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1.
利用2.5MeV的质子束激发单质金属元素靶或化合物靶产生的K线或L线特征x射线作为x光源,用Si(Li)谱仪系统测得了3.3KeV—27.8keV能区Cu的x射线质量衰减系数,对于较强而孤立的特征x射线峰,衰减系数的实验误差≤1%。在本能区里,由于瑞利散射和康普顿散射的截面很小,因此,由总衰减截面扣除散射截面便得到了光电截面的实验值,与一些早期的实验结果及理论值进行了比较,并作了讨论。 相似文献
2.
利用冷靶反冲离子动量谱仪装置系统研究了20—40 keV He2+-He碰撞体系的态选择单电子俘获过程,实验获得了单电子俘获过程的态选择截面以及角微分截面.在所研究的能区范围,电子俘获到L壳层的截面最大,为主要的反应道,这与分子库仑过垒模型的反应窗理论的预测一致.实验测量的态选择截面与原子轨道紧耦合的计算结果很好地符合,与光谱方法的测量结果存在一定的差别,主要原因是光谱方法不能测量完整的反应通道信息.实验结果表明,总角微分截面在小角度范围主要来源于电子俘获到基态的贡献,在大角度范围主要来自电子俘获到激发态的贡献;电子俘获到基态的和激发态的角微分截面均出现振荡结构,这种振荡来源于电子俘获反应中分子轨道之间的相干效应.实验测量的角微分截面与其他实验和紧耦合方法的计算结果进行了比较和分析.
关键词:
冷靶反冲离子动量谱仪
态选择电子俘获
态选择截面
角微分截面 相似文献
3.
本文报导了氮气(N_2)和氢气(H_2)对氢原子束剥离截面的测量系统及实验结果。当氢原子束能量从0.6千电子伏增至10千电子伏时,氮气截面由1.3×10~-17厘米增至2.44×10~-16厘米,当氢原子束能量从1千电子伏增至10千电子伏时,氢气截面在(2—6)×10~(-17)厘米。范围内变化。 相似文献
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基于处理裸核离子与中性原子碰撞电离过程的OBKN和ECPSSR理论模型,系统计算了不同裸核离子与中性原子碰撞K壳层电子俘获截面和直接电离截面,并与其它文献已有的理论和实验结果进行了比较.研究结果表明:碰撞能量较低时,电子俘获截面大于直接电离截面,随着碰撞能量的增加,电子俘获截面和直接电离截面均是先增大后减小且直接电离截面减小地非常缓慢,高能时,直接电离截面大于电子俘获截面.当入射炮弹离子速度接近0.67倍靶原子K壳层电子速度时,电子俘获截面达到最大值,而当入射炮弹离子速度接近靶原子K壳层电子速度时,直接电离截面达到最大值. 相似文献
6.
基于处理裸核离子与中性原子碰撞电离过程的OBKN和ECPSSR理论模型,系统计算了不同裸核离子与中性原子碰撞K壳层电子俘获截面和直接电离截面,并与其它文献已有的理论和实验结果进行了比较.研究结果表明:碰撞能量较低时,电子俘获截面大于直接电离截面,随着碰撞能量的增加,电子俘获截面和直接电离截面均是先增大后减小且直接电离截面减小地非常缓慢,高能时,直接电离截面大于电子俘获截面.当入射炮弹离子速度接近0.67倍靶原子K壳层电子速度时,电子俘获截面达到最大值,而当入射炮弹离子速度接近靶原子K壳层电子速度时,直接电离截面达到最大值. 相似文献
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快速氢粒子通过气体靶时电荷交换截面的测量 总被引:1,自引:1,他引:0
本文在厚靶条件下,测量了20—100keV的快速质子和快速氢原子通过H-2,He,N_2,Ne和Ar5种气体靶时的电子捕获截面σ_(10)和剥离截面σ_(01)。实验结果的系统误差小于±20%,与Barnett等人编辑的数据相当符合。 相似文献
10.
