A high resolution X-ray crystal spectrometer to study electron and heavy-ion impact atomic collisions

Abstract

We have studied fast ion-atom and electron-atom collision processes using a reconditioned high resolution X-ray spectrometer. The X-rays, generated by the collisions, are dispersed by a curved ADP crystal (Johansson geometry) and detected by a gas proportional counter. A self-written LabVIEW based program has been used to give precise and controlled movement to the crystal and for data acquisition. The performance was tested by detecting the Kα diagram and satellite lines of several elements. The Kα satellite lines of Al have been studied in collision with 3-12 keV electrons and 40 MeV C 4+ ions. In ion collisions as large as four L-vacancies are created simultaneously with the K-vacancy, compared to two satellites in case of the e-impact. In addition, we have measured the X-rays from H-, He-and Li-like Si ions which arise due to the electron loss/capture process in highly charged 80 MeV Si 7+ ions in collision with thin carbon foil. Approximate charge state distribution has been obtained using this new technique.

Al K-shell x-ray production cross section induced by proton and highly charged heavy ions

“…Besides, the width of the x-ray is broadened due to the distribution of the electron population in multiple inner-shell vacancies. By analyzing the Kα L-shell satellite energy shift of Mg, Al and Si and the results of the multi-configuration Dirac-Fock calculations [9,[25][26][27][28][29][30], one can find that moving one electron from the L-shell causes an energy shift of about 10 eV for the Al K-shell x-ray. Here, the energy shift of 37 eV allows us to estimate that the x-ray at an energy of 1.523 keV originates predominantly from the de-excitation of the multiply ionized Al atoms and about 3-4 L-shell vacancies are produced during the collision of Ar 11+ ions with Al atoms.…”