁵La的研究表明,具有轴对称形状的四极形变与具有反演不对称形状的八极形变在同一核中产生共存与竞争.在πh_11/2带中观测到的带交叉位于ω≈0.26—0.30MeV附近,由推转壳模型计算表明,它是由一对i_13/2中子的顺排所引起的.     

奇—奇核114Pm高自旋同质异能态及其衰变纲图的研究

用高自旋同质异能态次级束流线实验装置,对¹⁴⁴Pm的高自旋同质异能态进行了快速分离,并做了γ射线的符合测量.结合γ射线激发函数和各向异性的测量结果,首次建立了奇—奇核¹⁴⁴Pm的高自旋同质异能态的衰变纲图,其中19条高自旋能级和29条γ射线是由本工作指定的.离子γ射线关联测量确定了¹⁴⁴Pm的高自旋同质异能态的半衰期大于2μs.通过系统性比较以及变形的独立粒子模型理论计算,指定了高自旋同质异能态的粒子组态可能为π(1h²_11/2d_5/2)v(1i_13/21h_9/22f_7/2),自旋宇称为J^π=27⁺,并具有形变参数为β=－0.18的扁椭球形状.     

丰中子核125Sb的高自旋态

利用在束γ谱学方法,通过¹²⁴Sn(⁷Li,α2n)反应首次研究了丰中子核¹²⁵Sb的高自旋态.建立了自旋达23/2⁺、激发能至2637keV的能级纲图,其中包括21条新γ跃迁和14个新能级.在1970,2110和2471keV识别出了3个同质异能态,估计了它们的寿命范围,并建议分别具有πg_7/2ν(h_11/2s_1/2),πg_7/2ν(h_11/2d_3/2),πg_7/2ν(h²_11/2)三准粒子组态.根据价质子与¹²⁴Sn核芯激发态的耦合讨论了¹²⁵Sb的能级结构.     

131La形状共存和带终止

用组态相关推转Nilsson-Strutinsky模型研究了¹³¹La转动带结构性质.对一些特殊组态带的形状共存和带终止做了较为详细的探讨,并把理论计算结果与实验结果进行了比较.理论计算结果表明,¹³¹La是软γ形变核,很多具有不同组态的转动带都有形状共存.实验上测量的¹³¹La的宇称和辛量子数为(π,α)=(+,±1/2)的转动带的组态是[02,8],即组态π(h_11/2)²⊙ν(h_11/2)⁸,其中负辛量子数带几乎达到该带的带终止理论预言值I=41.5h,但是该带对实验上测量带终止不利,因为接近带终止态时能量增加太快.     

双奇核172Re高自旋态转动带结构实验研究

利用重离子熔合蒸发反应¹⁴⁹Sm(²⁷Al,4nγ)¹⁷²Re布居了形变双奇核¹⁷²Re的高自旋态,用12套带有BGO反康普顿抑制的高纯锗探测器阵列进行了在束γ实验测量,首次建立了形变双奇核¹⁷²Re由3个转动带构成的高自旋态能级纲图.研究和讨论了3个转动带的结构特征,基于已有的高自旋态核结构知识并通过系统学比较和分析指出它们的准粒子组态分别为πh_11/2⊙νi_13/2,πh_9/2⊙νi_13/2和π1/2^－[541]⊙ν1/2^－[521].发现前两个转动带在自旋小于18.5h时其转动能级呈现反常的旋称劈裂.     

形变双奇核178Ir转动带能级的旋称反转

利用¹⁵²Sm(³¹P,5nγ)¹⁷⁸Ir反应产生并研究了双奇核¹⁷⁸Ir的高自旋态.实验中进行了¹⁷⁸Ir核的在束γ测量,包括γ射线的激发函数测量、X–γ和γ–γ符合测量.首次建立了双奇核¹⁷⁸Ir基于πh_9/2νi_13/2和πh_11/2νi_13/2准粒子组态上的转动带能级纲图.发现在低自旋区,两个转动带能级均出现旋称反转.对此核区半退耦带的旋称反转作了简要的分析和讨论.     

125Ba高自旋态的测量

通过¹⁰⁹Ag(¹⁹F,3n)核反应布局了¹²⁵Ba核的激发态.使用带BGO康普顿抑制的高纯锗探测器阵列和常规在束γ实验技术,测量了它的高自旋态.建立在h_11/2中子支壳上的负宇称带和建立在g_7/2中子支壳上的正宇称带分别被延伸到了35/2^－和23/2⁺态.负宇称带显示出明显的正负Signature劈裂,而正宇称带则几乎没有这种劈裂.负宇称正负Signature带均出现反弯,其反弯处转动频率与¹²⁴Ba晕带反弯频率相近.正宇称带出开始出现反弯迹象.     

146Tb的能级结构研究

利用能量为161—175MeV的³²S束流,通过反应¹¹⁸Sn(³²S,1p3n)¹⁴⁶Tb研究了双奇核¹⁴⁶Tb的高自旋态能级结构. 实验进行了γ射线的激发函数、γ射线的各向异性度、X–γ和γ–γ–t符合测量. 基于这些测量结果,建立了激发能达8390kev的¹⁴⁶Tb核的能级纲图,其中包括新发现的41条γ射线和新建立的27个能级,并指定了¹⁴⁶Tb新发现能级的自旋值. 用一个h_11/2价质子和一个h_11/2^－1价中子空穴耦合、πh_11/2υh_11/2^－1与¹⁴⁶Gd核实激发态的耦合对¹⁴⁶Tb的能级结构进行了定性地讨论.     

188TL的πh9/2×υi13/2扁椭球转动带的旋称反转研究

利用能量为170MeV的³⁵Cl束流, 通过¹⁵⁷Gd(³⁵Cl,4n)熔合蒸发反应研究了¹⁸⁸Tl的 高自旋态能级结构. 依据实验结果建立了¹⁸⁸Tl基于πh_9/2×υi_13/2组态的转动带. 根据双奇Tl核能级结构的相似性, 指定了¹⁸⁸Tlπh_9/2×υi_13/2扁椭球转动带的自旋值. 结果表明在¹⁸⁸Tl中, πh_9/2×υi_13/2扁椭球转动带在低自旋区具有旋称反转性质. 利用包含了质子-中子剩余相互作用的准粒子-转子模型, 定性地解释了πh_9/2×υi_13/2扁椭球转动带的低自旋区旋称反转现象.     

134Ce核的高自旋态与形状共存

在中国原子能科学研究院H13串列加速器上,通过重离子核反应¹²²Sn(¹⁶O,4n)对A=130缺中子核区的¹³⁴Ce核的高自旋态进行了研究,建立了¹³⁴Ce的新的能级纲图,最高自旋态扩展到22.然而实验结果与近期发表的134Ce核的高自旋态结果不同,所谓在¹³⁴Ce核中存在的磁转动带结构不能被实验证实.对实验结果的分析表明,¹³⁴Ce核的高自旋态结构呈现出重要的形状共存特性在基带以上的回弯处的10+态起源于两个中子组态,基于此10+态的转动带具有γ≈–60°的扁椭形变;另一个10+同质异能态为yrast陷阱,也起源于两中子组态,为具有γ≈–120°的长椭形状;而由两个signature伙伴带组成的强耦合带,则起源于h_11/2与g_7/2质子组态,为具有γ≈0°的长椭形变带.     

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.     

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.     

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.     

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].     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

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.