Elastic Transfer Reactions of 25MeV/u 6He on 9Be Target

Angular distributions for elastic transfer in the ⁶He+⁹Be system were measured at the incident ⁶He laboratory energy of E=150MeV. From a distorted-wave Born approximation (DWBA) analysis,³He spectroscopic amplitude in ⁹Be were extracted and compared with values obtained by shell model calculations. The result shows that the spectroscopic amplitude is much greater than 0.70.     

高纯锗探测器的广泛应用和自主研制进展

以目前国际上极为活跃开展的暗物质探测、无中微子双 衰变研究为例,评述了高纯锗探测器的重要性及其广泛的应用前景。介绍了己开展的高纯锗单晶、探测器制备的关键技术研究进展:合作单位已研制出了用于高纯锗单晶材料制备的区熔炉、单晶炉;并制备出直径为20  50 cm、纯度为12N(< 41011  atoms/cm3)、位错< 5000 atoms/cm2 的锗单晶;掌握了高纯锗探测器(平面型、同轴型)制备的关键技术,用进口高纯锗单晶材料制备出的同轴型高纯锗探测器对射线的能量分辨率及探测效率均达到进口产品指标,使用自制的12N 高纯锗单晶材料己制备出平面型高纯锗探测器。呼吁加速高纯锗研制的自主创新步伐,尽早实现其国产化目标。The article reviews importance and wide applications of HPGe detector, especially the application on the dark matter search experiment and double beta decay experiment. The research progress on the Highpurity germanium single crystal and HPGe detector in China has been introduced. The cooperation partner developed new type zone-refining furnace and single crystal furnace. The ultra-purity germanium single crystal with 20~50 cm, purity up to 12N(net impurity concentration is less than 41011 atoms/cm3), and dislocation less than 5 000 /cm3 was prepared. The key technologies for preparing planar and coaxial HPGe detector were mastered. The coaxial detector, which has been made of imported ultra-purity germanium single crystal has excellent energy resolution and efficiency as the imported commercial detector. The planar detector using selfmade germanium single crystal was also successfully manufactured. The research group appeals for speeding up the pace of independent innovation on the high-purity germanium, and achieving the high-purity germanium localization as soon as possible.     

基于HI-13串列加速器在束γ终端原子核激发态寿命测量的核结构研究

利用在HI-13串列加速器的在束γ终端上建立的多普勒线移衰减法、反冲距离多普勒线移法和快时间延迟符合法等3种寿命测量方法,开展了原子核手征对称性、磁转动等核结构热点课题的研究工作。实验结果表明,130Cs的伙伴带具有很好的手征特性,而106Ag的候选带并非手征双带。根据测量的能级寿命提取的B（M1）值表明,106Ag的正宇称晕带和107Ag的正、负宇称晕带都具有典型的磁转动特性。此外,寿命测量数据还为解释和理解不同的同位素链中展现出的形状演化、形状共存、形状相变及临界点对称性等物理现象提供了有价值的实验证据。 The significance and principle of lifetime measurements of excited states in nuclei are briefly described. By using the recoil-distance Doppler-shift method, the Doppler-shift attenuation method, and the fast-timing technique established at the in-beam γ terminal of HI-13 tandem accelerator, nuclear structure studies on topical subjects including chiral symmetries and magnetic rotation have been performed. Our experimental results indicate that 130Cs shows better chiral characteristics, however, the two candidate bands of 106Ag could not be a pair of chiral doublet bands. For magnetic rotation, the deduced B(M1) values deduced from the measured level lifetimes clearly demonstrate that the yrast positive-parity band in 106Ag and both the yrast positiveand negative-parity bands in 107Ag are magnetic rotation bands. In addition, our lifetime measurement data also provide valuable experimental evidences for the interpretation and understanding of the shape evolution, the shape coexistence, and the critical-point symmetries of shape phase transition in the different isotope chains.     

Van der Waals状态方程可压缩多流体流动的PPM方法

基于流体体积分数的混合型多流体数值模型,将Piecewise Parabolic Method（PPM）方法应用于可压缩多流体流动的数值模拟,采用双波近似求解多流体van der Waals状态方程的Riemann问题．模拟高密度比且含有激波的可压缩多流体流动,典型的纯界面平移问题模拟结果表明,在接触间断的界面附近,压力和速度没有任何的振荡且界面数值耗散都被控制在2—3个网格之内;一维和二维算例表明,该数值方法可以有效地处理接触间断、激波和多维滑移线等物理问题,并能够比其它多流体数值方法更精细地模拟多流体交界面．     

