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ENERGY ESTIMATE OF NEUTRINO INDUCED UPGOING MUONS
WITH THE MACRO DETECTOR


HEP2001, Budapest, July 14

E. Scapparone INFN-LNGS

for the MACRO
Collaboration
Goal Study of atmospheric muon neutrino
oscillations using an energy
estimate of the upgoing muons by a Multiple
Coulomb Scattering (MS) analysis
Experimental procedure
- Use of the MACRO streamer tubes in drift mode,
using the MACRO monopole electronics (QTP
system), containing TDCs.
- Check with a dedicated test beam (CERN-PS)
- Definition of variables sensitive to MS
- Use of a neural network (NN) to separate
samples of events with different energies.
(L/E) analysis.
.
Results and perspectives
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SECTION OF THE MACRO DETECTOR
Neutrino analysis performed on several event
categories results all in good agreement with
(nm nt oscillation), strong internal
consistency.

nm
3 horizontal layers ot Liquid scintillators
m
7 Rock absorbers 25 Xo
14 horizontal planes of limited streamer tubes

hadrons
262 upgoing stopping downgoing stopping
154 Internal Upgoing
809 Up-througoing
nm
nm
nm
ltEn(GeV)gt
50 5 1
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UP THROUGOING MUON RESULTS
809 upgoing muons selected (1122 expected ).
Angular distribution distortion with respect to
no-oscillation hypothesis and deficit of upgoing
muon flux
Good agreement supposing nm nt
oscillation with Dm2 2.5 . 10-3 eV2 ,
sin2 2q 1

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If the n oscillation is the origin of such
effect, an energy dependence MUST be present.
Hadrons lost ( sigh ! )
m part of energy lost in rock, residual energy
can be measured. - The only possibility for
MACRO Multiple scattering(MS)
MACRO MS PARAMETERS a) 25 Xo ( rock
absorbers iron ) amount of MS b) 14 samples
splaneq
accuracy c) s streamer tubes system 1 cm
saturation
at Em10 GeV, sYplane sstreamer tubes
sYplane 10 cm/GeV
The space resolution has to be improved.
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The IDEA to use the slow monopoles electronics
(QTP) contoining TDCs to operate the streamer
tubes in drift mode. Monte Carlo simulation
shows its feasible, but such electronics was not
designed for this goal ( hot effects ? ) a test
was mandatory.
MACRO TEST BEAM (CERN-PS Nov. 2000)
Main goals

Each chamber was equipped with a QTP channel
standard TDC
ABSOLUTE CALIBRATION of
energy, reconstructed by multiple scattering.

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CERN PS
T9 - Nov. 2000
55 RUNS with 2 GeV lt Em lt 15 GeV
3 liquid scintillators
7 rock absorbers
m beam
4 streamer tubes
(MACRO attico)
10 streamer tubes
(MACRO lower part)
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The test beam showed a correct performance of
the electronics Method appplied to MACRO DATA
DOWN GOING MUON RESIDUALS
DISTRIBUTION
NO QTP (streamers in digital mode) s 1 cm
With QTP s 3 mm
An improvement of a factor 3.5 !
NIM paper soon.
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USE OF A NEURAL NETWORK (NN) JETNET 3.4 TO
SEPARATE SAMPLES OF DIFFERENT ENERGIES
Training at fixed E,q
- Average residuals
- Max residuals
- s of residuals distribution
- Slope of progressive fit
Neural Network
- Intercept of progressive fit
- Diff. of residuals for the 3
more distant tubes
0. lt Output lt 1.
NN OUTPUT
The NN response increases with energy up to 40
GeV
Log10( Em(G eV) )
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Real data 5.5 years of Macro livetime analysed (
Final Macro Configuration) Main selection cuts -
muon indentified as upgoimg by the MACRO
standard analysis - muon tracked in wire view and
strip view with q lt 600 - match between wires
digits and TDCs digits 348
events survived the cuts
m
Monte Carlo simulation live time 550 years FULL
SIMULATION Bartol group flux Neutrino
interactions QelRes.DIS(GRV94) Muon transport
FLUKA99 code( for each m !) Sampling of neutrinos
on a half-sphere of 2.6 Km radius
Macro
n
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MACRO shows a upgoing muon deficit and an angular
distorsion with respect to Monte Carlo. If the
oscillation is the motivation of that
The results
L 6500 Km(q 60o)
P(nm nm)
13000 Km(q 0o)
En(GeV)
IF YES,
THAN Beyond a given energy, for Dm2 10-3 eV2
,the oscillation effects MUST vanish ( if the
oscillation is the motivation of the MACRO
deficit and angular distortion)
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OUTPUT OF THE NEURAL NETWORK APPLIED TO THE
SPECTRUM OF NEUTRINOS WE CAN SUCCESFULLY SEPARATE
THE SPECTRUM IN FOUR ENERGY WINDOWS !
Median neutrino energy 12 GeV
Median neutrino energy 25 GeV
(A.U.)
Median neutrino energy 50 GeV
Median neutrino energy 120 GeV
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Monte CARLO no oscillation
fit shape only fit shapenorm.
c2 7.5/5 DoF P 18.3
c2 11.2/5 DoF P 4.8
c2 /DoF14.9/5 P 1.
c2/DoF 16/5 P0.6
c2 3.55/5 DoF P 61.6
c2 1.15/5 DoF P 95
c2 /DoF 4.4/5 P 50
c2 /DoF5.8/5 P 32.
c2 IS RUNNING WITH THE ENERGY !!!!
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fit shape only fit shapenorm.
Monte Carlo with oscillation ( Dm22.5 10-3 eV2 ,
sin22q1)
c2 5.5/5 DoF P 35.
c2/DoF 8.2/5 P 14.
c2 6.7/5 DoF P 24
c2/DoF 8.9/5 P 11.
c2 2.3/5 DoF P 80. c2 2.3/5 DoF P 80.

c2 1./5 DoF P 96.2 c2 1.3/5 DoF P 93
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Event by event analysis
NN calibration
Log10(En) reconstructed
Log10(Em) reconstructed
Saturation _at_ 200 GeV
Saturation _at_ 40 GeV
Log10(Em) true
Log10(En) true
.. MACRO can easily measure Ln, by tracking the
muon...
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DATA/MC(no oscillation) as a function of
reconstructed L/E
... another proof of the consistency of our
results with nm oscillation.
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RESULTS PERSPECTIVES
QTP analysis was successful to improve the MACRO
space resolution ( factor 3.5 , from s1 cm to s
3 mm )
The MACRO CERN PS test beam no hot effects
for QTP electronics used to operate streamer
tubes in drift mode.
The simulation properly reproduces drift
velocity, streamer tube space resolution, etc.
The output of the neural network increases with
m energy, up to Em40 GeV. Good agreement with
test beam data.
MACRO n induced upgoing muons can be divided and
studied in different energy samples. Good
agreement with oscillation hypothesis.
Study of neutrino oscillations in terms of (L/E)
where the muon energy is reconstructed event by
event again good agreement with the oscillarion
hypothesis
Coming soon allowed region (Dm2, sin22q) using
muon energy estimation