press release #10
Aragats Physicists Measure Energy Spectra of the Runaway electrons _ an important step to solve enigma of the Thunderstorms.
A. Chilingarian, A.Daryan, L.Melkumyan
The cosmic rays ionize enough of the atmosphere to be questioned as possible triggers of the thunderstorms. A mechanism proposed by A. Gurevich and his collaborators suggests that showers of energetic particles produced by high-energy cosmic rays in the terrestrial atmosphere might provide a conductive path that initiates lightning. Because cosmic-ray air showers do not produce enough particles for the electrical discharge by themselves, Gurevich postulated that the thunderstorm gave the cosmic-ray shower a boost by increasing the number of energetic electrons through an exotic process called "runaway breakdown." The Monte Carlo transport calculations of the cosmic-ray muons and associated particles (e.g. knock-on electrons and bremsstrahlung photons) in thunderstorm electric fields, using GEANT4 code indicate that the production of energetic electrons by cosmic ray muons plays an important role in the enhancement of electron and photon fluxes in the thunderstorm electric fields. The Aragats Space Environment Center (ASEC) facilities allow measurements of the charged particles energy from 7 up to 120 MeV. In 2008 we detected short count rate enhancements of the low energy charged component of secondary cosmic rays. In 2009 using unique possibility of the Aragats Solar Neutron Telescope (ASNT, Chilingarian et al., 2007) we for the first time measured the energy spectra of the _additional_ particles (so called, runaway electrons) appearing in correlation with thunderstorms.
In the left column are posted the time series (Unite Time = local time _ 4 hours) of the count rates measured by different particle detectors operating at the Aragats Space Environmental Center (ASEC, Chilingarian et al., 2005). In the right top picture we present 3 time series measured by ASNT and corresponding to low energy (7-10 MeV (pink), 10-16 MeV - black, >30 MeV _ blue. The energy spectrum of detected enhancement is posted in the left bottom picture. The energy spectra of enhancement (runaway electrons) fitted rather well by the exponential function in accordance with theory of the multiplication of high-energy electrons in atmosphere. Exponential decrease is in good agreement with Gurevich theory (Gurevich & Zibin, 2001), Baksan group results (Khaerdinov et al., 2005) and simulations, reported in (Torii et al, 2004).
References:
Chilingarian A.A., Arakelyan K.,
Avagyan K., et al. Correlated measurements of secondary cosmic ray
fluxes by the Aragats Space Environmental Center monitors. NIM, A543,
pp. 483-496, 2005.]
Chilingarian A, Melkumyan L., Hovsepyan G., Reymers A.,The response function of the Aragats Solar Neutron Telescope, Nuclear Instruments and Methods in Physics Research , A 574, (255-263), 2007.
Gurevich A. and Zibin K. Runaway breakdown and electrical discharge in
thunderstorms, Success in Physical Science 171, N 11, 1178 – 1199,
2001, in russian.
Torii, T., Nishijima, T., Sugita, T., Kawasaki, Z., Generation of Runaway Electrons Induced by Cosmic-Ray Muons in Thunderstorm Electric Fields. Geophys. Res. Lett., 2004.
N.S. Khaerdinov and A.S. Lidvansky. A strong enhancement of cosmic ray
intensity during thunderstorm: A Case study and implications. 29th
ICRC Pune(2005) 2, 393-396
last 10 press releases:
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- Ground Breaking ceremony of Nuclear Medecine Center, October 30, 2012
- Visit in Dubna, 3-4 May 2012
- National Scientific laboratory after A. I.Alikhanyan young scientist Artyom Hovhanisyan “Haykyan” award-winner.
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- The workshop “Low dimensional physics and gauge principles”
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