Bremsstrahlung induced atomic processes

Abstract

The observed spectra in the collisions of neon (Ne) projectiles of 1.8 and 2.1 MeV with an aluminum target (Al) have been successfully segregated from strong bremsstrahlung backgrounds and then analyzed by comparing the transition energies and rates with the theoretical predictions of the flexible atomic structure code and the general purpose relativistic atomic structure package. The spectra contain K{\alpha}, Kh{\alpha} , and K{\alpha}{\alpha} lines. The K{\alpha}{\alpha} emissions are due to two-electron one-photon transitions. Interestingly, the K{\alpha}{\alpha} lines in projectile ions are only seen with 1.8 MeV energy. In contrast, the K{\alpha}{\alpha} lines in the target ions are also well observed with 2.1 MeV energy. Surprisingly, the Al K x-ray line intensities are strongly suppressed, and the K{\alpha}{\alpha} line intensities are unexpectedly enhanced. The underlying physical process is found to be the photoionization caused by intense bremsstrahlung radiation. This photoionization process converts most of the singly ionized K shell states (\approx 82\% at 2.1 MeV) to doubly ionized K shell states. This phenomenon is silently present on many occasions. We take some of such events to validate this remarkable finding. This bremsstrahlung radiation induced secondary ionization process stands as an eye opening incidence to the plasma physics, astronomy and astrophysics communities; may revolutionize these fields of research.