Search results for: L. Gulyas

Items from 1 to 17 out of 17 results

chapter

CUSP studies for simple collision systems

D. Berényi, L. Gulyás, Á. Kövér, E. Szmola, more

Lecture Notes in Physics > Forward Electron Ejection in Ion Collisions > 71-74

chapter

Non-equilibrium convoy electron production in coincidence with outgoing projectile charge states

J. Kemmler, O. Heil, C. Biedermann, P. Koschar, more

Lecture Notes in Physics > High-Energy Ion-Atom Collisions > 362-373

The target thickness dependence of the convoy electron yield in carbon foils (3.1 < ϱx < 22 μg/cm²) from incident projectiles C^qi q_i=2, 4, 6 at 1 MeV/u has been measured in coincidence with the outgoing projectile charge states q_f. The observed charge state distributions of the carbon ions are in non-equilibrium for the thinnest targets. We find that the coincident convoy electron yield Y_e(q...

article

Wannier threshold theory for the description of the two-electron cusp in the ion-induced double ionization of atoms

R.O. Barrachina, L. Gulyás, L. Sarkadi

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions... > 2016 > 369 > C > 98-102

The double electron capture into the continuum states of the projectile (double ECC) is investigated theoretically in collisions of 100keV He²⁺ ions with He atoms. The process is described within the framework of the impact parameter and frozen-correlation approximations where the single-electron events are treated by the continuum distorted wave method. On the other hand, the Wannier theory is employed...

chapter

Reference database driven statistical analysis of automated frameless CT-MRI registration developed for radiosurgical investigations

G. Opposits, S.A. Kis, T. Spisak, E. Berenyi, more

2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC) > 2780 - 2782

2012 IEEE Nuclear Science Symposium and Medical Imaging Conference (2012 NSS/MIC)

The aims of this study were (1) to describe statistically the fluctuation of the goodness of automated CT-MRI registration method (2) to evaluate a numerical parameter, scaled to [0,1] interval (lambda), for characterizing the population level accuracy of any automated CT-MRI registration algorithm on voxel similarity basis. The population level distribution of cross-correlation values between the...

article

Projectile angular distribution in single electron capture from helium by fast protons

A. Igarashi, L. Gulyás, A. Ohsaki

The European Physical Journal D > 2012 > 66 > 3 > 1-6

In addition to the Thomas peak, occurs at 0.47 mrad, another peak has been observed at ≈ 0.75 mrad in a recent measurement for projectile angular differential cross sections of single electron capture in proton-helium collision at impact energies of MeV region [M. Gudmundsson et al., J. Phys. B 43, 185209 (2010)]. Stimulated by this report, the differential cross section is calculated based on the...

article

TDCS calculations for the ionization of H₂ by electron impact

I. Tóth, L. Nagy, V. Chiş, L. Gulyás

The European Physical Journal D > 2012 > 66 > 12 > 1-7

Triple differential cross sections (TDCSs) are calculated for the ionization of the hydrogen molecule by electron impact with asymmetric and symmetric kinematical configuration, respectively in coplanar arrangement and in the plane perpendicular to the incident direction. In the scattering plane we explore the angular distribution of the TDCS as well as the dependence of the cross section on the internuclear...

article

Annihilation of protonium by charged particle impact

A. Igarashi, L. Gulyás

Nuclear Inst. and Methods in Physics Research, B > 2009 > 267 > 2 > 354-357

Protonium (Pn) annihilates almost instantaneously when its initial high-ℓ states (ℓ denotes the angular momentum) are transferred to the low-lying s, p or d states. In this work, the annihilation of Pn induced by electron or proton impact is described in quantal and semi-classical close-coupling methods, where the scattering wave functions are expanded in terms of Pn orbitals. The chain of transitions...

article

Double differential distributions of electron emission in ion–atom and electron–atom collisions using an electron spectrometer

Deepankar Misra, K.V. Thulasiram, W. Fernandes, Aditya H. Kelkar, more

Nuclear Inst. and Methods in Physics Research, B > 2009 > 267 > 1 > 157-162

We study electron emission from atoms and molecules in collisions with fast electrons and heavy ions (C ⁶⁺ ). The soft collision electrons (SE), two center electron emission (TCEE), the binary encounter (BE) events and the KLL Auger lines along with the elastically scattered peaks (in electron collisions) are studied using a hemispherical electrostatic electron analyzer. The details of the...

article

Angular and energy differential electron emission cross sections in collisions between antiprotons and helium atoms