在中能区测量了Cq+(q=1-4)与He,Ne,Ar气体原子碰撞的电子损失截面,计算分析了入射离子损失两个电子与一个电子的总截面比 R21. 单反应道分析无法完全解释所有实验结果,必须同时考虑入射离子的电子损失、电子俘获和靶原子电离各种出射道间的耦合作用. 对于不同靶原子的碰撞,入射离子损失一个电子和两个电子的速度阈值可以由屏蔽和反屏蔽理论解释. 然而,该理论不能完全解释截面比 R21
关键词:
离子-原子碰撞
截面
电子损失 相似文献
11.
X射线质量衰减截面和光电截面的高精度测量 总被引:1,自引:0,他引:1
利用特征X射线源系统地测量了Si、Fe、Cu、Y、In、Sn等六种元素及SiH4的X射线质量衰减系数,实验误差为±1%. By using the characteristic X ray sources and the Si( Li) detector system, the X ray mass attenuation coefficients for Si,Fe,Cu,Y,In,Sn and SiH 4 have been systematically measured in the energy range of 1.486~29.109 keV. The accuracy of experimental data has been reduced to ±1% . 相似文献
12.
MASS ATTENUATION COEFFICIENTS FOR ELEMENTS MEASURED WITH CHARACTERISTIC X-RAYS FROM TARGETS EXCITED BY ENERGETIC PROTON
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The characteristic X-rays from elemental or compound targets excited by energetic proton are quasi-monochromatic X-ray sources. The advantages of high line/ background ratio, controllable intensity as well as many available energies, make them suitable for applications in many important fields. The total mass attenuation cross sections of yttrium have been systematically measured by using this kind of X-ray source. The accuracy of experimental data has been improved to ±1%, which is much better than that of earlier results. The contributions of the coherent and incoherent scattering crees sections have been calcu-lated in accordance with the present experimental condition. And the total photoelectric cross sections have been obtained by subtracting the scattering cross section from the measured total cross sections. The com-parisons of our experimental results with the available data of earlier investigations as well as with the theo-retical calculations have been presented and discussed. 相似文献
13.
S. Erzeneo?lu B. Gürbulak 《Journal of Quantitative Spectroscopy & Radiative Transfer》2006,102(3):343-347
The mass attenuation coefficients of InSe and InSe having different holmium concentrations were measured in the energy region 15.746-40.930 keV using a Si(Li) detector. InSe and InSe:holmium(0.0025), InSe:holmium(0.0050), InSe:holmium(0.025) and InSe:holmium(0.05) crystals were grown by the Bridgman-Stocbarger method. The measured values are compared with the theoretical ones obtained using WinXcom which is a Windows version of XCOM. The measurement of mass attenuation coefficients of ternary semiconductors is very important because of its use in technology. 相似文献
14.
Total attenuation cross sections of copper and silver have been measured in the energy range 5 to 85 keV in a narrow beam
good geometry set up using X- andγ-rays emitted from radio isotopes, by employing a high resolution hyper pure germanium detector. From the measured values,
the photoeffect cross-sections have been derived by subtracting a small contribution of the sum of the theoretical coherent
and incoherent scattering cross sections. The photoeffect cross-sections so obtained are found to be in better agreement with
the unrenormalized values of Scofield [10]. These photoeffect cross-sections have been used to evaluate the dispersion corrections
(also called anomalous scattering factors)f
+ andf″ for the forward Rayleigh scattering amplitude by a numerical evaluation of the dispersion integral that relates them at the
energies at which the cross-sections have been measured. To thef
+ values so obtained, the relativistic corrections proposed by different investigators are included separately and the valuesf′ so obtained are compared with the available data and discussed. Possible conclusions are drawn from the present study. 相似文献
15.
Absolute values of elastic scattering cross section of protons in the energy region 600–2,000 keV have been measured on oxygen for scattering angles between 110 and 160°. The method applied in the present work is advantageous in regard to determine absolute cross sections, since quantities such as proton particle fluence and detection geometry can be neglected. The results show that the measured cross sections are considerable higher than Rutherford cross sections for proton energies close to 2,000 keV. No resonances are observed in the energy region studied. 相似文献
16.
