共查询到20条相似文献,搜索用时 0 毫秒
1.
R. A. Nymmik 《Bulletin of the Russian Academy of Sciences: Physics》2013,77(5):490-492
The charge states of He, C, O, and Fe ions are determined for 51 gradual solar energetic particle (SEP) events of solar cycle 23 using the parameters of the particle energy spectra consisting of two power-law regions separated by the so-called knee. Experimental data from the GOES satellites (protons) and ULEIS (all particles) and SIS (H, C, O, Fe ions) instruments are employed. The charge states of the heavy ions are found to be independent of the SEP event magnitude and particle energy (in the interval of 0.3 to 30 MeV/nucleon). 相似文献
2.
E. I. Daibog K. Kecskemety Yu. I. Logachev 《Bulletin of the Russian Academy of Sciences: Physics》2009,73(3):319-321
The decay phase of solar energetic particle (proton and electron) events is considered. The propagation mechanisms for particles of different kind may differ in the same events, which should manifest itself in the pecularities of their decay phases. To compare the propagation parameters of protons and electrons, we used the data of simultaneous measurements of few-MeV proton and few-hundred-keV electron fluxes from IMP-8 CPME and SOHO COSTEP. Nearly half of clear-shaped simultaneously measured electron and proton decays have similar character (exponential or power-law), suggesting that at least in a part of events electrons can be subjected to the same propagation mechanisms as protons. 相似文献
3.
The selective generation of characteristic X-rays during heavy ion bombardment of solids is briefly described. The principles can be understood in terms of the Fano-Lichten model, which postulates that during heavy ion collisions, interactions occur between the electronic systems of the target and projectile atoms, leading to electron promotions and consequent inner shell vacancies. The resultant X-rays have the advantage of being essentially free from the continuous background radiation which accompanies X-rays produced by electron bombardment. It is shown how the characteristic X-rays of certain elements may be generated in a selective manner by bombardment with an appropriate heavy ion of optimum energy. The resultant technique is particularly applicable to the analysis of elements located on or near to surfaces, and may therefore be used for the elucidation of distribution profiles of ion-implanted elements. 相似文献
4.
In more than 25 years of almost continuous observations, the University of Chicago's Cosmic Ray Telescope (CRT) on IMP-8 has amassed a unique database on high-energy solar heavy ions of potential relevance to manned spaceflight. In the very largest particle events, IMP-8/CRT has even observed solar Fe ions above the Galactic cosmic ray background up to approximately 800 MeV/nucleon, an energy sufficiently high to penetrate nearly 25 g/cm2 of shielding. IMP-8/CRT observations show that high-energy heavy-ion spectra are often surprisingly hard power laws, without the exponential roll-offs suggested by stochastic acceleration fits to lower energy measurements alone. Also, in many solar particle events the Fe/O ratio grows with increasing energy, contrary to the notion that ions with higher mass-to-charge ratios should be less abundant at higher energies. Previous studies of radiation hazards for manned spaceflight have often assumed heavy-ion composition and steeply-falling energy spectra inconsistent with these observations. Conclusions based on such studies should therefore be re-assessed. The significant event-to-event variability observed in the high-energy solar heavy ions also has important implications for strategies in building probabilistic models of solar particle radiation hazards. 相似文献
5.
M. Kirm V. N. Makhov M. True S. Vielhauer G. Zimmerer 《Physics of the Solid State》2005,47(8):1416-1424
VUV 4f n → 4fn?15d transitions of Gd3+, Er3+, Tm3+, and Lu3+ in fluoride matrices have been analyzed with high-resolution luminescence and excitation spectroscopy. In trifluorides, strong electron-phonon coupling has been found. In the other matrices, the luminescence spectra clearly yield zero-phonon lines and phonon replica, indicating intermediate coupling. The energies of the zero-phonon lines observed are compared with theoretical predictions. Near the threshold of f → d excitations, some of the excitation spectra yield sharp structures which cannot be explained with phonon replica but will be discussed in terms of the energy levels of the 4fn?15d configuration. 相似文献
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7.
Projected ranges and range straggling of Ge- and As-ions with LSS-energies of ? < 0.2 have been measured with backscattering techniques using a high resolution electrostatic analyzer. 相似文献
8.
E. Casarejos P. Armbruster L. Audouin J. Benlliure M. Bernas A. Boudard R. Legrain S. Leray B. Mustapha S. Czajkowski T. Enqvist B. Fernandez J. Pereira M. Pravikoff F. Rejmund K. -H. Schmidt C. Stephan J. Taieb L. Tassan-Got C. Villagrasa C. Volant W. Wlazlo 《Physics of Atomic Nuclei》2003,66(8):1413-1420
The isotopic production cross sections of heavy residues in relativistic heavy-ion collisions have been investigated in inverse kinematics. The primary reaction products were fully identified in mass and atomic number prior to beta decay using the fragment separator FRS. The huge collection of data obtained helps in the understanding of the two main reaction mechanisms involved: fragmentation and fission. These data provide basic information for future radioactive ion beam facilities and for technical applications like intense neutron sources by means of spallation targets. 相似文献
9.
M. Schneider F. Hase 《Journal of Quantitative Spectroscopy & Radiative Transfer》2009,110(17):1825-1839
Current atmospheric remote sensing experiments measuring high resolution spectra apply instruments of similar quality as the laboratory experiments that are especially equipped to derive spectroscopic parameters. We propose a method that uses high quality atmospheric spectra to improve the spectroscopic parameterization. It is an optimal estimation method that applies the uncertainty ranges given in current spectroscopic databases as a priori covariance and the residuals between the simulated and measured atmospheric spectra as new measurements. We test the method by updating the current HITRAN parameters of 49 mid-infrared water vapor lines (situated in 15 spectral windows between 795 and ) by the information present in high quality ground-based Fourier transform infra-red (FTIR) spectra. We show that the application of a speed dependent Voigt line shape model is important. The updated water vapor parameterization, compared to the original one, leads to lower residuals, larger measurement information content, and better agreement between remotely sensed and coincident in situ water vapor profiles. Using the new line parameterization, a state-of-the-art ground-based FTIR system is able to monitor upper tropospheric water vapor amounts and middle/upper tropospheric HDO/H2O ratios. 相似文献
10.
V. P. Okhlopkov 《Moscow University Physics Bulletin》2009,64(4):470-473
The periodicities that take place in cosmic rays in the stratosphere, in the neutron component, and in various parameters
of solar activity and the interplanetary environment for the period from 1958 to 2007 were investigated by means of spectral
analysis. 相似文献
11.
The variation of the range of 2.72 GeV 209Bi with crystalline anisotropy has been studied using an anisotropic detector - muscovite mica and an isotropic detector - polycarbonate (Bayer). The two detectors were irradiated at five different angles ranging between 15° and 75°. The effect of the crystal structure on the range variance has also been discussed. 相似文献
12.
B. Deva Prasad Raju K.V. Narasimhulu J. Lakshmana Rao 《Journal of Physics and Chemistry of Solids》2005,66(5):753-761
X-band electron paramagnetic resonance (EPR) studies on divalent copper ions embedded in KMgClSO4·3H2O single crystals have been performed at low temperature (123 K). The angular variation of the EPR spectra reveals the presence of two Cu2+ sites, which have different orientations. The spin-Hamiltonian parameters of this six-coordinated cupric ion have been evaluated from the EPR spectra at 123 K. The forbidden lines due to ΔmI=±1 transitions are observed in between allowed transitions. The temperature variation EPR studies have also been performed both for a single crystal and a polycrystalline sample. The ground state wavefunction of Cu2+ ions has been estimated and is found to be an admixture of d3z2−r2 and dx2−y2. The temperature variation of the EPR spectra reveals that Cu2+ ions exhibit dynamic Jahn-Teller effect. From the polycrystalline EPR data, the temperature dependent magnetic susceptibilities are evaluated and discussed. 相似文献
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This paper reports the fluorescence properties of a new series of (La, Zn) OF:Sm3+ powder phosphors. The measured fluorescence spectra were analyzed by computing the color coordinates
and relative fluorescence intensity ratios (ED/MD). A bright yellowish-orange color was observed from these powder phosphors under a UV-source due to the confirmation of the transitions 4G5/2→6H5/2, 4G5/2→6H7/2, and 4G5/2→6H9/2. Scanning electron microscopic studies were performed to understand the average grain size of the synthesized powder phosphors. 相似文献
15.
