M.Tamada Kinki University Air showers accompanied by high energy atmospheric families observed by Chacaltaya hybrid experimemt M.Tamada Kinki University ICRC2007, Merida ; 10 Jul. 07

H.Aoki、K.Honda, N.Inoue, T.Ishii, N.Kawasumi, N.Martinic, N.Ochi, N.Ohmori, A.Ohsawa, M.Tamada and R.Ticona

(Mt. Chacaltaya, 5200m, Bolivia) 45 scintillation counters

emulsion chamber burst detector hadron calorimeter

EAS-array: shower size, Ne time, theta, phi time, position Hadron calorimeter: burst size, nb position, theta, phi Emulsion chamber: atmospehric family (ng,nh,SEg, SEh, E≥2TeV)

Coupling the family with the accompanied air shower 1. List the families in one block of the emulsion chamber 2. List the bursts which have their centers on the concerned block 3. Correspond the families to the bursts 4. Examine the consistency of the arrival direction, position between family and air shower Coupling rate ~ 80 % <Dq>=5.4 ± 0.5 deg, <Df>=17.0 ± 1.8 deg, <DR>=0.49 ± 0.04m

Selection of the events Air-showers Shower-size : Ne ≥ 106 & families: Eg, Eh(g) ≥ 2TeV Ng ≥ 5, Eg ≥2TeV (SEg ≥10TeV) 72 events in 43.7 m2year exposure of emulsion chambers

Simulations EAS above the detector CORSIKA v.6.502 + QGSJET01c, Sibyll 2.1 shower size : NKG-option Ecut=0.3GeV for hadrons, muons Ecut=0.003GeV for e,gamma Proton-dominant primary composition Heavy-dominant primay composition 20,000 events E0≥1015eV 6,000 events E0≥1016eV

Simulations inside the emulsion chamber (e,g) & hadrons in the families Hadron-Pb int. : QGSJET01 EM-cascade : Okamoto-Shibata algorithm electron number ---> spot darkness shower transition on spot darkness fitting using standard cascade curve : DT, E(g) showers of DT > 6 c.u. : hadron-induced

effect of gap between neighboring blocks families: Ng ≥ 5, Eg≥2TeV (SEg≥10TeV) in a block

effect of gap between neighboring blocks Random sampling of family-center in the emulsion chamber area including gaps of two neighboring blocks 613 among 2108 families with Ne ≥ 7 x 106 have its center outside the emulsion chamber. Effective area is 1.41 times of emulsion chambers : 1.41 x 8 m2 = 11.28 m2

air showers accompanied by families SEg≥10TeV Proton-dominant-composition sampled primary particles air showers accompanied by families SEg≥10TeV

heavy-dominant-composition sampled primary particles air showers accompanied by families SEg≥10TeV

EAS triggered family Proton-dominant

EAS triggered family

distribution of normalized family energy E0 ~ Ne x 2 GeV f = SEg/E0

proton-dominant

observed events are mainly due to Fe-primaries !?

lateral spread of g-rays in the family 107 ≤ Ne < 108 QGSJET01c Sibyll 2.1

lateral spread of g-rays in the family QGSJET01c Sibyll

107 ≤ Ne < 108

106 ≤ Ne < 107

size spectrum of air showers with families Chacaltaya

observed number of EAS with families is smaller than expectation in Ne<107.

106 ≤ Ne < 107

conclusion How is in Tibet Asg data ? Models can not well describe characteristics of air-shower triggered families with Ne≥106 • necessary to check validity of interaction model; Ne-SEg, Ne-sp., ER-sp., Correlation etc. How is in Tibet Asg data ? • necessary more statistics of EAS with families ! • necessary to modify the model of nuclear interactions !?