In this paper, we provide polynomial coefficients and a semi-empirical relation using which one can derive photon mass energy
absorption coefficient of any H-, C-, N-, O-based sample of biological interest containing any other elements in the atomic
number range 2–40 and energy range 200–1500 keV. More interestingly, it has been observed in the present work that in this
energy range, both the mass attenuation coefficients and the mass energy absorption coefficients for such samples vary only
with respect to energy. Hence it was possible to represent the photon interaction properties of such samples by a mean value
of these coefficients. By an independent study of the variation of the mean mass attenuation coefficient as well as mass energy
absorption coefficient with energy, two simple semi-empirical relations for the photon mass energy absorption coefficients
and one relation for the mass attenuation coefficient have been obtained in the energy range 200–1500 keV. It is felt that
these semi-empirical relations can be very handy and convenient in biomedical and other applications. One possible significant
conclusion based on the results of the present work is that in the energy region 200–1500 keV, the photon interaction characteristics
of any H-, C-, N-, O-based sample of biological interest which may or may not contain any other elements in the atomic number
range 2–40 can be represented by a sample-independent (single) but energy-dependent mass attenuation coefficient and mass
energy absorption coefficient.
相似文献
17.
《X射线光谱测定》2006,35(4):261-263
Dispersion corrections to the forward Rayleigh scattering amplitudes of tantalum and lead in the photon energy range 6.4–24.14 keV were determined by a numerical evaluation of the dispersion integral that relates them through the optical theorem to the photoelectric cross‐sections. The photoelectric cross‐sections were extracted by subtracting the coherent and incoherent scattering contribution from the measured total attenuation cross‐section, using a high‐resolution, high‐purity germanium detector in a narrow‐beam good geometry setup. The real part of the dispersion correction to which the relativistic corrections calculated by Kissel and Pratt (S‐matrix approach) or Creagh and McAuley (multipole corrections) have been included are in better agreement with the available theoretical values than those values to which the relativistic corrections calculated by Cromer and Liberman (dipole corrections) are added. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
18.
Orhan
elli Salih Erzeneo
lu Bekir Gürbulak 《Journal of Quantitative Spectroscopy & Radiative Transfer》2005,90(3-4):399-407
Measurements have been made to determine the mass attenuation coefficients of undoped n-type InSe, and Gd, Ho, Er doped n-InSe single crystals using a Si(Li) detector in the energy region 15.746–40.930 keV X-ray energies with energy dispersive X-ray fluorescence systems. InSe, InSe:Gd, InSe:Ho and InSe:Er single crystals were grown by using the stockbarger method. The measured values are graphically compared with the theoretical ones obtained using WinXcom. 相似文献
19.
We have measured the absolute values of the total cross section of the one-electron capture by He2+ ions in the kinetic energy range 2–30 keV at the Ar atoms. The absolute values of the differential scattering cross sections of He+ ions formed during the one-electron capture and the electron capture with ionization at energies of 2.2, 5.4, and 30 keV have been determined. The electronic states of the formed ions have been determined using collision spectroscopy based on analysis of the change in the kinetic energy of He+ after the interaction. We have measured doubly differential (with respect to the kinetic energy and the scattering angle) cross sections of the formation of free electrons. The free electron formation channels (direct ionization and electron capture with ionization) have been analyzed by calculating the electron terms of the (HeAr)2+ system. The calculated cross section of capture with ionization is in conformity with the cross section measured using collision spectroscopy. 相似文献
20.
The elastic and inelastic scattering of 12C by 12C has been measured over a wide angular range employing a kinematical analysis with the help of position-sensitive detectors. The bombarding energy was varied in 200 keV steps between 10 and 37.6 MeV. The cross sections are analysed in the framework of compound fluctuations and the direct reaction model. 相似文献