Measurements of the intensities of $K$ x rays in coincidence with fission were carried out in an experiment in which the energies of complementary fission fragment pairs and $K$ x rays were recorded event by event, using a multiparameter analyzer. Subsequent analysis of the data resulted in the determination of the x-ray intensities associated with intervals of fragment mass for each contributing element. Most probable charge and mass values for the emission of $K$ x rays were determined, and it was found that these most probable masses could be used to adequately define the ${Z}_{p}$ curve - without appreciable biasing due to details of nuclear structure. An examination of the effect of total kinetic energy on the x-ray distribution revealed a distinct enhancement of even-$Z$ $K$ x-ray contributions to the yields as the total kinetic energy increases. Apparent shifts in the values of most probable masses for the emission of $K$ x rays were also observed as a function of total kinetic energy.
The decay curves for 2p-1s and 3p-1s transitions in 32-MeV H-like oxygen projectiles excited by a thin carbon foil have been measured and compared with the results of a cascade computer program which calculates the intensities of these transitions for an assumed initial distribution of excited states as a function of decay time. The measured decay curves agreed best with those predicted by the cascade program using an l-independent population probability proportional to ${n}^{\mathrm{\ensuremath{-}}4}$ for each state.
The spectra of carbon $K$- and argon $L$-shell Auger electrons resulting from ionization produced by 0.15-0.50-MeV/amu $\ensuremath{\alpha}$ particles and deuterons incident on a thin gas cell have been measured. Absolute ionization cross sections were obtained from the Auger-electron yields and, in addition, the yields obtained with equal-velocity projectiles were used to test the projectile $z$ dependence of the ionization process. Intense satellite structure was observed in the Auger spectra and these features were attributed to Auger transitions from multiple vacancy states formed during the collision.
This paper discusses the following topics: charge distributions for Ar recoil-ions produced in one- and two-electron capture collisions by O{sup q+} projectiles; charge distributions of He, Ne, and Ar recoil-ions produced in collisions with 10 to 30 MeV/u N{sup 7+} ions; studies of recoil ions produced in collisions of 40 MeV Ar{sup 13+} with atomic and molecular targets; two-fragment coincidence studies of molecular dissociation induced by heavy ion collisions; resonant electron transfer to double K-vacancy states in oxygen compounds; quenching of metastable states in fast Mg projectiles; and design and construction of an atomic physics beamline for the ECR ion source.
The yields of $K$ x rays emitted by primary $^{252}\mathrm{Cf}$ fission products have been measured with a high-resolution [0.82 keV full width at half-maximum (FWHM) at 26.25 keV] lithium-drifted silicon spectrometer. The most noteworthy feature in the systematics of the observed x-ray yields is the presence of a pronounced even-odd fluctuation associated with the atomic numbers $Z=52$ through $Z=57$, in which the odd-$Z$-product x rays are found to be more intense than the even-$Z$-product x rays by approximately a factor of 2. This effect is not observed in the light-fission-product region. The x-ray yields observed in this experiment are compared with the results of previous experiments in which the $K$ x-ray yields were measured in association with the fission-fragment masses. Although general agreement is found in the over-all structural features, no evidence is seen in this study of the sudden drop in x-ray yield in the heavy-fission-product region corresponding to that which has previously been reported. The validity of the use of x-ray measurements as a method of determining the most probable charge distribution is examined in the light of the observed structure in the systematics of the x-ray yields.
As a fast heavy-ion passes through a material medium, it undergoes multiple collisions in which electrons are continuously lost and recaptured by the ion, and as a result, an equilibrium distribution of excited states is quickly established. The high density of electrons in a solid state environment enables these collisional excitation and decay processes to compete with x-ray and Auger decay. As a result, the widths of the x-ray lines exhibit a dependence on electron density due to collisional broadening. In addition, the potential of the ion is modified by the polarization of loosely bound electrons of the medium. In effect, these electrons act to screen the ion potential, thereby causing the core electron binding energies of the ion to decrease. As a result of this "dynamic screening" effect, the x-ray transition energies inside the medium differ from those in vacuum.
The energies and intensities of the $2^{3}P_{1}\ensuremath{\rightarrow}1^{1}S_{0}$, and $2^{1}P_{1}\ensuremath{\rightarrow}1^{1}S_{0}$ transitions in He-like sulfur ions, and of the $2^{2}P\ensuremath{\rightarrow}1^{2}S$ transition in H-like sulfur ions have been studied as a function of the thickness and electron density of the solid through which the ions travel. The thickness dependence of the x-ray intensities was analyzed in terms of a three-component model description of $K$-shell vacancy production and decay. Cross sections for electron excitation or ionization and capture deduced from this analysis were used to establish the energies of the x-ray peaks for complete emission in vacuum (i.e., outside the target). Energy shifts were obtained by comparing the peak energies for emission in thick targets to those for emission in vacuum. The results show that the energy shifts increase approximately linearly with the square root of the valence electron density of the target and are in good agreement with theoretical expectations.
The energies of the 3p1/2,3/2, 3d3/5,5/2, 4s, and 4d3/2,5/2 photopeaks have been measured for tellurium metal and 23 of its compounds. An attempt is made to interpret chemical bonding in some of the tellurium compounds by comparing core level binding energy shifts with isomer shifts observed through Mossbauer spectroscopy. The widths of the 3p3/2 photopeaks measured relative to the 3p1/2 photopeaks are examined for broadening by electric field gradients and Coster–Kronig transitions. Variations in the spin–orbit splitting of the tellurium 4d level in its various compounds do not seem to be dependent on crystal field interactions.
The spectrum of K alpha , K alpha h and K beta X-rays from H-, He-, Li- and Be-like sulphur, excited during the passage of 65 MeV sulphur ions through thin carbon foils, has been measured. The observed structure agrees quite well with the structure predicted by theoretical transition energy and intensity calculations. A low-energy component of the He-like K alpha line has been ascribed to the presence of a 3s spectator electron. The present results are compared with those obtained in laser-plasma experiments and those from previous beam-foil measurements.
