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RECENT RESULTS FROM L3+COSMICS AT CERN L3 - COLLABORATION presented by

RECENT RESULTS FROM L3+COSMICS AT CERN L3 - COLLABORATION presented by R. Nahnhauer - DESY Zeuthen. THE L3+COSMICS EXPERIMENT. LOCATION: 6.02  E, 46.25  N L3C under 30 m of Molasse:  magnet (0.5 T, 1000 m 3 )  muon drift chambers  t 0 -detector

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RECENT RESULTS FROM L3+COSMICS AT CERN L3 - COLLABORATION presented by

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  1. RECENT RESULTS FROM L3+COSMICS AT CERN L3 - COLLABORATION presented by R. Nahnhauer - DESY Zeuthen

  2. THE L3+COSMICS EXPERIMENT

  3. LOCATION: 6.02 E, 46.25 N L3Cunder 30 m of Molasse:  magnet (0.5 T, 1000 m3)  muon drift chambers  t0-detector (200 m2 scintillator)  GPS timing  independent trigger and DAQ  geometrical acceptance A ~ 200 m2sr  momentum resolution  p/p = 7.1% at 100 GeV/c  angular resolution  < 3.5 mrad above 100 GeV/c

  4. LOCATION: 6.02 E, 46.25 N EAS on top of the L3-hall:  50 scintillators of 0.5m2  area covered ~ 30*54 m2  independent DAQ  GPSL3C synchronisation  trigger for Ethr ~ 10 TeV  event flag for common trigger with L3C DATA TAKING  L3C: 1999-2000 11*109 trigger on tape  EAS: 2000-(2001) 33*106 trigger on tape  L3C+EAS : 2000 8*106 trigger in common

  5. THE VERTICAL ATMOSPHERIC MUON SPECTRUM .from Bugaev E.V. et al., Phys. Rev. D58 (1998) 5401 from Hebbeker T., ICHEP 2000, Osaka

  6. THE PRELIMINARY L3C SPECTRUM  data used up to now: 16.7-9.11.1999 ,  = 53.1 days  two independent analyses agree within errors selection criteria uncorrected data

  7. THE PRELIMINARY L3C SPECTRUM correct for detector inefficiencies: scintillator efficiency -chamber efficiency

  8. THE PRELIMINARY L3C SPECTRUM unfolding: Bayesian D‘Agostini, CERN-99-03 regularized Tikhonov, Sov.Math 5(1963)1035 systematical uncertainties:  scintill. efficiency and noise 3.%  trigger efficiency .2%  normalisation and unfolding 5.%  long term + seasonal stability 5.%  in total : 7.7%, goal < 3%  add. (Molasse) :  p  .6 GeV/c  mean eff. Temperature : 224.5 K  flux inside z < 10 

  9. THE PRELIMINARY L3C SPECTRUM a subjective comparison: errors given for L3C: „statistical“ have to use covariance matrix

  10. NEWS ABOUT COSMIC PRIMARIES ? from:Kampert et al., ICRC1999, V3, 156

  11. THE NEW POSSIBILITIES OF L3COSMICS EAS determines shower: L3C determines:  direction (arrival time)  direction  core position (charge density)   momentum (±)  energy ( MIPS)  number

  12. THE NEW POSSIBILITIES OF L3COSMICS inclusive features of muons studied as function of primary cosmic ray energy muon density muon spectrum  MC calculations are in progress which will allow a quantitative interpretation of the above results

  13. THE SUN: A SOURCE OF MULTI-GEV MUONS ON EARTH ? from: Karpov et al., Nuovo Cimento 21 (1998) 551

  14. THE INTENSE SOLAR FLARE OF 14th JULY 2000 10:24 UT, region 9077 X5.7/3B solar flare • solar proton events GOES-8  10 MeV ~5x104 increase  50 MeV ~3x104 increase  100 MeV ~2x104 increase • ground level enhancement  15 neutron monitors  solar protons up to 3 GeV  are there higher energy protons produced too ? days of July 2000

  15. THE INTENSE SOLAR FLARE OF 14th JULY 2000 E > 20 GeV : whole sky search by L3C data  3  excess seen for + in 10 min after 14:14 UT statistical fluctuation (~104 trials)

  16. THE INTENSE SOLAR FLARE OF 14th JULY 2000 E = 7-20 GeV : search in L3 shaft direction  data whole day, several time windows (8 min) no excess seen in „flare direction at flare time“

  17. WHAT IS THE ORIGIN OF „COSMIC“ RAIN ? from: Aglietta et al., ICRC1999, V7, 351

  18. EPISODES OF RATE INCREASE AT LOW ENERGIES all 50 EAS scintillator rates monitored at sec time scale  detectors are sensitive to ~MeV particles and photons  46 episodes seen since April 2000 ( 1h,  5% increase) no increase rain induced ? rain+sun induced ?

  19. EPISODES OF RATE INCREASE AT LOW ENERGIES new detector arrangement rates during rainfall rate increase most probably due to low energy electrons and photons from aerosols containing radio nucleids  no rate increase due to muons  no rate increase for shower trigger

  20. OTHER TOPICS UNDER STUDY WITH L3+COSMICS DATA ***extended muon spectrum analysis (systematics, angular dependence) *** moon shadow, sun shadow *** gamma ray bursts, sources *** large scale anisotropies *** long distant time correlations ( L3+Cosmics – CosmoAleph ) *** searches for exotic particles

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