High-Resolution Gamma-Ray Spectroscopic Studies of the Decays of 2.6-hNd141gand 60-secNd141m

Abstract

$\gamma$ rays emitted in the decays of 2.6-h ${\mathrm{Nd}}^{141g}$ and 60-sec ${\mathrm{Nd}}^{141m}$ have been investigated with Ge(Li) and NaI(Tl) detectors. Following the decay of ${\mathrm{Nd}}^{141g}$, $\gamma$ rays with the following energies (and relative intensities) have been observed: 145.4 (30.0), 981.3 (3.0), 1126.8 (≡ 100), 1147.1 (38.2), 1292.8 (61.2), 1298.7 (16.3), 1434.6 (3.0), 1579.9 (0.74), 1607.9 (2.3), and 1657.2 keV (0.12). On the basis of coincidence and anticoincidence experiments, energy sums, and relative intensities, states were placed in ${\mathrm{Pr}}^{141}$ at 0, 145.4, 1126.8, 1292.5, 1298.4, 1580.0, 1607.9, and 1657.2 keV. An upper limit of 0.1% of the intensity of the ${\mathrm{Nd}}^{141m}$ 756.5-keV isomeric-transition $\gamma$ ray was placed on the intensity of any other $\gamma$ ray between 130 and 2600 keV following direct transitions from the $\frac{11}{2}-$ ${\mathrm{Nd}}^{141m}$ to high-spin states of ${\mathrm{Pr}}^{141}$. Limits are placed on the spins of ${\mathrm{Pr}}^{141}$ states on the basis of $log\mathrm{ft}$ values and relative photon intensities, and the structures of the states are discussed in terms of current nuclear models.