Extreme Sensitivity of Differential Momentum Transfer Cross Sections to Target Atom Initial Conditions

Heavy-particle cross sections differential in the momentum transferred to the target are investigated using the classical trajectory Monte Carlo method. with the 3.6  MeV/u Au53++He system as a test case, it is shown that these cross sections are extremely sensitive to the initial target temperature. In particular, when thermal motion is varied for one of the target\u27s initial momentum components between 0 and 25 K the absolute cross sections vary by orders of magnitude and, in addition, their relative shapes undergo major changes. We find that by setting one of the target\u27s transverse momenta to a temperature of 16 K, previously reported major discrepancies between theory and experiment are removed

Molecular Treatment Of Electron Capture By Protons From The Ground And Excited States Of Alkali-metal Atoms

Electron-capture cross sections for H+ plus alkali-metal atom (Na, K, Rb, and Cs) systems have been computed for projectile energies from 10 eV to 10 keV. An impact parameter perturbed-stationary-state theory using molecular states that incorporate electron translation factors was used to calculate the cross sections. The wave functions were generated by employing the pseudopotential method. These yield equilibrium parameters Re and De for the A +2 molecular state that are in good agreement with ab initio results. Interaction energies are also presented for the LiH+ system. Basis sets of up to eight molecular states were used to calculate the electron-capture cross sections from ground (ns) as well as from the first excited (np) states of the alkali-metal atoms. Results for electron capture from the ground-state alkali-metal atom are in good agreement with the recent experiments of Nagata. Electron capture from excited alkali-metal (np) atoms does not yield enhanced cross sections relative to capture from the ground state and, in fact, shows decreased cross sections for the heavy alkali-metal atoms. Such behavior is contrary to predictions made using arguments based on the magnitude of the energy gap E to the electron-capture product states. © 1982 The American Physical Society

Line Emission From C⁶⁺, O8+ + Li Electron Capture Collisions

Electron capture cross sections to nl sublevels have been calculated for 1-10keVu−1 collisions of C6+ and O8+ projectiles on a Li target. The classical trajectory Monte Carlo method has been employed with the initial phase distributions for the Li(2s) target obtained from Hartree-Fock calculations. The cross sections are found to maximize at π = 7 for C6+ and n = 8−9 for O8+. The nl cross sections were used to calculate Δ n = 1 line emission cross sections. Comparison of these cross sections with the experimental results of Wolfruni et al indïoitçs good agreement between theory and experiment. © 1992 IOP Publishing Ltd

Electron-capture collisions of H+ with ground- and excited-state Na

Pseudopotential molecular-structure calculations have been used to obtain the low-lying interaction energies for NaH+. The wave functions were used to calculate accurate radial and rotational coupling matrix elements. Scattering calculations which include electron translational factors were performed using up to eight coupled channels for laboratory energies 0.1 to 10 keV. Electron capture from ground-state Na 3s yields cross sections in the 10-15-cm2 range of which the dominant products are H 2s and H 2p. Electron capture from excited Na 3p does not show an enhanced cross section relative to capture from the ground state even though the energy gap E(R=) to the dominant electron-capture channel is reduced from 1.74 to 0.36 eV. © 1982 The American Physical Society

Semiconductor manufacturing simulation design and analysis with limited data

This paper discusses simulation design and analysis for Silicon Carbide (SiC) manufacturing operations management at New York Power Electronics Manufacturing Consortium (PEMC) facility. Prior work has addressed the development of manufacturing system simulation as the decision support to solve the strategic equipment portfolio selection problem for the SiC fab design [1]. As we move into the phase of collecting data from the equipment purchased for the PEMC facility, we discuss how to redesign our manufacturing simulations and analyze their outputs to overcome the challenges that naturally arise in the presence of limited fab data. We conclude with insights on how an approach aimed to reflect learning from data can enable our discrete-event stochastic simulation to accurately estimate the performance measures for SiC manufacturing at the PEMC facility

State-selective Capture In Collisions Between Ions And Ground- And Excited-state Alkali-metal Atoms

Total cross sections for state-selective electron capture in collisions between ions and alkali-metal atoms have been calculated by means of a three-body classical-trajectory Monte Carlo (CTMC) method using model potentials to describe the electron ionic-core interactions. Calculations have been performed for Na+-Na(28d) collisions and for N5+ and Ar8+-Cs(6s) collisions. The collision velocity range corresponds to 0.5vp/ve2, where vp is the projectile velocity in the laboratory frame and ve is the initial orbital velocity of the electron bound to the alkali-metal core. In the case of Na++Na(28d) collisions, calculations of the final n,l,m distributions show the importance of the electron-capture cross sections into states with m\u3e1. For the case of multiply charged ion Cs(6s) collisions, a predominance of electron captures to nearly circular states (large l values) are predicted for cross sections near the maximum of the n distribution. When the e- Cs+ interaction is described by a realistic model potential, the CTMC calculations are found to be in good agreement with recent measurements of the final n values that are predominantly populated after single-electron capture. © 1990 The American Physical Society

Three-body Interactions In Proton-helium Angular Scattering

H++He scattering at 0.5 MeV has been investigated using a coincidence technique that completely determines the three-body transverse momentum exchange in single ionization collisions. Three scattering regions could be distinctly recognized that are dominated by proton helium-nucleus, proton-electron, or electron helium-nucleus interactions. Calculations and the experimental data show that the coupling between the electronic and nuclear degrees of freedom is required to understand the dynamics for more than 97% of the ionizing collisions. © 1989 The American Physical Society

Computing Specificity

This note reports on an effort to implement a version of Poole\u27s rule for specificity. Relatively, efficient implementation relies on correcting and improving a pruning lemma of Simari-Loui [92]. This in turn requires revision of Poole\u27s specificity concept. The resulting system is a usable knowledge representation system with first-order-language and defeasible reasoning. Sample input and output are included in an appendix. It is a good candidate for multiple inheritance applications; it is useful for planning, but limited by the underlying search for plans

Charge Transfer Of Hydrogen Ions And Atoms In Metal Vapors

Cross sections and equilibrium fractions for energetic H+, H−, and H0 in collisions with metal vapor targets have been compiled and evaluated. Both experimental and theoretical results are reported. Sources of errors are discussed, and recommended values for the data are presented. © 1985, American Institute of Physics for the National Institute of Standards and Technology. All rights reserved

Contribution Of Transfer Ionization To Total Electron Capture From A Helium Target

The contribution of transfer ionization (TI) to total electron capture has been measured for Oq+ ions (q=5, 6, 7, and 8) colliding with helium at energies from 0.5 to 1.5 MeV/u. These measurements, along with other published results, suggest a maximum TI contribution to total capture of 0.15q0.5 at E (in keV /u)q0.5100 The results demonstrate that the failure to account for transfer ionization in total single-charge-transfer cross sections may lead to large discrepancies between experiment and theory. © 1987 The American Physical Society