Eur. Phys. J. C (2012) 72: 1920
https://doi.org/10.1140/epjc/s10052-012-1920-6

Regular Article - Experimental Physics

Search for charge non-conserving processes in ¹²⁷I by coincidence technique

¹ Dip. di Fisica, Università di Roma “Tor Vergata”, 00133, Rome, Italy
² INFN, sez. Roma “Tor Vergata”, 00133, Rome, Italy
³ Dip. di Fisica, Università di Roma “La Sapienza”, 00185, Rome, Italy
⁴ INFN, sez. Roma, 00185, Rome, Italy
⁵ Laboratori Nazionali del Gran Sasso, INFN, Assergi, Italy
⁶ IHEP, Chinese Academy, P.O. Box 918/3, Beijing, 100039, China
⁷ Lab. Sperim. Policentrico di Ingegneria Medica, Università di Roma “Tor Vergata”, 00133, Rome, Italy
⁸ University of Jing Gangshan, Ji’an, Jiangxi, China

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

Received: 31 October 2011
Revised: 5 January 2012
Published online: 9 March 2012

Abstract

New lifetime limits on the charge non-conserving (CNC) electron capture with excitation of the 417.9 keV nuclear level in the ¹²⁷I are established by using the coincidence technique. The analysed exposure is 0.87 ton × yr, collected deep underground at the Gran Sasso National Laboratory of the INFN by the highly radiopure DAMA/LIBRA setup (≈250 kg of highly radiopure NaI(Tl)). The new limit on the mean life is τ>1.2×10²⁴ yr (90 % C.L.), about one order of magnitude larger than those previously available for CNC electron capture involving nuclear level excitations of ¹²⁷I and of the same order of magnitude than those achieved for analogous processes in ¹²⁹Xe.