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تسجيل مستخدم جديدRecent results of the DANSS experiment
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Mikhail Danilov
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We present new results of the DANSS experiment on the searches for sterile neutrinos. They are based on 2.1 million of inverse beta decay events collected at 10.7, 11.7 and 12.7 meters from the reactor core of the 3.1 GW Kalinin Nuclear Power Plant in Russia. This data sample is 2.5 times larger than the data sample in the previous DANSS publication. The search for the sterile neutrinos is performed using the ratio of $bar u_e$ spectra at two distances. This method is very robust against systematic uncertainties in the $bar u_e$ spectrum and the detector efficiency. We do not see any statistically significant sign for the $bar u_e$ oscillations. This allows us to exclude further a large and interesting part of the sterile neutrino parameter space. All results are preliminary.
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Power Plant 350~km NW from Moscow. The distance to the core is varied on-line from 10.7~m to 12.7~m. The reactor building provides about 50~m water-equivalent shielding against the cosmic background. DANSS detects almost 5000 $widetilde u_e$ per day at the closest position with the cosmic background less than 3$%$. The inverse beta decay process is used to detect $widetilde u_e$. Sterile neutrinos are searched for assuming the $4 u$ model (3 active and 1 sterile $ u$). The exclusion area in the $Delta m_{14}^2,sin^22theta_{14}$ plane is obtained using a ratio of positron energy spectra collected at different distances. Therefore results do not depend on the shape and normalization of the reactor $widetilde u_e$ spectrum, as well as on the detector efficiency. Results are based on 966 thousand antineutrino events collected at 3 distances from the reactor core. The excluded area covers a wide range of the sterile neutrino parameters up to $sin^22theta_{14}<0.01$ in the most sensitive region.
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