We present total cross sections in the energy range 7-1000 keV amu(-1) for electron capture by alpha-particles in collision with atomic hydrogen in the ground state. We describe this process theoretically by performin...
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We present total cross sections in the energy range 7-1000 keV amu(-1) for electron capture by alpha-particles in collision with atomic hydrogen in the ground state. We describe this process theoretically by performing a close-coupling calculation using the symmetrized variational (SV) continuum distorted-wave (CDW) collision ansatz. SVCDW views the collision in a unique way by including both incoming and outgoing CDWs in the wavefunctions at all finite times, while simultaneously guaranteeing the correct coulombic asymptotes. We compare the SVCDW results with the available experimental data, with a dose-coupling calculation in which outgoing CDWs only are used to describe the collision, and with CDW perturbation theory. At high energies the three theoretical curves converge, while at lower energies the SVCDW results are shown to reproduce experiments more accurately. We also compare the SVCDW results with other coupled-channel calculations which use pseudo-states to describe the interaction of the target and the projectile with the continuum.
We present the first results of an ab initio coupled-channel calculation of electron capture to the n=2 states of hydrogen in proton-hydrogen collisions using symmetrized variational (SV) continuum distorted-wave (CDW...
We present the first results of an ab initio coupled-channel calculation of electron capture to the n=2 states of hydrogen in proton-hydrogen collisions using symmetrized variational (SV) continuum distorted-wave (CDW) theory. In SVCDW theory the collision ansatz includes both outgoing- and incoming-wave components in the wave functions, and represents in a compact and elegant form a very complete basis set for describing the electron capture process. We calculate total cross sections for nonresonant capture to the 2s and 2p states of the projectile, in the energy range 7–150 keV. The results are a substantial improvement over a previous variational CDW theory, and in particular are found to be in good accord with the available experimental data.
A non-relativistic description of the differential cross section (DCS) for Thomas double-scattering electron capture at asymptotically high velocity is developed within the third-order continuum distorted-wave (CDW) p...
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A non-relativistic description of the differential cross section (DCS) for Thomas double-scattering electron capture at asymptotically high velocity is developed within the third-order continuum distorted-wave (CDW) perturbation theory for 1s --> 1s transitions in proton-hydrogen collisions. It is shown that at the critical proton scattering angles, namely the forward peak, Thomas maximum, small angles and the interference minimum, the CDW series has converged at second order. Moreover, it is proven that the third-order correction makes no contribution to the velocity-dependent upsilon-(11) and upsilon-(12) behaviour of the Thomas double-scattering total cross sections at the leading angles. The Oppenheimer-Brinkman-Kramers (OBK) travelling atomic orbital plane wave theory is compared to the CDW approximation. It is observed that the second-order OBK (OBK2) theory has not converged. It remains an open question as to whether fourth-order terms or higher in the OBK approximation contribute to the various differential cross sections. It is concluded that the CDW model gives a superior description of the Thomas double-scattering mechanism than the OBK model.
Numerical results for the Nikitin exponential model at non-zero impact parameters are presented. It is confirmed that in order to derive the correct strong-coupling approximation of the transition probability, one nee...
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Numerical results for the Nikitin exponential model at non-zero impact parameters are presented. It is confirmed that in order to derive the correct strong-coupling approximation of the transition probability, one need only include the leading terms of the asymptotic expansions of the confluent hypergeometric functions. Development beyond leading order is inappropriate to the particular model, because by construction the non-analytic wavefunction is discontinuous in its second-order derivative at the turning point, which follows from the cusp-like discontinuity in the first-order derivative of at least the off-diagonal Hamiltonian potential matrix elements. It is therefore concluded that the Stueckelberg phase-integral derivations of Crothers are essential if transition probabilities and cross sections are not to be underestimated at large impact parameters, due to neglecting the bending of the double Stokes line.
We solve a classical analog of the quantum traversal time problem. The classical diffusion equation is modified to control the amount of time spent by a particle in a specified region of space. The ‘‘clocked’’ dif...
Nonlinear Galerkin methods are new schemes for integrating dissipative systems:In the present paper, we obtain the estimates to the rate of convergence of such methods for Kuramoto-Sivashinsky equations. In particular...
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Nonlinear Galerkin methods are new schemes for integrating dissipative systems:In the present paper, we obtain the estimates to the rate of convergence of such methods for Kuramoto-Sivashinsky equations. In particular, by an illustrative example, we show that nonlinear Galerkin methods converge faster than the usual Galerkin method.
