chasing 13 with new experiments at nuclear reactors thierry lasserre saclay nufact04, osaka july 26...
TRANSCRIPT
Chasing 13 with new experiments
at nuclear reactors
Thierry Lasserre Saclay
NuFact04, OsakaJuly 26 2004
T.L. (Saclay) - NuFact04 -
The neutrino sector
[m221 - 12] – [m2
32 - 23] – sign(m232) - 13 -
superbeam +
reactor
sin2(213)<0.20 (CHOOZ) 13 ?(small angle)
Hierarchy sign(m232 ) ?
CP violation phase ?
solar +
KamLAND+
reactor ?
MSW-LMA
m212~O(10-4/-5) eV2
sin2(212)~0.8(large angle)
atmospheric +
K2K+
MINOS – Superbeams …
m232~2-3 10-3 eV2
sin2(223)~1(maximal angle)
But no absolute mass scale coming from oscillation experiments --> & 0 decays ?
T.L. (Saclay) - NuFact04 -
Measurement at reactors&
complementarity with LBL
T.L. (Saclay) - NuFact04 -
e disappearance experiment
Pth= 8.5 GWth, L = 1,1 km, M = 5t (300 mwe)
Best current constraint: CHOOZ
World best constraint !
@m2atm=2 10-3 eV2
sin2(2θ13)<0.2
(90% C.L)
e x
R = 1.01 2.8%(stat)2.7%(syst)
M. Apollonio et. al., Eur.Phys.J. C27 (2003) 331-374
T.L. (Saclay) - NuFact04 -
13 & beam experiments
LBL disappearance : sin2(223) 2 solutions : 23 & /2-23
|m213| 2 solutions m1>m3 or m3>m1
Appearance probability :
• K1,K2,K3: constants known with experimental errors)• dependence in sin(223), sin(23) 2 solutions• dependence in sign(m2
31) 2 solutions• -CP phase [0,2] interval of solutions
P( e) ~ K1 sin2(23 ) sin2(213 ) + K2 sin(223 ) sin(13 ) sign(m2
31) cos() K3 sin(223 ) sin(13 ) sin ()
13 & reactor experiments• <E> ~ a few MeV only disappearance experiments
sin2(213) measurement independent of -CP
• 1-P(e e) = sin2(213)sin2(m231L/4E) + O(m2
21/m231)
weak dependence in m221
• a few MeV e + short baselines negligible matter effects (O[10-4] ) sin2(213) measurement independent of sign(m2
13)
sin
2(2
1
3 )
P( e)
beam
reactor
T.L. (Saclay) - NuFact04 -
CP- phase induced ambiguity
0
0.01
0.06 0.1 0.14
0.03
0.05
0.07
sin2(213)
P(
e
)
)sin(2θ
δsin 0.11)(2θsin
2
1)νP(ν
1313
2eμ
T2K measurement
()P
sin correlation
T.L. (Saclay) - NuFact04 -
23 induced ambiguity
0
0.01
0.06 0.1 0.14
0.03
0.05
0.07
sin2(213)
P(
e
) T2K measurement
0.4)(θsin
0.6)(θsin0.95)(2θsin
232
232
232
reactor measurement
LBL + reactor combination might help to solve the 23 degeneracy
T.L. (Saclay) - NuFact04 -
Improving CHOOZ is difficult !
T.L. (Saclay) - NuFact04 -
50 years of reactor neutrino experiments …
1956 Discovery of neutrinos @Savannah River - First detection of reactor neutrinos1990’s Reactor neutrino flux measurements1995 Nobel Prize to Fred Reines2002 Discovery of massive neutrinos and oscillations confirmed by KamLAND
From discovery to metrology !G. Mention (APC)
Near detector Far detector
T.L. (Saclay) - NuFact04 -
One nuclear plant & two detectors
Nuclear reactor
1,2 core(s) ON/OFF : ok 4 cores ON/OFF : no !
