1. 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

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

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

4. emulsion chamber
burst detector
hadron calorimeter

5. 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)

6. 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

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

8. Simulations EAS above the detector
CORSIKA v 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

9. 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

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

11. 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 = m2

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

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

14. EAS triggered family
Proton-dominant

15. EAS triggered family

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

17. proton-dominant

18. observed events
are mainly due
to Fe-primaries !?

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

20. lateral spread of g-rays in the family
QGSJET01c
Sibyll

21. 107 ≤ Ne < 108

22. 106 ≤ Ne < 107

23. size spectrum of air showers with families
Chacaltaya

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

25. 106 ≤ Ne < 107

26. 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 !?