Eur. Phys. J. A (2013) 49: 24
https://doi.org/10.1140/epja/i2013-13024-9

Regular Article - Experimental Physics

First search for double-β decay of ¹⁸⁴Os and ¹⁹²Os

¹ INFN, Sezione di Roma “Tor Vergata”, I-00133, Rome, Italy
² Dipartimento di Fisica, Università di Roma “Tor Vergata”, I-00133, Rome, Italy
³ INFN, Sezione di Roma “La Sapienza”, I-00185, Rome, Italy
⁴ Dipartimento di Fisica, Università di Roma “La Sapienza”, I-00185, Rome, Italy
⁵ INFN, Laboratori Nazionali del Gran Sasso, 67100, Assergi, Italy
⁶ Institute for Nuclear Research, 03680, Kyiv, Ukraine
⁷ National Science Center “Kharkiv Institute of Physics and Technology”, 61108, Kharkiv, Ukraine

^* e-mail: rita.bernabei@roma2.infn.it

Received: 6 November 2012
Revised: 22 December 2012
Accepted: 28 January 2013
Published online: 18 February 2013

Abstract

A search for double-β decay of osmium has been realized for the first time with the help of an ultra-low background HPGe γ detector at the underground Gran Sasso National Laboratories of the INFN (Italy). After 2741 h of data taking with a 173 g ultra-pure osmium sample limits on double-β processes in ¹⁸⁴Os have been established at the level of T _1/2 ∼ 10¹⁴-10¹⁴ y. Possible resonant double-electron captures in ¹⁸⁴Os were searched for with a sensitivity of T _1/2 ∼ 10¹⁶ y. A half-life limit T _1/2≥5.3×10¹⁹ y was set for the double-β decay of ¹⁹²Os to the first excited level of ¹⁹²Pt . The radiopurity of the osmium sample has been investigated and radionuclides ¹³⁷Cs , ¹⁸⁵Os and ²⁰⁷Bi were detected in the sample, while activities of ⁴⁰K , ⁶⁰Co , ²²⁶Ra and ²³²Th were limited at the ≈ mBq/kg level.