Near detector
5-50 tons> 50 mwe
Far detector
5-50 tons> 300 mwe
D1 = 0.1-1 km D2 = 1-3 km
e e,,
Isotropic e flux (uranium & plutonium fission fragments) Detection tag : e + p e+ + n, <E>~ 4 MeV, Threshold ~1.8 MeV Disappearance experiment: suppression+shape distortion between the 2 detectors 2 IDENTICAL detectors (CHOOZ, BOREXINO/CTF type, KamLAND)
• Minimise the uncertainties on reactor flux & spectrum (2 % in CHOOZ)• Cancel cross section uncertainties • Challenge: relative normalisation between the two detectors < 1% !
T.L. (Saclay) - NuFact04 -
Improving CHOOZ is difficult …
@CHOOZ: R = 1.01 2.8%(stat)2.7%(syst)
Statistics Increase luminosity L = t x P(GWth) x Np(target) Increase fiducial volume & exposure ~2700 events in CHOOZ but >40,000 for the next experiment σ < 0.5%
Experimental error 2 detectors cancel neutrino flux and cross section systematic uncertainty [~2%] Identical detectors decrease detector systematic uncertainties [<1%] Movable VS non movable detectors : cross calibration, but error might be increased ?
Backgrounds (S/N~25 in CHOOZ ; Goal S/N >100 in the new experiment) Uncorrelated background (measurement in-situ) – Correlated backgrounds ( induced) Underground site required: >300 m.w.e for the far site to improve CHOOZ S/N equivalent for Near and Far detector (near detector could be shallower) Reactor ON/OFF measurement 1, 2, 4, or up to 7 reactor cores ?
T.L. (Saclay) - NuFact04 -
nepe
Reactor antineutrino detection
prompt event:delayed event:
MeV)2.2( dpn
E prompt E En 0.8 MeV
• Prompt e+, EP=1-8 MeV, visible energy
• Delayed neutron capture on Gd, ED=8 MeV
• Prompt(/) - Delayed(/) pulse shape discrimination
Time correlation: 30sec
Space correlation: < 1m3
Anti-e tag: e + p e+ + n, Q~1.8 MeV Threshold
Or Gd capture (8 MeV)
T.L. (Saclay) - NuFact04 -
Why two identical detectors …u
nlo
ad
ed
Gd
~0.1
%
scin
tillato
r
signal No signal
e+
n
Gdn
Gd
e+
e+
H
n
e+
H
n
=
0 % In
tera
ctio
n
=
100 %
spill in/out effect
Acrylic vessel
A ~1% irreducible systematic error from the spill in/out effect Boundary effect 2 identical inner vessels
Scintillator doped with 0.1% Gd MUST be perfectly stable over the life time of the experiment (>5 years)
Fiducial volume
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Observable: e+ spectrum (Double-CHOOZ configuration)
sin2(213)=0.04 sin2(213)=0.1 sin2(213)=0.2
sin2(213)=0.04 sin2(213)=0.1 sin2(213)=0.2
m2atm = 2.0 10-3 eV2
Near Detector: ~ 1.8 106 events-Reactor efficiency: 80%-Detector efficiency: 80%-Dead time: 50%
Far Detector: ~ 34 000 events-Reactor efficiency: 80%-Detector efficiency: 80%
E (MeV) E (MeV)
Events
/20
0 K
eV
/3 y
ears
T.L. (Saclay) - NuFact04 -
Example of e oscillation at reactor
(Double-CHOOZ configuration )Rate + shape information if 13 not too small
@1,05 km
Far/
Near
energ
y b
in
rati
o
Note: optimum baseline ~1.5km
T.L. (Saclay) - NuFact04 -
Detector size scale
Borexino300 t
KamLAND1000 t
Reactor/13
Example ~20 tCHOOZ
5 tDoubleCHOOZ
&KASKA
(10 tons)
X 2
Angra, Daya-Bay, Braidwood
T.L. (Saclay) - NuFact04 -
90% C.L. sensitivity if sin2(213)=0
Reactor1 (0.5 km, 2.3 km): ~13 tonsPXE x 10 GW x 3 years sin2(213)<~0.02, 90% C.LReactor2 (0.5 km, 2.3 km): ~270 tonsPXE x 10 GW x 3 years sin2(213)<~0.01, 90% C.L
