1. Space-time structure of signals in scintillation detectors of EAS L.G. Dedenko, G.F. Fedorova, T.M. Roganova and D.A. Podgrudkov

2. L.G. Dedenko, D.A. Podgrudkov, T.M. Roaganova et al. // Yad. Fiz. 2007. T70. N10, P.1806.

3. Possible reasons Hadron interactions model at high energies  will be checked at LHC Different chemical composition  seems to be checked in recent experiments Problem with absolute calibration of Cherenkov light  To be check in the experiment Experimental error in signal measurements  this point requires analysis!

4. A. Watson. 28 -th ICRC (2003, Tsukuba) Yakutsk data presents a higher number of ultra-high energy particles than the HiRes experiment. Rapid change in the steepness of measured signal lateral distribution function along with the energy increase. Possibly too narrow time gates at Yakutsk – only 2  s, while some showers at Haverah Park were wider than 2.2  s.

5. Time gates. Time gate – time span during which the detector collects particles as of a ‘single’ event. Some trigger event (a particle hits the detector, counting rate exceeds some level, a signal comes from another detector, etc.) opens the time gate. When should we close it? Should collect the full signal. Keep the S/N ratio high (existence of a background) Haverah Park, Yakutsk etc. have time gates of about 2 microseconds.

6. CORSIKA 6.500 with EGS4 codes QGSJet-II and Gheisha-2002d models Observation level, atmosphere and magnetic field parameters were set to fit the conditions of the Yakutsk array. Printout file contains particle type, distance from the shower axis, energy, cosine of the incidence angle, time delay and the weight of the particle. Thinning procedure with ε = 10 -6

7. detector from particles with 0 - 90  angles of incidence and different energies (from 1 MeV up to 10 GeV for , e -, e + and from 0.3 up to 1000 GeV for  ) A 5-point interpolation scheme was used to calculate the signal for each particle. Signals database calculations: GEANT4 The database contains signals in the scintillation

8. The signal at 100 m from the shower axis.

9. The signal at 600 m from the shower axis.

10. The signal at 1000 m from the shower axis.

11. The signal at 1260 m from the shower axis. Primary particle is a proton with energy E = 2  10 18 eV.

12. The signal at 1500 m from the shower axis.

13. The ratio of the signal collected for time  to the full signal

14. The shower’s forefront.

15. The shower’s fore and back fronts.

16. The signals LDF: infinite time gates (solid lines) and 2  s time gates (dashed lines)

17. The ratio of the 2  s time gates LDF to the infinite time gates LDF.

18. Energy estimations This work E 0 = 2.8·10 17 (S 600 ) 0.99 Yakutsk formula E 0 = 4.8·10 17 (S 600 ) 0.99 ~1.7 time lower energy with the same signal S 600

21. Conclusions Shower disk width at distances above ~1 km exceeds 2  s. And at 2 km is about 4  s.

22. Conclusions At distances less than 1 km the full signal is collected within 2  s so is measured the signal S 600 in experiment correctly. New estimation formula based on the signal S 600 gives a ~1.7 lower energy than the formula currently used at Yakutsk.

23. Authors thank RBRF (grant 07-02-01212 ) and G.T. Zatsepin LSS (grant 959.2008.2 ) for support.