Measurement of the 7Be branching ratio

Abstract The branching ratio in the electron-capture decay of 7 Be to the 478 keV and ground states of 7 Li has been measured employing an activation technique. Three 7 Li targets were bombarded with a proton beam and the neutrons resulting from the 7 Li(p, n) 7 Be reaction were counted in 4π geometry. After bombardment, the 478 keV γ-activity was determined. To calibrate neutron-detection efficiency, two 89 Y targets were bombarded, and the resulting neutrons and ensuing 909 keV γ-activity counted. Comparison of the neutron yields with the γ-activities results in a 7 Be branch of (10.49 ± 0.07)% to the 478 keV state of 7 Li.