At impact energies $ \stackrel{>}{\sim}1$ GeV/u the projectile-electron excitation and loss occurring in collisions between highly charged ions and neutral atoms is already strongly influenced by the presence of atomic electrons. In order to treat these processes in collisions with heavy atoms we generalize the symmetric eikonal model, used earlier for considerations of electron transitions in ion-atom collisions within the scope of a three-body Coulomb problem. We show that at asymptotically high collision energies this model leads to an exact transition amplitude and is very well suited to describe the projectile-electron excitation and loss at energies above a few GeV/u. In particular, by considering a number of examples we demonstrate advantages of this model over the first Born approximation at impact energies $\sim 1$--30 GeV/u, which are of special interest for atomic physics experiments at the future GSI facilities.
We study the fragmentation of He$_2$ dimers into He$^+$ ions by relativistic highly-charged projectiles. It is demonstrated that the interaction between an ultrafast projectile with an extremely extended object -- the helium dimer -- possesses interesting features which are absent in collisions with "normal" molecules. It is also shown that such projectiles, due to their enormous interaction range, can accurately probe the ground state of the dimer and even be used for a precise determination of its binding energy.
We study theoretically the fragmentation of the helium dimer, $^4$He$_2$, into singly charged ions in collisions with relativistic highly-charged projectiles. We discuss the main mechanisms driving this process with the focus on the fragmentation caused by direct ionization of both atomic sites of the dimer in a single collision with the projectile. This direct mechanism dominates the He$_2$ $\to $ He$^+$ + He$^+$ breakup events with the kinetic energies of the emerging ionic fragments below $4$--$5$ eV. We explore the energy and angular distributions of the He$^+$ ions produced in collisions …
We report on the fragmentation of the water molecule by $1$ MeV H$^{+}$, He$^{+}$ and 650 keV N$^{+}$ ion impact. The fragment-ion energy spectra were measured by an electrostatic spectrometer at different observation angles. The obtained double-differential fragmentation cross sections for N$^{+}$ is found to be more than an order of magnitude higher, than that for H$^{+}$. The relative ratios of the fragmentation channels are also different for the three projectiles. Additional fragmentation channels were observed in the spectra for He$^{+}$ and for N$^{+}$ impact, which are missing in the c…
In this chapter we analyze the multiple ionization by impact of |Z|=1 projectiles: electrons, positrons, protons and antiprotons. Differences and similarities among the cross sections by these four projectiles allows us to have an insight on the physics involved. Mass and charge effects, energy thresholds, and relative importance of collisional and post-collisional processes are discussed. For this purpose, we performed a detailed theoretical-experimental comparison for single up to quintuple ionization of Ne, Ar, Kr and Xe by particles and antiparticles. We include an extensive compilation of…
A classical description of electron emission differential ionization cross sections for highly-charged high-velocity ions ($\sim$ 10 a.u.) impinging on water molecules is presented. We investigate the validity of the classical statistical mechanics description of ionization ($\hbar=0$ limit of quantum mechanics) in different ranges of electron emission energy and solid angle, where mechanisms such as soft and binary collisions are expected to contribute. The classical-trajectory Monte Carlo method is employed to calculate doubly and singly differential cross sections for C$^{6+}$, O$^{8+}$ and…
Angular distribution of Kα x rays following nonradiative double electron capture in relativistic collisions of Xe54+ ions with Kr and Xe atoms
