RECENT RESULTS FROM L3+COSMICS AT CERN L3 - COLLABORATION presented by
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Transcript of RECENT RESULTS FROM L3+COSMICS AT CERN L3 - COLLABORATION presented by
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RECENT RESULTS FROM L3+COSMICS
AT CERNL3 - COLLABORATION
presented by
R. Nahnhauer - DESY Zeuthen
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THE L3+COSMICS EXPERIMENT
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LOCATION: 6.02 E, 46.25 N
L3C under 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
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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
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THE VERTICAL ATMOSPHERIC MUON SPECTRUM
.from Bugaev E.V. et al., Phys. Rev. D58 (1998) 5401 from Hebbeker T., ICHEP 2000, Osaka
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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
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THE PRELIMINARY L3C SPECTRUM
correct for detector inefficiencies:
scintillator efficiency -chamber efficiency
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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
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THE PRELIMINARY L3C SPECTRUM
a subjective comparison:
errors given for L3C: „statistical“have to use covariance matrix
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NEWS ABOUT COSMIC PRIMARIES ?
from:Kampert et al., ICRC1999, V3, 156
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THE NEW POSSIBILITIES OF L3COSMICS
EAS determines shower: L3C determines:
direction (arrival time) direction
core position (charge density) momentum (±)
energy ( MIPS) number
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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
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THE SUN: A SOURCE OF MULTI-GEV MUONS ON EARTH ?
from: Karpov et al., Nuovo Cimento 21 (1998) 551
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THE INTENSE SOLAR FLARE OF 14th JULY 2000
10:24 UT, region 9077
X5.7/3B solar flare
days of July 2000
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 ?
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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)
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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“
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WHAT IS THE ORIGIN OF „COSMIC“ RAIN ?
from: Aglietta et al., ICRC1999, V7, 351
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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 ?
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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
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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