Experimental Neutrino Physics

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Experimental Neutrino Physics

• Kai ZuberUniv. of Oxford/ Univ. of Sussex

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How to explain absolutely everything about
neutrino physics in 45 mins
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Contents

• Status of neutrino oscillation searches
• Determination of the PMNS matrix elements
• Absolute neutrino mass measurements
• Summary and conclusions

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Neutrino oscillations
Mass eigenstates might not be identical to
flavour eigenstates
2 Flavour scenario
oscillation probability
with
sensitivity
2 unknown parameters sin22?, ?m2
NO measurement of absolute neutrino mass !
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The LSND Evidence
87.9 22.4 6.0 eventsabove background,
about4 ? evidence
Most of allowed parameters in contradiction with
KARMEN and NOMAD
A. Aguilar et al, PRD 64, 112007 (2001)
Combined analysis of KARMEN and LSND
(E.D. Church et al, PRD 66, 013001 (2002))
Region around 0.1 lt ?m2 lt 10 eV2 still possible
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MiniBooNE
? Parallel session

• Use protons from the 8 GeV booster ? Neutrino
  Beam ltEngt 0.5 GeV
• Detector
• 12 m sphere filled with 950 000 liters of pure
  mineral oil and about 1500 PMTs
• Located at about 500m from neutrino source

?
e
?0
electron energy calibration
Need 1021 pot, about 30 achieved
Spectrum
27 oscillation
33 intrinsic
40 misID
First results in 2005
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SK-Zenith angle dependence
Deficit in upward going muons
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High Resolution L/E Analysis
T. Ashie et al, hep-ex/0404034
Oscillation probability shows sinusoidal L/E
dependence
downward
upward
stronger constraint on ?m2
dip at about 500 km/GeV
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K2K
? Parallel session
Analysis based on 8.9 ? 1019 pot
Best fit value in physical region sin2 2?
1.00 , ?m2 2.73 ? 10-3 eV2
Oscillations confirmed at 3.9 ?
Oscillation confirmed as ?? deficit and ?e
spectral distortion
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MINOS
? Parallel session
Sensitivity
732 km
5.4 kt magnetizediron spectrometer
Near detector underconstruction
Beam expected in December 2004
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CERN - Gran Sasso (CNGS)
OPERA
lead-emulsion sandwich
about 206 000 blocks
hall C at LNGS
LAr TPC
ICARUS
(electronic bubble chamber)
T 600 at LNGS
Beam by 2006
Expect about a dozen ?-events in both experiments
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AQUA-RICH
Use RICH technique and HybridPhotoDiodes
Multiple scattering provides momentum information
Simulation
Hardware
5 HPD
scatt. angle
momentum (GeV)
A. Großheim, K. Zuber, acc. by NIM A
3 t prototype at CERN
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Solar neutrinos
pp-cycle
0.01 of total flux
Ga
Cl
Ckov
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Super-Kamiokande
NO significant day/night asymmetry
SK-II data consistent with SK-I data
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SNO The smoking gun
1000 t heavy water (D20)
n
n
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SNO Run Sequence
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SNO Results
? Parallel session
S.N.Ahmed et al, PRL 92, 181301 (2004)
Matter effects at work (Large Mixing Angle)
Disfavours maximal mixing at 5.4 ? level
Results on invisible nucleon decay modes N ????
PRL 92, 102004 (2004)
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KamLAND
? Parallel session
-

• Large number of nuclear power plantsaround
  Kamioka mine
• Concentration atabout 160 km distance
• Test of LMA solution

?e p ? e n
1000 t Liquid scintillator
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KamLAND - Results
365 ? 24 events expected, 258 observed
K. Eguchi et al, PRL 90,021802 (2003)
LMA solution is correct
T. Araki et al, hep-ex/0406035
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Oscillation evidences
LSND
sin2 2? 10-1-10-3 , ?m2 0.1-6 eV2
Atmospheric
sin2 2? 1.00 , ?m2 2.1 ? 10-3 eV2
Solar reactors
sin2 2? 0.81 , ?m2 8.2 ? 10-5 eV2
If all three are correct... we need more (sterile
ones)
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Models of neutrino masses
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Other explanations
Super-Kamiokande
KamLAND
Decay rejected at 3.4 ?Decoherence rejected at
3.8 ?
Decay excluded at 95 CLDecoherence excluded at
94 CL
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Contents

