ИСТИНА

We discuss a new experiment based on the proposal [1] to observe for the first time the coherent elastic neutrino-atom scattering (CEνAS), using electron antineutrinos from tritium decay and a liquid He-4 target, and also to search neutrino electromagnetic properties [2], including the neutrino magnetic moment. The experiment is under preparation within the research program of the National Centre for Physics and Mathematics (NCPM) and the Branch of Lomonosov Moscow State University in Sarov (Russia). In CEνAS the neutrino scatters with the whole atom and the atomic electrons tend to screen the weak charge of the atomic nucleus as seen by the neutrino probe. With tritium neutrinos the interference between the He-4 nucleus and the electron cloud of the He atom produces a sharp dip in the recoil spectrum at atomic recoil energies of about 9 meV, reducing sizably the number of expected events with respect to the coherent elastic neutrino-nucleus scattering case. A low-background neutrino laboratory is being created at the NCPM with a record high-intensity tritium source of 10 MCi (1 kg) [3-5] and a 1-m liquid He-4 detector operating at temperatures as low as few tens of mK. With the estimated sensitivity of this apparatus, it is possible to detect CEνAS for the first time and also to observe or to set an upper limit on the electron neutrino magnetic moment μν on the level of few×10 at 90% C.L. It is possible that the intensity of the tritium source can be increased up to 40 MCi (4 kg). We also develop a 4-kg Si detector operating at temperatures of few tens of mK and having the energy threshold as low as ∼10 eV or even ∼1 eV due to the Neganov-Trofimov-Luke effect. This detector will allow us to test the neutrino magnetic moment of the order of 10 by measuring elastic neutrino-electron scattering [4]. References [1] M. Cadeddu, F. Dordei, C. Giunti, K. Kouzakov, E. Picciau, and A. Studenikin, Phys. Rev. D 100, 073014 (2019), arXiv:1907.03302 [hep-ph]. [2] C. Giunti and A. Studenikin, Rev. Mod. Phys. 87, 531 (2015), arXiv:1403.6344 [hep-ph]. [3] V. N. Trofimov, B. S. Neganov, and A. A. Yukhimchuk. Phys. Atom. Nuc. 61, 1271 (1998). [4] B. S. Neganov et al., Phys. Atom. Nuc. 64, 1948 (2001). [5] V. P. Martemyanov et al., Fusion Sci. Technol. 67, 535 (2015).