1. 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

2. 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

3. 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: 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

4. Baksan Underground Scintillation Telescope (BUST)
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

5. 50th anniversary of the Baksan Neutrino Observatory
Андырчи
Total count rate of detectors : с-1
50th anniversary of the Baksan Neutrino Observatory

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

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

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

9. 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

10. (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

11. Integral muon number spectrum
T = 9.8 years
θ ≤ 20°
X = hg/cm2
Eμ_th ≈ 230 GeV
m N(≥m)
50th anniversary of the Baksan Neutrino Observatory

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

13. 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

14. 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

15. 50th anniversary of the Baksan Neutrino Observatory
Спектр мощностей ШАЛ sec(θ) ≤ 1.05, Tlive = 1.297·108 s (≈ days), lg Nk ≈ 6.35
50th anniversary of the Baksan Neutrino Observatory

16. 50th anniversary of the Baksan Neutrino Observatory
<Nμ> (Nrp) dependence sec(θ) ≤ 1.05, – 2003, 5.75 ≤ lg Nr.p. ≤ 7.6 Tlive = 9.773·107 s (≈ days)
50th anniversary of the Baksan Neutrino Observatory

17. 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

18. 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

19. 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 = pc
for the H.E.S.S. array
50th anniversary of the Baksan Neutrino Observatory

20. 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 ( ) 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

21. 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

22. 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

23. 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