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arXiv · 2203.05990

Coherent Smith-Purcell $\gamma$-Ray Emission

Kamran Akbari·Simone Gargiulo·Fabrizio Carbone·F. Javier García de Abajo
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Abstract

We investigate the Smith-Purcell emission produced by electron- or ion-beam-driven coherent excitation of nuclei arranged in periodic crystal lattices. The excitation and subsequent radiative decay of the nuclei can leave the target in the initial ground state after $\gamma$-ray emission, thus generating a coherent superposition of the far-field photon amplitude emanating from different nuclei that results in sharp angular patterns at spectrally narrow nuclear transition energies. We focus on Fe-57 as an example of two-level nuclear lossy system giving rise to Smith-Purcell emission at 14.4\,keV with a characteristic delay of 1.2\,ns relative to the excitation time. These properties enable a clean separation from faster and spectrally broader emission mechanisms, such as bremsstrahlung. Besides its fundamental interest, our study holds potential for the design of high-energy, narrow-band, highly-directive photon sources, as well as a means to store energy in the form of nuclear excitations.

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Kamran Akbari, Simone Gargiulo, Fabrizio Carbone, F. Javier García de Abajo. 2022-02-11. Coherent Smith-Purcell $\gamma$-Ray Emission. https://arxiv.org/abs/2203.05990

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