• Evidence for neutrino oscillations
• Determination of the PMNS matrix elements
• Absolute neutrino mass measurements
• Summary and conclusions

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The PMNS matrix - 3 flavour case
only if neutrinos are Majorana particles
for neutrinos- for antineutrinos
Matter effects
Oscillation probabilities quite complex equations
All CP-violating effects are proportional to
8-fold degeneracy of parameters ? - sin 2?13, ?
- sign ?m312, ?23 - (?/2 - ?23)
M. Lindner, hep-ph/0209083
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?13 at reactors
Precision measurement, needs two identical
detectors
One close by, one at about 1-2 km
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Proposed sites around the world
Site Power (GWthermal) Baseline Near/Far (m) Shielding Near/Far (mwe) Sensitivity 90 CL
Krasnoyarsk, Russia 1.6 115/1000 600/600 0.03
Kashiwazaki, Japan 24 300/1300 150/250 0.02
Double Chooz, France 8.4 150/1050 30/300 0.03
Diablo Canyon, CA 6.7 400/1700 50/700 0.01
Angra, Brazil 5.9 500/1350 50/500 0.02
Braidwood, IL 7.2 200/1700 450/450 0.01
Daya Bay, China 11.5 250/2100 250/1100 0.01
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Sensitivity
small detectors - compare rates
large detectors - spectral shapes
Fits to spectral shape only
statistical errors only
P.Huber et al, hep-ph 0403068
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Future accelerator activities
Goal to measure ?13, CP violation, mass hierarchy
Requires precision measurements
Major issue Energy spectrum and composition of
neutrino beam

• Superbeams High intensity (MW) proton drivers
  , neutrino beam energies below 1 GeV

• Neutrino factories use muon decay, well
  predicted spectrum of ?e and (or vice versa)

• Beta beams Acceleration of beta unstable
  isotope, pure ?e (Ne-18) or (He-6) beam

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Ingredients
? Parallel session
X-section measurements
Hadroproduction
HARP 3-15 GeV at CERN PS MIPP 5-120 GeV at FNAL
MI NA49 100,160 GeV at SPS
Minerva
K2K, hep-ex/0408134
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Off axis beams
Loose intensity, but get narrow band beam
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No?a/ T2K-I
50.7 kt Liquid Scintillator
baseline about 810 km
T2K-I - 0.8 MW on SK
Start neutrino physics run in 2009
Start could be around 2009
T2K- II - 2 MW on HK
Hyper-Kamiokande
1 Mton water cerenkov detector
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Superbeams
Ep (GeV) Power (MW) Beam ltEngt (GeV) L (km) Mdet (kt) nmCC (/yr) ne _at_peak
K2K 12 0.005 WB 1.3 250 22.5 50 1
MINOS(LE) 120 0.4 WB 3.5 730 5.4 2,500 1.2
CNGS 400 0.3 WB 18 732 2 5,000 0.8
T2K-I 50 0.75 OA 0.7 295 22.5 3,000 0.2
NOnA 120 0.4 OA 2 810? 50 4,600 0.3
C2GT 400 0.3 OA 0.8 1200 1,000? 5,000 0.2
T2K-II 50 4 OA 0.7 295 500 360,000 0.2
NOnAPD 120 2 OA 2 810? 50? 23,000 0.3
BNL-Hs 28 1 WB/OA 1 2540 500 13,000
SPL-Frejus 2.2 4 WB 0.32 130 500 18,000 0.4
FeHo 8/120 4 WB/OA 13 1290 500 50,000
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Neutrino factories
Ultimate accelerator neutrino beam Use muon decay
Well definedflavour composition
HARP
Well knownenergy spectrum
MICE
Explore matter effects, CP-violation
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Sensitivity on sin2 2?13
8-fold degeneracy in parameters
5 years each
5 flux uncertainty
sin2 2?13
GLOBES code available (P. Huber et al,
hep-ph/0407333)
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Contents

