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Report No.

Simultaneous measurements of super-radiance at multiple wavelengths from helium excited states, 1; Experiment

Nakajima, Kyo*; Harries, J.; Iwayama, Hiroshi*; Kuma, Susumu*; Miyamoto, Yuki*; Nagasono, Mitsuru*; Ohae, Chiaki*; Togashi, Tadashi*; Yabashi, Makina*; Shigemasa, Eiji*; Sasao, Noboru*

In this paper, we report the results of measurements of the intensities and delays of super-radiance decays from excited helium atoms at multiple wavelengths. The experiment was performed using extreme ultraviolet radiation produced by the free electron laser at the SPring-8 Compact SASE Source test accelerator facility as an excitation source. We observed superradiant transitions on the 1s3p$$rightarrow$$1s2s ($$lambda$$=502 nm), 1s3d$$rightarrow$$1s2p ($$lambda$$=668 nm), and 1s3s$$rightarrow$$1s2p ($$lambda$$=728 nm) transitions. The pulse energy of each transition and its delay time were measured as a function of the target helium gas density. Several interesting features of the data, some of which appear to contradict with the predictions of the simple two-level super-radiance theory, are pointed out.



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Category:Physics, Multidisciplinary



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