共查询到18条相似文献,搜索用时 296 毫秒
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本文在q×(20—150)keV的能量范围内,通过光学测量,对He+和He2+离子与碱余属原子Li碰撞过程中的靶激发过程进行了研究。由光学多道分析系统(OMA),测得LiI 670.8nm(2p→2s),LiI610.4nm(3d→2p),LiI460.3nm(4d→2p)和LiI812.6nm(3s→2p)谱线。给出所观察到的谱线的发射截面和相立的Li(2p)激发截面。对He+与Li碰撞过程,LiI670.8nm谱线发射截面与Aumayr
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实验用光学多道分析系统(OMA)测量了He2+和Ne,Ar碰撞过程中的发射光谱,结果表明,这些碰撞体系存在着三种激发过程:双电子俘获激发过程、单电子俘获激发过程和直接激发过程。给出了HeI,HeII,NeI,NeII和ArI,ArII谱线的发射截面,并对He2++Ne和He2++Ar两个碰撞体系的发射截面作了一些比较,发现在入射离子速度相同的情况下,后者的发射截面要比前者大得多,并对此进行了定性讨论。OMA的光谱波长范围为200—800nm。入射离子He2+的能量范围为140—340keV。
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本文通过光学方法,在q×(20—140)keV能量范围内,研究了He+和He2+离子与碱金属原子Na碰撞中的靶激发过程。通过光学多道分析系统(OMA),对He+与Na碰撞过程,观察到NaI589.0+589.6nm(3p→3s),NaI818.3nm(3d→3p)和NaI568.8nm(4d→3p)等谱线。对He2+与Na碰撞过程,只观察到NaI589.0+589.6nm谱线。计算了所有观察到的谱线的发射截面和Na(3
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The cross sections for proton capture by 11B to the ground and excited states of 12C have been measured in the proton energy interval between 18 and 43 MeV. The ground-state cross section shows good agreement with theoretical calculations including correlations. Capture photons have also been observed to all the residual 1p-1h states of 12C having a dominant hole: the corresponding cross sections systematically show a giant resonance whose energy increases with the increasing excitation energy of the “background” level. The resonances at 27.4, 31, 33.2, 37 and 43 MeV, seem to show observable interference effects. 相似文献
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Using the effective operator formalism, the importance of ground-state correlations on photonuclear cross sections is studied. For purposes of orientation, a bound-state calculation is first performed to take into account the mixing of 2p-2h and 3p-3h configurations into the 1p-1h dipole states. Inclusion of these configurations is found to affect the energies of the 1p-1h states in opposite directions and the combined effect, including that on the transition strengths, is negligible. Most of the reduction in the absorption comes from the ground-state correlations of which the A-dependence is examined with a model interaction. We then proceed to calculate the excitation function for the reactions using effective dipole matrix elements obtained from the continuum wave functions of the coupled-channels calculation. Application to the case of 16O leads to a reduction of about 25 % in the cross sections. 相似文献
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Yu. M. Smirnov 《Optics and Spectroscopy》2012,112(6):836-843
The excitation cross sections of transitions from the 3 P o and 3 D o levels of a nickel atom in electron-atom collisions at an exciting-electron energy of 50 eV have been analyzed by the method of extended crossing beams with detection of the optical signal from excited atoms. Eleven optical excitation functions have been recorded in the electron-energy range of 0?C200 eV. The direct excitation cross sections of the energy levels and the contribution of the cascade transitions were calculated using the data obtained. 相似文献
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The 210Po(t, α)209Bi reaction has been studied at 20 MeV triton energy with an overall resolution of 20 keV FWHM. Absolute cross sections were established by a comparison of the (t, α) intensities to elastic triton scattering. The three lowest single-proton states in 209Bi were observed and spectroscopic factors were extracted from the measured cross sections by DWBA analysis. Starting at 2.43 MeV, six levels were strongly excited. These states have large 2p-1h proton components. The spectroscopic factors were extracted by a comparison of 210Po(t, α) cross sections to 208Pb(t, α)207T1 single-proton-hole cross sections measured previously at the same bombarding energy. The observed states and their properties were analyzed within the framework of the particle- (or hole) vibration coupling model. Surface vibrational states in 208Pb coupled to single protons as well as the proton pair addition modes (states in 210Po) coupled to a proton-hole were included in the analysis. 相似文献
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R. Wichmann J. Ahrens H. J. Arends R. Beck G. Galler A. Hünger A. Kraus I. J. D. MacGregor J. Peise B. Seitz M. Schmitz M. Schneider O. Selke M. Schumacher F. Wissmann 《Zeitschrift für Physik A Hadrons and Nuclei》1974,355(2):169-177
High resolution proton energy spectra from the 4He(γ,p) reaction have been measured with tagged photons in the range Eγ = 130–525 MeV using the large Mainz NaI(Tl) spectrometer at \([Theta _p^{lab} = 37.1^circ ]\) . Three separate reaction channels were identified, viz. 4He(γ,p)t two-body breakup, 4He photodisintegration via two-nucleon photon absorption processes and the quasifree pion production channel. Differential cross sections are presented for each of these channels as a function of photon energy. The sum of the two-nucleon photon absorption and the quasifree pion production differential cross sections, in the CM system, resembles that of the corresponding free-nucleon differential cross section when Fermi motion is taken into account. 相似文献
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Nasir Amin S. Mahmood S.U. Haq M. Rafiq 《Journal of Quantitative Spectroscopy & Radiative Transfer》2008,109(5):863-872
New measurements of the photoionization cross sections from the 4p 2P1/2,3/2, 5d 2D5/2,3/2 and 7s 2S1/2 excited states of potassium are presented. The cross sections have been measured by two-step excitation and ionization using a Nd:YAG laser in conjunction with a thermionic diode ion detector. By applying the saturation technique, the absolute values of the cross sections from the 4p 2P3/2 and 4p 2P1/2 states at 355 nm are determined as 7.2±1.1 and 5.6±0.8 Mb, respectively. The photoionization cross section from the 5d 2D5/2,3/2 excited state has been measured using two excitation paths, two-step excitation and two-photon excitation from the ground state. The measured values of the cross sections from the 5d 2D5/2 state by two-photon excitation from the ground state is 28.9±4.3 Mb, whereas in the two-step excitation, the cross section from the 5d 2D3/2 state via the 4p 2P1/2 state and from the 5d 2D5/2,3/2 states via the 4p 2P3/2 state are determined as 25.1±3.8 and 30.2±4.5 Mb, respectively. Besides, we have measured the photoionization cross sections from the 7s 2S1/2 excited state using the two-photon excitation from the ground state as 0.61±0.09 Mb. 相似文献