太阳能甲醇分解吸收-反应器研制与实验研究

利用中温太阳能为甲醇分解的吸热反应供热,可以将中温太阳能转化为合成气燃料的化学能,同时提高燃料热值和太阳能的可用性,还可以实现太阳能与化石燃料的互补.本研究提出了太阳能热化学系统的一体化设计原则,建立了综合考虑太阳能集热、反应动力学和反应器结构参数的太阳能甲醇分解反应器的理论分析模型,并首次研制了5 kW热功率的抛物槽式太阳能甲醇分解一体化实验装置.太阳能甲醇分解的实验结果表明太阳能集热器可以为甲醇分解提供200～300 ℃的反应温度,在辐照300～800 W/m2,甲醇进料量为0.5～4l/h条件下,甲醇转化率可以达到50%～95%,投射到吸收-反应器上的太阳能转换为燃料化学能的效率可以达到30%～60%,具有良好的甲醇分解和太阳能转换性能.研制的实验装置体现了一体化设计特征,同时理论分析结果与实验结果也具有很好的一致性.本文研究成果将为开拓太阳能与化石能源互补的能量系统提供理论支撑和实验数据.     

以改进的迈克尔逊干涉仪测量LED封装材料的热膨胀系数

LED封装材料在封装的过程中由于热膨胀的缘故会产生应力,将对LED的发光效率产生较大影响。改装的迈克尔逊干涉仪用于测量二氧化钛/有机硅复合的LED封装材料在不同温度范围内的热膨胀系数,具有测量准确,分辨率高等优点。     

Intelligibility enhancement for noisy whispered speech using asymmetric cost function

We proposed two whispered speech enhancement methods based on asymmetric cost functions in this paper to deal with the amplification and attenuation distortions of whispered speech distinctively.The modified Itakura-Saito（MIS）distance function provides more penalties to speech amplification distortion,whereas the Kullback-Leibler（KL）divergence function gives more penalties to speech attenuation distortion.The experimental results show that the MIS function based method achieves significant improvement of intelligibility in contrast to the conventional speech enhancement algorithms when the signal-to-noise ratio（SNR）falls below-6 dB,whereas the KL function based one achieves the similar result as the minimum mean square error（MMSE）speech enhancement method.The results show that the effects of the amplification and attenuation distortions on the intelligibility of the enhanced whisper are different,where larger attenuation distortion may result in better intelligibility of speech with low SNR.However,the attenuation distortion has small effects on intelligibility of speech with high SNR.     

纳米Zn_2SiO_4∶Mn包覆SiO_2颗粒的制备及表征

采用水热合成方法添加KOH在SiO2颗粒表面包覆Mn2+掺杂纳米Zn2SiO4,通过X射线衍射(XRD)仪、扫描电子显微镜(SEM)、能谱、光致发光(PL)光谱仪对产物的晶体结构、形貌及光学性能进行表征,并对Zn2SiO4晶体在水热反应过程中的反应机制进行了讨论。XRD测试结果表明:220℃水热条件下,添加少量KOH,反应不同时间后,可在石英砂表面生成一层Zn2SiO4;SEM照片显示所生成的Zn2SiO4为六棱柱形,并且不同反应条件下Zn2SiO4的包覆程度不同。反应产物经光致发光性能研究表明:Mn2+掺杂纳米Zn2SiO4包覆SiO2样品中显示两套光致发光谱,一套为250nm左右激发产生的522nm绿色发光带,另一套为340～410nm宽带激发的440nm蓝色发光带,前者为典型的Mn2+离子发光,后者440nm发光带则有可能来源于基体SiO2的氧空位缺陷。     

SmBa2Cu3O7-x超导块材纳米粉合成工艺研究

本文采用不同相成分纳米前驱粉，制备了一系列SmBa2Cu3O7-x块材，并对其制备工艺进行了研究．纳米前驱粉制备采用本中心自行研发的一种简便高效的“凝胶快速分解法”．研究结果表明，采用“凝胶快速分怨法”，经650℃-950℃的适当热处理可以得到不同相成分的纳米前驱粉；在一定的温度和时间范围内，前驱粉的粒度基本不受热处理温度的影响．磁测量的结果表明，化学成分相同时，前驱粉的相组成对最终的SmBa2Cu3O7-x块材的临界超导转变温度（Tc）并无明显影响．     

均一球形PDP用荧光粉(Y,Gd)BO3:Eu的合成

利用共沉淀法通过控制稀土离子浓度、沉淀温度等得到稀土氧化物前驱体沉淀,再将其和H3BO3按化学计量比混合煅烧制备出了平均粒径在0．5～1．0μm的球形、粒径分布较小和无团聚的(Y,Gd)BO3：Eu荧光粉,其性能在一些方面优于商用荧光粉。利用X射线衍射、SEN、粒度分析仪和PL光谱进行表征。研究了不同的煅烧温度对荧光粉性能的影响,结果发现用本实验方法在800℃煅烧即可得到纯相的(Y,Gd)BO3：Eu。而传统固相合成纯相的(Y,Gd)BO3：Eu反应温度高达1200℃。因本方法工艺较易控制,适于在工业生产上推广。