Recently, there has been great interest in the linear polarization of photons produced by radiative electron capture (REC, the time reversed photoionization in ion-atom collisions). No such data are available for the ...Recently, there has been great interest in the linear polarization of photons produced by radiative electron capture (REC, the time reversed photoionization in ion-atom collisions). No such data are available for the high-Z regime till now. By using high efficiency by by a new generation of segmented germanium detectors that have energy as well as position resolution this field can be investigated experimentally. The展开更多
The study of structure of few-electron heavy ions is of important interest due to the strong field effects. Helium-like ions are the simplest atomic multi-body systems. A considerable improved precision has been made ...The study of structure of few-electron heavy ions is of important interest due to the strong field effects. Helium-like ions are the simplest atomic multi-body systems. A considerable improved precision has been made in both theory and experiments recently. The experiment exploits the radiative recombination (RR) transitions into the vacant 1 s shell of bare and H-like ions. In this process, the energy carried by the emitted photon is the energy difference between the initial and final electron state, hω=Ekin+EB. For bare展开更多
We measured the charge exchange cross-sections in collisions of Ar^q+(q=8, 9, 11, 12) on Ne atoms at low impact energies from 80 keV to 240 keV, and obtained a set of cross-section data. In order to understand the cha...We measured the charge exchange cross-sections in collisions of Ar^q+(q=8, 9, 11, 12) on Ne atoms at low impact energies from 80 keV to 240 keV, and obtained a set of cross-section data. In order to understand the charge exchange processes, we combined the Molecular Classical over-Barrier Model (MCBM) developed by Niehaus[1] with auto-ionization and electron evaporation of multiply excited states. This was described in detail in Refs.[2, 3]. The de-excitation was considered only via Auger process (auto-ionization) in Refs.[4]. In our treatment, the multiply excited states of the projectile undergo Auger decay while the electrons in the multiply excited states of target ions undergo statistical evaporation[5'6]. For projectile auto-ionization, some criterions based on the Auger electron spectra are applied in order to proceed the sequential decay. To calculate the evaporation probability, one has to get the excitation energy of the system. In our case, the excitation energy was obtained according to the states occupied by the captured electrons based on the MCBM. The values are different from the ones in, but more realistic. If one traces each molecularized electrons to its final states in the processes, one can reproduce each possible reaction channel. The processes discussed can be summarized in the following展开更多
Charge-changing processes between highly charged ion-atom collisions are of great importance in applied fields such as fusion plasmas and astrophysics. They are also of interest in basic atomic physics, especially in ...Charge-changing processes between highly charged ion-atom collisions are of great importance in applied fields such as fusion plasmas and astrophysics. They are also of interest in basic atomic physics, especially in the understanding of the multi-electron processes. Until now, the major processes in low energy ion-atom collisions are understood, and can be described by classical over-barrier model and coupled channel calculations. For larger number of active electrons and for higher projectile charges the number of needed states becomes展开更多
For the heaviest and simplest atomic system resonant transfer and excitation involving the innermost shell shave been investigated . We measured for H-like U^91.+ projectiles the KLjLj-RTE Using a H(2) gas target prov...For the heaviest and simplest atomic system resonant transfer and excitation involving the innermost shell shave been investigated . We measured for H-like U^91.+ projectiles the KLjLj-RTE Using a H(2) gas target providing the narrowest possible Compton profile for atomically confined quasi-free target electrons. We studied the emission patterns of the cascade decay of doubly excited He-like U90^+ ions where the first hypersatellite (Kαi-H) and the second satellite (Kαi′-S) transitions are energetically separated . Although the REC cascadecontributions to the satellite lines (Kαi′-S) dominate, the RTE contributions could be isolated. In particular,the hypersatellite (Kαi-H) transitions are free of REC contributions - neglecting possible small interference effects.展开更多
文摘Recently, there has been great interest in the linear polarization of photons produced by radiative electron capture (REC, the time reversed photoionization in ion-atom collisions). No such data are available for the high-Z regime till now. By using high efficiency by by a new generation of segmented germanium detectors that have energy as well as position resolution this field can be investigated experimentally. The
文摘The study of structure of few-electron heavy ions is of important interest due to the strong field effects. Helium-like ions are the simplest atomic multi-body systems. A considerable improved precision has been made in both theory and experiments recently. The experiment exploits the radiative recombination (RR) transitions into the vacant 1 s shell of bare and H-like ions. In this process, the energy carried by the emitted photon is the energy difference between the initial and final electron state, hω=Ekin+EB. For bare
文摘We measured the charge exchange cross-sections in collisions of Ar^q+(q=8, 9, 11, 12) on Ne atoms at low impact energies from 80 keV to 240 keV, and obtained a set of cross-section data. In order to understand the charge exchange processes, we combined the Molecular Classical over-Barrier Model (MCBM) developed by Niehaus[1] with auto-ionization and electron evaporation of multiply excited states. This was described in detail in Refs.[2, 3]. The de-excitation was considered only via Auger process (auto-ionization) in Refs.[4]. In our treatment, the multiply excited states of the projectile undergo Auger decay while the electrons in the multiply excited states of target ions undergo statistical evaporation[5'6]. For projectile auto-ionization, some criterions based on the Auger electron spectra are applied in order to proceed the sequential decay. To calculate the evaporation probability, one has to get the excitation energy of the system. In our case, the excitation energy was obtained according to the states occupied by the captured electrons based on the MCBM. The values are different from the ones in, but more realistic. If one traces each molecularized electrons to its final states in the processes, one can reproduce each possible reaction channel. The processes discussed can be summarized in the following
基金Supported by the Key Project of the National Natural Science Foundation of China.
文摘Charge-changing processes between highly charged ion-atom collisions are of great importance in applied fields such as fusion plasmas and astrophysics. They are also of interest in basic atomic physics, especially in the understanding of the multi-electron processes. Until now, the major processes in low energy ion-atom collisions are understood, and can be described by classical over-barrier model and coupled channel calculations. For larger number of active electrons and for higher projectile charges the number of needed states becomes
文摘For the heaviest and simplest atomic system resonant transfer and excitation involving the innermost shell shave been investigated . We measured for H-like U^91.+ projectiles the KLjLj-RTE Using a H(2) gas target providing the narrowest possible Compton profile for atomically confined quasi-free target electrons. We studied the emission patterns of the cascade decay of doubly excited He-like U90^+ ions where the first hypersatellite (Kαi-H) and the second satellite (Kαi′-S) transitions are energetically separated . Although the REC cascadecontributions to the satellite lines (Kαi′-S) dominate, the RTE contributions could be isolated. In particular,the hypersatellite (Kαi-H) transitions are free of REC contributions - neglecting possible small interference effects.
