Speaker
Description
Double beta (2$\beta$) decay is one of the most promising ways to search for effects beyond the Standard Model of particles and interactions (SM). Observation of neutrinoless mode of the decay ($0\nu2\beta$) will indicate the Majorana nature of the neutrino (particle is equivalent to its antiparticle), and the lepton number violation. Allowed in the SM two neutrino mode of the decay is the rarest nuclear process observed in several nuclei with the half-lives on the level of $10^{18} – 10^{24}$ years. An observation of the two neutrino double electron capture process was claimed in 2019, while other second-order weak-interaction “beta plus” processes such as electron capture with positron emission ($\varepsilon\beta^+$) and double positron decay ($2\beta^+$) have not been observed yet. A 215 g cadmium tungstate $^{106}CdWO_4$ crystal scintillator enriched in $^{106}Cd$ to 66% has been developed to search for 2$\beta$ processes in $^{106}Cd$. The experiment is carried out deep underground at the Gran Sasso National Laboratory of the INFN (Italy). In the third stage of the experiment the $^{106}CdWO_4$ detector was operated in coincidence with two $CdWO_4$ scintillation crystals with the natural abundance of cadmium and volume 114 cm$^3$ each. The $CdWO_4$ detectors are used to register $\gamma$-quanta expected in the 2$\beta$ processes in $^{106}Cd$, in particular 511 keV annihilation $\gamma$-quanta emitted in the $\varepsilon\beta^+$ and $2\beta^+$ decays. The new improved limit on half-life to the 2$\nu$EC$\beta^+$ decay of $^{106}Cd$ ($T_{1/2} > 2.1×10^{21}$ yr. 90% C.L.) approaches the region of the theoretical predictions of the decay half-life $T_{1/2} \sim 10^{21} - 10^{22}$ yr.
Details
Volodymyr Klavdiienko
| Is the speaker for that presentation defined? | Yes |
|---|---|
| Internet talk | Yes |
