Recent Progress in X-Ray Spectroscopy Experiments at HIRFL-CSRe Gas TargetONLINE ONLY

Heavy-ion storage ring operation with the combined of gaseous targets and cooling of stored beam allows high precision experiments to be made under clean conditions. The gas target terminal of HIRFL-CSRe (Heavy Ion Research Facility at Lanzhou–Cooling Storage Ring) was proposed and built mainly for atomic physics at the beginning and now has been extended for nuclear physics experiment. In atomic physics, we concentrate on x-ray spectroscopic investigations of the double K-shell vacancy both in projectile and atoms produced during heavy ion-atoms collision in the past decade.
In this seminar, I will first introduce previous status and recent upgrades of CSR internal gas-jet target terminal. Then I will introduce recent research activities in X-ray spectroscopy experiments at HIRFL-CSRe, mainly including the following work.
1) The production and decay of double K-shell vacancy atoms in collision with heavy ions. I will show the measured X-ray spectra of K-shell hollow krypton/xenon atoms produced in single collisions with 52–197-MeV/u Xe54+ ions. Then I will discuss the dependence of the production ratio of double-to-single K-shell vacancy target atom on the perturbation strength, κ= Zp/Vp, from the projectiles ion.
2) Simultaneous K-shell double ionization of target and projectile in symmetric collision between Kr26+ and Kr atom at 153 MeV/u. The present experiment is expected to eliminate the influence of M-shell and higher shell electrons on the collision process as well as cascade process by measuring the relative intensity of ions and target lines and their respective structures.
3) Besides, the state-selective non-radiative electron capture in collision of 50-200 MeV/u Xe54+-Xe/Kr collision and the following decay of Xe53+∗ ions are investigated by means of the intensity ratios I(Ly-β)/I(Ly-α) and I(Ly-γ)/I(Ly-α) and by means of anisotropic distributions of the Ly-α1 transition.
Finally I will talk about the problems in current experiments and the proposal of our next experiments.