New search for correlated e+e- pairs in the α decay of 241Am (full text)
In a conservative approach the upper limit λ < 5.5 · 10-9 (90% C.L.) can be derived. It is worth noting that this is the first result on IPP obtained in an underground experiment, and that the λ value obtained in the present work is independent of the live-time estimate.
Further investigations are foreseen in the future with different dedicated sources and set-up.