A.U. Kudzhaev, D.D. Dzhappuev, V.V. Alekseenko,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. StenkinV.B. Petkov and Yu. V. Stenkin

Institute for Nuclear Research of RASInstitute for Nuclear Research of RAS

A study of penetrating EAS component A study of penetrating EAS component at Carpet-2 EAS array:at Carpet-2 EAS array:

I. Hadrons with E I. Hadrons with Ehh > 30 GeV. > 30 GeV.

Contents of this talkContents of this talk

1. Experimental Set Up1. Experimental Set Up

2. The method separation of hadrons2. The method separation of hadrons

3. Estimation of average energy hadrons3. Estimation of average energy hadrons

4. Some characteristics of hadron 4. Some characteristics of hadron componentscomponents

“Carpet-2” array is located at the Baksan Neutrino Observatory at altitude 1700 m. a.s.l. (840 g/cm2 ). It consists of:

big central detector “Carpet” (400 liq. scint. det. 200m2 in total).

Big underground 1 GeV muon detector of 175 m2.

6 outer detectors of 9 m2

The Carpet-2 EAS arrayThe Carpet-2 EAS array

Baksan Neutron Baksan Neutron MonitorMonitor

Large Area Muon DetectorLarge Area Muon Detector

The central part of CarpetThe central part of Carpet

Outside detectorOutside detector

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

The “Carpet-2” configuration allows to measure

parameters of EAS for interval

Ne=105÷106 with the following accuracy:

core location: Δ Xo=ΔYo=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.

1.For studying hadrons in EAS were choosed such showers, that 1.For studying hadrons in EAS were choosed such showers, that satisfied to next conditions:satisfied to next conditions:1. Cores of showers in “Carpet” ;1. Cores of showers in “Carpet” ;2. Showers are near vertical(2. Showers are near vertical(<30<30oo););3. 0.8<s<1.5;3. 0.8<s<1.5;4. 104. 1055<N<Nee<10<106 6 ;;The cascades are accompanied a showers is choosed accordinglyThe cascades are accompanied a showers is choosed accordinglyto results of calculations: the size stain of cascade less 5mto results of calculations: the size stain of cascade less 5m22 and anda density of particles in stain more 10/ma density of particles in stain more 10/m22 correspond to deposit correspond to depositenergy equal 100MeV. For such events have been dependence ofenergy equal 100MeV. For such events have been dependence ofnumber such cascades in showers from total number particles in number such cascades in showers from total number particles in showers in interval Nshowers in interval Nee=10=1055101066 which describe by power law which describe by power lawNNk k N Nee

αα, where , where αα=0.89±0.08. =0.89±0.08.

The characters of hadron component EASThe characters of hadron component EAS

jet m2

corem2

The dependence of the meanThe dependence of the meanenergy deposit in MD,<energy deposit in MD,<εε> on> onhadron energy Ehadron energy Ehh is the results is the resultsof Monte-Carlo simulation forof Monte-Carlo simulation forsingle hadrons (protons and single hadrons (protons and ππ--mesons) interacting in the mesons) interacting in the absorber of 500g/cmabsorber of 500g/cm2 2 thickness.thickness.Calculation for hadrons with ECalculation for hadrons with Eh h ininthe range of 5-500GeV was the range of 5-500GeV was performed for zenith angles:performed for zenith angles:00oo,15,15oo,30,30oo and 45 and 45oo

The average size of the hadron The average size of the hadron cascades in MD depends on cascades in MD depends on hadron energy and zenith hadron energy and zenith angle.From this results is angle.From this results is followsfollowsthat events caused by hadronsthat events caused by hadronswith energy Ewith energy Ehh>20GeV(energy>20GeV(energydeposit≥100MeV or 10r.p.) candeposit≥100MeV or 10r.p.) canclearly separated from muons.clearly separated from muons.

Separation muon and hadron components inSeparation muon and hadron components inEASEAS

[[гг//смсм22]]==-100%/-100%/ %/%/мбмб

Events withEvents with εε<<33rr..pp.. is is muonsmuons

EventsEvents withwith εε>10r>10r..pp.. is is hadronshadrons

From efficiency registration of hadrons and hadron’s From efficiency registration of hadrons and hadron’s spectrum is followed that by threshold energy ones spectrum is followed that by threshold energy ones

is Eis Ethth=20 GeV and average energy of hadrons is =20 GeV and average energy of hadrons is

E=30GeV that followed from calculationE=30GeV that followed from calculation

Experimental Experimental and and simulated simulated relationrelation N Nh h vs Nvs Nee

Experimental data can be fitted by power law: NExperimental data can be fitted by power law: Nhh N Neeαα, where, where

index index αα=0.89±0.08.=0.89±0.08.

M4

M5

M3

M2

M1

DISCR.Trigger M3

A schematic view for trigger of muon detector

The differential size spectrum of hadrons in interval 1-40 is The differential size spectrum of hadrons in interval 1-40 is obtained inobtained inexperiment are described by power law dN/dNexperiment are described by power law dN/dNh h N Nhh

, where , where =-2.8. At=-2.8. Atthe KASCADE shower array was measured differential size the KASCADE shower array was measured differential size spectrum ofspectrum ofhadrons (Ehadrons (Ehh>50GeV) near cores of EAS that is described by >50GeV) near cores of EAS that is described by power law with index of spectrum power law with index of spectrum γγ=-2.81±0.05(J.R. =-2.81±0.05(J.R. Horandal et al. (KASCADE).Horandal et al. (KASCADE). Proc. of 21th ICRC, 2001.Hamburg,(2001),137. Proc. of 21th ICRC, 2001.Hamburg,(2001),137.

Decoherent curve for hadronsDecoherent curve for hadrons

Decoherent curve are Decoherent curve are obtainedobtainedfor experimental data MD for experimental data MD of of “Carpet-2” shower array “Carpet-2” shower array withoutwithoutcorrection on efficiencycorrection on efficiencyregistration. registration.

Decoherent curve are Decoherent curve are obtainedobtainedfor experimental data using for experimental data using correction on efficiency correction on efficiency registration. The curve are registration. The curve are fit.:fit.:F(d) F(d) exp(-d/d exp(-d/doo) ,d) ,doo=13.1m=13.1m

ConclusionConclusionAt the 1GeV muon detector of “Carpet-2” EAS At the 1GeV muon detector of “Carpet-2” EAS

are obtained: are obtained:

1. Separation muon component from hadron 1. Separation muon component from hadron

2. Dependence n2. Dependence nhh-N-Nee

3. Differential size spectrum of hadrons3. Differential size spectrum of hadrons

4. Decoherent curve for hadrons 4. Decoherent curve for hadrons