The Carbon Isotopes of Mass Ten and Eleven

${\mathrm{C}}^{11}$ has been produced by two new reactions; namely, ${\mathrm{B}}^{11}\mathrm{}(p,n)\mathrm{}{\mathrm{C}}^{11}$ and ${\mathrm{N}}^{14}(p,\alpha ){\mathrm{C}}^{11}$. The upper limit of the positron spectrum of ${\mathrm{C}}^{11}$ has been measured in a cloud chamber and the value 0.95±0.03 Mev obtained. A new isotope, ${\mathrm{C}}^{10}$, has been produced by the reaction ${\mathrm{B}}^{10}\mathrm{}(p,n)\mathrm{}{\mathrm{C}}^{10}$. This nucleus has a disintegration period of 8.8±0.8 sec. The upper limit of the positron spectrum was found to be 3.36±0.1 Mev. A discussion is given of the relation which these measurements bear to the isobaric splitting and systematic properties of light nuclei.