Measurement of the L/K electron capture ratio of the 207 Bi decay to the 1633 keV level of 207 Pb with a BGO scintillating bolometer

The ROSEBUD Collaboration has dedicated several underground runs to study different types of bolometers, mainly for the search of dark matter. Some of these runs, profiting from the good energy resolution of one bolometer of BGO and the ultra-low background of the underground laboratory of Canfranc (LSC), allowed the measurement of the L / K electron capture ratio of the 207 Bi decay to the 1633 keV level of 207 Pb. This paper constitutes the first published measurement of this magnitude.