We present new experimental and theoretical results for e−−O2 collisions which demonstrate the dominant contribution of the Σu−4 resonance and the significant contribution of the Σu−2 resonance to the X3Σg− ground ...
We present new experimental and theoretical results for e−−O2 collisions which demonstrate the dominant contribution of the Σu−4 resonance and the significant contribution of the Σu−2 resonance to the X3Σg− ground state vibrational excitation cross sections in the energy range 4–15 eV. This work, combined with earlier studies by the present and other workers, shows that low-energy vibrationally and electronically inelastic cross sections can be quantitatively understood in terms of four resonances with Πg2, Πu2, Σu−4, and Σu−2 symmetries.
The temperature dependence of the microstructure and local dynamics in the paramagnetic phase of the d = 2 and d = 3 ± J Ising spin glass model is examined by comparing the equilibrium distributions of local flip...
The temperature dependence of the microstructure and local dynamics in the paramagnetic phase of the d = 2 and d = 3 ± J Ising spin glass model is examined by comparing the equilibrium distributions of local flip-rates and local energies calculated in large-scale Monte Carlo simulations. The emergence in this model of fast processes as the glass transition is approached corresponds with recent experimental results
作者：
Schulte, DPSkolnick, AHe has supported the development and operation of several naval systems
including advanced component selection for Trident II fire control and navigation systems. He served as branch manager of the Surface Ship ASW Combat System Branch which acted as the acquisition engineering agent for the AN/SQQ-89 Surface Ship Anti-Submarine Warfare Weapon System. He was then selected to manage the Module Engineering Department which provided engineering support to numerous naval systems including the AN/BSY-1 Submarine Combat System and the Trident II fire control and navigation system. He then served as the deputy program manager for NAVSEA Progressive Maintenance (2M/ATE). He holds a B.S. degree in Electrical Engineering from Purdue University and currently is pursuing a Maste's degree in Public Environmental Affairs at Indiana University—Purdue University
Indianapolis. He served at Applied Physics Laboratory/The Johns Hopkins University in missile development
then aboard USS Boston (CAG-1) and played leading roles in several weapon system developments (Regulus Terrier Tartar Talos) inertial navigation (Polaris) deep submergence (DSRV) and advanced ship designs (SES). He later was director Combat System Integration Naval Sea Systems Command and head Combat Projects Naval Ship Engineering Center. He led the Navy's High Energy Lasers and Directed Energy Weapons development efforts. He was vice president advanced technology at Operations Research Inc. and vice president maritime engineering at Defense Group Inc. before starting SSC in 1991. Dr. Skolnick holds a B.S. degree in Mathematics and Economics
Queens College an M.A. degree in Mathematics and Philosophy Columbia University an M.S. degree in Electrical/Aeronautical Engineering U.S. Naval Postgraduate School and a Ph.D. in Electrical Engineering and Applied Mathematics from Polytechnic University in New York. He is the author of many published papers on engineering design issues source selection procedures and large-scale complex technology problems
The Fleet continues to require high performance systems that can operate with dependability in the seas' unforgiving environments and under hostile action. Those demands are not new. What has changed is the urgent...
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The Fleet continues to require high performance systems that can operate with dependability in the seas' unforgiving environments and under hostile action. Those demands are not new. What has changed is the urgent priority formerly assigned to national defense issues. The arguments for continued superpower military strength are now roiled in politics along with unsettled budgets and uncertain force level projections. Current expectations revolve about indefinite fiscal and operational issues (difficult funding constraints and broadband threats). In the actual event of ''doing more with less,'' a practical response is to apply the creative power available from sound engineering judgement and the crucible of experience to the immediate needs of the Fleet. The attempt to shorten the path between advanced development effort and Fleet use has been tried occasionally in the past, often, without exemplary results. The Sustainable Hardware and Affordable Readiness Practices (SHARP) program, is a generic R&D effort under OpNav sponsorship that has been working steadily on sensible solutions to product engineering problems. Armed today with fast-time, large-scale computation abilities and modern tools for technical problem solving coupled with specialized engineering knowledge, it has been refreshed and is underway satisfying existing Fleet needs. The relationship between fully responsive engineering services and current operational needs is always demanding. The connection between advanced engineering development (6.3 category funds) and immediate Fleet usage brings added complexity and challenge, both technical and organizational. Illustrative examples of affordable engineering solutions to ''retain, revise, replace or retire'' questions are presented within the context of both Fleet realities and budgetary limitations. The discussion covers legacy system support, civil/military considerations and Fleet maintenance issues. It describes the substantial and critical payoffs i
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