Transient nuclear inversion by X-Ray Free Electron Laser in a tapered x-ray waveguide

Wen-Te Liao^1*

¹Department of Physics, National Central University, Taoyuan, Taiwan

* Presenter:Wen-Te Liao, email:wente.liao@gmail.com

We theoretically show that transient nuclear population inversion can be generated by a focused x-ray free electron laser pulse in a tapered waveguide where a nuclear sample is placed at the focal point [Phys. Rev. Research 4, L032007 (2022)]. This is a long-standing goal related to gamma-ray lasers or nuclear state population control for energy storage. We show that inverted nuclei numbers of up to approximately 2×10^5 are achievable in the realistic region of longitudinal x-ray-free-electron-laser coherence time ≤ 10fs. Our results anticipate the important role of tapered x-ray waveguides and strategically embedded samples in the field of x-ray quantum optics.

Keywords: x-ray free electron laser, nuclear population inversion, waveguide