1. Low-Energy Interaction Models in CORSIKA Dieter Heck, Ralph Engel Forschungszentrum Karlsruhe, Germany Giuseppe Battistoni, Alberto Fassò, Alfredo Ferrari, Johannes Ranft, and Paola R. Sala ICRC 2003, Tsukuba, Japan

2. Motivation and Outline shower observables sensitive to both low- and high-energy hadronic interactions FLUKA 2002 as alternative hadronic interaction model implemented new correction patches available for GHEISHA (R.E. Cassell and G. Bower, SLAC) comparison of model predictions to low-energy data calculation of influence on EAS predictions R. Engel, ICRC 2003, Tsukuba, Japan

3. Comparison to low-energy p-Be data (1) R. Engel, ICRC 2003, Tsukuba, Japan double-differential data integrated PLB 472 (2000) 113 uncertainties: inter- and extrapolation GHEISHA: multiplicity too low QGSJET: multiplicity too high

4. Comparison to low-energy p-Be data (2) R. Engel, ICRC 2003, Tsukuba, Japan double-differential data integrated PLB 472 (2000) 113 uncertainties: inter- and extrapolation very limited amount of data available

5. Comparison to low-energy p-C data R. Engel, ICRC 2003, Tsukuba, Japan fully inclusive measurements positive pions difficult to measure energy below Feynman scaling region

6. Cross-check: p-N predictions R. Engel, ICRC 2003, Tsukuba, Japan predictions similar to p-Be and p-C QGSJET: higher multiplicity than FLUKA GHEISHA: lower multiplicity than FLUKA

7. R. Engel, ICRC 2003, Tsukuba, Japan example: multiplicity of p-p interactions default transition energy: E lab = 80 GeV similar results for charged kaons Transition: low- and high energy models 80 GeV

8. R. Engel, ICRC 2003, Tsukuba, Japan vertical proton induced showers significant change in baryon energy spectrum strong model dependence of lateral distribution EAS predictions: baryon distributions R. Engel, ICRC 2003, Tsukuba, Japan

9. vertical proton- induced showers very small changes in longitudinal profile differences of same order as statistical fluctuations EAS predictions: longitudinal shower profile R. Engel, ICRC 2003, Tsukuba, Japan

10. R. Engel, ICRC 2003, Tsukuba, QGSJET: dependence on low-energy model and threshold SIBYLL: dependence on threshold difference between QGSJET and SIBYLL bigger than low-energy model dependence EAS predictions: muon energy spectrum R. Engel, ICRC 2003, Tsukuba, Japan

11. vertical proton showers partial cancellation of low-energy model dependence differences between high-energy models dominate R. Engel, ICRC 2003, Tsukuba, Japan Integral muon energy spectrum

12. R. Engel, ICRC 2003, Tsukuba, Japan vertical proton- induced showers E µ > 300 MeV changes at small and large lateral distances changes compatible with energy spectra R. Engel, ICRC 2003, Tsukuba, Japan EAS predictions: muon lateral distribution

13. R. Engel, ICRC 2003, Tsukuba, Japan vertical proton showers, E = 10 19 eV E µ > 150 MeV E e > 250 keV drastic changes at large lateral distance see also talk by H.J. Drescher EAS predictions at Auger energies R. Engel, ICRC 2003, Tsukuba, Japan

14. vertical proton showers, E = 10 19 eV E µ > 150 MeV E e > 250 keV drastic changes at large lateral distance see also talk by H.J. Drescher R. Engel, ICRC 2003, Tsukuba, Japan EAS predictions at Auger energies

15. R. Engel, ICRC 2003, Tsukuba, JapaR. Engel, ICRC 2003, Tsukuba, Japan Summary and outlook significant differences between low-energy models FLUKA gives best description of low-energy data strong effect on hadronic distributions no effect on longitudinal shower profiles muonic observables sensitive to low-energy model: change of muon energy spectrum cancellation: small change of total muon number drastic change of lateral distributions at high energy

16. R. Engel, ICRC 2003, Tsukuba, JapaR. Engel, ICRC 2003, Tsukuba, Japan References D. Heck et al., Report FZKA 6019 (1998), Forschungszentrum Karlsruhe; http://www-ik.fzk.de/http://www-ik.fzk.de/ A. Fassò, A. Ferrari, J. Ranft, P.R. Sala: FLUKA: Status and Prospective of Hadronic Applications, Proc. Monte Carlo 2000 Conf., Lisbon, Oct. 23-26, 2000, A. Kling et al. eds., Springer (Berlin) 955 (2001); http://www.fluka.org/http://www.fluka.org/ H. Fesefeldt, Report PITHA-85/02 (1985), RWTH Aachen R.E. Cassell and G. Bower (SLAC), private communication (2002)

17. R. Engel, ICRC 2003, Tsukuba, JapaR. Engel, ICRC 2003, Tsukuba, Japan Kaon multiplicity in p-p interactions GHEISHA: multiplicity too low SIBYLL and neXus similar

18. R. Engel, ICRC 2003, Tsukuba, JapaR. Engel, ICRC 2003, Tsukuba, Japan GHEISHA: differences at large lateral distances lateral distributions almost threshold independent Pion and muon lateral distribution

19. R. Engel, ICRC 2003, Tsukuba, JapaR. Engel, ICRC 2003, Tsukuba, Japan dependence on low- energy model small differences comparable to statistical error Lateral distribution of electrons

20. R. Engel, ICRC 2003, Tsukuba, JapaR. Engel, ICRC 2003, Tsukuba, Japan strong dependence on model strong dependence on threshold Lateral distribution of neutrons