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1.
介绍了中高能电子散射全截面绝对测量装置的设计,采用直线透射技术.因采用了恒温控制作用室,以便较准确测量反应室的绝对气压值;同时采用静电型圆柱能量分析器,并用计数率测量模式代替通常的束流强度测量模式,从而可以大幅度减小接收立体角,抑制零度角的弹性散射贡献.通过以上几项措施,可以有效地提高测量的精度,从而可以对一些有意义的分子的中、高能电子散射全截面进行绝对测量.  相似文献   

2.
介绍一台用于中能电子散射全截面的测量装置,并给出了500-2600ev电子与氮分子散射全截面的实验结果。 关键词:  相似文献   

3.
低能电子与氩原子散射总截面的绝对测量   总被引:1,自引:0,他引:1  
利用电子散射飞行时间谱仪,测量了1—50eV能量范围的电子与氩原子散射绝对总截面(TCS),测量精度达到5%。实验结果与同类实验和近期的理论结果进行了比较,在实验误差范围内符合得较好。  相似文献   

4.
250—1400eV能区N2分子的电子散射全截面测量   总被引:2,自引:0,他引:2       下载免费PDF全文
建立了一套直线透射式全截面测量装置,并测量了250—1400eV能区N2分子的电子散射全截面,实验误差为3.5%。测量的结果与已报道实验和理论工作做了比较。 关键词:  相似文献   

5.
李树 《物理学报》2018,67(21):215201-215201
高温全电离等离子体的辐射输运问题中,光子与电子的Compton散射与逆Compton散射是其中重要的特性,光子与相对论麦克斯韦电子散射的描述及截面的计算非常复杂且费时.本文提出了一种用于模拟计算光子与相对论麦克斯韦速度分布电子散射截面的蒙特卡罗计算方法.给出了各步骤的具体实现办法,推导了对应的计算公式,研究了相对论电子速率抽样方法,编写了光子与相对论电子散射的微观截面的蒙特卡罗计算程序.开展了高温全电离等离子体中,不同能量光子与不同温度电子散射的微观散射截面计算和分析.模拟计算结果显示,在电子温度低于25 keV情况下,本文方法与多重数值积分方法的计算结果非常接近;但随着电子温度继续升高,二者差异逐渐增大并较明显,经分析,可能是本文方法目前的电子速率抽样偏差所致,希望将来能够找到更好的相对论电子速率抽样方法以克服此缺陷.  相似文献   

6.
500—4250eV电子对CO2的散射全截面绝对测量   总被引:2,自引:0,他引:2  
对中能电子与二氧化碳分子碰撞的散射全截面测量,给出500-4250eV电子对CO2的绝对散射全截面。对测量结果作了曲线拟合,并与已有的实验和理论结果进行了比较  相似文献   

7.
电子散射是一个老的题目,也是当今中高能核物理学发展的前沿.早在 1929年莫特[1]从理论上研究了快电子被原子核散射的问题.他假设原子核为点电荷,电子用狄喇克波函数来描述,这样得到的截面公式与熟知的卢瑟福公式是不同的,后来称之为莫特散射截面,其中α=e2/hc 1/37是精细结构常数,E是入射电子的能量,θ是散射角.1934年Eug-ene Guth[2]用波恩近似方法研究快电子被原子核散射问题,其结果与电子被点库仑电荷散射有偏差,这预示电子散射可以用来研究原子核的大小.但是由于当时实验条件的限制,电子散射的实验研究宜到第二次大战结束后才开始. …  相似文献   

8.
在考虑分子内成键原子间的电子云重叠效应的基础上, 提出了一种能够准确计算“中、高能电子-分子”散射的微分截面、动量转移截面及弹性积分截面的修正势方法. 利用可加性规则、使用Hartree-Fock波函数并采用被这一方法修正过的复光学势, 在100—1000eV内对电子被SO2分子散射的微分截面、动量转移截面及弹性积分截面进行了计算, 并将计算结果与实验及其他理论结果进行比较. 结果表明, 利用这一修正过的复光学势及可加性规则获得的微分截面比利用未修正的复光学势及可加性规则得到的结果准 关键词: 可加性规则 微分截面 动量转移截面 电子散射  相似文献   