T2K
Huber, Lindne
r, Schw
etz & W
inter: hep-ph/0303
232
G. M
en tion &
T. L.
σbkg
σbkg
σbkg
reactor 1 (2 RNU) reactor 2 (40 RNU)
1%
0.1%
@m2=2.0 10-3 eV2
RNU = Reactor Neutrino Unit : 1 RNU = 1031 free H GWth year
T.L. (Saclay) - NuFact04 -
Huber, Lindner, Schwetz & Winter (‘extremum’ of projection of the 2 manifold on the sin2(213) axis)
Double-CH1313Z
sin2(213) at LBL & reactors
CHOOZ alone90% C.L
@m2=2.0 10-3 eV2
(3 ktons ?)
T.L. (Saclay) - NuFact04 -
Current proposal for new reactor experiments …
T.L. (Saclay) - NuFact04 -
Nuclear reactors in the world
T.L. (Saclay) - NuFact04 -
World momentum December 2002: First European meeting, MPIK Heidelberg April 2003: Second European meeting, PCC, Paris May 2003: First international workshop, University of Alabama, US October 2003: Second international workshop, TUM, Germany March 2004: Third international workshop, Niigata, Japan Next workshop in Brazil, January 2005
125 authors, 40 Institutions White Paper Report on Using Nuclear Reactors to search for a value of theta 13 hep-ex/0402041
T.L. (Saclay) - NuFact04 -
Which site for the experiment ?
Diablo Canyon
Braidwood
Angra
PenlyChoozCruas
Krasnoyarsk
Taiwan
Kashiwasaki
One reactor complexTwo underground cavities @0.1-1 km & ~1-2 km
Daya bay
T.L. (Saclay) - NuFact04 -
The Krasnoyarsk site: Kr2DetRussian Research Center “Kurchatov Institute”
Completely underground facility was used by the Soviets for weapons production.
Single reactor core P=1.6 GWth
ON/OFF cycle [50 days ON & 7 days OFF]
No civil construction
>50 tons detectors Near: >50 tons – 115 m – 600 mwe Far: >50 tons - 1.1 km - 600 mwe
Sensitivity 0.5% systematic error sin2(213) < 0.015 (m2 =2.5 10-3 eV2, 90%
C.L.)
Prospects Visit in summer 2003 cancelled by Russian
authorities Site not available for “political” reasons
T.L. (Saclay) - NuFact04 -
Current proposals
Braidwood
Angra
Double-Chooz
Kaska
Daya bay
1st generation: sin2(213)~0.01-0.03
2nd generation: sin2(213)~0.01 + shape only analysis
T.L. (Saclay) - NuFact04 -
Braidwood (Illinois)Two reactor cores P=2 x 3.6 GWth
Civil construction Flat topology Near & Far: 120m shafts (10m diameter) + laboratories (25-35 M$)
Two 50 tons detectors Near: 25-50 tons – 300 m – 450 mwe Far: 25-50 tons – 1.5-1.8 km - 450 mwe Movable detector (move on the surface, lift with crane)
3 years Sensitivity 0.5% systematic error No signal: sin2(213) < 0.01 (90% C.L.)
Prospects (not yet approved) Construction in 39 month - running in 2009. Cost ~45 M$ Geological studies ongoing
T.L. (Saclay) - NuFact04 -
Braidwood (Illinois)
Civil construction
Detector sketch
ANL, Chicago, Columbia, FNAL, Kansas, Oxford, Pittsburgh, Texas
T.L. (Saclay) - NuFact04 -
Daya BayFour reactor cores P=4 x 2.9 = 1.6 GWth
+ two new cores for 6 GWth in 2011
Civil construction Near: 1 km tunnel + laboratory Far: 2 km tunnel + laboratory
~10 tons detector modules Near: 25 tons - 300 m – 200 mwe Far: 50 tons - 1.5-1.8 km - 700 mwe Movable detector concept
Sensitivity 0.4% systematic error sin2(213) < ~ 0.01 (90% C.L.) ?
