Single-electron detection and spectroscopy via relativistic cyclotron radiation

• Published in: Physical review letters 2015-04, Vol.114 (16)
• Main Authors: Asner, D. M., Bradley, R. F., de Viveiros, L., Doe, P. J., Fernandes, J. L., Fertl, M., Finn, E. C., Formaggio, J. A., Furse, D., Jones, A. M., Kofron, J. N., LaRoque, B. H., Leber, M., McBride, E. L., Miller, M. L., Mohanmurthy, P., Monreal, B., Oblath, N. S., Robertson, R. G. H., Rosenberg, L. J., Rybka, G., Rysewyk, D., Sternberg, M. G., Tedeschi, J. R., Thummler, T., VanDevender, B. A., Woods, N. L.
• Format: Article
• Language: English
• Subjects: NUCLEAR PHYSICS AND RADIATION PHYSICS; Single electron detection and spectroscopy via relativistic cyclotron radiation
• ISSN: 0031-9007; 1079-7114

It has been understood since 1897 that accelerating charges should emit electromagnetic radiation. Cyclotron radiation, the particular form of radiation emitted by an electron orbiting in a magnetic field, was first derived in 1904. Despite the simplicity of this concept, and the enormous utility of electron spectroscopy in nuclear and particle physics, single-electron cyclotron radiation has never been observed directly. Here we demonstrate single-electron detection in a novel radiofrequency spectrometer. We observe the cyclotron radiation emitted by individual electrons that are produced with mildly-relativistic energies by a gaseous radioactive source and are magnetically trapped. The relativistic shift in the cyclotron frequency permits a precise electron energy measurement. Precise beta electron spectroscopy from gaseous radiation sources is a key technique in modern efforts to measure the neutrino mass via the tritium decay endpoint, and this work is a proof-of-concept for future neutrino mass experiments using this technique.