DAMA/R&D

Investigations on the performances of BaF2 detectors and results on ββ decays modes in 130Ba

1998/1999 - Preliminary results on some 2β decay modes in 130Ba:

    130Ba 2β+0ν: τ > 0.5 x 1015 years (68% C.L.)
    130Ba EC-2β+ 0ν: τ > 1.2 x 1015 years (68% C.L.)

2004 - Results on 2β decay modes in 130Ba by exploiting the coincidence technique (90% C.L.):

    τ[2β+0ν(0+ → 0+)] > 1.1 x 1017 years,
    τ[2β+0ν(0+ → 2+1)] > 1.5 x 1017 years,
    τ[ECβ+0ν(0+ → 0+)] > 2.0 x 1017 years,
    τ[ECβ+0ν(0+ → 2+1)] > 1.6 x 1017 years,
    τ[ECβ+0ν(0+ → 2+2)] > 2.0 x 1017 years,
    τ[ECβ+0ν(0+ → 4+)] > 1.1 x 1017 years.

Although the limits on the 0ν(0+ → 0+) modes are modest, they represent a relevant improvement with respect to those previously available. Moreover, the experimental limits on decay modes involving excited states are set here for the first time.

The performances of the detector (such as α/β light ratio, pulse shape discrimination capability between α particles and γ and residual contaminations) have been investigated as well.