New limits on nucleon decays into invisible channels with the BOREXINO Counting Test Facility

New limits on nucleon decays into invisible channels with the BOREXINO counting test facility

Physics Letters B  Volume 563, Issues 1–2,
19 June 2003, Pages 23-34

doi:10.1016/S0370-2693(03)00636-1

Abstract

The results of background measurements with the second version of the BOREXINO Counting Test Facility (CTF-II), installed in the Gran Sasso Underground Laboratory, were used to obtain limits on the instability of nucleons, bounded in nuclei, for decays into invisible channels (inv): disappearance, decays to neutrinos, etc. The approach consisted of a search for decays of unstable nuclides resulting from N and NN decays of parent ¹²C, ¹³C and ¹⁶O nuclei in the liquid scintillator and the water shield of the CTF. Due to the extremely low background and the large mass (4.2 t) of the CTF detector, the most stringent (or competitive) up-to-date experimental bounds have been established:  τ(n→inv)>1.8×10²⁵ yr,  τ(p→inv)>1.1×10²⁶ yr, τ(nn→inv)>4.9×10²⁵ yr  and  τ(pp→inv)>5.0×10²⁵ yr,  all at 90% C.L.