激光功率计的变换与显示电路

介绍了激光功率计的变换与显示电路,该电路的主要功能是直接指示激光功率的大小。该电路把由激光功率计输出的模拟电压量变为数字脉冲输出,并且把输出脉冲的频率实时显示出来。本电路具有精度高、线性好、工作稳定的特点。

Reconstruction of late glacial and Holocene climate evolution in southern China from geolipids and pollen in the Dingnan peat sequence

IEECAS SKLLQG

25MeV/u~6He+~9Be破裂反应的α碎片发射

测量了在 2 5MeV/u6 He轰击9Be靶的破裂反应产生的α碎片双微分截面及角分布 ,并在Serber模型的框架下计算了在破裂反应中衍射破裂与擦去过程的贡献 ,并对结果进行了讨论 .结果表明基于包含衍射破裂和擦去过程的Serber模型可以对6 He的直接反应进行较好地描述 ,擦去过程的贡献远大于衍射破裂的贡献 .相对于6 Li而言 ,6 He较大的去 2n微分截面源于它的弱束缚特性

放射性核束物理与核天体物理

基于兰州重离子加速器国家实验室 (HIRFL )的中能放射性核束线 (RIBLL)及北京串列加速器国家实验室 (HI- 1 3 )的低能放射性核束线 (GIRAFFE) ,开展放射性核束物理和核天体物理研究 ,拟解决的关键科学问题是 :远离β稳定线核的结构与反应 ;超重新核素及近滴线核素的合成和性质研究 ,极端同位旋非对称核物质特性和关键的天体核反应研究 .研究内容分成 7个课题 :(1 )晕核研究 ;(2 )新核素合成及超重新核素研究 ;(3 )丰中子核结构和反应 ;(4)丰质子核结构和反应 ;(5 )高自旋的同位旋相关性 ;(6 )关键天体核反应 ;(7)系统的理论研究 .上述研究也将是 2 0 0 5年建成的国家大科学工程——兰州冷却贮存环的主要科学目标的研究基础 .简述了近期的主要工作进展 .

低能质子注入金属靶实验中的核现象研究

在低能 ( 60～ 360keV)质子注入氘化钛 (Ti2 Hx)、钛 (Ti)、钼底衬钛箔及钼 (Mo)和不锈钢 (SS)等金属样品的实验中 ,观测到了能量分别约为 3 9、5 6和 8 4MeV的带电粒子产物。用符合望远镜和吸收片法进行粒子鉴别的结果表明 :这些带电粒子均具有α粒子特性。 3种α粒子来自质子与不同靶核发生的垒下核反应。其中 ,能量为 3 9MeV的α粒子具有很高的产额 ,其对应核反应的准激发函数曲线在 150～ 330keV能区内 ,随入射质子能量增大呈指数增长趋势。上述反应产物可能源于11N( p ,α) 12 C ,11B( p ,α) 8Be和7Li( p ,α) 4 He等核反应。但相关靶核的来源仍有待解释。利用扫描电子显微镜观测到有微球状的奇异形貌

Di-nuclear systems studied with the velocity filter SHIP

Various nuclear reactions like quasi-fission, fusion-fission or particle and cluster evaporation from excited compound nuclei were studied in heavy-ion reactions at the velocity filter SHIP of GSI. The velocity filter offers the possibility to detect all reaction products under zero degree relative to the beam direction. Together with the measurement of the product velocity distribution this allows for an identification of the underlying reaction mechanism. This article is focussed on reactions of Mg-25 and Ni-64 beams on Pb-206,Pb-207 targets at energies of 5.9 x A MeV and 8.7 x A MeV. Besides evaporation residues from Mg-25 + Pb-206 collisions we found evidence for rotation and quasi-fission of nuclear molecules formed in the entrance channel after the capture stage. The break-up of the systems showed a preferred clustering leading to isotopes in the region 84 <= Z <= 88 and 122 <= N <= 127 of the chart of nuclei.

Damage accumulation in gallium nitride irradiated with various energetic heavy ions

