Astroparticle physics experiments in the Baksan Neutrino Observatory V.B. Petkov Institute for Nuclear Research of RAS, Baksan Neutrino Observatory 50th anniversary of the Baksan Neutrino Observatory

50th anniversary of the Baksan Neutrino Observatory Baksan Neutrino Observatory of INR RAS: unique complex of surface and underground experimental facilities “Andyrchy EAS array” “Carpet-2”→ “Carpet-3” EAS array BUST Tunnel entrance 50th anniversary of the Baksan Neutrino Observatory

Neutrino physics and astrophysics Baksan Underground Scintillation Telescope (BUST) EAS array “Carpet” → “Carpet-2” → “Carpet-3” EAS array “Andyrchy” Cosmic-ray physics 1. Galactic cosmic rays: (1013 – 1017) eV – spectrum, composition, anisotropy, “knee” in the spectrum at ~ (2–5) ×1015 eV. 2. Variations of CR intensity, including variations of atmospheric origin (temperature, thunderstorms, etc) 3. High energy muons: interactions, energy spectrum, muon groups. Gamma-astronomy 1. Search for point sources and diffuse radiation for Eγ > 100 TeV. 2. Search for cosmic gamma-ray bursts: 1 GeV – 100 TeV. 3. Experimental search for evaporating primordial black holes. Neutrino physics and astrophysics 1. Search for neutrino bursts from supernovae (best limit on the mean frequency of collapses in the MW: 0.074 year-1) 2. Search for neutrinos coincident with gamma-ray bursts and gravitational wave events 3. Search for point sources of muon neutrinos with Eν > 1 GeV. 50th anniversary of the Baksan Neutrino Observatory

Baksan Underground Scintillation Telescope (BUST) 1977 - ... Stable scintillator, stable telescope work 3180 scintillation counters 17 m 17 m 11 m Threshold for coordinate measurements: inner planes – 8 MeV outer planes –10 MeV 50th anniversary of the Baksan Neutrino Observatory

50th anniversary of the Baksan Neutrino Observatory Андырчи Total count rate of detectors : 11390 с-1 50th anniversary of the Baksan Neutrino Observatory

EAS array “Carpet” → “Carpet-2” Muon detector: 175 m2 (175 plastic scintillation counters) 50th anniversary of the Baksan Neutrino Observatory

“Carpet-2”: Limits on the diffuse flux of cosmic gamma rays 50th anniversary of the Baksan Neutrino Observatory

→ “Carpet-3” Muon detector: 410 m2 (410 plastic scintillation counters) ~ 20 additional surface units, ~ 9 m2 50th anniversary of the Baksan Neutrino Observatory

50th anniversary of the Baksan Neutrino Observatory “Carpet-3”: search for diffuse cosmic gamma rays of energy Eγ > 100 TeV 50th anniversary of the Baksan Neutrino Observatory

(θ, φ) - direction of arrival BUST: muon groups nμ – the number of muons m – the number of tracks Relatively large size of individual detector → The saturation of the number of trajectories: m ≤ nμ 50th anniversary of the Baksan Neutrino Observatory

Integral muon number spectrum T = 9.8 years θ ≤ 20° X = 1015.6 hg/cm2 Eμ_th ≈ 230 GeV m N(≥m) 100 295 120 166 140 88 170 49 200 30 250 10 50th anniversary of the Baksan Neutrino Observatory

Saturation: m ≤ nμ m = 170 → nμ / m = 1.5 50th anniversary of the Baksan Neutrino Observatory

Integral muon number spectrum: sensitivity to the primary composition Ek(Z) = Ek(p)*Z Ek(p) = 2.0*1015 eV 50th anniversary of the Baksan Neutrino Observatory

50th anniversary of the Baksan Neutrino Observatory Integral muon number spectrum: m = 1 – 170 corresponds to primary energy range ~ (1012 – 1016) eV → connection between direct measurements and EAS experiments Ek(Z) = Ek(p)*Z Ek(p) = 2.0*1015 eV 50th anniversary of the Baksan Neutrino Observatory

50th anniversary of the Baksan Neutrino Observatory Спектр мощностей ШАЛ sec(θ) ≤ 1.05, Tlive = 1.297·108 s (≈1501.2 days), lg Nk ≈ 6.35 50th anniversary of the Baksan Neutrino Observatory

