New results of116Cddouble β decay study with116CdWO

Abstract

A new phase of a 116 Cd double β decay experiment is in progress in the Solotvina Underground Laboratory. Four enriched 116 CdWO 4 scintillators with total mass of 339 g are used in a set up, whose active shield is made of 15 natural CdWO 4 crystals (20.6 kg). The background rate in the energy interval 2.5-3.2 MeV is 0.03 counts/yr•kg•keV. The half-life for 2ν2β decay of 116 Cd is measured as T 1/2 (2ν) = 2.6 ± 0.1(stat) +0.7 −0.4 (syst)×10 19 yr. The T 1/2 limits for neutrinoless 2β decay of 116 Cd are set at T 1/2 ≥ 0.7(2.5)×10 23 yr at 90%(68%) C.L. for transition to ground state of 116 Sn, while for decays to the first 2 + 1 and second 0 + 1 excited levels of 116 Sn at T 1/2 ≥ 1.3(4.8)×10 22 yr and ≥ 0.7(2.4)×10 22yr with 90%(68%) C.L., respectively. For 0ν2β decay with emission of one or two Majorons, the limits are T 1/2 (0νM1) ≥ 3.7(5.8)×10 21 yr and T 1/2 (0νM2) ≥ 5.9(9.4)×10 20 yr at 90%(68%) C.L. Restrictions on the value of the neutrino mass, right-handed admixtures in the weak interaction, and the neutrino-Majoron coupling constant are derived as: m ν ≤ 2.6(1.4) eV, η ≤ 3.9×10 −8 , λ ≤ 3.4×10 −6 , and g M ≤ 12(9.5)×10 −5 at 90%(68%) C.L., respectively.

Measurement of the intrinsic radiopurity of 137Cs/235U/238U/232Th in CsI(Tl) crystal scintillators

“…Our work complements and extends the scope of those previous efforts on this [8,9] and other crystal scintillators: NaI(Tl) [11,12,13], CdWO 4 [14], GSO(Ce) [15], CeF 3 [16], BaF 2 [17] and CaF 2 (Eu) [18]. The achieved sensitivities match the best among these results as well as those from massive liquid scintillator facility [19].…”

Search for 2βdecay of116Cd with the help of enriched116CdWO4crystal scintillators

“…[5]). Moreover, existence of excellent detector, cadmium tungstate (CdWO 4 ) scintillator, already used for 2β decay searches [13][14][15] allows to realize "source = detector" experiment with a high detection efficiency. In addition, detector based on cadmium tungstate scintillator has several features (see e.g.…”

α activity of natural tungsten isotopes

“…In this paper the new results of Kiev-Firenze experiment (2975 h of exposition) on α decay of natural tungsten isotopes are described (the preliminary analysis of the 975 h data was presented in [9]). They were obtained with the help of the super-low background spectrometer [10] based on enriched 116 CdWO 4 crystal scintillators. The sensitivity of this apparatus to measure α activity was enhanced substantially in comparison with our previous work [6] mainly due to the developed technique of pulse-shape analysis of the data, which allows us to distinguish events caused by α particles from those by γ rays (β particles).…”