氧离子与氦、氖原子碰撞中转移电离过程的研究

采用位置灵敏探测和散射离子-反冲离子飞行时间测量技术,测量了氧离子与氖和氦原子碰撞过程中转移电离截面与单电子俘获截面之比.通过比较发现测量结果与文献结果的趋势一致,并对测量结果进行了讨论.     

Experimental evidence of (2)He decay from (18)Ne excited states

Two-proton decay from (18)Ne excited states has been studied by complete kinematical reconstruction of the decay products. The (18)Ne nucleus has been produced as a radioactive beam by (20)Ne primary projectile fragmentation at 45 AMeV incident energy on a Be target. The (18)Ne at 33 AMeV incident energy has been excited via Coulomb excitation on a (nat)Pb target. The obtained results unambiguously show that the 6.15 MeV (18)Ne state two-proton decay proceeds through a (2)He diproton resonance (31%) and democratic or virtual sequential decay (69%). The quoted branching ratio has been deduced from relative angle and momentum correlations of the emitted proton pairs.     

Theoretical study on the complexes of He, Ne and Ar

This paper investigates the effect of basis sets through the potential energy curves(PECs) of six rare gas complexes He 2,Ne 2,Ar 2,He-Ne,He-Ar,and Ne-Ar.The coupled cluster singles and doubles method with perturbative treatment of triple excitations,doubly augmented basis sets of d-aug-cc-pVQZ,bond functions,and basis set superposition errors are employed.The diffuse function is more effective than the polarization function on describing the dissociation energy.The PECs are fitted into analytical potential energy functions(APEFs) using three expressions.It is found that all the expressions are suitable for describing the complexes of rare gases.Based on these APEFs,the spectroscopic parameters are calculated and the results are compared with the theoretical and experimental data available in the literature.     

Reionization contributions in low-energy scattering of He,Ne and Ar ions from Sn,Au, and BaTiO3

The proportion of reionized neutrals to the total scattering yield of rare-gas ions is reported for primary energies E₀ from 0.1 to 2.0 keV. The measurements were made for several ion-target combinations by comparing the ion yield obtained from incidence of ions with that obtained from incidence of neutrals. The ration of the reionized neutrals to the total ion yield is strongly dependent on the combination of projectile ion and target atom. In some combinations, e.g. Ne on Sn for E₀ > 1 keV and Ar on Ba for E₀ > 0.5 keV, the reionized neutrals constitute the main part of the total ion yield, while the proportion of reionized Ne⁰ scattered from Au is very small and increases gradually with increasing E₀.     

Excited states of Ne isoelectronic ions: SAC-CI study

Excited states of the s, p, and d symmetries up to principal quantum number n = 4 are studied for the first eight members of Ne isoelectronic sequence (Ne to Cl⁷⁺) by the SAC-CI (symmetry-adapted-cluster configuration-interaction) method. The valence STO basis sets of Clementi et al. and the optimized excited STO are used by the STO-6G expansion method. The calculated transition energies agree well with the experimental values wherever available. Received 26 July 2000 and Received in final form 14 September 2000     

Electron capture by slow multiply charged Ar and Ne ions from atomic hydrogen

At collision energies below 15 keV total charge transfer cross sections have been measured for multiply charged Ar^ζ+(2≦ζ≦6) and Ne^ζ+(2≦ζ≦4) ions colliding with atomic hydrogen. A Wood discharge was used to provide a hydrogen target with a sufficiently high degree of dissociation. Results are compared with measurements performed at higher energies and with theoretical calculations. For ζ=2 cross sections in atomic hydrogen are much smaller than in the molecular case, for ζ>2 the ratio of these cross sections varies between 0.7 and 1.6.     

Track detector study of fission of bismuth nuclei induced by He, radioactive He and Li ions

The cross-sections for fission of ²⁰⁹Bi induced by secondary beams of ⁶He by ⁴He and ⁷Li were measured. For the registration of fission fragments polyterephtalate plastic and muscovite mica detectors were used. In the case of the reaction of helium ions with bismuth the cross-section of the fission of ²⁰⁹Bi induced by ⁶He are significantly higher than the corresponding -particle-induced fission cross-section.     

