Sterile neutrino and dark matter

We consider the equation that describes the dynamics of the sterile neutrino density in primeval plasma. The analysis of this equation results in the 5% contribution of the sterile neutrino with mixing parameters $\Delta m^2_{14} = 7.3\text{eV}^2$ and $\sin^2 2\theta_{14} = 0.33$ to the energy density of the Universe. The considered parameters of the sterile neutrino correspond to the warm dark matter.Comment: 7 pages, 11 figure

Project of NNbar Experiment at the WWR-M Reactor

Supersource of ultracold neutrons on the basis of superfluid helium is under construction in PNPI NRC KI. It must provide UCN density 2-3 orders of magnitude higher than existing sources. For the new source we propose an experiment on search for neutron–antineutron oscillations based on the storage of ultracold neutrons in a material trap. The sensitivity of the experiment mostly depends on the trap size and the amount of UCN in it. The results of simulations of the designed experimental scheme show that the sensitivity can be increased by ∼ 10–40 times compared to sensitivity of previous experiment depending on the model of neutron reflection from walls