1. The Behavior of the Mean Multiplicity Coefficients of ASEC Neutron Monitors During Thunderstorm Activity Armen Hovhannisyan

2. Aragats Neutron Monitor

3. 3 Dead Times of Neutron Monitor

4. Mean Multiplicity Coefficient

5. Nucleon double counting effect

6. Correlation Matrix of ArNM – Dead Time 1250mcs Det123456789101112131415161718 1*142-450-5-4-3242133-4 214*12320 -4 40 124 3212*105-3051 0-21-6-2 2 4310* 7590-20 2-40-2 5-42510*16303-51-21124 65-3716*61-36 14 02 7000536*151013-33-5214 8-5590 15*1919611-211 4 9-4 10311019*1173-70120 10-4 -31611* 1311-220 11-3-4-2-531711*15153-4000 12200 6-313115*534-20 1344-2 13-2335*128161 142012-21-51-71-4312* 53-6 151-6-414210104812*1131 1631-21 1-2-21511*197 1732-20201220063319*16 18-442-242440001-61716*

7. Estimated Mean Multiplicities Section1Section2Section3NM median ANM1.43±0.0081.425±0.0081.42±0.0091.425 NANM1.44±0.0131.43±0.0121.42±0.0121.43

8. The dependence of mean multiplicity on the cutoff rigidity (measurements by ship borne 3NM-64 of IQSY type in December 1966 – April 1967, Kodama & Ishida, 1967). By open circles are denoted mean multiplicities of the ArNM and NANM

9. Mean Multiplicity and EAS Average number of > 4σ spikes: 4±2 Expected Number of > 4σ spikes according to gaussian( ) distribution: 0.1 A.Chilingarian G. Hovsepyan, E. Mamidjanyan, Study of Extensive Air Showers and Primary Energy Spectra by MAKET-ANI Detector on Mountain Aragats, Astroparticle Physics, 28, pp 58-71, 2007.

10. Cross Sections of Photonuclear Reactions with air Cross Section of Photo Nuclear Reaction of Photons with Nitrogen(continuous line) and Carbon(dotted line) Nucleus Cross Section of Photo Nuclear Reaction of Photons with Oxygen Nuclei

11. Distribution of Mean Multiplicities of ARNM During Thunderstorm Activity Multiplicity, m 123456 Nucleon Energy (Gev) NM64 0.070.120.180.250.40.64 C.J. Hatton, The Neutron Monitor, in J., G. Wilson and S.A. Wouthuysen (eds.), Progress in Elementary Particle and Cosmic-ray Physics, vol. 10, chapter 1, North Holland Publishing Co., Amsterdam, 1971

12. Conclusions The notion of the multiplicity, introduced several decades ago, despite its elegance did not become yet a basis of the physical analysis of any importance in the cosmic ray physics and space weather research. Here we introduce method of calculation of the mean multiplicity and demonstrate its relation to the high energy primary cosmic ray physics and to new observed high energy phenomena in the thunderstorm atmospheres. We demonstrate the “bursts” in the mean multiplicity time series measured by Aragats Neutron Monitor are connected with the incident Extensive Air Shower initiated by the primary particles with energies greater than 1 PeV and by the low energy neutron photo production by the gamma rays from the RREA process.