1. Aspen, April 19, 2007Tom Gaisser1 10 17 eV decade Breakout summary

2. Allard, Olinto, Parizot, astro-ph/0703633 Alternatives for transition to E.G.

3. Aspen, April 19, 2007Tom Gaisser3 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

4. Aspen, April 19, 2007Tom Gaisser4 Berezhko & Völk arXiv:0704.1715v1 [astro-ph] Model galactic component Subtract from observed to get extragalactic Transition predicted: 10 16.5 to 10 17.5 eV

5. Aspen, April 19, 2007Tom Gaisser5 Depth of Maximum Early transition favored –HiRes prototype + CASA/MIA –HiRes (E > 10 18 ) G. Archbold, P. Sokolsky, et al., Proc. 28 th ICRC, Tsukuba, 2003 HiRes new composition result: transition occurs before ankle 0.3 EeV

6. Aspen, April 19, 2007Tom Gaisser6 Composition from density of muons ρ µ (600) vs. E 0 (Akeno, AGASA) From heavy toward protons Calculations by Bruce Dawson with MoccaSibyll

7. Aspen, April 19, 2007Tom Gaisser7 KASCADE-Grande : first analyses muon density investigations KASCADE-Grande preliminary T. Pierog (EPOS) MIA

8. Cross section summary M Block Note: old data are rescaled

9. Aspen, April 19, 2007Tom Gaisser9 Interaction models QGSjet01 SIBYLL QGSjet02 EPOS Ralph Engel

10. Aspen, April 19, 2007Tom Gaisser10

11. Hard  0 production of EPOS readily detectable in LHCf

12. More  in EAS with EPOS Attribute to NN production in EPOS

13. Aspen, April 19, 2007Tom Gaisser13 Xmax more stable

14. Aspen, April 19, 2007Tom Gaisser14 Summary comments Two very different models of transition –10 17 to 10 18 -or- 10 18 to 10 19 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