Hollow-cathode transverse discharge He−Ne and He−Cd+ lasers

An all-metal hollow-cathode laser tube consisting of a perforated cylindrical cathode surrounded by a coaxial cylindrical anode has been operated as a He?Ne laser at 0.6328, 1.15 and 3.39 μm, and as a He?Cd laser at red, green and blue visible wavelengths, using both de and pulsed-plus-dc excitation. Laser oscillation in He?Zn, Ne?Cd, Xe?Cd and Ar?Cd mixtures has also been obtained. The hollow-cathode discharge consists primarily of an intense cathode glow inside the cathode cylinder, giving a quiet, stable, low-voltage, positive-resistance discharge. Results for the He?Ne and He?Cd laser output versus partial and total pressures and discharge currents are presented. The unoptimized laser performance for the He?Ne case approaches but does not yet equal the conventional positive-column case, while the He?Cd performance for the charge-transfer-pumped green 5378Å line appears particularly promising.     

Elastic scattering of electrons from He, Ne and Ar atoms at 35 keV

The eikonal Born series (EBS) method is applied to the elastic scattering of electrons by He, Ne and Ar atoms at 35 keV. The differential cross-sections are compared with the numerical results obtained by the partial-wave analysis. A simple analytical Dirac-Hartree-Fock-Slater (DHFS) field is used for these atoms. The results are also obtained by Wallace, Das and modified Das method. An oscillatory nature and a strong forward peak in the cross-section are not found at 35 keV. The results are nearer to the experimental data of Coffmann and M. Fink as well as numerical results based on relativistic partial-wave treatment.     

提高稳频He－Ne激光器输出功率的研究

稳频Ｈｅ－Ｎｅ激光器的输出功率与谐振腔的损耗密切相关。本文对其中的布儒斯特角窗口带来的附加损耗进行了定量的分析，指出布儒斯特窗片封接引起的各向异性损耗是主要的腔内损耗来源。在实践上采用具有独特优点的锢封接技术，大大提高了布儒斯特窗片的封接质量，从而减小了腔的损耗，提高了稳频Ｈｅ－Ｎｅ激光器的输出功率。比如，腔长为１１０ｍｍ的６３３ｎｍ稳频Ｈｅ－Ｎｅ激光器的输出功率达到２．５～３．０ｍＷ。     

High resolution Ne KLL Auger spectra produced by H+ and He+ bombardment

Ne KLL Auger satellite lines are measured with an energy resolution of 0.02% FWHM. The relative intensities of initial 2p vacancy satellite lines are observed to be four times larger with He⁺ than with H⁺ bombardment. The He⁺ beam also produces new satellite lines which are assigned to double initial 2p vacancies.     

Radiation damage in solid butane irradiated by Xe+, Kr+, Ar+, Ne+ and He+ ions with energies below 1500 eV

Thick solid butane targets cooled at 77°K, containing known molar fractions of iodine, have been irradiated by monoenergetic rare gas ions with energies between 10 eV and 1500 eV. The nature and the importance of the fragmentation of the target molecules have been studied through the analysis of the formed organic iodides. The G values for the overall yield of organic iodides are roughly the same for the various ions investigated and they are energy-independent between 150 eV and 1500 eV. However the mode of fragmentation depends strongly on the nature of the particles, the probability of C-C bonds rupture increasing with the LET. The neutralization energy of the incoming ions is also assumed to play a part in the radiolysis of the target.     

Fission of209Bi induced by6He ions

Secondary beams of⁴He and⁶He were produced through the transfer reactions with the 18.5 MeV/u¹¹B and 35.5 MeV/u⁷Li primary beams. The fusion-fission cross sections have been measured for the^4,6He +²⁰⁹Bi reactions at energies E_cm>1.5*B_fus. In the present experiment it was found that the fission excitation function for the neutron rich nuclei⁶He is significantly higher than for the⁴He nuclei.