The spectrum of the internal bremsstrahlung accompanying the electron-capture decay of ${}_{}{}^7{}_{}{}^{}\mathrm{Be}$ has been measured in coincidence with the 477-keV $\gamma$ rays. From the extrapolated endpoint energy of the spectrum, the transition energy to the first excited state of ${}_{}{}^7{}_{}{}^{}\mathrm{Li}$ was determined to be 395 ± 25 keV. The intensity of the internal bremsstrahlung in the energy range from 120 to 360 keV was determined to be (5.45 ± 1.1) × ${10}^{-5\mathrm{}}$ per ordinary nonradiative $1s$ capture (based on a theoretically predicted $\frac{L}{K}$ ratio of 12.4 × ${10}^{-2\mathrm{}}$) as compared with the value of 7.86 × ${10}^{-5\mathrm{}}$ predicted by the theory of Martin and Glauber.

• Received 3 September 1970

DOI:https://doi.org/10.1103/PhysRevC.3.465