1. 2. Present Understandings
Solar, Kamland
MSW-LMA
Atmospheric
Oscillation!
Decay, decoherence
LSND and Sterile

2. Solar neutrinos (Non-historical)

3. Neutrino Production in the Sun
Light Element Fusion Reactions
p + p 2H + e+ + e
99.75 %
p + e- + p  2H + e
0.25 %
3He + p 4He + e+ + e
~10-5 %
7Be + e- 7Li + e
15 %
8B  8Be* + e+ + e
0.02 %

4. Types of Experiments Radio-Chemical
ft-value of b decay can give cross sections with a few % accuracy
n +A(Z,,N)→e + A’(Z+1,N-1)
Give rates
37Ar(g.s.) - 37Cl = 0.816MeV
Convenient Ar life time (t = 35 days)
71Ge(g.s.)-71Ga=0.233MeV
electron capture (t = days)

5. Real time measurements
Water Cherenkov Super-Kamiokande
n +e → n + e
well defined by standard model s (ne) ; s (nm,nt)=1:1/6
forward peaked
Heavy water Cherenkov :SNO
n + e → n + e
Same as water
n + d → e + p + p (CC)
measure ne component, slightly backward peaked
n + d → n + p + n (NC)
same cross section for all neutrinos, thermalized neutron capture,

6. Sudbury Neutrino Observatory
2092 m to Surface (6010 m w.e.)
PMT Support Structure, 17.8 m
cm PMTs
~55% coverage within 7 m
Acrylic Vessel, 12 m diameter
1000 tonnes D2O
1700 tonnes H2O, Inner Shield
5300 tonnes H2O, Outer Shield
Urylon Liner and Radon Seal
Energy Threshold = MeV

7. Neutrino Reactions in SNO
Produces Cherenkov
Light Cone in D2O CC n + d  p + p + e− e
Q = MeV
good measurement of ne energy spectrum
some directional info  (1 – 1/3 cosq)
ne only
n captures on deuteron
2H(n, g)3H
Observe 6.25 MeV g NC x n +  p d
Q = 2.22 MeV
measures total 8B n flux from the Sun
equal cross section for all n types n +  +
Produces Cherenkov
Light Cone in D2O ES e− n e− x x
low statistics
mainly sensitive to ne, some n and n
strong directional sensitivity

8. Shape Constrained Signal Extraction ResultsCC
1967.7
+61.9
+60.9
+26.4
+25.6 ES
263.6
+49.5
+48.9 NC
576.5
#EVENTS

9. Shape Constrained Neutrino Fluxes
Signal Extraction in FCC, FNC, FES with
E > MeV
Fcc(ne) = (stat.) (syst.) x106 cm-2s-1
+0.06
-0.05
+0.09
-0.09
Fes(nx) = (stat.) (syst.) x106 cm-2s-1
+0.24
-0.23
+0.12
-0.12
Fnc(nx) = (stat.) (syst.) x106 cm-2s-1
+0.44
-0.43
+0.46
Signal Extraction in Fe, Fmt

10. SNO NC in D2O (April 2002)
~ 2/3 of initial solar ne are observed at SNO to be nm,t
Flavor change
at 5.3 s level.
Sum of all the fluxes agrees with SSM.
FSSM = 5.05
+1.01
- 0.81
106 cm-2 s-1
FSNO = 5.09
+0.46
-0.43
+0.44
-0.43
106 cm-2 s-1
Phys. Rev. Lett. 89 (2002)

11. What have been clarified
NC measurement confirmed main sequence star calculation
SNO-NC = SSM calc. = .
electron neutrino component for >5MeV reduced to ~35% of SSM

12. The Solar Neutrino deficiencies
Experiment Exp/SSM
SAGE+GALLEX/GNO
Homestake
Kamiokande+SuperK 0.47
SNO CC
We need survival probabilities of
8B: ~1/3
7Be: <1/3
pp: ~2/3
Hard to accommodate by vacuum oscillation

13. Definition of mixing angle and components
Define n1, n2 such that m2 > m Dm2 >0
Small angle solution n1~ne, n2 ~ nx
Large angle solution
q>45o cos2q <0 equivalently negative Dm2
Ares (>0) =Dm2 cos2q is not realized
Matter effect determine sign of (m22-m12)

14. MSW in the Solar neutrinos
In(Dm2) m2 n2 m1
In(sin2q)
Matter in earth may regenerate ne more events in the night!

15. Matter-Enhanced Neutrino Oscillations
Pee
Spectrum
Neutrinos produced in weak state e
High density of electrons in the Sun
Superposition of mass states 1, 2, 3 changes through the MSW resonance effect
Solar neutrino flux detected on Earth consists of e + m,t
Day/night
Spectrum

16. Super-Kamiokande
Known 8B- b decay spectrum predict spectrum of neutrinos
Spectrum distortion
Day-Night comparison

17. Bad fit for SMA and Just-so(vacuum oscillation) solutions.
(0.75, 6.310-11eV2) Justso
(6.310-3, 510-6eV2) SMA
(0.8, 3.210-5eV2) LMA
Bad fit for SMA and Just-so(vacuum oscillation) solutions.