50th anniversary of the Baksan Neutrino Observatory <Nμ> (Nrp) dependence sec(θ) ≤ 1.05, 1996 – 2003, 5.75 ≤ lg Nr.p. ≤ 7.6 Tlive = 9.773·107 s (≈1131.1 days) 50th anniversary of the Baksan Neutrino Observatory

Experimental search for evaporating primordial black holes Primordial black holes (PBHs) can be formed in the early Universe through the gravitational collapse of primordial cosmological density fluctuations. Theoretical predictions of the PBH formation probability depend strongly on the theory of gravitation and the model of gravitational collapse used. The evaporation of black holes has not been completely studied to date (there are many theoretical models of the evaporation process). PBHs might arguably be the most natural candidates to solve the dark matter problem (they are cold, weakly-interacting, and do not require extensions of the Standard Model of particle physics.) → Therefore, experimental detection of PBHs could provide a unique probe of the early Universe, gravitational collapse, high energy physics and quantum gravity. The nondetection of PBHs at the current level of the experimental technique may place interesting constraints on the physics relevant to these areas. 50th anniversary of the Baksan Neutrino Observatory

At the final PBH evaporation stage the high-energy gamma-ray bursts are generated. Burst duration tb: the time left until the end of PBH evaporation during which 99% of the photons that can be detected at given threshold (or by a given array) Different technique of experimental searching for non-chromospheric and chromospheric models: non-chromospheric - searching for temporal and directional concentrations of EAS (EAS detection by EAS arrays and Cherenkov telescopes); chromospheric- searching for the spikes in the total count rate of (EAS arrays working in single particle operation mode). Until now - search for chromospheric models at Andyrchy and Carpet-3 EAS arrays only. Burst duration versus threshold photon energy: 1 - MW90, 2 - DK02, 3 - H97. 50th anniversary of the Baksan Neutrino Observatory

MW90 model: the upper limits on the number density of evaporating PBHs vs. Eγ J.H. MacGibbon and B.R. Webber, "Quark- and gluon-jet emission from primordial black holes: The instantaneous spectra", Phys. Rev. D 41, 3052, 1990. local region of the Galaxy: Rmax = 0.064 pc for the H.E.S.S. array 50th anniversary of the Baksan Neutrino Observatory

Astroparticle physics experiments in the BNO: Prospects (1). Cosmic ray origin and gamma-astronomy. Study of spectrum and composition of primary cosmic rays in the energy range (1012 – 1016) eV at the BUST, “Carpet-3”, “Andyrchy” and (BUST + “Andyrchy”). Study of spectrum and composition of primary cosmic rays in the energy range (1016 - 1018) eV by means of simultaneous EAS registration at the complex of facilities (BUST + “Andyrchy” + “Carpet-3”). Search for diffuse cosmic gamma rays of energy Eγ > 100 TeV Search for (Galactic) sources of VHE gamma-rays 50th anniversary of the Baksan Neutrino Observatory

Astroparticle physics experiments in the BNO: Prospects (2). Multi-messenger astronomy. Run-time search for optical counterparts of the high energy events from astrophysical objects (BNO facilities and optical telescopes of peak Terskol observatory, SAO, ….) Run-time search for optical counterparts of the high energy (Eν ≥ 1 GeV) muon neutrinos (BUST + MASTER telescopes in the south hemisphere + ….) 50th anniversary of the Baksan Neutrino Observatory

Astroparticle physics experiments in the BNO: Prospects (3). Low energy neutrino astrophysics (neutrino from core-collapse supernovae, diffuse supernova neutrino background, Solar neutrinos etc.) and geophysics The search for neutrino bursts from core-collapse supernovae (ccSN) with the Baksan Underground Scintillation Telescope. Low-energy neutrino astrophysics and geophysics with large volume scintillation detector at BNO. At present a complex of research and development aimed at the creation of a new-generation geoneutrino detector using an extra-pure scintillator of 10 – 20 kiloton mass is performed. 50th anniversary of the Baksan Neutrino Observatory

50th anniversary of the Baksan Neutrino Observatory Underground Laboratories of the BNO INR RAS Entrance BUST’s hall Low Bkg Lab2 + Laser Interferom. 620 m – 1000 m w.e. Low Bkg Lab1 «НИКА» Low Bkg Lab3 «DULB-4900» GeoPhys Lab1 OGRAN’s hall GeoPhys Lab2 4000 m GGNT’s hall BLVSD Baksan Large Volume Scintillation Detector: ~ 10 – 20 kt 4900 m.v.e., ~ 1 muon/(m2∙10 h) 50th anniversary of the Baksan Neutrino Observatory