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Properties of neutrino and weak interactions, search for effects beyond the Standard Model

Work number - P 2 AWARDED

Yu.G. Zdesenko, F.A. Danevich, V.V. Kobychev, V.I. Tretyak, G.P. Kovtun, A.P.Shcherban, L.L. Nagornaya, I.A. Tupitsyna

Presented by the Institute for Nuclear Research of NASU, Kyiv, Ukraine

The purposes of the research werestudy of neutrino and weak interaction, test of the fundamental laws (the Pauli principle, conservation laws of the electric charge, lepton and baryon numbers), search for dark matter (axions, sterile neutrinos, weakly interacting massive particles), measurements of neutrino fluxes from the Sun, Earth's mantle and other sources, study of rare alpha, beta, double beta and cluster decays. The Solotvina Underground Laboratory was built on the initiative of Yu.G. Zdesenko, ultra-low background scintillation spectrometry, techniques of deep purification of materials were developed, a few novel crystal scintillators were grown and investigated, several existing scintillation materials were studied, new methods of data analysis were developed. Cadmium tungstate scintillator from enriched isotopes of cadmium and molybdenum were developed for the first time to realize double beta experiments.

An extremely rare two neutrino decay of selenium, zirconium , molybdenum and cadmium was observed. Double beta decay of more than 20 isotopes of calcium, zinc, strontium, ruthenium, molybdenum, cadmium, cerium, dysprosium, gadolinium, tungsten, osmium, platinum and mercury were investigated on a new level of sensitivity. The strict limits on the effective Majorana neutrino mass (< 0.3 - 1.7 eV), right-handed admixtures in the weak interaction, the effective Majoron-neutrino coupling constant were set. New restrictions on axions mass, which can be emitted in the Sun, were established. Strong limits on the photon electric charge, processes violating the electric charge conservation (electron and nucleon decay, charge non-conserving beta decay), disappearance of matter into additional dimensions were established. The Pauli principle was tested in atoms and atomic nuclei. The flux of the 7-Be solar neutrinos was precisely measured for the first time, which allowed to obtain new information about the neutrino oscillation, mass and mixing angles. The most stringent limit on antineutrino flux from the Sun was set, the flux of neutrino from Earth's mantle (geo-neutrino) was registered with highest accuracy, new limits on the neutrino magnetic moment and heavy sterile neutrino mixing were established. Beta decay of 113-Cd was investigated, alpha activity of natural tungsten and europium, alpha decay of platinum and beta decay of indium to the excited levels of daughter nuclei were discovered.

Number of publications: 2 books, 414 papers, 17 patents. The publications were cited 5915 (2718)times in Scopus, h-index = 46 (27) (without self citations of all authors).