• Evidence for neutrino oscillations
• Determination of the PMNS matrix elements
• Absolute neutrino mass measurements
• Summary and conclusions

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Mainz and Troitsk
Electrostatic filter with magnetic adiabatic
collimation (MAC-E)
Isotope 3H
Only about 10-13 electrons in the last eV
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Results
Alternative technique
Lowest Q-value (2.46 keV)
Usage of ?-calorimeters
Mainz and Troitsk m?e lt 2.2 eV (sensitivity limit)
Milano, Genoa m?e lt 15 eVProposal Down to
about 2 eV by 2007
pion decay m??lt 170 keV
tau decay m?? lt 18.2 MeV
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KATRIN-The ultimate beta-decay experiment
Discovery potential m?e 0.35 eV at 5?
Sensitivity m?e lt 0.2 eV (90 CL)
Commisioning in 2008
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Double beta decay
-

• (A,Z) ? (A,Z2) 2 e- 2?e 2???

• (A,Z) ? (A,Z2) 2 e- 0???

0
In nature there are 35 isotopes
2??? Seen in 9 isotopes, important for nuclear
physics input
0??? Only possible if neutrinos are Majorana
particles
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Measuring quantities
? Parallel session
T1/2 ln2 a NA M t / N?? (t??T)
Double beta decay Effective Majorana neutrino
mass
Signal sensitivity ? stat. precision of
background Nobs ?NBG
Background ? detector mass
T1/2 ? a ? (Mt/?EB)1/2

• a isotopical abundance

B

• M mass

• t measuring time

• ?E energy resolution

• B background (c/keV/kg/yr)

Q
E
Q?E/2
Q-?E/2
1 / T1/2 PS ME2 (m? / me)2
ltmeegt ? Uek2 mk
me ? Uek2 mk
??-decay
?-decay
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Heidelberg -Moscow

• Fünf Ge Dioden (Masse 10.9 kg)
• isotopenangereichert ( 86) in 76Ge
• Bleiburg and Stickstoffspülung Peak bei
  2039 keV

H.V. Klapdor-Kleingrothaus et al, Europ. Phys. J.
A 12, 147 (2001)
T1/2 gt 1.9 x 1025 yr (90 CL)
m lt 0.35 eV
Evidence ?
Subgroup of collaboration
T1/2 0.6 - 8.4 x 1025 yr
m 0.17 - 0.63 eV
H.V. Klapdor-Kleingrothaus et al, Phys. Lett. B
586, 198 (2004)
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Running experiments
CUORICINO cryogenic bolometers40.7 kg TeO2
T1/2 gt 7.5 x 1023 yr (90 CL)
NEMO-3 TPC
Future CUORE 760 kg TeO2 approved
10 kg enriched foils, 6 kg 100Mo
Idea Super-NEMO (100 kg)
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COBRA
Use CdZnTe semiconductors
K. Zuber, Phys. Lett. B 519,1 (2001)
Room temperaturetwo isotopesPixelisation/Segment
ation
Solid state TPC
4 detectors running at LNGS, upgrade to 64 by end
of 2004
Sensitivity to right-handed weak currents
106Cd
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Future - Ge approaches
? Parallel session
MAJORANA
500 kg of enrichedGe detectors
GENIUS/ ALTERNATIVEHD APPROACH
Segmentation and pulse shape discrimination
Naked enriched crystals in LN2or in LAr with
lead shield
20 kg enriched Ge-detectorsat hand (former HD-MO
and IGEX)
MERGE
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EXO
Tracking and scintillation
New feature
136Xe ? 136Ba e- e- final state can be
identified using optical spectroscopy (M.Moe
PRC44 (1991) 931)
200 kg enriched Xe prototype under construction
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Future projects
O.Cremonesi, n 2002
Experiment Author Isotope Detector description T5y1/2(y) ltmngt
COBRA Zuber 2001 130Te 10 kg CdTe semiconductors 1 x 1024 0.71
CUORICINO Arnaboldi et al 2001 130Te 40 kg of TeO2 bolometers 1.5 x 1025 0.19
NEMO3 Sarazin et al 2000 100Mo 10 kg of bb(0n) isotopes (7 kg Mo) with tracking 4 x 1024 0.56
CUORE Arnaboldi et al. 2001 130Te 760 kg of TeO2 bolometers 7 x 1026 0.027
EXO Danevich et al 2000 136Xe 1 t enriched Xe TPC 8 x 1026 0.052
GEM Zdesenko et al 2001 76Ge 1 t enriched Ge diodes in liquid nitrogen water shield 7 x 1027 0.018
GENIUS Klapdor-Kleingrothaus et al 2001 76Ge 1 t enriched Ge diodes in liquid nitrogen 1 x 1028 0.015
MAJORANA Aalseth et al 2002 76Ge 0.5 t enriched Ge segmented diodes 4 x 1027 0.025
DCBA Ishihara et al 2000 150Nd 20 kg enriched Nd layers with tracking 2 x 1025 0.035
CAMEO Bellini et al 2001 116Cd 1 t CdWO4 crystals in liquid scintillator gt 1026 0.069
CANDLES Kishimoto et al 48Ca several tons of CaF2 crystal in liquid scintillator 1 x 1026
GSO Danevich 2001 160Gd 2 t Gd2SiO5Ce cristal scintillator in liquid scintillator 2 x 1026 0.065
MOON Ejiri et al 2000 100Mo 34 t natural Mo sheets between plastic scintillator 1 x 1027 0.036
Xe Caccianiga et al 2001 136Xe 1.56 t of enriched Xe in liquid scintillator 5 x 1026 0.066
XMASS Moriyama et al 2001 136Xe 10 t of liquid Xe 3 x 1026 0.086
Staudt, Muto, Klapdor-Kleingrothaus Europh.
Lett 13 (1990) 31
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Neutrino masses from cosmology
New WMAP measurement 2dFGRS data
D.N. Spergel et al., astro-ph/0302209
A. Pierce, H. Murayama, hep-ph/0302131
S. Hannestadt, astro-ph/0303076
G. Bhattacharyya et al., hep-ph/0302191
Mass bound strongly correlated with other
cosmological parameters
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Apologies
and everything else I might have not mentioned...
Low energy real -time experiments -Borexino -KamL
AND-CLEAN -Xmass -LENS -MOON
Precisionmeasurements in ?N scattering -Weinberg
angle - Structure functions - ...
UHE neutrinos-Baikal -Nestor -Antares -Amanda -Ic
ecube-Auger
Supernovaneutrinos
Neutrinos in Cosmology
Relic 1.96 K neutrino background
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Summary

• Neutrino physics made extreme progress in the
  last decade
• A non-vanishing neutrino mass is established due
  to oscillation results
• Solar neutrino problem basically solved (matter
  effects, LMA)
• Next steps Confirm/Disprove LSND (MiniBooNE),
  work on atmospheric neutrino parameters (K2K,
  MINOS, tau-appearance with ICARUS/OPERA)
• Long term Determine PMNS matrix elements,
  explore ?13 (reactors beams, factories),
  ultimate goal leptonic CP violation
• Different, but important issue Absolute
  neutrino mass scale, beta and double beta decay
  searches, likely have to go to 50 meV or less
• Double beta unique in probing fundamental
  character of neutrinos (Majorana particles) and
  a handle on Majorana CP-phases

Exciting times behind us, very exciting time in
front of us
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A lot to do ...
E. Ma, UCR
?13
PMNS
mass hierarchy
??-decay
leptonic CPV