1301.3465 (F. A. Danevich et al.)

Search for $α$ decay of $^{151}$Eu to the first excited level of
$^{147}$Pm using underground $γ$-ray spectrometry    [PDF]

F. A. Danevich, E. Andreotti, M. Hult, G. Marissens, V. I. Tretyak, A. Yuksel

The alpha decay of $^{151}$Eu to the first excited level of $^{147}$Pm ($J^\pi = 5/2^+$, $E_{exc}=91.1$ keV) was searched for at the HADES underground laboratory ($\approx 500$ m w.e.). A sample of high purity europium oxide with mass of 303 g and a natural isotopic composition has been measured over 2232.8 h with a high energy resolution ultra-low background n-type semi-planar HPGe detector (40 cm$^3$) with sub-micron deadlayer. The new improved half-life limit has been set as $T_{1/2} \geq 3.7\times 10^{18}$ yr at 68% C.L. Possibilities to improve the sensitivity of the experiment, which is already near the theoretical predictions, are discussed. New half-life limit for $\alpha$ decay of $^{153}$Eu is also set as $T_{1/2} \geq 5.5\times 10^{17}$ yr.

View original: http://arxiv.org/abs/1301.3465