In this work a study of damage production in gallium nitride via elastic collision process (nuclear energy deposition) and inelastic collision process (electronic energy deposition) using various heavy ions is presented. Ordinary low-energy heavy ions (Fe+ and Mo+ ions of 110 keV), swift heavy ions (Pb-208(27+) ions of 1.1 MeV/u) and slow highly-charged heavy ions (Xen+ ions of 180 keV) were employed in the irradiation. Damage accumulation in the GaN crystal films as a function of ion fluence and temperature was studied with RBS-channeling technique, Raman scattering technique, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). For ordinary low-energy heavy ion irradiation, the temperature dependence of damage production is moderate up to about 413 K resulting in amorphization of the damaged layer. Enhanced dynamic annealing of defects dominates at higher temperatures. Correlation of amorphization with material decomposition and nitrogen bubble formation was found. In the irradiation of swift heavy ions, rapid damage accumulation and efficient erosion of the irradiated layer occur at a rather low value of electronic energy deposition (about 1.3 keV/nm(3)),. which also varies with irradiation temperature. In the irradiation of slow highly-charged heavy ions (SHCI), enhanced amorphization and surface erosion due to potential energy deposition of SHCI was found. It is indicated that damage production in GaN is remarkably more sensitive to electronic energy loss via excitation and ionization than to nuclear energy loss via elastic collisions.

beta(+)/EC-decay study of Ir-176 neutron-deficient isotope

The beta(+)/EC decay of doubly odd Ir-176 has been investigated using Nd-146(Cl-35, 5n gamma)Ir-176 heavy ion fusion evaporation reaction at 210MeV bombarding energy. With the aid of a helium-jet recoil fast tape transport system, the reaction products were transported to a low-background location for measurements. Based on the data analysis, the previously published gamma rays in Ir-176 decay were proved, moreover, 3 new levels and 10 new gamma rays were assigned to Ir-176 decay. The new level scheme of Os-176 with low excitation energy has been established. The time spectra of typical gamma rays clearly indicate a long-lived low-spin isomer in Ir-176 nuclide.

空间辐射生物学研究进展；Research Progress on Space Radiation Biology

空间电离辐射尤其是高能带电粒子辐射可造成生物机体的严重损伤,是载人航天飞行的关键性限制因素之一。研究表明,带电粒子的生物学效应与其性质、剂量以及不同生物学终点有关;此外,微重力环境可能会影响空间辐射生物学效应。从多年来的空间搭载实验研究和地基模拟实验研究两个方面,综述了空间辐射的生物损伤效应及其与微重力环境复合作用的生物效应。

206At的高自旋态能级结构研究

利用能量为60MeV到80MeV的~(12)C束流，通过~(197)Au(~(12)C, 3n)~(206)At反应，产生并布居了~(206)At的高自旋态。用七台BGO(AC)HPGe探测器和一台用于探测低能γ跃迁的小平面探测器进行了γ射线的激发函数、γ-γ-t 符合及γ射线的DCO测量。基于这些测量，首次建立了~(206)At的能级纲图，发现了一个新的同质异能态，提取了它的寿命值。本工作首次建立了包括25条γ跃迁的~(206)At高自旋能级纲图，确定了一个半寿命为908 ± 400 ns. 、自旋字称为10~-的同质异能态。基于较重的双奇At核能级结构的系统性，用半经验的方法对~(206)At的10~-同质异能态进行了解释。通过与在实验上和理论上进行了详细研究的~(208)At的能级结构的比较，研究了~(206)At, ~(208)At 能级结构的系统性。

Development of functionalized terbium fluorescent nanoparticles for antibody labeling and time-resolved fluoroimmunoassay application

Silica-based functionalized terbium fluorescent nanoparticles were prepared, characterized and developed as a fluorescence probe for antibody labeling and time-resolved fluoroimmunoassay. The nanoparticles were prepared in a water-in-oil (W/O) microemulsion containing a strongly fluorescent Tb3+ chelate. N,N.N-1,N-1-12,6-bis(3'-aminomethyl-1'-pyrazolyl)phenylpyridine] tetrakis(acetate)-Tb3+ (BPTA-Tb3+), Triton X-100, octanol, and cyclohexane by controlling copolymerization of tetraethyl orthosilicate (TEOS) and 3-[2-(2- aminoethylamino)-ethylamino]propyl-trimethoxysilane (AEPS) with ammonia water. The characterizations by transmission electron microscopy and fluorometric quantum methods show that the nanoparticles are spherical and uniform in size, 45 +/- 3 nm in diameter, strongly fluorescent with fluorescence yield of 10% and a long fluorescence lifetime of 2.0 ms. The amino groups directly introduced to the nanoparticle's surface by using AEPS in the preparation made the surface modification and bioconjugation of the nanoparticles easier. The nanoparticle-labeled anti-human alpha-fetoprotein antibody was prepared and used for time-resolved fluoroimmunoassay of (x-fetoprotein (AFP) in human serum samples. The assay response is linear from 0.10 ng ml(-1) to about 100 ng ml(-1) with the detection limit of 0.10 ng ml(-1). The coefficient variations (CVs) of the method are less than 9.0%. and the recoveries are in the range of 84-98% for human serum sample measurements. (C) 2004 Elsevier B.V. All rights reserved.