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Universality of the High Energy Physics in Atmosphere (HEPA): origin of particle fluxes from thunderclouds

and lightning origination A.Chilingarian, Yerevan Physics Institute

South peak of Aragats (3700 m), Kare lake (3200m, already under ice) and ancient (4,000 BC) “Vishape” stone – the owner of water.

MAKET Experimental Hall and MAKET Array (scintillators in the iron boxes)

November 7 morning

NaI network is located under 0.6 mm of iron tilt, energy threshold 200-300 KeV

Electron energy losses in the atmosphere and energy gain from the intracloud electric field:

RB/RREA process

E = 2.83kV/cm (sea level)0,6 = 1.7kV/cm (5000 m asl)

Gurevich et al., (1992), Symbalisty et al. (1998), Babich et al. (1998), Dwyer (2003), Chilingarian (2014)

F = 2,76 keV/cm(sea level threshold)0,6

= 1.66 keV/cm (5000 m asl)

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Cold runaway, fields above 100kV/cm required

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MAKET experimental hall; Aragats station, 3200 m asl

Time-series on different time

scales

Detectors with different thresholds: NaI, STAND1 (100) and STAND3 (1000)

Snow started at 21:00

High-energy particle bursts

NaI network (1,2,3, 6 and7). Energy threshold ~ 200-300 KeV)

STAND1 MAKET upper

STAND1 GAMMA middle

STAND1 MAKET 3 cm thick

STAND1 GAMMA upper

STAND1 SKL 3 cm thick

STAND1 SKL upper

Lightning flashes terminated TGE

Huge TGE of 19 September, 2009 was detected by all ASEC monitors : ASNT (10) – > 5cm (1) and 60 (0)cm thick; ASNT (01) – 5cm (0) and 60 (1)cm thick; ASNT (11) – electrons E>25 MeV - 19 September event is only event with high energy

A. Chilingarian, A.Daryan, K.Arakelyan, et al., Ground-based observations of thunderstorm-correlated fluxes of high-energy electrons, gamma rays, and neutrons, Phys.Rev. D., 82, 043009, 2010

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PureEAS-25eventsperminute;8scint.trigger

EAS+ECS,120events

19Sept.2009

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EAS+ECS-120eventsperminute;8scint.trigger

In situ detection of EAS and ECS at Aragats at fair weather and during the minute of the maximal particle flux (TGE).

Random ECS initiation In strong intracloud electric field from CR seeds

Extensive cloud showers (ECSs) are systematically different from Extensive air showers (EASs). Density spectra of 2 particle showers:

ECS (red, with ~20% EAS contamination) and pure EAS

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1-sec time series of count rate of 3 cm thick plastic scintillator (blue), near surface electric field (black); temperature (~1.3 C°) and dew point (~1.1 C°) used for the spread calculation (red).

Strong lightning flash abruptly terminates TGE on14:13:38. Distance to cloud base 0.2 x 122 m ~ 25 m. Maximal energy of

electrons: 20+20+5 MeV ~ 45 MeV

a) b) c)

d)

Long lasting low energy TGEs: stochastic electric fields in the cloud

• TGE consists of a few minutes long high-energy emission (up to 30-40 MeV) and hours lasting low energy emission (<3MeV). Usually TGE started by high-energy emission;

• Emission is terminated by lightning flash occurred within 10 km from the detector site; • The particle flux can decrease by ~50% (high-energy particles vanish) after flash. Flux can rise again

to be killed by the second or third flash; • If lightning flashes occurred at distances greater than 10 km, TGE can prolong up to 10 minutes and

the shape of bump will be symmetrical; • The distance to the thundercloud base on Aragats is usually 25-150 m measured by “spread” -

difference of the outside temperature and the dew point; • NaI crystals located on the first floor and in the underground tunnel demonstrate much weaker

enhancement of the flux compared with the NaI network located on the roof of building under 0.6 mm of iron tilt. Thus, the radiation come not from the ground (Radon daughters scenario), but from the cloud above;

• The flux enhancement is well correlated with electric field disturbances and not with rain or snow. The decay of the flux started after termination of the disturbances of electric field and is linear, not exponential;

• Rain do not influence duration and intensity of low-energy TGE. On fair weather also small clouds can slightly disturb electric field and cause LLL TGE;

• The particle flux comes from the clouds, due to electric field giving additional energy to the charged particles. Usually, after strong storm calms down, near surface electric field also stabilized to fair weather one. However, the stochastic fields remain in the cloud and continue to enhance particle flux for hours.

