A nuclear emulsion study of the radioactive decay of actinium X( ²²³Ra)

A nuclear emulsion method has been used to obtain the absolute intensity of the conversion electron spectrum following the radioactive decay of AcX. The results have been used in conjunction with the other available knowledge about the decay to show that in the level scheme of An there are three strong transitions having energies of 144, 154 and 268 keV and probably a fourth of 122 keV, all of which are either pure M1 or M1 with only a small admixture of E2. All four of these transitions probably go directly to the ground state of An. Estimates of the absolute intensities of these transitions and of several other less strong transitions have been made, and it is shown that the absolute intensity of K x-ray fluorescence is at least 0.3 and probably 0.5 quanta per disintegration.