Institute of Modern Physics, Chinese Academy of Sciences（中国科学院近代物理研究所）；University of Chinese Academy of Sciences（中国科学院大学）；Department of Physics, St. Petersburg State University（圣彼得堡国立大学物理系）；Petersburg Nuclear Physics Institute named by B.P. Konstantinov of National Research Centre “Kurchatov Institute,”（俄罗斯国家研究中心“库尔恰托夫研究所”以B.P.康斯坦丁诺夫命名的圣彼得堡核物理研究所）；Key Laboratory of Atomic and Molecular Physics & Functional Materials of Gansu Province, College of Physics and Electronic Engineering, Northwest Normal University（西北师范大学物理与电子工程学院甘肃省原子分子物理与功能材料重点实验室）；Department of Medical Imaging, Hangzhou Medical College（杭州医学院医学影像系）；School of Basic Medical Sciences, Shanxi Medical University（山西医科大学基础医学院）
Nonrelativistic collision of proton and antiproton with hydrogen atom described by solving time-dependent Schrodinger equation numerically. Coulomb wave function discrete variable method (CWDVR) had been used to calculate electron wave function evolution, while projectile defined classically, moving along the straight line trajectories with constant velocity. The ionization amplitude calculated by projection of the wave function into continuum wave function of the hydrogen electron. The differential cross sections calculated depending on projectile impact energy, scattering angle and electron …
A new relativistic method based on the Dirac equation for calculating fully differential cross sections for ionization in ion-atom collisions is developed. The method is applied to ionization of the atomic hydrogen by antiproton impact, as a non-relativistic benchmark. The fully differential, as well as various doubly and singly differential cross sections for ionization are presented. The role of the interaction between the projectile and the target nucleus is discussed. Several discrepancies in available theoretical predictions are resolved. The relativistic effects are studied for ionizatio…
We studied nonrelativistic collision of antiproton with hydrogen atom by solving time-dependent Schrodinger equation numerically. Coulomb wave function discrete variable method (CWDVR) had been used to calculate electron wave function evolution, while projectile defined classically, moving along the straight line trajectories with constant velocity. The ionization amplitude calculated by projection of the wave function into continuum wave function of the hydrogen electron. The fully differential cross sections calculated depending on projectile impact energy, scattering angle and electron ejec…
Transfer excitation reactions in fast proton-helium collisions
继续以前的工作，我们测量了快质子（300-1200 keV/u）与氦（p+He $\rightarrow$ H + He $^{+ *}$）碰撞转移激发的射弹散射角依赖性。我们的高分辨率全微分数据伴随着计算，在平面波第一玻恩近似和程函波玻恩近似。实验上，我们发现一个深的最小值的微分截面约为0.5 $mrad$。与我们的计算结果的比较表明，描述快碰撞中转移激发对散射角的依赖性需要超越第一玻恩近似，并使用包含一定角度关联的初态波函数。
Doppler-shifted X-ray Spectroscopy of Nonradiative Electron Capture in Relativistic Collisions of Xe54+ Ions with Kr and Xe Atoms
Institute of Modern Physics, Chinese Academy of Sciences（中国科学院近代物理研究所）；University of Chinese Academy of Sciences（中国科学院大学）；Department of Physics, St. Petersburg State University（圣彼得堡国立大学物理系）；Petersburg Nuclear Physics Institute named by B.P. Konstantinov of National Research Centre “Kurchatov Institute,”（俄罗斯国家研究中心“库尔恰托夫研究所”下属的B.P.康斯坦丁诺夫彼得堡核物理研究所）；Key Laboratory of Atomic and Molecular Physics & Functional Materials of Gansu Province, College of Physics and Electronic Engineering, Northwest Normal University（西北师范大学物理与电子工程学院甘肃省原子分子物理与功能材料重点实验室）；Department of Medical Imaging, Hangzhou Medical College（杭州医学院医学影像系）；School of Basic Medical Sciences, Shanxi Medical University（山西医科大学基础医学院）
Interactions of protons with nuclei are modeled in a form that is suitable for Monte Carlo simulation of proton transport. The differential cross section (DCS) for elastic collisions of protons with neutral atoms is expressed as the product of the Rutherford DCS, which describes scattering by a bare point nucleus, and two correction factors that account for the screening of the nuclear charge by the atomic electrons and for the effect of the structure of the nucleus. The screening correction is obtained by considering the scattering of the projectile by an atom with a point nucleus and the ato…
