1. A.U. Kudzhaev, D.D. Dzhappuev, V.V. Alekseenko, A.B. Chernyev, N.F. Klimenko, A.S. Lidvansky, A.B. Chernyev, N.F. Klimenko, A.S. Lidvansky, V.B. Petkov and Yu. V. Stenkin V.B. Petkov and Yu. V. Stenkin Institute for Nuclear Research of RAS A study of penetrating EAS component at Carpet-2 EAS array: I. Hadrons with E h > 30 GeV.

2. Contents of this talk 1. Experimental Set Up 2. The method separation of hadrons 3. Estimation of average energy hadrons 4. Some characteristics of hadron components

3. “Carpet-2” array is located at the Baksan Neutrino Observatory at altitude 1700 m. a.s.l. (840 g/cm 2 ). It consists of: big central detector “Carpet” (400 liq. scint. det. 200m 2 in total). Big underground 1 GeV muon detector of 175 m 2. 6 outer detectors of 9 m 2

4. The Carpet-2 EAS array Baksan Neutron Monitor Large Area Muon Detector The central part of Carpet Outside detector

5. Central part of array (just “Carpet”)

7. The “Carpet-2” configuration allows to measure parameters of EAS for interval Ne=10 5 ÷10 6 with the following accuracy: core location: Δ X o =ΔY o =0.35m; shower size ΔNe / Ne≈0.1; arrival direction Δψ ≈ 3.5°; studying EAS central density structure; studying the structure of muonic component with 1 GeV threshold energy.

8. 1.For studying hadrons in EAS were choosed such showers, that satisfied to next conditions: 1. Cores of showers in “Carpet” ; 2. Showers are near vertical(<30 o ); 3. 0.8<s<1.5; 4. 10 5 <N e <10 6 ; The cascades are accompanied a showers is choosed accordingly to results of calculations: the size stain of cascade less 5m 2 and a density of particles in stain more 10/m 2 correspond to deposit energy equal 100MeV. For such events have been dependence of number such cascades in showers from total number particles in showers in interval N e =10 5 10 6 which describe by power law N k  N e α, where α=0.89±0.08. The characters of hadron component EAS

9.  jet  m 2  core  m 2

10. The dependence of the mean energy deposit in MD, on hadron energy E h is the results of Monte-Carlo simulation for single hadrons (protons and π- mesons) interacting in the absorber of 500g/cm 2 thickness. Calculation for hadrons with E h in the range of 5-500GeV was performed for zenith angles: 0 o,15 o,30 o and 45 o The average size of the hadron cascades in MD depends on hadron energy and zenith angle.From this results is follows that events caused by hadrons with energy E h >20GeV(energy deposit≥100MeV or 10r.p.) can clearly separated from muons.

12. Separation muon and hadron components in EAS  [г/см 2 ]=-100%/  %/мб Events with ε 10r.p. is hadrons

13. From efficiency registration of hadrons and hadron’s spectrum is followed that by threshold energy ones is E th =20 GeV and average energy of hadrons is E=30GeV that followed from calculation

14. Experimental and simulated relation N h vs N e Experimental data can be fitted by power law: N h  N e α, where index α=0.89±0.08.

16. The differential size spectrum of hadrons in interval 1-40 is obtained in experiment are described by power law dN/dN h  N h , where  =-2.8. At the KASCADE shower array was measured differential size spectrum of hadrons (E h >50GeV) near cores of EAS that is described by power law with index of spectrum γ=-2.81±0.05(J.R. Horandal et al. (KASCADE). Proc. of 21th ICRC, 2001.Hamburg,(2001),137.

17. Decoherent curve for hadrons Decoherent curve are obtained for experimental data MD of “Carpet-2” shower array without correction on efficiency registration. Decoherent curve are obtained for experimental data using correction on efficiency registration. The curve are fit.: F(d)  exp(-d/d o ),d o =13.1m

18. Conclusion At the 1GeV muon detector of “Carpet-2” EAS are obtained: 1. Separation muon component from hadron 2. Dependence n h -N e 3. Differential size spectrum of hadrons 4. Decoherent curve for hadrons