Experimental study for measuring the decay branching ratio for nuclear excitation by electron transition in 189Os

Nuclear excitation by electron transition (NEET) is a fundamental mechanism of atomic deexcitation. In the last decades a series of experiments has been performed to study the NEET probability (PNEET) of 189Os. The determination of the PNEET of 189Os involves a crucial parameter B, which is the branching ratio for populating the isomer state from the 69.535 keV nuclear state in 189Os nucleus. But so far there is still ambiguity in the deduced value of B and no experimental data is available to verify the value. In this work, for the first time we carry out experimental study of nuclear resonance fluorescence in Shanghai Synchrotron Radiation Facility (SSRF) to attempt to measure B. We put forward an experimental method to determine the value of B by employing monochromatic x-ray beam. The feasibility for the measurement of B is verified through theory analysis and a preparation experiment on the experimental station BL13W1 in SSRF. In the future, once the requirement of the beam flux (up to 1012 photons/s) is met, by using this promising method we can conduct the measurement of B readily.