Neutron-Deficient Members of the $A = 139$ Decay Chain. I. 5.5-h ${Nd}^{139 m}$ and 30-min ${Nd}^{139 g}$

We have studied the

γ

rays emitted following the decays of 5.5-h

{Nd}^{139 m}

and 30-min

{Nd}^{139 g}

with Ge (Li) and NaI (T1) detectors in singles, coincidence, and anticoincidence configurations. Our study has indicated 51

γ

rays accompanying

{Nd}^{139 m}

decay and 21 that follow

{Nd}^{139 g}

decay. Of these, 56 have been placed in decay schemes containing a total of 22 excited states. The decay scheme of

\frac{3}{2} + {Nd}^{139 g}

has much in parallel with those of similar nuclei in this region, and states are populated in

\Pr^{139}

0 (\frac{5}{2} +)

113.8 (\frac{7}{2} +)

405.0 (\frac{3}{2} +, \frac{1}{2} +)

589.2 (\frac{5}{2} +)

916.8 (\frac{1}{2} +, \frac{3}{2} +)

1074.4 (\frac{1}{2} +, \frac{3}{2} +)

1311.8 (\frac{1}{2} +, \frac{3}{2} +, \frac{5}{2} +)

1328.2 (\frac{5}{2} +)

1405.5 (\frac{1}{2} +, \frac{3}{2} +, \frac{5}{2} +)

1449.5 (\frac{1}{2} +, \frac{3}{2} +, \frac{5}{2} +)

, and

1501.2 keV (\frac{1}{2} +, \frac{3}{2} +)

. On the other hand, 11/2-

{Nd}^{139 m}

decays only 12.7% via a 231.2-keV

M 4

isomeric transition and independently decays by electron capture to a set of almost completely different states in

\Pr^{139}

. These are at

0 (\frac{5}{2} +)

113.8 (\frac{7}{2} +)

This publication has 28 references indexed in Scilit:

Neutron-Deficient Members of the A=139 Decay Chain. I. 5.5-h Nd139m and 30-min Nd139g