188 research outputs found
Single-photon emission associated with double electron capture in F9+ + C collisions
Radiative double electron capture (RDEC), the one-step process occurring in
ion-atom collisions, has been investigated for bare fluorine ions colliding
with carbon. RDEC is completed when two target electrons are captured to a
bound state of a projectile simultaneously with the emission of a single
photon. This work is a follow-up to our earlier measurement of RDEC for bare
oxygen projectiles, thus providing a recipient system free of electron-related
Coulomb fields in both cases and allowing for the comparison between the two
collision systems as well as with available theoretical studies. The most
significant mechanisms of x-ray emission that may contribute to the RDEC energy
region as background processes are also addressed.Comment: Submitted to Phys. Rev.
Single Transfer-Excitation Resonance Observed Via the Two-Photon Decay in He-like Ge³⁰⁺
We measured the 2E1 decay of the 1s2s 1S0 →1s2 1S0 transition in He-like germanium for 12- to 19-MeV/u Ge31+ +H2 collisions. The resonant population of the 2s2p 1P1 state by transfer excitation was isolated due to its cascading to the 1s2s 1S0 state. The experimental cross sections compare well with calculations using dielectronic recombination rates. The method gives the unique possibility to populate selectively the 1S0 state in heavy He-like ions
Magnetic Sublevel Population and Alignment for the Excitation of H- and He-like Uranium in Relativistic Collisions
We have measured the alignment of the L-shell magnetic-substates following
the K-shell excitation of hydrogen- and helium-like uranium in relativistic
collisions with a low-Z gaseous target. Within this experiment the population
distribution for the L-shell magnetic sublevels has been obtained via an
angular differential study of the decay photons associated with the subsequent
de-excitation process. The results show a very distinctive behavior for the H-
and He-like heavy systems. In particular for excitation of
He-like uranium, a considerable alignment of the L-shell levels was observed. A
comparison of our experimental findings with recent rigorous relativistic
predictions provides a good qualitative and a reasonable quantitative
agreement, emphasizing the importance of the magnetic-interaction and many-body
effects in the strong-field domain of high-Z ions
Cochlear ribbon synapse maturation requires Nlgn1 and Nlgn3
Hearing depends on precise synaptic transmission between cochlear inner hair cells and spiral ganglion neurons through afferent ribbon synapses. Neuroligins (Nlgns) facilitate synapse maturation in the brain, but they have gone unstudied in the cochlea. We repor
Triple coalescence singularity in a dynamical atomic process
We show that the high energy limit for the amplitude of the double electron
capture to the bound state of the Coulomb field of a nucleus with emission of a
single photon is determined by behavior of the wave function in the vicinity of
the singular triple coalescence point.Comment: 3 page
Subshell-selective x-ray studies of radiative recombination of ions with electrons for very low relative energies
Radiative recombination (RR) into the K shell and L subshells of U92+ ions interacting with cooling electrons has been studied in an x-ray RR experiment at the electron cooler of the Experimental Storage Ring at GSI. The measured radiative recombination rate coefficients for electron-ion relative energies in the range 0–1000 meV demonstrate the importance of relativistic effects. The observed asymmetry of the measured K-RR x-ray emission with respect to the cooling energy, i.e., zero average relative velocity (⟨vrel⟩=0), are explained by fully relativistic RR calculations. With our new approach, we show that the study of the angular distribution of RR photons for different relative energies opens new perspectives for detailed understanding of the RR of ions with cooling electrons in cold magnetized plasma
Characteristic X-ray emission in close collisions between heavy ions and atoms
zugl.: Kraków, Poland, Univ., Habil., 198
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