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Final results on atmospheric oscillations with MACRO at Gran Sasso
Bari, Bologna, Boston, Caltech, Drexel, Frascati, Gran Sasso, Indiana, L’Aquila, Lecce, Michigan, Napoli, Pisa, Roma1, Texas,
Torino, Oujda
• Gran Sasso Lab. – MACRO
• oscillations. Atmospheric neutrinos
• Upthroughoing muons (E 50 GeV )– Zenith distribution– Absolute value– L/E distribution: E from M.C.S.
• Monte Carlos
• Semicontained muons Upstopping muons
• Combining all information
• Conclusions
E 4 GeV
G. GiacomelliUniversity of BolognaEPS, Aachen
RatioAbsolute value
- Oscillations
Weak flavour eigenstates e, ,
Mass eigenstates 1, 2, 3
Decays, Interactions + + , n -p
Propagation 1(t) = 1(0) e-E t
Mixing 1 = 3m = 1 Ulm m
2-Flavour = 2 cos23 + 3 sin 23
Mixing = -2 cos23 + 3 sin 23
Oscillations in Vacuum (over a distance L)
Disappearance P( ) = 1 – sin2 223 sin2 (1.27 m2
23 L/E)
Appareance P( ) = 1 – P( )
m223 = m2
3 – m22
Simple formulae -Additional flavour oscillations
Modified by -Matter effects
In case of -Neutrinos have masses m ≠ 0
Oscillations -Le, L, L, L violation
-neutrino decays
E : 0.1 GeV 100 GeV
L : 20 km 13000 km
L/ E : 1 km/GeV 105 km/GeV
Downgoing : “near” neutrino source
Upgoing : “far” neutrino source
Atmospheric neutrinos
The MACRO detector
3 types of Scintillators ( 600 t)Subdetectors Streamer tubes
Nuclear track detectors
Acceptance in : 10-4 1S 10,000 m2 sr for isotropic flux
12 m horizontalDimensions: 76.6 m in length
9.3 m height
Subdivided in 6 supermodules, with a lower
and an upper part
NIM A324(1993)337NIM A486(2002)663
MACRO cross section (schematic)
Upthroughgoing muons
MC SIMULATION (17% scale error):Bartol Group flux Phys. Rev. D53 (1996) 1314 inter. Cross sections: Z. Phys. C67 (1995) 433 Transport in the rock CERN-EP / 85-03 (1985)Detector simulation: GEANT3
Shape of zenith distribution + L/E distributionm2 = 2.5 10-3 eV2, sin2 2 = 1 Significance ~ 4.7
PL B357(1995)481PL b434(1998)451hep-ex/0206027
Monte Carlos
• New FLUKA and HKKM: complete three dimensional MCs with improved hadronic model
• Predictions of FLUKA and HKKM agree perfectly
• Shapes of zenith distributions with and without oscillations are the same in old Bartol flux, new FLUKA and new HKKM
• Using the latest primary Cosmic Ray fits:
Absolute values are ~ 20-30% lower than MACRO and SUPER K data
• Using previous Cosmic Ray fits:
Absolute values are 5-10% lower than MACRO, SUPER K
Need to improve these fits
L/E Distribution
● Black points : upthroughgoing data
○ Open point : Internal Up (IU) data
Green and red lines: MC predictions for
oscillations with the mentioned parameters
point-to-point syst. error (12%)Shaded region:
NIM A492(2002)376 hep-ex/0304037
Zenith distributions for IU and (ID+UGS)
Shaded regions: no oscillation MC (21% scale error)Black lines: MC predictions for oscillationswith m2 = 2.5 10-3 eV2 and sin2 2 = 1
Data are in agreement with MCOSC with the quoted parameters
262 events
164 events
< E > 4 GeV
PL B478(2000)5hep-ex/0206027
Combination of indipendent data
Zenith distrib.
Energy measur.
).(cos).(cos4070
1
NN
NN
Rhoriz
vert
highE
lowE
NN
R 2
H.E.50 GeV
L.E.4 GeV )(
)(ainedupsemicontN
ntaineddownsemicoupstoppingNR
3
Absolute H.E. Scale error 17%
Values L.E. Scale error 21%
MACRO data are consistent with
oscillations, with Maximal mixing m2 = 0.0023 eV2
( 5 significance)
Conclusions