Reactions between 14·7-MeV neutrons and nickel-64

Discovery of the cobalt isotopes

“…"The 0.4 sec activity can be tentatively assigned to 64 Co since its β end point energy of 7.0±0.5 MeV is within reasonable agreement with the estimate of 7.5 MeV by Yamada and Matumoto." This half-life agrees with the currently adopted value of 0.30(3) s. Previously, several measurements of different incorrect half-life measurements were reported, for example, 4-5 m by Parmley et al [38], 2.0(2) m and 7.8(2) m for the ground and an isomeric state, respectively by Preiss and Fink [42], and 28(2) s by Strain and Ross [41]. 65…”

“…We credit Morinaga et al with the discovery of 63 Co because of this explanation for the discrepancy of the half-life and because the correct determination of the β -endpoint energy. A 28(2) s half-life had also been observed in 1966 by Strain and Ross, however, they attributed it to 64 Co [41]. Also, two months prior to the submission of Morinaga et al, Preiss and Fink had assigned an incorrect half-life of 1.40(5) h to 63 Co [42].…”