• Thus, clouds are full of fields and radiation lasting a long time. The electric fields can introduce biases in the EAS and ACT research. Monitoring of clouds by Lidars or/and particle detectors with low energy threshold is the necessary condition of unbiased operation of surface arrays and ACTs.

TGEs and Gamma glows terminated by lightnings

• Historical data;

• Aragats data;

• Lightning initiation

“The balloon passed through a region of high electric field on which time increase in X ray intensity of 2 orders of magnitude occurred, lasting for approximately 1 min. The X ray intensity returned to background level at the time of a

lightning flash that reduced the electric field strength measured at the balloon”, near Norman, Oklahoma in the spring of 1995.

Eack, K.B, W.H. Beasley, W.D. Rust, T.C. Marshall, M.Stolzenburg, Initial results from simultaneous observations of x rays and electric fields in a thunderstorm, J.Geophys. Res., 101, 29637-29640, 1996.

The left- most peak precedes an observed flash near aircraft. Center peak precedes a strike to the aircraft. Rightmost "'hump” is not associated with any observed lightning McCarthy, M.P., Parks, G.K. 1985. Further observations of X-rays inside thunderstorms. Geophys. Res. Lett. 97, 5857–5864

Lightning terminates particle fluxes on Earth’s surface and in aircraft

The large distance to lightning channels probably means that the above enhancements are not directly related to the lightning activity. We can rather suppose that the lightning serves in our case as a switch-off for the electric field.

Alexeenko V.V., Khaerdinov N.S., LidvanskyA.S., and PetkovV.B., 2002. Transient Variations of Secondary Cosmic Rays due to Atmospheric Electric Field and Evidence for Pre-Lightning Particle Acceleration, Physics Letters A, 301, 299-306.

Examining the strongest glow measured by the airborne detector for energetic emissions, we show that this glow is measured near the end of a downward RREA, consistent with occurring between the upper positive charge layer and the

negative screening layer above it. N. A. Kelley, D. M. Smith, and J. R. Dwyer et al., Relativistic electron avalanches as a thunderstorm discharge competing with

lightning, Nat. Commun. 6, 7845 (2015).

An Airbus A340 aircraft flew over Northern Australia with ILDAS system installed on-board: The most intense emission was

observed at 12 km altitude and lasted for 20 s. Its intensity was 20 times the background counts and it was abruptly terminated

by a distant lightning flash.

The gamma glow was abruptly terminated by a distant lightning flash. This is consistent with previously formulated assumption that

glows are created by high E-filed regions inside thunderclouds.

2016 TGEs occurs at prolonged (3-7 min)deep negative electrostatic field(~ -30 kV/m);

lightning abruptly terminates TGE; largest TGEs occurred when there is no nearby lightnings.

Electric field measured by the GAMMA EFM-100 and 50 msc time series of count rate of STAND1 upper scintillator. Note that 3 triggers: black, green and red dots coincide within 2 microseconds. Hotel 14:07:52.886694, SKL 14:07:52.886690, MAKET 14:07:52.886692. After 50 ms flux decreases by 36% and after 250 ms by 64%. Distance to lightning was estimated by MAKET EFM ~ 6.8 km

One from numerous randomly emerging TGEs in the thundercloud open path to the lightning leader!

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TGE energy spectra

Research of Thunderstorm Ground Enhancements (TGEs)

• 1. In the thunderstorm cell randomly emerge extended regions of enhanced electric field with strength above the breakeven limit (for instance electric field of 1.8 kV/cm on 4–6 km heights and ~1 km extension); these regions are randomly distributed in the cloud and are continuously moved due to rather strong wind on 4–8 km heights;

• At the same heights, the flux of secondary cosmic ray (CR) electrons with energies appropriate for the run- away regime (100 KeV − 2 MeV) is significantly high - several thousands of particles per (s · m2). CR seed electrons entering high electric field regions unleash the RB/RREA process producing large particle fluxes.

• Intense particle flux create a system of the random clusters of ionization in a huge 3-dimension storm cell. Due to some, yet unspecified stochastic mechanism (for an example of such a mechanism, see ref. 28) in some place in the cloud a discharge occurred, stopping TGE and initiated lightning.

• Due to working charging machine in the cloud at another time in another place points 1–3 will be repeated as a storm prolonged 29

Research of Thunderstorm Ground Enhancements (TGEs)

• Observations during 2009-2016 of the TGEs and their energy spectra on Aragats as well as detection on the millisecond time scales particle fluxes, lightning flashes and disturbances of the electrostatic field allows:

• Confirm the RB/RREA process as a source of the high-energy particle fluxes from thunderclouds;

• Confirm the mechanism of lightning initiation (RB/RREA).

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