New results from the DANSS experiment

Abstract

The DANSS experiment collected 5.5 million Inverse Beta Decay (IBD) events during 5 years of operation. Data were collected at 3 distances (10.9 m, 11.9 m, and 12.9 m) from the center of the core of the industrial 3.1 GW reactor. The IBD event rate exceeds 5000/day at the smallest distance. The detector position was changed usually 3 times a week. Therefore in the analysis that uses information only about relative IBD counting rates and changes in positron energy spectra shapes many systematic uncertainties were canceled out. No statistically significant evidence for sterile neutrinos is found. The significance of the best-fit point in the 4ν case is only 1.3σ . The excluded area covers a very interesting range of the sterile neutrino parameters up to sin 2 2θ ee < 0.008 in the most sensitive region. The IBD rate dependence on the fission fraction of 239 Pu was measured. It agrees with predictions of the Huber-Mueller model. The reactor power was measured during more than 4 years with ≈ 2% accuracy in 2 days using the rate of neutrino events normalized to the thermal power at the initial period. *** The European Physical Society Conference on High Energy Physics (EPS-HEP2021), *** ** 26-30 July 2021 *** ** Online conference, jointly organized by Universität Hamburg and the research center DESY *** * Speaker.

Status of the search for light sterile neutrinos at short baselines

“…The DANSS [13,14], NEOS [11,15], STEREO [16,17], and PROSPECT [18] experiments published oscillation results that exclude large portions of the RAA region and its best fit (sin(2 ee ) = 0.14, Δ 2 41 = 2.4 eV 2 ) at > 90 % CL, while Neutrino-4 alone claims the observation of a Δ 2 41 ∼ 10 eV 2 oscillation [19]. Figure 1 shows allowed contours from the RAA and Neutrino-4, as well as exclusion contours from the short baseline reactor neutrino experiments described in this work, together with the contribution from tritium neutrino experiments such as KATRIN [20].…”

The Physics of Light Relics

“…These experiments range in energies from MeV to TeV and have baselines from meters to the diameter of the Earth as shown in Figure 9. At the lowest energies they search for electron-neutrino disappearance using reactor neutrinos [219][220][221][222][223][224][225][226][227][228][229][230][231][232][233][234][235][236], at the intermediate energy ranges O (1 GeV) they use pion decay-in-flight beams [237][238][239][240][241][242][243][244][245],…”

Sterile neutrino from D-brane models

“…The DANSS [18,19], NEOS [20,21], STEREO [22,23], PROSPECT [24] oscillation experiments suggest sin 2 θ 41 = 2.4 eV 2 at > 90 % CL.…”