K. Tőkési, J. Wang, L. Gulyás, J. Burgdörfer

Hyperfine Interactions > 2009 > 194 > 1-3 > 45-50

We present theoretical singly- and doubly-differential ionization cross sections in collisions between antiprotons and helium atoms at 50 and 100 keV impact energies. The calculations were performed within the frame work of the continuum distorted wave eikonal initial state approximation and a three-body classical trajectory Monte Carlo method. We find clear evidence for the formation of the anti-cusp...

article

CEPAS2005

L. Gulyás, K. Tőkési, B. Paripás

Radiation Physics and Chemistry > 2007 > 76 > 3 > 365-366

article

Evaluation of the single ionisation transition amplitude using the CDW-EIS model within the framework of the impact-parameter method

A. Igarashi, L. Gulyás, P. D. Fainstein

The European Physical Journal D > 2007 > 42 > 1 > 73-77

. The continuum distorted-wave model with an eikonal initial state for ionisation is discussed within the framework of the impact-parameter method. Particular attention is paid to the surface term, which describes the transition by a distorting potential, and which has been omitted in all of the previous calculations performed using the model. However, this term is included in the transition amplitude...

article

Theoretical study of the Bethe surface in non-perturbative single ionization of He by swift highly charged ions

P.D. Fainstein, L. Gulyás

Nuclear Inst. and Methods in Physics Research, B > 2005 > 235 > 1-4 > 306-308

We analyze in detail the single ionization of He by 3.6MeV/u ions. The doubly differential cross sections as a function of impact parameter at fixed values of the electron energy are used to determine the average interaction range for different values of the projectile charge. It is seen that while for proton impact the interaction range varies very little with the electron energy, huge variations...

article

Singly differential electron emission cross sections for ionization of helium by protons

I.F. Barna, A.C. Gagyi-Pálffy, L. Gulyás, K. Tőkési, more

Nuclear Inst. and Methods in Physics Research, B > 2005 > 233 > 1-4 > 176-181

Angular differential cross sections are calculated for electrons emitted in proton–helium collisions within the framework of the time-dependent coupled channel-method. The channel wave functions are constructed from Slater functions and Coulomb wave packets. As projectiles we consider protons with energies between 0.3 and 1.5MeV. We compare our results with experimental data and other theoretical...

article

Single ionization of Ar(2p) by antiproton and electron impact

K. Tőkési, L. Gulyás, B. Paripás, Gy. Víkor, more

Nuclear Inst. and Methods in Physics Research, B > 2005 > 233 > 1-4 > 324-329

Doubly differential cross-sections for ionization of Ar(2p) are presented within the framework of a three-body classical trajectory Monte Carlo method and the continuum-distorted-wave approximation. As a projectile we consider an antiproton with an energy of 3.67MeV. We also present classical cross-sections for 2keV electron impact where the electron velocity is equal to that of the investigated antiproton...

article

Correlation effects in differential electron-emission spectra obtained from double ionisation of He by fast Au53+ impact

T. Kirchner, L. Gulyás, R. Moshammer, M. Schulz, more

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions... > 2003 > 205 > C > 479-483

We have measured and calculated doubly differential electron-emission cross sections (DDCS’s) for well-defined degrees of target ionisation in 3.6 MeV/amu Au⁵³⁺+He collisions. The calculations are based on the continuum distorted wave with eikonal initial state approximation. We focus on DDCS’s obtained in coincidence with double ionisation of the target, and investigate different models for the final...

article

Theoretical investigation of transfer-loss process in 0.2–2 MeV/u collisions of O5+ ions with H2 and He targets

B. Sulik, T.J.M. Zouros, A. Orbán, L. Gulyás

Journal of Electron Spectroscopy and Related Phenomena > 2001 > 114-116 > Complete > 191-197

We report first calculations of transfer-loss probabilities and differential cross-sections performed within the framework of the independent particle model (IPM) for the process:O5+ (1s22s)+He→O5+ (1s2s2p4P)+He++e−For the projectile final state there exist three 1s2s2p alternatives, with the spectroscopic notation ⁴ P, ² P ₋ and ² P ₊ . One of the possible...

article

Ionization of Li by fast highly charged ion impact

B. Skogvall, M. Tschersich, J. Tanis, B. Sulik, more

Nuclear Inst. and Methods in Physics Research, B > 1997 > 124 > 2-3 > 186-190

Angular distributions of ejected electrons in fast N ⁷⁺ + Li collisions have been measured. By calculating the individual amplitudes in a multipole expansion, we evaluate the relative importance of dipole transitions. Using a Li target, we find the relative importance of dipole transitions to depend strongly on the initial state.

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