Aspen, April 19, 2007 Tom Gaisser 1

1017 eV decade

Breakout summary

Allard, Olinto, Parizot, astro-ph/0703633

Alternatives for transition to E.G.

Aspen, April 19, 2007 Tom Gaisser 3

Model dependence of composition in galactic-extragalactic transition

Allard, Olinto, Parizot, astro-ph/0703633

proton model mixed model

• Model extragalactic component• Subtract from observed to get galactic component

Aspen, April 19, 2007 Tom Gaisser 4

Berezhko & Völk

arXiv:0704.1715v1 [astro-ph]

• Model galactic component• Subtract from observed to get extragalactic

Transition predicted:

1016.5 to 1017.5 eV

Aspen, April 19, 2007 Tom Gaisser 5

Depth of Maximum

• Early transition favored– HiRes prototype

+ CASA/MIA– HiRes (E > 1018)

G. Archbold, P. Sokolsky, et al.,Proc. 28th ICRC, Tsukuba, 2003

HiRes new composition result: transition occurs before ankle

0.3 EeV

Aspen, April 19, 2007 Tom Gaisser 6

Composition from density of muonsρµ(600) vs. E0 (Akeno, AGASA)

From heavy

toward protons

Calculations by Bruce Dawson with MoccaSibyll

Aspen, April 19, 2007 Tom Gaisser 7

KASCADE-Grande : first analyses muon density investigations

KASCADE-Grandepreliminary

T. Pierog (EPOS)

MIA

Cross section summary M BlockNote: old data are rescaled

Aspen, April 19, 2007 Tom Gaisser 9

Interaction models

• QGSjet01

• SIBYLL

• QGSjet02

• EPOS

Ralph Engel

Aspen, April 19, 2007 Tom Gaisser 10

Hard 0 production of EPOS readily detectable in LHCf

More in EAS with EPOS

Attribute to NN production in EPOS

Aspen, April 19, 2007 Tom Gaisser 13

Xmax more stable

Aspen, April 19, 2007 Tom Gaisser 14

Summary comments

• Two very different models of transition– 1017 to 1018 -or- 1018 to 1019 eV– Strong composition change signature– HiRes favors low-energy transition

• Model dependence a problem

• Good energy resolution important

• KASCADE-Grande, IceCube/IceTop, TALE, Amiga/HEAT at Auger