Experimental evidence of giant electron–gamma bursts generated by extensive atmospheric showers in thunderclouds
Introduction
A new physical concept of an avalanche type increase of a number of relativistic electrons in gas under the action of the electric field was proposed by Gurevich et al. [1]. The avalanche can grow in electric field E⩾Ec. The field Ec is almost an order of magnitude less than the threshold electric field of conventional breakdown Eth. The growth of number of electrons with energies ε>εc≈0.1–1 MeV is determined by the fact that under the action of electric field E>Ec fast electrons could become runaways, what means that they are accelerated by electric field E as suggested by Wilson [2]. Due to collisions with gas molecules they can generate not only large number of slow thermal electrons, but the new fast electrons having energies ε>εc as well. Directly this process—acceleration and collisions lead to the avalanche type growth of the number of runaway and thermal electrons, which was called in [1] “runaway breakdown” (RB). The detailed kinetic theory of RB was developed in [3], [4], [5], [6], [7], [8].
In atmosphere, the critical field Ec is 100–150 kV/m and exactly these values of electric field are often observed during thunderstorms [9], [10]. When the electric field in thunderstorm cloud reaches the critical value E⩾Ec every cosmic ray secondary electron (its energy ε>1 MeV) initiates a micro runaway breakdown. It serves as a source of intensive ionization of air and manifests itself in a strong amplification of X- and γ-rays emission in thundercloud [1], [11], [12]. This emission was observed at airplanes [13], baloons [14], and in the mountain experiments [15], [16], [17], [18], [19].
Extensive atmospheric showers (EAS) are generated by a high energy ε cosmic ray particles. EAS are accompanied by a very strong local growth of cosmic ray secondaries number and γ-emission in a high energy range ε∼10–100 MeV. This flux interacts effectively with thundercloud electric field if runaway breakdown conditions are fulfilled (RB–EAS interaction) [35]. The energy obtained by fast electrons from thundercloud electric field due to the RB–EAS combined effect can serve for the explosive generation of a very large number of a newborn electrons and gamma quanta (see accompanying theoretical paper [20]).
The experimental study at the Tien Shan Mountain Scientific Station of this phenomena is our goal.
At the station a special system of gamma-spectrometers exist for “thunderstorm” measurements. It is based on the Geiger–Muller counters SI5G and NaJ detectors. The system permit to measure intensity of electrons, X and gamma quanta in wide energy range. A detailed description of “thunderstorm” detector complex can be found in [15], [18].
For the present work a special air shower trigger array was created. The array system has to fix the EAS coming on an extensive region with high accuracy. The system consists of a set of shower electrons and γ-quanta detectors (based on proportional Geiger–Muller counters) widely spread over Tien Shan Station territory.
The RB–EAS combined action lead to a strong radio pulses emitted from thundercloud [21]. A specially constructed radio installation was used to study the short electromagnetic pulses of this radio emission [22]. The installation allows to determine pulse form, its maximal intensity and arrival direction (inclination and azimuth angles). The moments of EAS coming is fixed by piping the trigger signal from shower array to the radio installation. That allows to study the EAS and radio emission simultaneously.
The results of measurements are presented. More then 150 simultaneous EAS-radio events are observed. The analysis of the obtained experimental data allows to establish the existence of a new phenomena—giant electron–gamma bursts generated in thunderclouds.
Section snippets
The cosmic showers trigger array
The cosmic showers trigger array has to fix coming EAS and inform about it radio installation piping there trigger signal. The array is fixed around Tien Shan Mountain Scientific Station situated 3340 m high above see level (43°02′N, 76°56′E)
Receiving antennas
Radio measurements were carried out using specially designed installation (analogous to described in [22]) for short electromagnetic pulse observations in the frequency range from 0.1 to 30 MHz. This installation contains three spaced receiving antennas connected to the receiving apparatus (central unit). It allows signal arrival angle determination using correlation technique as well as waveform recording with high temporal resolution (16 ns).
Each receiving antenna of the installation (antenna
Quiet time
Observations were carried out from July 19 till October 09, 2003 almost continuously. The radio receiving system was triggered by the EAS facility. Recording time was slightly above 100 μs with 83.2 μs pre-history. Data sampling rate of 60 MHz was used. Short radio pulses with few hundred nanosecond length correspondent to EAS's were searched. Wide band radio interferometer in frequency range 0.1–30 MHz was used in our experiment. The electromagnetic noise in this frequency range is always
I. Radio pulses
RB–EAS combined action. The process which is called RB–EAS combined action take place when high energy cosmic ray particle cross the thundercloud. The thundercloud is supposed to be in RB state, what means that the maximal electric field in thundercloud is close to Ec: Em∼1.0–1.4Ec. Exactly these values of maximal electric field are observed in thundercloud at balloon experiments [9], [34]. Large scale thundercloud electric field is directed close to vertical z [10].
The secondary electrons of
Conclusions
In conclusion we formulate briefly main results of the experiments described in the paper:
- (1)
At Tien Shan Mountain Scientific Station a new EAS-radio installation is constructed. The installation consists of a wide spread EAS trigger array and a high time resolution radio interferometer what allows to study the EAS and radio pulses emission simultaneously.
- (2)
The absence of simultaneous EAS and radio pulses in a quiet (non-thunderstorm) atmosphere is established.
- (3)
During two thunderstorms 150
Acknowledgements
The authors are grateful to Prof. V.L. Ginzburg, Prof. E.L. Feinberg and Dr. H. Carlson for useful discussions. The work was supported by EOARD-ISTC grant No. 2236, ISTC grant No. 1480, by the President of Russian Federation Grant for Leading Scientific Schools Support and by the Russian Academy Fundamental Research Program “Atmosphere Physics: Electric Processes, Radio Physics Methods”.
References (35)
- et al.
Phys. Lett. A
(1992) Phys. Lett. A
(1998)- et al.
Phys. Lett. A
(2004) Phys. Lett. A
(2001)Phys. Lett. A
(2000)Phys. Lett. A
(2002)Phys. Lett. A
(2003)Phys. Lett. A
(2002)Phys. Lett. A
(2003)- et al.
Phys. Lett. A
(1999)
Proc. Cambridge Philos. Soc.
Phys. Rev. E
Geophys. Res. Lett.
Phys. Lett. A
Phys. Usp.
J. Geophys. Res.
The Electrical Nature of the Storms
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