Results and plans
of the
KamLAND experiment
Yoshihito Gando (RCνS, Tohoku Univ.)
for the KamLAND Collaboration
ICFP2005 @ Chung-li, Taiwan, 4 October 2005
Various Physics Targets
with wide energy range
0.4
1.0
2.6
8.5
Visible energy [MeV]
neutrino electron elastic scattering
inverse beta decay
7
Be solar neutrino
geo-neutrino
reactor neutrino supernova relic neutrino
etc.
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ÅB
Neutrino Astrophysics
Neutrino Geophysics
Neutrino Physics
Neutrino Cosmology
verification of SSM
verification of earth
evolution model
Precision measurement
of oscillation parameters
verification of
universe evolution
future
2nd phase
Nature 436, 28 (2005)
1st results
Solar
PRL 90, 021802 (2003) PRL 92, 071301 (2004)
2nd results
PRL 94, 081801(2005)
KamLAND detector
1000m
Cosmic ray 's are suppressed
by 1/100,000.
20 inch : 225
13m
1.75m thickness
17 inch :1325
20 inch : 554
Photo - coverage: 34%
~ 500 p.e. / MeV
1,000 ton liquid scintillator
Dodecane
: 80%
Pseudocumene : 20%
PPO
: 1.5g/l
~8000 photons / MeV
λ: ~10m
Mineral oil
Dodecane : 50%
Isoparaffin : 50%
νe detection in KamLAND
e + p

e
e+ + n
p
E1.8MeV
(0.51)
Te+
e+ e-
Prompt e+ signal
Te++annihilation
=Eν - 0.8MeV
(0.51)
n
~210μs
• Position
• Time correlation
• delayed energy information
p
d
 (2.2 MeV)
Delayed γ by
neutron capture
Greatly removes backgrounds
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Reactor Neutrino
Reactors near the KamLAND
PThermal (MW/ cm 2 )
80% of total contribution comes from
130~220km distance
effective distance ~180km
Reactor neutrino flux,
~95.5% from Japan
(2nd result period)
~3% from Korea
Reactors in Taiwan have
~0.1% contribution.
Event Selection
Delayed Coincidence:
Prompt Energy Window:
2.6 < Eprompt < 8.5 MeV
0.5 < ΔT < 1000μsec
ΔR < 200 cm
1.8 < Edelayed < 2.6 MeV
Fiducial Volume:
Rprompt < 550 cm (500 :1st result)
Rdelayed < 550 cm (500 : 1st result)
μ
3m
9Li
Spallation Cuts:
ΔTμ < 2 msec
ΔTμ < 2 sec (showering muons)
or
ΔTμ < 2 sec (showering muons)
ΔL < 300 cm (non-showering)
Isotope Halflives
Decay Mode
9Li/8He 178.3ms/119.0ms β－ + n
Efficiency : 89.82%(I,II), 89.83%(III)
Time Variation of Reactor ν
Expected event rate
Observed event rate
First result
Expected signal : 86.8±5.6
BG
:1±1
Observed : 54
Neutrino disappearance at 99.95%
• R = 0.658 ±0.044(stat) ± 0.042(syst)
⇒ neutrino disappearance at 99.998% C.L.
High statistic from 1st result
oscillation study
Energy Spectrum
•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 99.999995% C.L.
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.
Oscillation Analysis
KamLAND best-fit (rate + shape)
KamLAND + Solar
assuming CPT invariance
m 2  7.9 10 -5 eV 2
tan 2   0.46
several orders -> less than 10%
m 2  7.9-00..65 10-5 eV 2
10
tan 2   0.40-00..07
Precise determination of oscillation parameters
made possible to use neutrinos as a new probe.
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Geo - Neutrino
Earth Energetics
• Terrible earthquakes, eruptions, etc. are originally caused
by mantle convection driven by heat.
• Terrestrial magnetism is caused by a core movement,
it requires some heat source.
• Observed Surface Heat Flow :
～44TW (31TW : re-evaluation)
• Radiogenic Heart : ~20TW ?
U-chain 8TW / Th-chain 8TW / 40K 3TW??? (BSE model)
• Radioactive heat sources contribute to about the half of the
total heat outflow of the earth.
• Geo-Neutrino is Produced by β-decay of radioactive
element in the earth
Methods of research about
inside of the earth
Seismic analysis
Meteorite analysis
Composition of the earth
(Proto material ) is presumed
by meteorite analysis
BSE (bulk silicate Earth) model
McDonough et al.(1995)
• Physical parameter
(density, elastic parameter etc…)
• It does not tell chemical composition
• Th/U mass ratio ~ 3.9
• It expect that 20TW comes
from radioactivity
• There are no direct measurements
Direct measurement is desired!!
Geophysics with Neutrino
• Determination of the amount and distribution of U,
Th in the earth from geo-ν observation
- Test for BSE model
Verification of basic paradigm of geochemical
earth formation and generation
- Determination of heat balance
Information for earth dynamics, evolution,
terrestrial magnetism
- Understanding of chemical composition of
deep interior of the earth
Determination of chemical structure model
(mantle model)
Reference Earth Model
Upper continental crust U : 2.8ppm / Th: 10.7ppm
Middle continental crust U : 1.6ppm / Th: 6.1ppm Rudnick et.al. (1995)
Lower continental crust U : 0.2ppm / Th: 1.2ppm
continental crust
Oceanic crust U: 0.08ppm / Th: 0.32ppm
Th/U ~3.9
Radiogenic heat ~16TW
U: 0ppm / Th: 0ppm
mantle
Core
U: 0.012ppm / Th: 0.048ppm
Ionic radius of U/Th are large
Core is very high density
do not exist
Mantle = Meteorite (BSE model) - Crust
U/Th distribution maps in Japan
Average component of upper continental crust
Geological map + rock sample (Togashi et al.)
U : 2.32 ppm
Th : 8.3 ppm
Assume the surface U, Th distribution extends to 5km in depth
Geo-neutrino flux is calculated from global
and local U, Th composition
Geo-Neutrino spectrum
238
U 
206
232
Th 
208
40
K

Pb  8 4 He  6 e -  6 ν e  51.7 [MeV]
Pb  6 4 He  4 e -  4 ν e  42.7 [MeV]
40
Ca  e -  ν e  1.31 [MeV]
Event Selection (Geo-ν)
Delayed Coincidence:
0.5 < ΔT < 1000μsec
ΔR < 100 cm
0.9 < Eprompt < 2.6 MeV
1.8 < Edelayed < 2.6 MeV
Fiducial Volume:
Rprompt < 500 cm
Rdelayed < 500 cm
ρxy > 120 cm
Spallation Cuts:
ΔTμ < 2 msec, total volume (for all muons)
ΔTμ < 2 sec, total volume (showering muons)
or
ΔTμ < 2 sec, ΔL < 300 cm (Non-showering muons)
Efficiency
U-Series : 69.2% , Th-Series : 68.0%
(α, n) Background
αcomes from 210Po decay
(daughter nuclei of 222Rn)
Unfortunately, we inputted 222Rn
at the construction
Recent paper shows
few % lower cross section of 13C (α,n) 16O
(Harissopulos et al, nucl-ex/0509014)
We could reduce about B.G. uncertainty
Expected spectrum
reactor
BG + Geo-ν
BG total
(α,n) reaction
Accidental coincidence
Reactor ν
Th-chain geo-ν
U-chain geo-ν
Expected + observed spectra
749.1 live days
Observed
152
B.G.
127.4±13.3
Signal
24.2±17.9
Rate + Shape analysis
Th/U Mass ratio=3.9
90%CL
2
NU+NTh
C.L. contours for detected
U and Th geo-s.
Th/U mass
Ratio=3.9
54.2
4.5
(NU-NTh)/(NU+NTh)
Prediction from
the BSE model
NU+NTh
N U+ N Th :
Consistent with prediction of BSE model.
We observed 4.5 - 54.2 geo-neutrinos with 90%C.L
99% C.L. upper limit ：70.7 events
Geo-ν after purification
Assume 210Pb : 10-5 level
(α,n) reaction and other
radioactive backgrounds are negligible
749days data
• fiducial volume :
R < 5m
5.5m
• detection efficiency : 90%
• error ： 54%
28%
(statistical error of reactor neutrino
is dominant)
• Significance : 99.96%
precise measurement
Signal (U+Th) [TNU]
Signal v.s. heat
99% C.L. upper limit
from KamLAND data
Fiorentini et al. (hep-ph/0508048)
Re-calculation with new cross
section for (α,n) reaction for 13C
Relationship line from geochemical
and geophysical constraints
BSE
Fully radiogenic
Heat (U+Th) [TW]
• Analysis improvement
• B.G. reduction
• More statistics
We will contribute to geology
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Future Plan
Next target of KamLAND
0.4
1.0
2.6
8.5
Visible energy [MeV]
neutrino electron elastic scattering
inverse beta decay
7
Be solar neutrino
geo-neutrino
reactor neutrino supernova relic neutrino
etc.
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ÅB
Neutrino Astrophysics
Neutrino Geophysics
Neutrino Physics
Neutrino Cosmology
verification of SSM
7Be
νe : neutrino electron elastic scattering
(We couldn’t use delayed coincidence methods)
Very low level background is required
KamLAND-II : toward solar 7Be
neutrino detection
4 m radius fiducial
Total 1.2 m cylindrical cut
14C
210Po
85Kr
7Be
210Bi
11C
Required Improvements :
210Pb
: 10-4~10-5
85Kr, 39Ar: ~10-6
LS Purification
Distillation System : Test Bench
• N2 gas purge (N2/LS = 25)
Rn: ~1/10
Kr : ~1/100
• Distillation (110 ℃, 37 hPa, 1time)
Pb: 10-4 - 10-5
Rn: (3.3 - 8.4) ×10-3
Kr : <10-5
2, 3, … , times distillation (1time : ~ 1 month)
We will achieve required performance
Purification Outline
The specification of
the purification system
was already decided.
And the tender of the
system was started.
We will start purification at next year
and 7Be neutrino observation!!
After the purification…
• Solar 7Be neutrino observation with few %
accuracy
• Solar 8B neutrino observation (<5MeV)
• Solar pep , CNO neutrino (with 11C tagging)
• Geo-neutrino improvements
- no backgrounds from (α,n) reaction of 13C
- accidental coincidence will be reduced
- larger fiducial volume
Summary
• Rector neutrino
- Rate + Shape analysis excluded no-oscillation
at 99.999995% C.L.
- Spectrum distortion (L/E) shows oscillatory behavior.
- Oscillation parameters are precisely measured:
m 2  7.9 -00..65 10 -5 eV 2 , tan 2   0.40 -00..10
07
• Geo-neutrino
- It was proven that KamLAND can detect
Geo-Neutrino for the first time.
- We observed 4.5 - 54.2 geo-neutrinos with 90%C.L.
• KamLAND-II
- For the solar 7Be neutrino detection,
purification studies have been advanced.
- We will start purification at next year.
LS Purification and Radioactive Impurity
before
U: ~10-10 g/g, Th: <10-12 g/g, K: 7×10-11 g/g
after
U: 3.5×10-18 g/g, Th: 5.2×10-17 g/g, K: 2.7×10-16 g/g
measurable only by KamLAND itself !
Detector Calibration
Radio-Active Source
Deployment
Muon Spallation
Products
Vertex Resolution
20.6 cm/ E (MeV)
Energy Resolution
6.2 %/ E(MeV)
Fiducial Volume Error: 4.7%
Detector Activity (Singles Spectrum)
Normal Trigger Range
Low Energy Region
Major Background Sources:
LS impurity (210Pb, 85Kr, 39Ar)
extrinsic gamma (40K, 208Tl)
muon spallation (10C, 11C, 12B, ...)
Event Display : Low Energy Event
Event Display : Muon Event
Event Selection(1)
Delayed Coincidence:
0.5 < ΔT < 1000μsec
ΔR < 200 cm
1.8 < Edelayed < 2.6
MeV
12C
captured γ
Prompt Energy Window:
2.6 < Eprompt < 8.5
MeV
Fiducial Volume:
Rprompt < 550 cm
Rdelayed < 550 cm
Event Selection(2)
Isotope
6He
7Be
8Li
8B
9C
10C
11Be
11C
9Li/8He
μ
Halflives
Decay Mode
806.7ms
β－
53.24day
EC
838ms
β－
170ms
β－
126.5ms
β＋
19.25sec
β＋
13.81sec
β－
20.39min
β＋
178.3ms/119.0ms β－ + n
9Li
3m
Spallation Cuts:
ΔTμ < 2 msec
ΔTμ < 2 sec (showering muons)
or
ΔTμ < 2 sec (showering muons)
ΔL < 300 cm (non-showering)
(α, n) Background
Recent paper shows
few % lower cross section of 13C (α,n) 16O
(Harissopulos et al, nucl-ex/0509014)
We could reduce about B.G. estimation
Accidental Coincidence Background
Off - time coincidence spectrum
⇒ 2.69 ± 0.02 events
(α, n) Background
210Pb
222Rn
22.3 y
3.8 d
210Bi
210Po
5.013 d
α
138.4 d
206Pb
stable
(5.3 MeV)
13C
(α,n) 16O
13C (α,n) 16O*
14N (α,n) 17F
15N (α,n) 18F
17O (α,n) 20Ne
18O (α,n) 21Ne
16O*(6.13)
→ 16O + γ (6.1MeV)
16O*(6.05) → 16O + e+ + e－(6.0MeV)
n
n + p → n + p (B.G for Geo neutrino)
n + 12C → n + 12C*
12C
+ γ(4.4MeV)
Backgrounds Summary
Correlation with Reactor Power
constrained to
expected BG
 2  2.4 / 4
