HR: 0830h
AN: AE21A-1096    [PDF]
TI: COSMIC RAYS AND RUNAWAY ELECTRONS: EVIDENCE FOR ACCELERATION OF ELECTRONS DURING THUNDERSTORMS
AU: * Lidvansky, A S
EM: lidvansk@sci.lebedev.ru
AF: Institute for Nuclear Research, 60th October Anniversary pr. 7a, Moscow, 117312 Russian Federation
AU: Khaerdinov, N S
EM: khaerdinovs@yandex.ru
AF: Institute for Nuclear Research, 60th October Anniversary pr. 7a, Moscow, 117312 Russian Federation
AU: Petkov, V B
EM: vpetkov@yandex.ru
AF: Institute for Nuclear Research, 60th October Anniversary pr. 7a, Moscow, 117312 Russian Federation
AB: We present the data on correlations of the intensity of the soft component (10 -30 MeV) of cosmic rays with the local electric field of the near-earth atmosphere during thunderstorm periods at the Baksan Valley (North Caucasus, 1700 m a. s. l.). The large-area array for studying the extensive air showers of cosmic rays is used as a particle detector. An electric field meter of the `electric mill' type is mounted on the roof of the building in the center of this array. The data were obtained in the summer seasons of 2000--2002. We have observed strong enhancements of the soft component intensity before some lightning strokes [1]. The largest enhancement detected in the first season demonstrated an exponential growth of intensity before lightning and was interpreted as a confirmation of runaway electron breakdown mechanism [2]. However, this event is apparently very rare (a single event for three seasons of observation). The enhancements of a different pattern (slow events several minutes long) turned out to be much more numerous. Recently, a special experiment was made to estimate the minimum distance to lightning events [3], and the distances were found to be fairly large (2-5 km). At the same time, the analysis of the regression curve `intensity versus field' [4] discovers a bump at the field sign that is opposite to the field sign corresponding to acceleration of electrons (see Fig. 1). It is interpreted as a precipitation of runaway electrons from the region of the strong field (with the opposite sign) overhead. If this interpretation is true, one can conclude from these data that (i) Wilson's runaway electrons do exist, (ii) their energy can be pretty high (more than ten MeV), and (iii) they are not necessarily directly related to lightning events. Fig. 1. Deviation of the soft component intensity from its mean value versus the near-earth electric field during thunderstorms. The left-hand side of the plot corresponds to acceleration of electrons near the ground. The bump in the right-hand side is interpreted as a signature of runaway electrons accelerated and multiplied in the stronger field of opposite sign at the cloud layer. REFERENCES 1. Alexeenko, V.V., Khaerdinov, N.S., Lidvansky, A.S., and Petkov, V.B., Transient Variations of Secondary Cosmic Rays due to Atmospheric Electric Field and Evidence for Pre-Lightning Particle Acceleration, Phys. Lett., A301, 299-306, 2002. 2. Roussel-Dupre, R.A., Gurevich, A.V., Tunnell, T., and Milikh G.M., Kinetic theory of runaway air breakdown, Phys. Rev. E, 49, 2257-2271, 1993. 3. N.S. Khaerdinov, A.S. Lidvansky, V.B. Petkov, Yu.P. Surovetsky, and A.F. Yanin, Estimate of Distance to Lightning Events Associated with Cosmic Ray Enhancements during Thunderstorms, Proc. 28th ICRC, Tsukuba, Japan, July 31- August 7, 2003, 4165-4168. 4. N.S. Khaerdinov, A.S. Lidvansky, V.B. Petkov, and Yu.P. Surovetsky, Effect of the Disturbed Electric Field of the Atmosphere on Cosmic Rays: 1. Soft Component, Proc. 28th ICRC, Tsukuba, Japan, July 31- August 7, 2003, pp. 4169-4172.
DE: 3304 Atmospheric electricity
SC: Atmospheric and Space Electricity [AE]
MN: 2003 Fall Meeting