采用“多功能相对论原子结构计算程序”GRASP2 (1 992 ) ,分别计算了类氢离子 Mg11 ,Al12 能级之间电偶跃迁 (E1 )的波长、几率和振子强度 ,其中跃迁波长值与实验值相吻合。充分利用计算结果 ,采用等电子线率法对文献 [4 ]的谱线强度比测温实验进行理论上的探讨 ,即利用原子序数相差不大 (ΔZ=1 ,2 )的两种示踪原子相同离化态的同种跃迁谱线进行电子温度诊断 ,以期望提高测温精度 相似文献
16.
Zi-Yuan Yang 《Journal of luminescence》2007,126(2):753-758
An extended complete diagonalization method/microscopic spin-Hamiltonian (CDM/MSH) program has been developed, which is applicable for d3 ions at sites of tetragonal symmetry type I (C4v, D2d, D4, D4h) and trigonal symmetry type I (C3v, D3, D3d). The Hamiltonian includes the spin-spin (SS) and spin-other-orbit (SOO) magnetic interactions besides the spin-orbit (SO) magnetic interaction usually taken into account. Utilizing the extended CDM/MSH program, the optical spectra, the spin-Hamiltonian (SH) parameters of the ground state 4B1, and the splitting δ(2E) of the first excited 2E state for Cr3+ (3d3) ions at C4v symmetry sites in MgO crystals have been successfully investigated. It is found that although the SO magnetic interaction is the most important one, the contributions to the SH parameters and the optical spectra from the SS and SOO magnetic interactions for Cr3+:MgO crystals are appreciable and should not be omitted, especially reaching 27.8% for the zero field splitting parameter D. 相似文献
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18.
E. G. Sheikin 《Technical Physics》1998,43(9):1039-1042
Based on a theory of the passage of low-energy, heavy ions through matter, simple analytical expressions are obtained for
calculating the average projected ranges of the ions and the rms deviations of the projected ranges. The theoretical and experimental
ranges of heavy ions with atomic numbers 29⩽Z
1⩽83 in targets of Be, B, C, and Si are compared. The theory is found to be in good agreement with experiment.
Zh. Tekh. Fiz. 68, 33–36 (September 1998) 相似文献
19.
This study has revealed the advantages of the use of 116 keV X-rays as an excitation source of X-ray fluorescence (XRF) analyses. This technique is suitable for nondestructive multielemental analyses of heavy elements such as rare-earth elements. The lowest MDL value evaluated for the bulk analysis of a JG-1 standard reference sample (granite rock) was 0.1 ppm for W for a 500 s measurement. The spectrum of standard glass samples of SRM612 demonstrated clearly resolved K-line peaks of more than 30 elements, including all the existing rare-earth elements, at 50 ppm levels. The calibration curve for the determination of a rare-earth element shows a linear relation between the XRF intensity and concentrations from 10 to 0.03 ng. This powerful technique should be useful for nondestructive analyses of rare-earth and heavy elements in geological, geochemical and archaeological samples as well as industrial materials. 相似文献
20.
In this paper, the crystal field (CF) levels and spin-Hamiltonian (SH) parameters (g factors g ∥ and g ⊥ and hyperfine structure constants A ∥ and A ⊥) of the rare-earth ion Yb3+ in lithium yttrium fluoride crystals are calculated under D 2d point symmetry assumption. Two main methods are used in the calculation to study the SH parameters: one is the perturbation theory method and the other is the complete diagonalization (energy matrix) method (CDM). Comparing the calculated results with the experimental data, we can see that the CDM is more effective to calculate the SH parameters. In addition, the CF J-mixing of all excited-state multiplets into the ground-state multiplet 2F7/2 is considered. The validity of the calculated results is discussed. 相似文献