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I. Angelov, E. Malamova, J. Stamenov INRNE – BAS, SWU “N. Rilski”

Muon Telescopes at Basic Environmental Observatory Moussala and South-West University - Blagoevgrad. I. Angelov, E. Malamova, J. Stamenov INRNE – BAS, SWU “N. Rilski”. Presenter : I. Angelov. Observation sites. Institute for Nuclear Research and Nuclear Energy, BAS

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I. Angelov, E. Malamova, J. Stamenov INRNE – BAS, SWU “N. Rilski”

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  1. Muon Telescopes at Basic Environmental Observatory Moussala and South-West University - Blagoevgrad I. Angelov, E. Malamova, J. Stamenov INRNE – BAS, SWU “N. Rilski” Presenter : I. Angelov

  2. Observation sites Institute for Nuclear Research and Nuclear Energy, BAS Basic Environmental Observatory – Moussala 42°11’N , 23° 35’E , 2925 m a.s.l. South West University “N. Rilski” Blagoevgrad Department of Physics 42°01’N , 23° 06’E , 383 m a.s.l.

  3. 1) Description of the instruments. 2) Main characteristics of the telescopes. 3) Examples of experimental data. Summary Future plans. Outline

  4. Detectors setup Both telescopes use water cherenkov detectors Blagoevgrad – 2.25 m2 , 3x3 configuration, 1.5 m between detectors planes Moussala – 1 m2 , 2x2configuration, 1m between detectors planes

  5. Detectors setup • Mirror container 50x50x12.5 cm • 10 cm distilled water as radiator • 2.5” , 12 dynodes photomultiplier FEU-110, FEU-139 • PMT in single electron counting • 300 Ohm anode load • 90 MHz bandwidth amplifier with gain x50 • discriminator threshold 15 – 50 mV • 60 ns ( 45 ns ) TTL pulses formed

  6. Coincidence circuits and data acquisition system

  7. Detectors adjustment • Detectors adjustment : • plateau in the counting characteristics • fixed thresholds are selected – 28 mV for Moussala • – 22 mV for Blagoevgrad • optimal HV is chosen for each detector Dependance of the count rate – vertical coincidences on the HV for the four pairs of detectors of the telescope at BEO

  8. Angular directions and count rates SWU telescope count rates => BEO telescope count rates =>

  9. Energy thresholds and response to primary protons • BEO telescope : • 40 cm concrete above the detectors; 5 cm Pb ; • ~ 0.45 GeV energy threshold for CR muons the MMC (Muon propagation Monte Carlo) software was used for calculation (Chirkin and Rhode, 2004, 2005) • SWU telescope : • 160 cm concrete above the detectors; 5 cm Pb ; • ~ 1 GeV energy threshold for CR muons Count rate  580 min-1 - Moussala telescope 2925 m a.s.l. , Rc=6.3 Gv, corresponds to I0 0.0188 cm-2s-1ster-1 BESS spectrometer at mount Norikura – 2770 m a.s.l. , Rc=11.2 GV. (Sanuki et al., 2003) kinetic energies ~ 0.48 – 106 GeV I0 0.0105 cm-2s-1ster-1

  10. Energy thresholds and response to primary protons Results from simulations with PLANETOCOSMICS code Response to primary protons generated muons – BEO telescope 90% of the counted muons generated from protons with energies above 10 GeV Rc6.24 GV Response to primary protons generated muons – SWU telescope 90% of the counted muons generated from protons with energies above 15-20 GeV Rc6.34 GV

  11. Meteorological corrections Barometric effect for CR muons SWU muon telescope = -0.1245 / % hPa Barometric effect for CR muons BEO muon telescope = -0.2845% / hPa

  12. Forbush decrease October – November 2003, SWU telescope FD in october – november 2003 (HALLOWEEN SPACE WEATHER STORMS OF 2003) <= SWU telescope, pressure corrected 1h data. <= Athens NM data

  13. Forbush decrease December 2006, BEO telescope FD in December 2006 (after the GLE of 13 December) <= BEO telescope, pressure corrected 1h data. <= Athens NM data

  14. Summary • Two operational muon telescopes in BG ( Rc6.3 GV ) • at ~380 m. a.s.l., 2.25m2 detectors , 1 GeV energy threshold, 0.45% statistical error for 1h intervals (after reconstruction since November 2007) • at ~2925 m. a.s.l., 1m2 detectors, 0.45 GeV energy threshold, 0.27% statistical error for 1h intervals, (since August 2006) • Detectors of original construction, easy to build and cost effective.

  15. Future plans • Coincidence circuits and counters controller upgrade, • using FPGA - all combinations of UP and Down detectors • A possibility to upgrade to higher number of detectors at South West University exists – enough room space ;

  16. The BEO muon telescope was constructed and funded as a part of the FP6 BEOBAL project - BEO Centre of Excellence Research Capacity Improvement for Sustainable Environment and Advanced Integration into ERA. Thanks for the attention ! Questions, comments and ideas are WELCOME.

  17. Basic references Hamamatsu Photonics K. K. Photon counting using photomultiplier tubes, 2005 http://sales.hamamatsu.com/assets/applications/ETD/PhotonCounting_TPHO9001E04.pdf Chirkin D., Rhode W., All Lepton Propagation Monte Carlo, Proceedings of the 29th ICRC, Pune, 2005, http://icrc2005.tifr.res.in/htm/Vol-Web/Vol-19/19093-usa-chirkin-D-abs2-he21-poster.pdf Chirkin D., Rhode W., Muon Monte Carlo: a high-precision tool for muon propagation through matter, 2004, http://arxiv.org/PS_cache/hep-ph/pdf/0407/0407075v1.pdf Sanuki T., Fujikawa M., Abe K. et al, Measurements of atmospheric muon spectra at mountain altitude, 2003,http://arxiv.org/PS_cache/astro-ph/pdf/0205/0205427v3.pdf Desorgher L., PLANETOCOSMICS Software User Manual, 2005,

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