Impact parameter dependence of the probability for removal of the 2s and 2p atomic electrons by nuclei

The probability W(x) of inner shell ionization by nuclei as a function of the impact parameter x is expressed through the ionization matrix element M_if. Values of W(x) for removal of the 2s and 2p electrons are calculated with the first Born M_if and compared with the SCA result.     

K-shell ionization by high energy electrons

It is shown that the data of Middleman, Ford and Hofstader on K-shell ionization by electrons with energy from 150 to 900 MeV is fit very well by a relativistic form of Bethe's theory of ionization.     

A scaling law for K-shell ionization by relativistic electrons

Data on K-shell ionization by relativistic electron impact have been correlated for a wide range of elements (Z=13–83) and incident electron energies (E=3–900 MeV). A semi-empirical scaling law that has been developed using the Kolbenstvedt virtual photon theory is presented.     

Projectile Z dependence of double K-shell ionization in light elements by hydrogen- and helium-ion bombardment

The K² X-rays from Be, B and O atoms by H- and He-ion bombardment were measured. The ratio of σ_2K(He) to σ_2K(H) exhibits the projectile Z⁴₁ dependence. This is the first observation of the Z₁-dependence of σ_2K predicted by the Coulomb excitation.     

Projectile charge and mass dependence of large angle K-shell ionization probabilities on copper

The dependence on the scattering angle of the K-shell ionization probability has been measured with 0.5 MeV H⁺, 1 MeV D⁺ and 2 MeV He⁺ on copper targets. The experimental values are compared to SCA calculations corrected for binding, retardation and relativistic effects. The angular dependences are in good agreement with the theoretical predictions if the rapid variation of the nuclear relative velocity at the distance of closet approach is correctly taken into account (“hair-spin curve” effect).     

Energy dependence of the ionization probability of sputtered Cu and Ni

Despite its great sensitivity, the usefulness of secondary ion mass spectrometry (SIMS) for many applications has been limited by an inadequate understanding of the probability of sputtering an atom in an ionized state. To determine this ionization probability for clean Cu and Ni surfaces, I have measured the energy distribution of sputtered neutrals and ions by quadrupole mass filtering and retarding potential analysis using potential modulation differentiation. Analysis of sputtered neutrals was accomplished by electron impact ionization. Because the neutrals outnumber the ions by at least two orders of magnitude, the ratio of sputtered ions to neutrals is an accurate measure of the ionization probability. For energies below 20 eV the dependence of the ionization probability on energy goes as P(E) α Eⁿ, where n = 0.65 for clean Cu. The absorption of oxygen on the Cu surface increases the total ion yield while causing a reduction in the value of the exponent n. Similar results are found for nickel, where n = 0.54 for the clean surface.     

K-shell ionization of atoms and ions by relativistic projectiles

We evaluate the total cross section for the single K-shell ionization of atoms and ions by the impact of relativistic electrons. The study is performed to leading orders of the QED perturbation theory with respect to the parameters αZ and 1/Z. The results obtained are in good agreement with experimental data for different atomic targets. In the case of moderate values of the nuclear charge Z, the total cross section is described by a simple analytic formula. The K-shell ionization by relativistic heavy particles is also considered.     

Projectile charge-state dependence in K-shell ionization of neon,silicon, and argon gases by lithium projectiles

The ratios of X-ray yields from the K-shells of gaseous ₁₀Ne,₁₄Si, and ₁₈Ar by ⁶₃Li^+1,2,3 and protons were measured at projectile velocities comparable to the orbital velocities of the target K-shells. Projectile charge-state dependence is accounted for quantitatively when electron capture by the projectile and screening of the projectile by its electrons are included.     

Projectile dependence of K-shell ionization in Cl and Ca at 200 keV/amu

Relative K-shell ionization cross sections of Cl and Ca measured with 200 keV/amu singly ionized projectiles of ²H, ⁴He, ¹²C, ¹⁴N, ¹⁶O and ²⁰Ne exhibit features which are adequately described by the combination of binding effect in Coulomb ionization and charge exchange to the empty orbitals of the projectile.     

Light intensity dependence of the multiphoton ionization probability in the resonance case

The general intensity dependence of the five-photon ionization probability of triplet metastable helium was measured.     

Impact parameter dependence of electronic energy loss

Energy-loss moments of the electronic energy loss are calculated as functions of impact parameter for protons of 1 to 7 MeV incident upon Be, Al, Cu, Ag, and Ta targets. The Lindhard dielectric-function formalism is used, in the local-density approximation. The target-atom electron densities are Lenz-Jensen, and the projectile is a point charge. The moments are fitted by a simple algebraic function, and the energy and Z₂ dependence of the parameters of this function are given.     

Ratio of single K-shell ionization cross section to double K-shell ionization cross section in heavy-ion-atom collisions

The spectra of Ti Kα X-rays induced by He, C, N and O ions were measured with the use of a Bragg crystal spectrometer. The ratios of the integrated hypersatellite to diagram-plus-satellite X-ray yields were obtained. The previously obtained data on Cr, Fe and Ni Kα X rays induced by N ions were also analysed. It is found that the double K-shell vacancy production cross section is proportional to Z⁴₁.     

Atomic K-shell ionization induced by 20–50 MeV protons

By varying the energy of fast protons incident on gold, europium, silver, ribidium and copper targets, it has been possible to produce several self consistent sets of relative K-shell ionization cross sections covering the region from below to above the velocity matching peak.     

Influence of the pairing parameter rotation dependence on signature splitting in odd-A nuclei

The influence of the rotation dependence of the pairing correlations on the signature splitting is analysed in terms of the core quasiparticle coupling model. The quenching of the pairing parameter with increasing the rotational angular momentum, and the different rotational structures of the favoured and unfavoured states cause a rising of the signature splitting. An additional growth of the signature splitting results from the different particle-hole structures of the favoured and unfavoured states and from the fact that theA?1 andA+1 cores, to which the quasiparticle is coupled in the odd-A nucleus, have different moments of inertia. The calculated results are in agreement with experiment.     

K-shell ionization by protons for Cr,Cu, In and by alpha-particles for Cr,Cu

K-shell ionization cross sections have been determined for Cr, Cu and In at proton bombardment in the energy region from 0.9 to 2.5 MeV. The same cross sections were determined for Cr and Cu at alpha bombardment in the 0.9–4.0 MeV region. The experimental results are compared with five different theoretical calculations.     

Impact parameter dependence ofL- andK-shell excitation in I-Ag collisions

The impact parameter dependence of theL- andK-vacancy production of target and projectile was measured in I-Ag collisions at 40 MeV and 63 MeV in a X-ray particle coincidence experiment. A largeL-vacancy production is found for impact parametersb smaller than theL-shell radius with a pronounced increase forb<250fm. TheL-shell excitation is discussed in terms of 4fσ excitation and vacancy transfer in the 3pσ, 3dπ, 3dσ molecular orbitals through 3pπ-3pσ and 3dδ-3dπ-3dσ rotational-couplings. The 2pσ excitation probability is obtained from the summedK-vacancy production probability, and compared with the prediction of 2pσ excitation in a multiple collision process. The latter is determined by folding the measured IL-shell excitation probability with the impact parameter dependence of the 2pπ-2pσ rotational coupling. The discrepancy observed at small impact parameters suggests an enhanced 2pπ and 2pσ excitation at small impact parameters in a one-collision process. TheL- andK-vacancy sharing probabilities are found to be impact parameter independent over a large impact parameter range.