New Isotopes:Er172andTm172

Two new isotopes,

{Er}^{172}

of half-life 49.8±1 hr, and

{Tm}^{172}

of half-life 63.6±0.3 hr, have been found. The mass assignment of

{Tm}^{172}

was proven by direct mass separation, and that of

{Er}^{172}

by genetic relationship. The

{Tm}^{172}

isotope was found to emit a 1.5-Mev

β^{-}

particle,

γ

rays of 1.79, 1.44, 1.09, 0.40, 0.18, and 0.076 Mev, and a

K

x-ray of 0.049 Mev. The mass assignments of

{Er}^{165}

{Er}^{171}

, and

{Tm}^{171}

were verified.