Search

The low energy electron spectrum from the α-decay of 225Ac has been measured with 20 eV instrumental resolution using an electrostatic spectrometer and radioactive sources prepared by vacuum evaporation. The predicted 10.642(5) keV M1 + < 0.05% E2 nuclear transition in 221Fr have been revealed. Energies of 26.015(5), 36.660(5), 38.543(3) and 108.37(1) keV nuclear transitions in 221Fr have been essentially improved. Relative intensities of the measured conversion electron lines of these transitions have also been determined.

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.

The ν GeN is new experiment at the Kalinin Nuclear Power Plant (KNPP) for detection of coherent Neutrino–Ge Nucleus elastic scattering. Recent neutrino and Dark Matter search experiments have revolutionized the detection of rear events, and rear events with low energies, in particular. Experiments have achieved sensitivities on the level of several events per hundred kg of detector material per day with energy thresholds from few hundred eV. This opens up a new unique possibility for experimental detection of neutrino-nucleus coherent scattering that has been considered to be impossible so far. The νGeN project uses low threshold high-purity Ge-detectors (HPGe) developed by JINR (Dubna, Russia) in collaboration with BSI (Baltic Scientific Instruments, Riga, Latvia) for creation of a setup designated for first observation of neutrino coherent scattering on Ge. As a powerful neutrino source the experiment will use electron antineutrinos from one of the power-generating units (reactor unit #3) of the KNPP. The coherent neutrino scattering will be observed using a differential method that compares 1) the spectra measured at the reactor operation and shut-down periods; 2) the spectra measured at different distances from the reactor core during the reactor operation. For a setup placed at a 10 m distance from the center of reactor core and with an energy threshold of 350 eV up to tens of events corresponding to neutrino coherent scattering on Ge are expected to be detected per day in the constructed setup with four HPGe low-energy-threshold detectors (~ 400 grams each). The setup sensitivity will be even more increased by using new detectors with total mass up to 5 kg.