https://doi.org/10.1140/epja/i2014-14134-6
Regular Article - Experimental Physics
Investigation of rare nuclear decays with BaF2 crystal scintillator contaminated by radium
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, I-00185, Rome, Italy
4
Dipartimento di Fisica, Università di Roma “La Sapienza”, I-00185, Rome, Italy
5
INFN, Laboratori Nazionali del Gran Sasso, I-67100, Assergi (AQ), Italy
6
Institute for Nuclear Research, 03680, Kyiv, Ukraine
* e-mail: rita.bernabei@roma2.infn.it
Received:
26
February
2014
Revised:
4
July
2014
Accepted:
11
August
2014
Published online:
1
September
2014
The radioactive contamination of a BaF2 scintillation crystal with mass of 1.714 kg was measured over 101 hours in the low-background DAMA/R&D set-up deep underground (3600 m w.e.) at the Gran Sasso National Laboratories of INFN (LNGS, Italy). The half-life of 212Po (present in the crystal scintillator due to contamination by radium) was measured as 
= 298.8±0.8(stat.)±1.4(syst.) ns by the analysis of the events' pulse profiles. The 222Rn nuclide is known as 100% decaying via the emission of the 
particle with T
1/2 = 3.82 d; however, its 
decay is also energetically allowed with 
keV. Search for decay chains of events with specific pulse shapes characteristic for or for 
signals and with known energies and time differences allowed us to set, for the first time, the limit on the branching ratio of 222Rn relatively to decay as 
% at 90% C.L. (equivalent to limit on partial half-life 
y). The half-life limits of 212Pb, 222Rn and 226Ra relatively to 2 decays are also improved in comparison with the earlier results.
© SIF, Springer-Verlag Berlin Heidelberg, 2014
