Decay properties of ${}^{153}{Yb}$ and ${}^{153}{Tm}$ ; Excitation energies of the $s_{1 / 2}$ and $h_{11 / 2}$ proton states in ${}^{153}{Tm}$

The decay properties of

{}^{153}{Yb}

and

{}^{153}{Tm}

, produced in

{}^{64}{Zn}

bombardments of

{}^{92}{Mo}

, were investigated following on-line mass separation. A decay scheme, incorporating 34 transitions and 25 levels in

{}^{153}{Tm}

, was constructed for

{}^{153}{Yb}

. It establishes the

s_{1 / 2}

proton level in

{}^{153}{Tm}

to be isomeric at an excitation energy of 43.2 keV. The α-decay branch of the

h_{11 / 2}

{}^{153}{Tm}

ground state was determined to be 91±3%. In addition, a partial decay scheme was put together for the 9%

β^{+}

branch. About 66% of this

β^{+}

decay proceeds to the

h_{9 / 2}

neutron state located at 299.3 keV in

{}^{153}{Er}

. Only one transition, 266.5 keV, could be assigned to the

β^{+}

decay of the

{}^{153}{Tm}

s_{1 / 2}

isomer; it is suggested that the γ ray deexcites the

p_{3 / 2}

neutron level to the

f_{7 / 2}

{}^{153}{Er}

ground state. Based on the intensity of this 266.5-keV γ ray, the isomer’s α branch was estimated to be ∼93%.

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Decay properties ofYb153andTm153; Excitation energies of thes1/2andh11/2proton states inTm153