M. Shirchenko

Gemma experiment: The results of neutrino magnetic moment search

The result of the neutrino magnetic moment (NMM) measurement at the Kalinin Nuclear Power Plant (KNPP) with GEMMA spectrometer is presented. The antineutrino-electron scattering is investigated. A high-purity germanium (HPGe) detector with a mass of 1.5 kg placed at a distance of 13.9 m from the 3 GWth reactor core is exposed to the antineutrino flux of 2.7 × 1013 cm−2s−1. The recoil electron spectra taken in 18134 and 4487 h for the reactor ON and OFF periods are compared. The upper limit for the NMM μν < 2.9 × 10−11 μB at 90% C.L. is derived from the data processing.

Gemma experiment: Three years of the search for the neutrino magnetic moment

The result of the 3-year neutrino magnetic moment measurement at the Kalinin Nuclear Power Plant (KNPP) with the GEMMA spectrometer is presented. Antineutrino-electron scattering is investigated. A high-purity germanium detector of 1.5 kg placed at a distance of 13.9 m from the 3 GWth reactor core is exposed to the antineutrino flux of 2.7 × 1013 cm−2 s−1. The scattered electron spectra taken in (5184 + 6798) and (1853 + 1021) h for the reactor ON and OFF periods are compared. The upper limit for the neutrino magnetic moment μv < 3.2 × 10−11μ B at 90% CL is derived from the data processing.

First result for the neutrino magnetic moment from measurements with the GEMMA spectrometer

AbstractThe first result obtained in the measurements of the neutrino magnetic moment at the Kalinin nuclear power plant with the GEMMA spectrometer is presented. A high-purity germanium detector of mass 1.5 kg placed at a distance of 13.9 m from the reactor core is used in the spectrometer. The antineutrino flux at the detector position is 2.73 × 1013

Search for sterile neutrinos at the DANSS experiment

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DANSS Neutrino Spectrometer: Detector Calibration, Response Stability, and Light Yield

/(cm2 s). The differential method is used to select events of electromagnetic antineutrino-electron scattering. The spectra taken in the reactor-on and reactor-off modes over 6200 and 2064 h, respectively, are compared. On the basis of a data analysis, an upper limit of 5.8 × 10−11 μB was set on the neutrino magnetic moment μν at a 90% C.L.

Muon capture in 40Ar. Muon life‐time and isotope yields.

The DANSS project is aimed at creating a relatively compact neutrino spectrometer which does not contain any flammable or other dangerous liquids and may therefore be located very close to the core of an industrial power reactor. As a result, it is expected that high neutrino flux would provide about 15,000 IBD interactions per day in the detector with a sensitive volume of 1 m3. High segmentation of the plastic scintillator will allow to suppress a background down to a ~1% level. Numerous tests performed with a simplified pilot prototype DANSSino under a 3 GWth reactor of the Kalinin NPP have demonstrated operability of the chosen design. The DANSS detector surrounded with a composite shield is movable by means of a special lifting gear, varying the distance to the reactor core in a range from 10 m to 12 m. Due to this feature, it could be used not only for the reactor monitoring, but also for fundamental research including short-range neutrino oscillations to the sterile state. Supposing one-year measurement, the sensitivity to the oscillation parameters is expected to reach a level of sin2(2θnew) ~ 5 × 10−3 with Δ m2 ⊂ (0.02–5.0) eV2.

Detector of the reactor AntiNeutrino based on Solid-state plastic Scintillator (DANSS). Status and first results.

Abstract DANSS is a highly segmented 1 m3 plastic scintillator detector. Its 2500 one meter long scintillator strips have a Gd-loaded reflective cover. The DANSS detector is placed under an industrial 3.1 G W th reactor of the Kalinin Nuclear 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 ν ˜ e per day at the closest position with the cosmic background less than 3%. The inverse beta decay process is used to detect ν ˜ e . Sterile neutrinos are searched for assuming the 4ν model (3 active and 1 sterile ν). The exclusion area in the Δ m 14 2 , sin 2 u2061 2 θ 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 ν ˜ e spectrum, as well as on the detector efficiency. Results are based on 966 thousand antineutrino events collected at three different distances from the reactor core. The excluded area covers a wide range of the sterile neutrino parameters up to sin 2 u2061 2 θ 14 0.01 in the most sensitive region.

Measurements of the Reactor Antineutrino with Solid State Scintillation Detector

The results of the research in the field of neutrino physics obtained at Kalinin nuclear power plant during 15 years are presented. The investigations were performed in two directions. The first one includes GEMMA I and GEMMA II experiments for the search of the neutrino magnetic moment, where the best result in the world on the value of the upper limit of this quantity was obtained. The second direction is tied with the measurements by a solid scintillator detector DANSS designed for remote on-line diagnostics of nuclear reactor parameters and search for short range neutrino oscillations. DANSS is now installed at the Kalinin Nuclear Power Plant under the 4-th unit on a movable platform. Measurements of the antineutrino flux demonstrated that the detector is capable to reflect the reactor thermal power with an accuracy of about 1.5% in one day. Investigations of the neutrino flux and their energy spectrum at different distances allowed to study a large fraction of a sterile neutrino parameter space indicated by recent experiments and perform the reanalysis of the reactor neutrino fluxes. Status of the short range oscillation experiment is presented together with some preliminary results based on about 170 days of active data taking during the first year of operation.