The Radioactive Isotopes of Scandium and Their Properties

The results of further studies of the radioactive isotopes of scandium can be summarized as follows. (a) The activity of half-life 53±3 min., now measured more accurately as 57±2 min., produced by bombarding calcium with deuterons, which emits $\beta -\mathrm{p}\mathrm{a}\mathrm{r}\mathrm{t}\mathrm{i}\mathrm{c}\mathrm{l}\mathrm{e}\mathrm{s}$ of energy 1.8±0.1 Mev previously assigned to ${\mathrm{Sc}}^{41}$ is shown to be probably due to ${\mathrm{Sc}}^{49}$. ${\mathrm{Sc}}^{49}$ can be produced by the decay of ${\mathrm{Ca}}^{49}$ and from titanium by bombardment with fast neutrons. It emits no $\gamma -\mathrm{r}\mathrm{a}\mathrm{d}\mathrm{i}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}$. (b) ${\mathrm{Sc}}^{42}$, half-life 13.4±0.3 days, emits positrons of maximum energy 1.4±0.1 Mev. (c) The continuous spectrum of ${\mathrm{Sc}}^{43}$ is complex, there being two groups of positrons and $\gamma -\mathrm{r}\mathrm{a}\mathrm{d}\mathrm{i}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}$ of energy 1.0±0.1 Mev. (d) The 52-hour isomer of ${\mathrm{Sc}}^{44}$ is the metastable form decaying by emitting highly internally converted $\gamma -\mathrm{r}\mathrm{a}\mathrm{d}\mathrm{i}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}$ of energy 250 kev. (e) There is only one form of ${\mathrm{Sc}}^{46}$ of half-life 85±1 days, emitting $\beta -\mathrm{r}\mathrm{a}\mathrm{y}\mathrm{s}$ of energy 0.26±0.01 Mev (>95 percent) and 1.5±0.1 Mev ($\gamma -\mathrm{r}\mathrm{a}\mathrm{d}\mathrm{i}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}$ of energy 1.25±0.1 Mev. (f) ${\mathrm{Sc}}^{47}$, half-life 63±2 hours, emits $\beta -\mathrm{r}\mathrm{a}\mathrm{y}\mathrm{s}$ of energy 1.1±0.1 Mev. (g) ${\mathrm{Sc}}^{48}$, half-life 44±1 hours, emits $\beta -\mathrm{r}\mathrm{a}\mathrm{y}\mathrm{s}$ of energy 0.5±0.1 Mev (∼90 percent) and 1.4±0.1 Mev (∼10 percent) and $\gamma -\mathrm{r}\mathrm{a}\mathrm{d}\mathrm{i}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}$ of energy 0.9±0.1 Mev. The following previously unreported reactions have been established: