Geo-neutrinos - University of Hawaii at Manoa - …hanohano/post/AAP2012/AAP_2012_Geonu_Dy… ·...
Transcript of Geo-neutrinos - University of Hawaii at Manoa - …hanohano/post/AAP2012/AAP_2012_Geonu_Dy… ·...
Geo-neutrinos Status and Prospects
Steve DyeHawaii Pacific University
University of Hawaiip n
u du ud d
νe e+
W
Applied Antineutrino PhysicsOctober 2012
Outline
• Earth energy balance Aq = Mh – Mc(∂T/∂t)
• Radiogenic heat/geo-neutrinos• Detecting geo-neutrinos• Geo-neutrino data• Geo-neutrino analyses• Project updates• Prospects
νe e+
p nu du ud d
W
Neutrino energy (MeV)
Eve
nts/
10 k
eV (1
032p
y)-1
Daya Bay II
TotalReactorGeo-nuThU
0
1
2
3
4
5
0 2 4 6 8 10
Surface Heat Flow
mW m-2
Total Flow Aq = 47 ±2 TW
Heat flow probe-thermal conductivity,dT/dx
Heat conduction-q = -k dT/dx
Pollack et al., 1993Added for Davies, Davies, 2010
Stat error only
Internal Heating
?
Geology predicts16-42 TW of
radioactive powerMass loss rate
dm/dt = -(6-15) tonne y-1
Internal heatingMh = 11 – 31 TW
~20% escapes to space as geo-neutrinos
~80% remains to heat planet
Other known sources ofinternal heating small
Thermal Evolution of Earth
Surface heat flow- Aq = 47 ±2 TW (Davies, Davies, 2010)
Internal heating- Mh = 11 to 31 TW (various models)
Planetary Urey ratio - U = Mh/Aq = 0.2 to 0.7
Temperature change rate:∂T/∂t = Aq/Mc (Mh/Aq – 1)
U = Mh/AqU > 1 T ↑ U < 1 T ↓
Geology predicts a cooling planet
Predicted Heating: Earth Models• Cosmochemical (CC)
– Enstatite chondrite - Javoy et al., 2010• ~11 TW heating
– Primitive mantle petrology- Palme & O’Neill, 2003• ~21 TW heating
• Geophysical (GP)– Viscosity with water- Crowley et al., 2011
• ~19 TW– Mantle convection- Turcotte, 1980
• ~38 TW heating
Heating in Earth: Mh = 11 - 38 TWwith 8 +/- 1 TW in crust
Earth Heating Elements
U, Th, K produce heat and geo-neutrinosexpected in silicate earth- crust and mantle
238U → 206Pb + 8α + 6e + 6 eν + 51.698 MeV 235U → 207Pb + 7α + 4e + 4 eν + 46.402 MeV 232Th→208Pb + 6α + 4e + 4 eν + 42.652 MeV 40K → 40Ca + e + eν + 1.311 MeV (89.3%) 40K + e → 40Ar + eν + 1.505 MeV (10.7%) (1)
Goldschmidt Classification
h(μW/kg) l(kg‐1μs‐1)
Uranium 98.5 76.4 Thorium 26.3 16.2 Potassium 3.33 x 10‐3 27.1 x 10‐3
Lithophilic- “rock-loving”
3-October-2010 Steve Dye, HPU 8
PMTs measure position and amount of deposited energy
Antineutrino Detection
γγ
e+e-
γγ
n p+
γγ
Prompt event depositsenergy of Eν-0.8 MeV
Delayed event depositsenergy of 2.2 MeV
p+νe
Antineutrino (Eν>1.8 MeV)interacts with free proton
~10,000 γ/MeV
Antineutrino energy (MeV)
dn/d
E ν (1
0-44 c
m2 M
eV-1
)
238U
232Th
10-1
1
1.5 2 2.5 3 3.5
Geo-neutrino Event Spectrum
212Bi
228Ac
232Th
1α, 1β
4α, 2β
208Pb
1α, 1β
νe
νe
2.3 MeV
2.1 MeV
238U
234Pa
214Bi
1α, 1β
5α, 2β
206Pb
2α, 3β
νe
νe2.3 MeV
3.3 MeV
Th/U in source regions determines spectral shape
Neutrino energy (MeV)
arbi
trar
y un
its
δE = 7% E1/2
Th/U = 8
Th/U = 4
Th/U = 2
0
0.5
1
1.5
2
1.5 2 2.5 3 3.5
Neutrino Oscillations- θ13>0
221
232
231 mmm δδδ >>≈
( ) ( )[ ]132
212
122
134 2sin5.0)(sin)2(sincos1 θθθ +Δ−≅eeP
)]}(sin)2(sin)(sin)2()[cos2(sin
)(sin)2(sin)({cos1
322
122
312
122
132
212
122
1343
Δ+Δ+
Δ−=
θθθ
θθνeeP
eELmjiji νδ /)(27.1 2=Δ 222
ijji mmm −≡δ
3-ν mixing
( )[ ] 024.013.13
212
213
4 536.0)2(sin)2(sincos5.01 +−=+−≅ θθθeeP
Fogli et al., 2011 ; An et al., 2012 ; Ahn et al., 2012
Error dominatedby solar mixing
angle
Energy (MeV)
P ee/<
P ee>
Oceanic planet
Continental planet
0.99
1
1.01
1.02
1.03
1.04
1.05
2 2.5 3
Dye, 2012Rev. Geophys. 50, RG3007
Adjust Average Oscillation Probabilityθ13 : 0 º → 10 º
<Pee> : 0.58 → 0.54
Lowers reactor & crust flux predictions
Using <Pee> overestimates
mantle signal and
underestimates Th/U
Pronounced at sitesenriched in U & Th such as
Sudbury basin
Perry et al., 2009
Reactor Antineutrino Background
Geo Geo ννσ(E)
Φ(E) N(E)
(Enomoto, Neutrino Sciences 2007)
)/27.1(sin)2(sin1 221
212
2
eeeELmP ννν θ Δ−≅→
Expected reactor signal3-60 TNU depending on location
OLD- Kamioka
OLD- θ13=0
Existing Gν Detectors
1 kT LS80% dodecane
20% PCw/ 1.36 g/l PPO
~1800 PMTs34% solid angle
~250 pe/MeVvis
(5.98±0.12)x1031 p
KamLAND- Kamioka, Japan
Both existing detectorsare in Eurasia at
~40 ⁰ N and separatedin longitude by ~120 ⁰
0.278 kT PCw/ 1.5 g/l PPO
2212 8-in PMTs~30% solid angle
~500 pe/MeVvis
~0.17x1031 p
Borexino- Gran Sasso, Italy
Published Gν Data
Total events- 841Background- 730±32
Geo-nu- 111±43
Gando et al., 2011 Nature Geoscience 4, 647
KamLAND
Mar-02 to Nov-09 : 3.49±0.07 TNU-1
Total events- 15Background- 5.3±0.3
Geo-nu- 9.7±3.9
Borexino
Dec-07 to Dec-09 : 0.152 TNU-1
Bellini et al., 2010Phys. Lett. B 687, 299
Gν Data Analysis
Gando et al., 2011 Nature Geoscience 4, 647
unconstrained fitNU = 65 ; NTh = 33
Th/U ~ 8
ε(U) = 0.807 ε(Th) = 0.751
“Fixing” Th/U=3.9N(U+Th) = 106±29
KamLAND
40.0±10.5(stat)±11.5 (sys) TNU
systematic > statistical
Best fit: 9.9(+4.1/‐3.4) gν events
ε=0.85±0.01
Bellini et al., 2010Phys. Lett. B 687, 299
Borexino
64±25(stat)±2(sys) TNUstatistical >> systematic
“Fixing” Th/U=3.9
Surface heat flux
Observed Gν Residual mantle GνGν Analysis- I
Gando et al., 2011 Nature Geoscience 4, 647
Old value. Revised lowerby Coltorti et al., 2011. Mh (U+Th) = 20 ± 9 TW GC
modelGC
model
BX > KLbut consistent
with BX=KL
Gν Analysis- II
1.7 ≤ Th/U ≤ 3.9
• Geophysical- consistent• Cosmochemical- excluded ~90% CL
No model excluded at ~>2σ
Fiorentini et al., 2012arXiv:1204.1923v1
Rmantle = 23 ± 10 TNUR>0 at ~2.4σ
Mh(U+Th) > 19 TW (68% CL)
Residual mantle signalw/ model comparisons
Gν Analysis- III
Homogeneousmantle
DM w/ enrichedbasement layer
KamLAND (2011) data consistent with models,
prefers Mh < Aq
Borexino (2010) dataconsistent with GP and
Mh = Aq
Dye, 2012Rev. Geophys. 50, RG3007
KL+BX (weighted averages)consistent w/ GP & GC
weakly exclude CC
Min Mh = 28 ± 13 TWMax Mh = 33 ± 16 TW
νν
Neutrino energy (MeV)
Eve
nts/
10 k
eV (1
032p
y)-1
Gran Sasso
TotalReactorGeo-nuThU
0
0.2
0.4
0.6
0.8
1
0 2 4 6 8 10
Neutrino energy (MeV)
Eve
nts/
10 k
eV (1
032p
y)-1
Kamioka- now
TotalReactorGeo-nuThU
0
0.2
0.4
0.6
0.8
1
0 2 4 6 8 10Neutrino energy (MeV)
Eve
nts/
10 k
eV (1
032p
y)-1
KamiokaTotal
Reactor
Geo-nu
Th
U
0
0.5
1
1.5
2
2.5
0 2 4 6 8 10
Predicted Signals: Existing Sites
Kamioka before and after all
reactors shutdown
A new Gνbeginning for KL
BX can operate for many years beforesystematic uncertainty significant
Neutrino energy (MeV)
Eve
nts/
10 k
eV (1
032p
y)-1
Pyhäsalmi
TotalReactorGeo-nuThU
0
0.2
0.4
0.6
0.8
1
0 2 4 6 8 10
Neutrino energy (MeV)
Eve
nts/
10 k
eV (1
032p
y)-1
Baksan
TotalReactorGeo-nuThU
0
0.2
0.4
0.6
0.8
1
0 2 4 6 8 10
Neutrino energy (MeV)
Eve
nts/
10 k
eV (1
032p
y)-1
Sudbury
TotalReactorGeo-nuThU
0
0.2
0.4
0.6
0.8
1
0 2 4 6 8 10
Neutrino energy (MeV)
Eve
nts/
10 k
eV (1
032p
y)-1
Homestake
TotalReactorGeo-nuThU
0
0.2
0.4
0.6
0.8
1
0 2 4 6 8 10
Predicted Signals: Continental Sites
Continental Observatories
Neutrino energy (MeV)
Eve
nts/
10 k
eV (1
032p
y)-1
Daya Bay II
TotalReactorGeo-nuThU
0
1
2
3
4
5
0 2 4 6 8 10
Neutrino energy (MeV)
Eve
nts/
10 k
eV (1
032p
y)-1
Pacific
TotalReactorGeo-nuThU
0
0.2
0.4
0.6
0.8
1
0 2 4 6 8 10
Resolving Radiogenic Heating
Assumes H = 20 TW Systematic error only
Continental δ(Mh)/Mh ~ 0.4
Existing δ(Mh)/Mh ~ 0.3
Oceanic δ(Mh)/Mh ~ 0.15
Dye, 2012Rev. Geophys. 50, RG3007
Enriched Deep Mantle?Pyhäsalmi
HomestakeBaksan
Sramek et al., 2012arXiv:1207.0853
Neutrino energy (MeV)
Eve
nts/
10 k
eV (1
032p
y)-1
Pacific
TotalReactorGeo-nuThU
0
0.2
0.4
0.6
0.8
1
0 2 4 6 8 10
Deep ocean observatoryresolves earth heating,
potentially super-plumes
Pacific
SudburyGran Sasso
Kamioka
Project Updates
• Borexino– “… doubled statistics and improved FV definition... Data look
nice.” Aldo Ianni
• KamLAND– “… acquiring good data but wont publish for a year until reactors
come back…” Kunio Inoue
• SNO+: Data next year, crust study in progress
• LENA: White paper published in Astropart. Phys.- M. Wurm
• Baksan: Discussing10-50 kT detector- V. Sinev
• Daya Bay II:10-50 kT detector- fun challenge to extract Gν signal
• Hanohano: possible synergy with Watchman, geology
Gν Summary
• Observing planetary U & Th; no Th/U; no K; no direction• KL & BX data: Mantle radiogenic heating >10 TW (1σ)
– Beginning to constrain earth heating
• Potential for resolution of geological models– Constrain thermal evolution, formation processes, origin
• Network of continental observatories– KL, BX, SNO+, LENA, Baksan, Homestake– 50 TNU-1 δm ≈ 3 TNU
• Single oceanic observatory– Hanohano 3 TNU-1 δm ≈ 3 TNU– Potential to resolve super-plumes
• Study as background to precision θ12 and reactor monitor
Thank You
• Backup slides follow
Planetary Power
Surface heat flow- Aq
Internal heating- Mh
Heat to change temperature- Mc(∂T/∂t)
Aq = Mh – Mc(∂T/∂t)
Temperature change rate: ∂T/∂t = Aq/Mc (Mh/Aq – 1)
Planetary Urey ratio - U = Mh/Aq
Cross Sections−− +→+ ee ee νν
e
e
EmE
Te ν
ν
21max +=
442
2max3max2
max2 10
2)1()1(1
3)1(43.0)( −×
⎥⎥⎦
⎤
⎢⎢⎣
⎡+−
⎪⎭
⎪⎬⎫
⎪⎩
⎪⎨⎧
−−++=ee
e
e ETmxx
ETE
xTxE ee
νν
ννσ
nepe +→+ +ν
( ) 44222 101)(52.9)( −×Δ−−Δ−=eee
EmEE ep νννσ
ee mETe
−Δ−= ν
Antineutrino Interactions
Electron elastic scattering• νe + e- → νe + e-
• Electron target– No energy threshold
• Cross-section– σ(Eν)~4.0x10-45 Eν
1 cm2
Inverse β-decay• νe + p → n + e+
• Proton target– Ethresh ≈ 1.80 MeV
• Cross-section– σ(Eν)~9.5x10-44 (Eν-1.3)2 cm2
p nu du ud d
νee+
W
e- e-
νeνe
Z0
Nue-bar elastic scattering observed by Reines, Gurr, Sobel in 1976
Sensitivity below 1.8 MeV; no tag
4 e- / p+ in CH2 LS
Resolve e- direction to find signal?
Cross Sections
Nue-bar quasi-elastic scatteringused by Reines and Cowan in 1950’s
Coincidence counting; weak direction
Works great for geo-nue-bars
Uncertainties small
Geo-neutrino Intensity Spectra
[ ] [ ] βν QeZAZA e ++++→ 1,,
)(e
EmQw ee νβ −+=
[ ] 2/122)( eee mEmQpe
−−+= νβ
( )2122/)( ηγπηγννν iepEwdEEdn ee eee
+Γ∝ −
22 )1(1 +−= Zαγ
ee pwZ )1( +=αη
Internal heating and geo-neutrinos connected
per decay
Detected Spectra
x =
Inverse-β Interaction Kinematicstr
ansv
erse
longitudinal
Initial-ptrans= 0
Final-ptrans= 0
ppννe
n
e+
θn
e+
θe
pν
θ'e
WatanabeBatygov
Coincidence Counting
Prompt event• Positron
– Ee ≈ Eν – 1.8 MeV– Evis ≈ Eν – 0.8 MeV– Ionization energy + 2γ– Deposition time ~ few ns– <Re> ~ 0.4 cm
Delayed event• Neutron
– En ≈ 1-100 keV– Thermal diffusion– Evis depends capture nucleus– Deposition time ~ 20 – 200 μs– <Rn> ~ 5 – 15 cm
Watanabe
Seeing with Sound
Seismology- PREM• density profile• internal structure• solid vs liquid phase
(Dziewonski, Anderson, 1981)
Chemical Affinity
U, Th, K in silicate earth- crust and mantle only
Goldschmidt Classification
Lithophilic- “rock-loving”
Crust Model
Seismic model- CRUST 2.0 (Bassin et al., 2000)Composition model- (Rudnick,Gao, 2003)
Heating in crust (Mh)crust = 8 ±1 TW
Non-antineutrino Background
Mei and Hime, 2006
Fast neutronbackgroundfrom muonsoutside veto<1 TNU at
Gran Sasso
Abe et al., 2010
Isotope background (β,n) ~0.5 TNU
Accidental background3.4±0.2 TNU KL (2005)1.3±0.2 TNU BX (2010)
Radon contamination210Po → 206Pb + α
13C(α,n)16O<0.3 TNU
Gν Analysis- II
Fiorentini et al., 2012arXiv:1204.1923v1
θ13>0 decreases expected crust
KL (Enomoto et al., 2007) .54/.59=.92BX (Coltorti et al., 2011) .54/.57=.95
Increased total signalsKL R(U+Th) 40→43 TNUBX R(U+Th) 64→67 TNU
R(U+Th) >0at ~4.2σ
Add to increase mantle signalMantle = Total – Crust
Gando et al., 2011
Gν Analysis- III
Dye, 2012arXiv:1111.6099v2
Weighted average
MethodM = N - B – C
δM = (N + δB2 + δC2)1/2
AssumptionsTh/U = 3.9 ; C model
MKL= MBX
Combined result:consistent w/ GP, GCweakly excludes CC
Rmantle = 17 ± 10 TNU
Sramek et al., 2012
BX > KLbut consistent
with BX=KL
GP
GC
CC
Man
tle ra
te (T
NU
)
0
10
20
30
40
50
60
70
80
KL(2011) BX(2010) KL+BX
Projection to Year 2020
KamLAND : 9 TNU-1 δm = ± 6 TNU
Borexino : 1 TNU-1 δm = ± 10 TNU
SNO+ : 3 TNU-1 δm = ± 9 TNU------------------------------------------------Total : 13 TNU-1 δm = ± 4-5 TNU
OR
GeoHano : 3 TNU-1 δm = ± 3 TNUGeoHano : 6 TNU-1 δm = ± 2 TNU
OR
Network- Five x 10 TNU-1 δm = ± 3 TNU