Final results on atmospheric oscillations with MACRO at Gran Sasso Bari, Bologna, Boston, Caltech,...
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Transcript of Final results on atmospheric oscillations with MACRO at Gran Sasso Bari, Bologna, Boston, Caltech,...
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