at present statistics is not enough to state something
(α, n) Background
Energy Scale Determination
Fiducial Volume Calibration
With Muon Spallation (12B)
Systematic Errors Summary (Reactor-ν)
Systematic Errors Summary (Geo-ν)
Systematic
Cross section
Livetime
Fiducial volume
Trigger efficiency
(U / Th / Reactor)
Spatial Cut Efficiency
Timing Cut Efficiency
Total
%
0.2
0.06
4.91
0.04 / 0.09 / 0.007
1.0
0.3
5.0
νdetection
efficiency (Reactor)
e
Space correlation
MC simulation
Vertex resolution: 30cm/√E(MeV)
Time correlation
Capture time of spallation neutron
211.2±2.6μs
99.84%
ΔR(<2m) cut
1
91.32±1.49%
Fiducial cut
1000 s
 0.5  s
Parameter
Space correlation
Time correlation
Trigger efficiency
Delayed energy
Neutron capture
Total
e -t / d t  98.89  0.05%
Efficiency(%)
91.32±1.49
98.89±0.05
99.98
99.48(I,II),99.48(III)
89.82(I,II),89.83(III)
Detection efficiency (Geo-ν)
Neutron
capture
99.5 %
Trigger
U-Series: 99.96 %
Th-Series: 99.90 %
Spatial
Correlation
U-Series: 77.0 %
Th-Series: 75.7 %
Spatial Correlation (MC)
Reactor: 77.3%
(α,n):
76.1%
Time
correlation
90.4%
Energy of
delayed event
99.97%
total
U-Series: 69.2%
Th-Series: 68.0%
MC/Data Comparison
Event Selection (Geo-ν)
Delayed Coincidence:
0.5 < ΔT < 1000μsec
ΔR < 100 cm
0.9 < Eprompt < 2.6 MeV
1.8 < Edelayed < 2.6 MeV
Fiducial Volume:
Rprompt < 500 cm
Rdelayed < 500 cm
ρxy > 120 cm
Spallation Cuts:
ΔTμ < 2 msec, total volume (for all muons)
ΔTμ < 2 sec, total volume (showering muons)
or
ΔTμ < 2 sec, ΔL < 300 cm (Non-showering muons)
Backgrounds (Geo-ν)
•
Cosmic ray muon
Neutron (inner of detector)
Fast neutron (external)
Spallation (9Li)
•
•
negligible
< 0.1
0.30±0.047
Radioactive contamination
accidental coincidence
2.38±0.0077
spontaneous fission
correlated fission
(α, n) reaction
(γ, n) reaction
< 0.1
negligible
42.4±11.1
negligible
Reactor neutrino
80.4±7.2
Long lived nuclear (spent fuel rod)
1.9±0.2
total 127.4±13.3

Time variation of reactor neutrino flux
e
/cm 2 /day

1/2
Time
190km
L (km)
Neutrino flux from
distance of ~160km
decreased.
Oscillation pattern
depend on this
variation.
160km
Observed / expected
L/E Analysis
spectrum shape test
χ2/ndf
GOF
24.2/17
11.1%
35.8/17
0.7%
32.2/17
1.8%
11C
Tagging
Neutrino Propagation through
the Earth
Mantle or Oceanic crust?
Seismic wave velocity anomaly
KamLAND
Subducting plate
Low speed
(high temp.)
Accumulation of
cold slab?
Subducting plate thickness ~50km
(oceanic crust ~6km)
high speed
(low temp.)
Cold slab
Oceanic crust : mantle = 1 : 9
Effect of the high speed region gives
~2% uncertainty of the total neutrino flux
Distance and Cumulative Flux
Total
<500km
50%
Crust
Mantle
Sediment
50% of the total flux originates within 500km.
For the discussion of deep interior of the earth,
we need understanding about surface geological features within ~500km
Result of KamLAND
and Geochemical model
• KamLAND result is consistent with prediction of BSE model.
• Fully-Radiogenic (44TW) is within 99%C.L., but out of 1σ.
• 99%C.L. limit is corresponding to 60 TW.
Spectrum Shape Analysis
2
 shape
 - 2 log 
k
dP( Ek ; NU , NTh , BG - parameters )
2
  BG
- parameters
dE
• number of events ：28.0 ＋15.6
(corresponding to 57.4 ＋32.0
TNU)
－14.6
－30.0
• 99% C.L. upper limit ： 70.7 events (corresponding to 145 TNU)
• No sensitivity for U/Th ratio
Extrinsic Gammas Screening
Current KamLAND Rate
MC of extrinsic gammas (40K, 208Tl)
7Be
ν: ~1μHz
40K:
< 3.4μHz
208Tl:
< 5.6μHz
Solar Neutrino Prospects
7Be
neutrinos will be seen
between 14C and 11C background
11C
can be reduced with neutron tagging
(pep and CNO neutrinos extractable???)
11C