First search for double β decay of dysprosium

Abstract

A search for double β decay of dysprosium was realized for the first time with the help of an ultra-low background HP Ge γ detector. After 2512 h of data taking with a 322 g sample of dysprosium oxide limits on double beta processes in 156Dy and 158Dy have been established on the level of T⩾1014-1016 yr. Possible resonant double electron captures in 156Dy and 158Dy were restricted on a similar level. As a by-product of the experiment we have measured the radioactive contamination of the Dy2O3 sample and set limits on the α decay of dysprosium isotopes to the excited levels of daughter nuclei as T⩾1015-1017 yr

Experimental searches for rare alpha and beta decays

“…in Ref. [23], where the quoted calculated values are in the range (10 28 − 10 30 ) for 162 Er and even (10 39 − 10 41 ) for 164 Er.…”

“…In Ref. [162] a search for α decay of the dysprosium isotopes to the excited levels of the daughter gadolinium isotopes was realized by analysing the low background energy spectrum measured by a low background HPGe γ detector with a purified 322 g Dy 2 O 3 sample for 2512 h. No peculiarities, that could be interpreted as γ peaks from α decays of the dysprosium isotopes to the lowest excited levels of the daughter nuclei, were observed in the energy spectrum measured with HPGe spectrometer; thus, only limits were set on these decays. As an example in Fig.…”

“…[56]. The strong Table 6: Characteristics of possible alpha decays of dysprosium isotopes to the lowest excited levels of the daughter nuclei [162].…”

“…Erbium has six naturally occurring isotopes (see Table 1). They are stable, but potentially all of them can decay emitting α particles [70], in particular: 162 Er is considered to undergo α decay to 158 Dy (with a half-life larger than 1.40 ×10 14 yr).…”

Search for2βdecays of96Ru and104Ru by ultralow-background HPGeBelli1, Bernabei2, Cappella3 et al. 2013Phys. Rev. CSelf Cite

“…+ , 555.8 keV) ≥ 6.6 × 10 20 yr, As for resonance 0ν2ε capture, intensive high-precision measurements of Q 2β values during last few years (see reviews [52] [53] were set on the level of only T 1/2 > 10 16 yr (this is related with 156 Dy low natural abundance δ = 0.056% [12]). …”