9.
介绍了离子-原子碰撞过程中双微分绝对截面的计算方法.利用符合技术测量了中能区C3++Ne碰撞系统的纯电离微分绝对截面. 将实验结果与多体经典蒙特卡罗方法计算结果进行对比后发现,纯电离截面随入射能量变化的趋势基本一致,对理论与实验产生差异的原因作了分析. 对多重电离的电离机制分析表明:高价态的反冲离子主要来自于俄歇贡献;随着入射能量的升高,电子-电子间的库仑作用也逐渐显现. 此实验方法可以用于相同实验装置上的各种反应出射道的绝对截面测量,入射离子种类及入射离子能量范围将得到拓展. 关键词: 离子-原子碰撞 绝对截面 纯电离  相似文献   

10.
中高能电子电离He原子的二重微分截面   总被引:1,自引:1,他引:0  
这篇文章用BBK和DS3C模型,计算了入射能为100,200,300,400和600 eV等中、高能情况下,电子入射电离He原子的二重微分截面(DDCS),给出了散射电子和敲出电子截面的角分布.散射电子和敲出电子的二重微分截面分别通过敲出电子和散射电子三重微分截面(TDCS)在全空间的角度积分而得到,所有的理论结果与有效的实验测量进行了比较.研究表明:除400和600 ev的高入射能之外,理论结果均能与绝对测量的实验结果较好的符合.  相似文献   

11.
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.  相似文献   

12.
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.  相似文献   

13.
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.  相似文献   

14.
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.  相似文献   

15.
16.
A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines the best features of both. In particular, the hybrid scheme retains the large information carrying capacity of wavelength division multiple access (WDMA) and flexibility of code division multiple access (CDMA). In this paper WDMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA networks, concept of incoherent and coherent coding including inverse decoding and matched filter is introduced. The delay performance of both WDMA and WCDMA networks, under the simple suboptimum access protocols based on cyclic search, is computed. It has been shown quantitatively that tuning delay significantly affects the delay performance of both WDMA and WCDMA networks. Futhermore, delay performance of WCDMA networks is always better than the WDMA networks for the same tuning delay, load, and number of users.  相似文献   

17.
A transient suppression method for piezoelectric ceramic transducer is presented. By adding some special pedestal pulses to the original transmitted signal, the transient effects in the output of the transducer can be just precisely transmission by use of a narrowband transducer. canceled, thereby achieving the broadband The experimental results show that the transient responses of the sinusoid pulses and coded signals are suppressed successfully and the acoustic waveforms radiated into the surrounding water are improved significantly.  相似文献   

18.
We experimentally demonstrate amplitude squeezed soliton utilizing intensity-dependent self-phase modulation in an asymmetric Sagnac interferometer.The system.whose components are connected via ferrule connector/physical connection(FC/PC)fiber connectors,constitutes all-fiber configuration to generate squeezed soliton.Soliton amplitude reduction measured by homodyne detection is near 4.0 dB below the shot-noise level.Optimal squeezing fields in both simple and compact all-fiber configuration are obtained.  相似文献   

19.
The(2 1)-dimensional nonlinear Schr(o)dinger(NLS)equation with spatially inhomogeneous nonlinearities is investigated,which describes propagation of light in(2 1)-dimensional nonlinear optical media with inhomogeneous nonlinearities.New types of optical modes and nonlinear effects in optical media are presented numerically.The results reveal that the regular split of beam can be obtained in (2 1)-dimensional nonlinear optical media with inhomogeneous nonlinearities,by adjusting the guiding parameter.Furthermore,the stability of beam regular split is discussed numerically,and the results reveal that the beam regular split is stable to the finite initial perturbations.  相似文献   

20.
In the real-world application of face recognition system, owing to the difficulties of collecting samples or storage space of systems, only one sample image per person is stored in the system, which is so-called one sample per person problem. Moreover, pose and illumination have impact on recognition performance. We propose a novel pose and illumination robust algorithm for face recognition with a single training image per person to solve the above limitations. Experimental results show that the proposed algorithm is an efficient and practical approach for face recognition.  相似文献   

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