We report measurements of the intensity ratio of the 1s 2 2s 2 2p 5 1/2 3d 3/2 → 1s 2 2s 2 2p 6 resonance line to the 1s 2 2s 2 2p 5 3/2 3d 5/2 → 1s 2 2s 2 2p 6 intercombination line in neonlike Kr 26+ and Mo 32+. The measurements were performed at the EBIT-I electron beam ion trap facility at the Lawrence Livermore National Laboratory and utilized an x-ray microcalorimeter. The measured ratio for Mo 32+ , is in four times closer agreement with theoretical predictions than earlier measurements of ions with lower atomic number. Our measurement, thus, suggests a narrowing of the disagreement with atomic number, which had not been observed in the previously existing data. This implies that the disagreement with theory may be localized to ions within a range of atomic numbers in which intermediate coupling dominates.

We report a measurement of the two x-ray transitions that proceed from the (1s 2 2s 2 2p 5 1/2 3d 3/2 ) J=1 and (1s 2 2s 1/2 2p 6 3p 1/2 ) J=1 upper levels to the (1s 2 2s 2 2p 6 ) J=0 ground level in neonlike Eu 53+ (Z = 63), i.e. near the previously documented avoided crossing of the two upper levels at Z = 68. The measurement was carried out using the calorimeter spectrometer on the Livermore EBIT-I electron beam ion trap. It affirms the trends set by the neighboring neonlike ions both in terms of the relative intensity of the two lines and in terms of the magnitude of disagreement with theoretical energy level predictions.

We report the measurements of the n = 3 → n = 2 L-shell X-ray transitions of neon-like Eu53+. These include all seven allowed electric dipole (E1) transitions, five electric quadrupole (E2) transitions, and one magnetic quadrupole (M2) transition. The measurements were carried out at the EBIT-I electron beam ion trap facility at Livermore using an X-ray calorimeter. The measured values agree with many-body perturbation theory calculations within the experimental uncertainties. This includes the transitions that involve a 2s electron and that are, therefore, strongly affected by quantum electrodynamical effects.

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Many resonant photo-pumped X-ray laser schemes that use a strong pump line such as Ly-a or He-a to populate the upper laser state of a separate lasing material have been proposed over the last four decades but none have been demonstrated. As a first step to creating a photo-pumped X-ray laser we have decided to reinvestigate some of these schemes at the Orion laser facility with the goal to show enhanced fluorescence. In particular we look at using the Ly-a or He-a K lines to pump the 1s-3p and 4p transitions in H-like Cl and see fluorescence on the 4f-3d line at 65 Å and the 3d-2p line at 23 Å. Preliminary experiments are presented that show a modest enhancement. As an alternative we also look at enhancing the 2p-2s line in Ne-like Ge at 65Å using the Ly-a Mg line to photo-pump the 2s-3p line of Ne-like Ge. Calculations are presented that suggest modest enhancements of 2.5.