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

RECENT RESULTS FROM L3+COSMICS

AT CERNL3 - 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 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

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

THE VERTICAL ATMOSPHERIC MUON SPECTRUM

.from Bugaev E.V. et al., Phys. Rev. D58 (1998) 5401 from Hebbeker T., ICHEP 2000, Osaka

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


correct for detector inefficiencies:

scintillator efficiency -chamber efficiency


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


a subjective comparison:

errors given for L3C: „statistical“have to use covariance matrix

NEWS ABOUT COSMIC PRIMARIES ?

from:Kampert et al., ICRC1999, V3, 156

THE NEW POSSIBILITIES OF L3COSMICS

EAS determines shower: L3C determines:

direction (arrival time) direction

core position (charge density) momentum (±)

energy ( MIPS) number

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

THE SUN: A SOURCE OF MULTI-GEV MUONS ON EARTH ?

from: Karpov et al., Nuovo Cimento 21 (1998) 551

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



ground level enhancement

15 neutron monitors

solar protons up to 3 GeV

are there higher energy protons produced too ?


E > 20 GeV : whole sky search by L3C data

3 excess seen for + in 10 min after 14:14 UT statistical fluctuation (~104 trials)


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“

WHAT IS THE ORIGIN OF „COSMIC“ RAIN ?

from: Aglietta et al., ICRC1999, V7, 351

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 ?

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

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

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

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