18. Energy distribution for day/night-6binsZ
mantle
core
Day
MAN5
CORE
MAN4
MAN3
MAN2
MAN1 SK
SK 1258 days kt
SSM = BP new B8 spec.
(Preliminary)

19. zenith spectrum shape alone using SSM 8B  flux prediction
SK Constraint on mixing parameters
zenith spectrum shape alone
using SSM 8B  flux prediction
Excluded Regions
Allowed Regions
Phys. Lett. B (2002) 179

20. 391-day salt phase flux measurements
vertex
SSM 68%CL
SNO NC 68%CL
SNO CC
68%CL
SNO ES
SK ES
cosqsun
~ isotropy CC NC

21. global solar data with 391-day SNO salt

22. Kamland

23. KamLAND detector Photo - coverage: 34% ~ 500 p.e. / MeV 13m 1000m
Cosmic ray 's are suppressed
by 1/100,000.
20 inch : 225
13m
1,000 ton liquid scintillator
Dodecane : 80%
Pseudocumene : 20%
PPO : 1.5g/l
Mineral oil
Dodecane : 50%
Isoparaffin : 50%
1.75m thickness
KamLAND is located 1000m underground in Kamioka mine, and muon event rate is about 0.34Hz.
The detector consist of 1000 tons of ultra-pure liquid scintillator and 1879 PMTs
17 inch :1325
20 inch : 554
~8000 photons / MeV
λ: ~10m
Photo - coverage: 34%
~ 500 p.e. / MeV

24. e e- Greatly removes backgrounds ν detection in KamLAND e+ Position
e+ + n e
(0.51)
Prompt e+ signal e e- e+
Te++annihilation
=Eν - 0.8MeV
Te+ p
E1.8MeV
(0.51) n
 (2.2 MeV) p
Delayed γ by
neutron capture
~210μs
Position
Time correlation
delayed energy information
Neutrinos are detected by the inverse beta-decay reaction.
Space and time correlations of prompt and delayed signal provide effective background reduction. d
Greatly removes backgrounds

25. Reactors near the KamLAND
80% of total contribution comes from 130~220km distance
effective distance ~180km
This map shows the location of the Japanese power reactors and KamLAND.
And this figure shows distances from KamLAND to reactors and thermal power of reactors.
80% of total contribution comes from 130 ~ 220km distance.
KamLAND group also calculate effects from reactors of other countries, Taiwan effect is about 0.1%
Reactor neutrino flux,
~95.5% from Japan
~3% from Korea
(2nd result period)

26. Energy Spectrum
This figure shows energy spectra of KamLAND data, no oscillation expected, scaled no oscillation expected, and backgrounds.
From the hypothesis test of scaled no-oscillation, spectral distortion is 99.6% confidence level.
And we use rate with shape information, no oscillation is excluded at % confidence level.
Hypothesis test of scaled no-oscillation: χ2/ndf = 37.3/18 ⇒ spectral distortion at > 99.6% C.L.
Rate + Shape: no oscillation is excluded at % C.L.

27. L/E plot with data for geo-ν analysis
(759 days, 5m fiducial)
low energy window
best fit reactor +
geo-neutrino model prediction
Oscillation pattern
with real reactor
distribution
Lo = 180 km is used for KamLAND
There is clear Oscillatory behavior (peak and dip)
oscillation parameter is determined.

28. q12 -Solar(ne) and Reactor(ne) Neutrino -
hep-ex/

29. Two mass eigen-states have Dm2 ~8x10-5 eV2
Lighter mass state contain ne more than 50% 8

30. Atmospheric Neutrinos
Mixture of ne, ne, nm & nm
Primary cosmic rays
nm+nm flux nm
(protons, He, , ,) 3D
calculation
L=10~20 km
p, K m
En(GeV) nm e
p→m+nm
→e+nm+ne
Flux ratio
Low EnergyLimit
nm : ne = 2 : 1 ne nm
nm+nm
ne+ne 2
En(GeV)

31. Event topology ne + N  e + X nm + N  m + X nt + N  t + X PCFC PC
Initial neutrino energy spectrum
Stopping muons
Through-going muons
FC + PC
Interaction in the rock
stopping muons
through-going muons

32. A half of nm lost!

33. p=1 GeV/c, sin2 2q=1 Dm2=310–3(eV/c2)2
Earth
~6000 km
Survival Probability
p=1 GeV/c, sin2 2q=1 Dm2=310–3(eV/c2)2
Half of the up-going ones get lost

34. Cross Section of nt
interacts very weakly with matter (nucleons) due to
threshold effect of charged lepton mass
Disappearance of neutrinos
if nm→nt in atmospheric n
nm CC
nt CC
En(GeV)

35. SK-I Zenith angle distributions (w/ 100yr MC)
SK-I Atmospheric n Full Paper
hep-ex/
1R e
1R m
MR m
up-m
<400MeV
<400MeV
sub-G
stopping
1R e
1R m
MR m
up-m
Number of events
>400MeV
>400MeV
multi-G
through
1R e
1R m
cosQ
data PC
CR MC F? s?
multi-GeV
multi-GeV
w/ oscillation fit
cosQ
cosQ
cosQ up
down

