1. Jan Ridky and Petr Travnicek Inst. of Physics, Czech Academy of Sciences, Prague for DELPHI collaboration Muon Bundles from Cosmic Ray Showers Detected by DELPHI at LEP Jan Ridky, ISVHECRI, Pylos, Greece, 6-12 Sept. 2004

2. Detection of cosmic rays at LEP DELPHI (100 m, E cut = 50 GeV) ALEPH (140 m, E cut = 70 GeV) L3 (30 m, E cut = 15 GeV) Jan Ridky, ISVHECRI, Pylos, Greece, 6-12 Sept. 2004

3. Simulation and detection Jan Ridky, ISVHECRI, Pylos, Greece, 6-12 Sept. 2004

4. Description of the overburden 5 layers with proper rock density & experimental cavern description different kinds of molasses Jan Ridky, ISVHECRI, Pylos, Greece, 6-12 Sept. 2004

5. Detektor DELPHI MUB HCAL TOF TPC Jan Ridky, ISVHECRI, Pylos, Greece, 6-12 Sept. 2004

6. Hadron calorimeter barrel module Sensitive units - streamer tubes 1 tube has x-section 8  1 cm in (x,y) plane Read-out only YES or NO, length of a tube in barrel part 350 cm Jan Ridky, ISVHECRI, Pylos, Greece, 6-12 Sept. 2004

7. Typical high multiplicity event RUN 107634, EVT 4731 Jan Ridky, ISVHECRI, Pylos, Greece, 6-12 Sept. 2004

8. Saturated event … we have 6 such cases Jan Ridky, ISVHECRI, Pylos, Greece, 6-12 Sept. 2004

9. Data selection - DELPHI cosmic trigger coincidence of 3 sectors in TOF, parasitic data taking to e + e - and several dedicated cosmic runs Duty cycle of LEP  total live time  1.6 10 6 s N muons > 4 Jan Ridky, ISVHECRI, Pylos, Greece, 6-12 Sept. 2004

10. Projected angle  background rejection HCAL projected angle Jan Ridky, ISVHECRI, Pylos, Greece, 6-12 Sept. 2004

11. 4 saturated events 2 saturated events (MUB) 1999, 2000 Muon multiplicity Jan Ridky, ISVHECRI, Pylos, Greece, 6-12 Sept. 2004

12. Track saturation yes/no signals in streamer tubes  track pile up Jan Ridky, ISVHECRI, Pylos, Greece, 6-12 Sept. 2004

13. Saturated events ● too many hits, reconstruction in HCAL fails ● 6 such events, parallel ‘tracks’ of un-hit tubes -> cosmic ● 2 events in MUB  multiplicity >150 Jan Ridky, ISVHECRI, Pylos, Greece, 6-12 Sept. 2004

14. MC simulation of cosmic rays ● QGSJET, CORSIKA, GEANT3, DELSIM ● Primary particles: p, Fe ● Primary energies 10 12 – 10 18 eV ● Events generated according to E -1 and weighted by E -2.7(3.0) ● Shower smearing within radius R = 200 m at the detector level Jan Ridky, ISVHECRI, Pylos, Greece, 6-12 Sept. 2004

15. MC comparisons Which model provides more muons? LDF of p > 50 GeV muons => QGSJET > SIBYLL > DPMJET Jan Ridky, ISVHECRI, Pylos, Greece, 6-12 Sept. 2004

16. HCAL – MC (QGSJET) vs. DATA Jan Ridky, ISVHECRI, Pylos, Greece, 6-12 Sept. 2004

17. rock density cross-talk Systematic errors – rock density, cross-talk Jan Ridky, ISVHECRI, Pylos, Greece, 6-12 Sept. 2004

18. Simulations – supposed flux Jan Ridky, ISVHECRI, Pylos, Greece, 6-12 Sept. 2004

19. HCAL – MC (QGSJET) vs. DATA flux no. 1 Jan Ridky, ISVHECRI, Pylos, Greece, 6-12 Sept. 2004

20. Comparison – MC vs. DATA flux 1, 2, 3- influence of the flux of primary particles Jan Ridky, ISVHECRI, Pylos, Greece, 6-12 Sept. 2004

21. Simulations – energy contributions – flux 1 Jan Ridky, ISVHECRI, Pylos, Greece, 6-12 Sept. 2004

22. Simulations – energy contributions – flux 1 Jan Ridky, ISVHECRI, Pylos, Greece, 6-12 Sept. 2004

23. TPC sky plot (galactic coordinates), HCAL multiplicity > 15 Jan Ridky, ISVHECRI, Pylos, Greece, 6-12 Sept. 2004

24. Other LEP results Aleph Delphi multiplicity L3-C

25. Conclusions DELPHI cosmic data in qualitative agreement with other LEP measurements (L3+C). High energy models fail to describe muon multiplicity Data are sensitive to the dynamics of the high energy interactions (talk of Jörg Hörandel) Cosmic data …. the only measurement at LEP unexplained by theory