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Systematics of cross sections for target K-vacancy production in heavy ion collisionsPeng, Yong 25 April 2007 (has links)
Cross sections for K-shell ionization by heavy ions have been determined from the
measurements of target K x-ray yields. The measurements were performed with Ar, Kr,
and Xe ions at energies from 2.5 to 25 MeV/amu and self-supported metallic foil targets
of Al, Ti, Cu, Zr, Ag, Sm, and Ta. The x-ray yields were measured with a Si(Li)
detector, while the projectile ions were counted in coincidence with the x-rays using a
plastic scintillation detector. In addition, the amount of secondary K-shell ionization and
the degree of simultaneous L-shell ionization in primary K-shell ionizing collisions were
assessed by performing high-resolution x-ray measurements on targets of Al, Ti, V, Co,
and Cu with a curved crystal spectrometer.
The results of the high resolution measurements revealed that the apparent average Lshell
spectator vacancy fraction at the time of Kñ x-ray emission, L p , may be represented
by a universal function of the Geometrical ModelâÂÂs parameter X for Z2 = 17 - 32.
Multiple-vacancy Kñ fluorescence yields and corrections for K-shell ionization by
secondary processes were determined with the aid of the high resolution spectra for the targets Al, Ti, and Cu. Fluorescence yields for the other targets were determined using
an extrapolation procedure.
The resulting K-vacancy production cross sections for 2.5 to 6 MeV/amu projectiles
were compared with a limited amount of available experimental data and shown to be in
relatively good agreement.
The ECPSSR predictions for all the targets except Al agreed reasonably well with
experimental cross sections for Ar projectiles. The experimental cross sections for Kvacancy
production in Al, Ti, Cu, Zr, and Ag were greatly deviated from the ECPSSR
predictions. The cross sections for Kr on Sm and Ta were in good agreement with
theory.
The scaling properties of the Kñ x-ray production cross sections were examined and a
semiempirical âÂÂuniversalâ curve was deduced that reproduces the measured cross
sections to within ñ30% on average.
The relationship between the Kñ x-ray production cross sections and the geometrical
modelâÂÂs universal variable also was examined.
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Electron-Ion Time-of-Flight Coincidence Measurements of K-K Electron Capture, Cross Sections for Nitrogen, Methane, Ethylene, Ethane, Carbon Dioxide and Argon (L-K) TargetsToten, Arvel D. 05 1900 (has links)
Protons with energies ranging from 0.4 to 2.0 MeV were used to measure K-shell vacancy production cross sections (oVK) for N_2, CH_4, C_2H_4, C_2H_6, and CO_2 gas targets under single collision conditions. An electron-ion time-of-flight coincidence technique was used to determind the ration of the K-K electron capture cross section, OECK, to the K-vacancy production cross section, oVK. These ratios were then combined with the measured values of oVK to extract the K-K electron capture cross sections. Measurements were also made for protons of the same energy range but with regard to L-shell vacancy production and L-K electron capture for Ar targets. In addition, K-K electron capture cross sections were measured for 1.0 to 2.0 Mev 42He^_ ions on CH_4.
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K-shell x-ray production cross sections in carbon, oxygen, fluorine, sodium, magnesium, and aluminum by 0.5 to 8.0 mev protons, helium, and lithium ionsYu, Yueh-Chung 08 1900 (has links)
The goal of this work reported here is to test the limits of the ECPSSR theory in the transition region of the low Z1/Z2.
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Low-Velocity K-Shell Ionization Cross Sections for Protons, Deuterons and Alpha Particles Bombarding Thin Metal TargetsRice, Roger Karl 05 1900 (has links)
The purpose of this work was to examine the effect of the use the assumption κω2K/ΕCM «1 in calculating K-shell ionization cross sections in the plane wave Born approximation (PWBA) where κω2K is the observed binding energy of the K-shell and ECM is the energy of the incident particle in the center of mass system. Avoiding this assumption produces a threshold for ionization at Ecm = κω2K. Calculations employing the assumption, which leads to the use of approximate limits of integration, do not go to zero for even the .Lowest values of the incident energy.
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Fluorine K-Shell X-Ray Cross Section Measurements for ⁷Li, ¹⁰B, ¹²C, ¹⁴N, and ¹⁶O Ions on Ultra-Clean, Ultra-Thin Yf₃ Solid Target FoilsMarble, Daniel Keith 08 1900 (has links)
In this study, procedures were developed to produce ultra-clean, ultra-thin target foils and to remove x-ray interference from electron bremsstrahlung and low energy K-shell x-rays from contaminant elements.
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