A New Investigation of $^{94}$Zr with the $(n,n'\gamma)$ Reaction

Measurements of the low-lying structure of $^{94}$Zr with the $(n,n'\gamma)$ reaction revealed anomalous behavior not observed in other nuclei [1]. The B(E2) for the transition from the $2_2^+$ state at 1671.4 keV to the ground state was found to be larger than that from the $2_1^+$ to the ground state, 7.8(7) W.u. [1] vs. 4.9(3) W.u. [2], respectively. This nucleus then became the only example where such an inversion of the B(E2) strength occurs. Recently, we have carried out $(n,n'\gamma)$ measurements using metallic zirconium, zirconium (IV) oxide, and zirconium (IV) hydroxide samples of natural isotopic composition. The lifetime of the $2_2^+$ state was determined by the Doppler-shift attenuation method and the B(E2; $2_2^+ \rightarrow 2_1^+$) was obtained; the results differ significantly from those published [1]. A new analysis of the original $\gamma$-ray data [1] failed to reveal the source of this discrepancy. However, powder x-ray diffraction and scanning electron microscopy performed on each sample material, including that used previously [1], provide clues to the answer.\\[4pt] [1] E. Elhami \textit{et al.}, Phys. Rev. C {\bf75}, 011301(R) (2007). \newline[2] D. Abriola and A.A. Sonzogni, Nucl. Data Sheets {\bf197}, 2423 (2006).