36. L/E analysis and Parameter determination
All the data
1489.2days
Data/prediction
100
1000
L/E (km/GeV)
Rejected events
horizontally going events:  due to large dL/dcosq
low energy events:  due to large qnm angle
Guide line
L/E (km/GeV)
Data/prediction
2726 events (3726 ev. expected)
~ 1 /5 of total data

37. Result of L/E analysis (SK-I)
The first dip has been observed at ~500km/GeV
This provide a strong confirmation of neutrino oscillation
The first dip observed cannot be explained by other hypotheses
days FC+PC
Decoherence
Decay
(%)
Resolution Cuts
vs Dc2
Dc2
Mostly PC through-going
Decay rejected at 3.4 sigma
Decoherence rejected at 3.8 sigma
Oscillation
3.4 s to decay
3.8 s to decoherence

38. Constraint on the neutrino oscillation parameters from L/E analysis
Best Fit (Physical Region)
Dm2=2.4x10-3,sin22q=1.00
c2min=37.8/40 d.o.f.
(sin22q=1.02, c2min=37.7/40 d.o.f)
Dm2
Allowed region
1.9x10-3 < Dm2< 3.0x10-3 eV2
0.90 < sin22q
Consistent with the standard zenith angle analysis
1.5x10-3 < Dm2 < 3.4x10-3 eV2
0.92 < sin22q

39. nm →Sterile ?

40. matter effect in the earth for sterile neutrinos
PC, Evis>5GeV
<Eν>～25GeV
up/down ratio ns ns Z
νμーνs
νμーνs n
νμーντ
νμーντ
up through going μ
<Eν>～100GeV
vertical/horizontal ratio n
Compare high-low energy events

41. Three Flavor Mixing in Lepton Sector
mass eigenstates
Weak eigenstates m1 ne m2 nm nt m3
cij = cosqij, sij=sinqij
Atm.
Sol.
q12, q23, q13
+ d (+2 Majorana phase)
Dm122, Dm232, Dm132

42. q13

43. CHOOZ 425 GWth L=1km 5t Liquid Scintillator H richparaffin
Gd loaded (g 8MeV)
sin22q13 <0.10 9°
90%CL
sin22q13 <0.17
12°

44. Two mass eigen-states have Dm2 ~8x10-5 eV2 Define n1, n2 such that
mn2 > mn1
Solar n MSW in neutrino (not anti-neutrino)
n1 is the largest component in ne
Third mass eigen-sate (n3) is separated by Dm2 ~ ±3x10-3 eV2
Small ne component in n3 (n3 consists of nm, nt, almost 50;50) which is larger in nt ? (q23<p/4 ?)
neutrino mass and charged lepton mass ordering
same or inverted 8
atm.
3x10-3eV2

45. LSND/KARMEN Experiment

46. The LSND Experiment View of the PMTs inside
the detector vessel. (Vessel
is filled with scintillator oil.)

47. Decay at Rest (DAR) Signal Prompt e+ Delayed g from n-capture
Small intrinsic ne contamination
few x 10-4

48. Gamma Ray Distribution

49. LSND Final Results

50. ISIS and KARMEN

51. KARMEN Distributions

52. KARMEN and LSND

53. ‘Evidence’ of oscillations Cannot be accommodated in three neutrinos
sin2 2q
Dm2 (eV2)
nmne
nenm,nt
nmnt
(m22 –m12) +(m32 –m22)+
(m12 –m22)=0 ; need more than 3 mass eigen-states
number of neutrinos, which couple to Z is 3
Sterile n or exotics or faulty experiment
First, existence of the LSNDeffect…..

54. MiniBooNE Overview

55. MiniBooNE Flux

56. Approximate number of events and Background expected in MiniBooNE
nm Charged Current, Quasi-elastic
500,000 events
Intrinsic νe (from K&μ decay) : events
Background
π0 mis-ID: events
(Neutral Current Interaction)
Other νμ mis-ID: events
Signal
LSND-like nmne signal: events

57. Particle Identification: m, e, and p0
Neutrino interactions in oil produce:
Prompt Čerenkov light in a cone centered on the track.
Delayed scintillation light distributed isotropically.
Čerenkov to scintillation ratio ~ 4 to 1
Particle ID is based on ring fuzziness, track length, ratio of prompt/late light.
Fuzzy rings distinguish electrons from muons.
p0 look like 2 electrons (usually)
Short
Exiting

58. Sensitivity to a Signal
Mis-ID
Intrinsic νe
Δm2 = 1 ev2
Δm2 = 0.4 ev2

59. Present constraints Dm13, q13 Dm12, q12 Dm23, q23 SK Atm n K2K
Reactor
K2K
SK Atm n
K2K
Dm122 (10-5eV2)
sin22q13<~0.15
(q13<~10deg)
@Dm13~2.5x10-3eV2
Dm13 unknown
sin22q23 > 0.93
2.1 < Dm232 < 3.0×10-3eV2
(SK Zenith 90%CL)