重丰中子新同位素——238Th

利用兰州重离子加速器（ＨＩＲＦＬ）提供的６０ＭｅＶ／ｕ的１８Ｏ离子束照射天然铀靶,通过多核子转移反应生成２３８Ｔｈ．用快速放射化学分离技术从铀及其反应产物的混合物中分离出Ｔｈ同位素．使用两台高纯锗（ＨＰＧｅ）探测器测量了样品的γ射线活性,观测到了２３８Ｔｈ的β－衰变子体２３８Ｐａ的γ射线的生长、衰变行为,测定２３８Ｔｈ的半衰期为9.4±2.0min A new nuclide 238Th has been produced via multinucleon transfer reaction by 60 MeV/u 18 O ion irradiation of natural uranium. The produced thorium was radiochemically separated from the mixture of uranium and its reaction products. The activity of thorium was measured by using a HPGe detector and a planar HPGe detector. 238 Th has been identified for the first time by measuring the growth and decay of the γ rays from its daughter nucleus 238 Pa.     

^229Ra的衰变纲图

用１４ＭｅＶ中子轰击钍靶，通过＾２３２Ｔｈ（ｎ，α）＾２２９Ｒａ反应产季了＾２２９Ｒａ，由放射化学分离技术从被照靶物质中分离出＾２２９Ｒａ活性，利用γ（Ｘ）谱学方法，首次观测到了＾２２９Ｒａ的能量为１４．５，１５．６，１８．８，２１．８，２２．５，４４．０，４７．５，５５．０，６３．０，６９．６，９３．６，９４．１，９８．５，１０２．２，１０４．５，１０６．１，１６１．１和１７１．５ｋｅＶ的１８条     

101Mo衰变的研究

采用γ－γ－ｔ三参数快慢符合谱仪研究了＾１０１Ｍｏ→β＾－＾１０１Ｔｃ的衰变,利用符合测量结果构造了一个新的＾１０１Ｍｏ→β＾－＾１０１Ｔｃ的衰变纲图,首次确定了１０４．７０,１０５．９５,７７４．１５ｋｅＶγ射线的位置,首次观测到１５０８．０１ｋｅＶ的γ射线并确认了其跃迁位置。     

Si（Li）谱仪测定X射线荧光谱中CrKβ谱线化学位移的探索

采用放射源＾２４１Ａｍ５９．６ｋｅＶγ射线分别激发金属Ｃｒ、Ｃｒ２Ｏ３和Ｋ２ＣｒＯ４，用Ｓｉ（Ｌｉ）谱仪比较测量其Ｋｘ射线的能量。实验表明Ｋ２ＣｒＯ４和ＣｒＫβ能峰相对于金属Ｃｒ有２．１２±０．２７ｅＶ的位移。     

^76Ge的2vββ衰变寿命和矩阵元

利用＾７６Ｇｅ的壳模型波函数计算＾７６Ｇｅ的２ｖββ衰变矩阵元和寿命。结果可以与最近观察到的＾７６Ｇｅ的２ｖββ衰变寿命相比拟。进而从最近的ｏｖββ衰变的实验寿命可以算出有效中微子质量上限量是０．４ｅＶ。     

电子—离子束缚态及其引发核聚变

在文献「１」关于电子－离子束缚态的基本概念的基础上，对电子－离子束缚态三体系统给出严格的薛定谔方程，给出能量的的近似解：（１）对ｐ－ｅ－ｐ束缚态，释放单能Ｅｐ≈１２．５ｋｅＶ的Ｘ射线；（２）对Ｄ－ｅ－Ｄ束缚态，释放单能ＥＤ≈２５ｋｅＶ的Ｘ射线，同时引发少量的核聚变，放出γ、质子、中子、氚、＾３Ｈｅ和＾４Ｈｅ。这是两个独立发生的过程，以Ｎｉ－Ｈ和氘气辉光放电实验为例，用束缚态模型给出定量的解释。进而     

超铀区缺中子新同位素~（235）Am的合成与鉴别

用３５ＭｅＶ质子轰击同位素靶２３８Ｐｕ，通过２３８Ｐｕ（Ｐ，４ｎ）２３５Ａｍ反应，合成了新的缺中子同位素２３５Ａｍ．利用Ｈｅ－ｊｅｔ及毛细管传输技术收集反应产物，然后用放射化学法除去产物中的裂变碎片并分离出Ａｍ活性．根据观测到的２３５Ｐｕ的衰变Ｙ及ＮＰ的特征Ｘ射线的生长－衰变行为和Ｘ－Ｙ符合测量，肯定了２３５Ａｍ的首次合成，测得２３５Ａｍ的半衰期为１５±５ｍｉｎ．     

229Ra的衰变纲图

用１４ＭｅＶ中子轰击钍靶,通过￣（２３２）Ｔｈ（ｎ,α）￣（２２９）Ｒａ反应产生￣（２２９）Ｒａ,由放射化学分离技术从被照靶物质中分离出￣（２２９）Ｒａ活性;利用γ（Ｘ）谱学方法,首次观测到了￣（２２９）Ｒａ的能量为１４．５、１５．６、１８．８、２１．８、２２．５、４４．０、４７．５、５５．０、６３．０、６９．６、９３．６、９４．１、９８．５、１０２．２、１０４．５、１０６．１、１６１．１和１７１．５ｋｅＶ的１８条新衰变γ射线,并建立了￣（２２９）Ｒａ的部分衰变纲图． The￣(229)Ra has been produced in the￣(232)Th (n,α)￣(229)Ra reaction by 14 Mev neutron irradiation of natural Thorium.The￣(229)Ra activities were separated from irradiated target material by radiochemical separation technique. The 18 new γ rays of !(229)Ra decay with energies of 14. 5, 15. 6, 18. 8, 21. 8, 22. 5, 44. 0, 47. 5, 55. 0, 63. 0, 69. 6, 93. 6, 94. 1,98. 5, 102. 2, 104. 5, 106. 1, 161. 1 and 171. 5 keV were found for the first take by using y (X ) ...     

在Ar和Xe低温基体中Fe（CO）3与CO扩散控制反应研究

本文用２８０ｎｍ脉冲激光光解被Ａｒ和Ｘｅ基体隔离的Ｆｅ（ＣＯ）５以产生配位不饱和的Ｆｅ（ＣＯ）３。用傅里衰变换红外光谱仪实时监察光解停止后Ｆｅ（ＣＯ）３和ＣＤ的复合，并以Ｓｍｏｌｕｃｈｏｗｓｋｉ扩散控制反应动力学理论模型求得Ｆｅ（ＣＯ）３与ＣＯ的反应半径为４．０×１０＾－１０ｍ，ＣＯ在１０Ｋ的Ａｒ和Ｘｅ基体中的扩散系数分别为２．２×１０＾－２３ｍ＾２／ｓ和４．５×±∩＾－２３ｍ＾２／ｓ。     

Si(Li)谱仪测量X射线荧光谱中CrK_β谱线化学位移的探索

采用放射源２４１Ａｍ５９．６ｋｅＶγ射线分别激发金属Ｃｒ、Ｃｒ２Ｏ３和Ｋ２ＣｒＯ４，用Ｓｉ（Ｌｉ）谱仪比较测量其Ｋｘ射线的能量。实验表明Ｋ２ＣｒＯ４中ＣｒＫβ能峰相对于金属Ｃｒ有２．１２±０．２７ｅＶ的位移。     

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.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

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.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.