Prospects (not yet approved) 2004-05: R&D, 2006-07: Construction 1 Near detector running in 2008 Geological & safety studies ongoing
T.L. (Saclay) - NuFact04 -
Daya Bay
Near detector: 2 x 10 tons modulesFar detector: 4 x 10 tons modules 3 years of data takingsin2(213) < ~ 0.01-0.02 (90% C.L.)
IHEP, CIAE, Tsinghua Univ., Hong Kong Univ., Hong Kong Chinese Univ, (Berkeley, Caltech) R&D
T.L. (Saclay) - NuFact04 -
Kaska (Kashiwasaki, Japan)Seven reactor cores P=24.3 GWth 2 near detector mandatory
Civil construction 2 Near: ~70 m 6m shafts + laboratories Far: ~250 m 6m shaft + laboratory
Multiple detectors 2 Near: 8 tons – 300-400 m – 100 mwe Far: 8 tons - 1.3-1.8 km - 500 mwe
Sensitivity 0.5% systematic error sin2(213) < 0.025 (90% C.L.)
Prospects (not yet approved) 2004-05: R&D, 2006-07: Construction. Running in 2008. Cost ~20 M$ Geological studies ongoing – Prototype to be built for R&D.
T.L. (Saclay) - NuFact04 -
KASKA (Japan)Tohoku Univ., Niigata Univ., Rikkyo Univ., KEK, Kobe Univ.Tokyo Institute of Technology, Tokyo Metropolitan Univ.
Sensitivity (3 years): sin2(213)<0.026 @90%
C.L
T.L. (Saclay) - NuFact04 -
Near site: D~100-200 m, overburden 50-80 mweFar site: D~1.1 km, overburden 300 mwe
Type PWR
Cores 2
Power 8.4 GWth
Couplage 1996/1997
(%, in to 2000) 66, 57
Constructeur Framatome
Opérateur EDF
Chooz-Far
Chooz-Near
Double-Chooz (France)
T.L. (Saclay) - NuFact04 -
Double-Chooz featuresTwin reactor cores N4 type P=2x4.2 GWth
Civil construction Near: 20x10x5m experimental hall Artificial overburden
Two 10 tons detectors Near: 100-200 m – 60-80 mwe Far: 1.05 km - 300 mwe
3 years Sensitivity 0.6% systematics No signal: sin2(213) < 0.02-03 (90% C.L.)
Signal: sin2(213) > 0.04-05 (3σ)
Prospect (approved & funded in France) 2007: far detector running 2008: near detector running Cost ~7Meuros + civil constr.
Near detector site (to be built)
Existing Far detector site
@DAPNIA
T.L. (Saclay) - NuFact04 -
The CHOOZ-far detector
CHOOZ existing pit
Non scintillating buffer: scintillator+quencher(r+0.95m, , V=100 m3)
-catcher: 80% dodecane + 20% PXE (acrylic, r+0,6m – V= 28,1 m3)
7 m
7 m
PMT supporting structure
Muon VETO: scintillating oil (r+0.6 m – V=110 m3)
7 m
Shielding: 0,15m steel
target: 80% dodecane + 20% PXE + 0.1% Gd (acrylic, r=1,2m, h = 2,8m, 12,7 m3)
@DAPNIA
T.L. (Saclay) - NuFact04 -
Reactor induced systematics
systematics Error type CHOOZFuture
Experiment
2 identical detectorLow background
Reactor
Flux, cross section 1.9% - O(0.1%)
Thermal power 0.7% - O(0.1%)
E/Fission 0.6% - O(0.1%)
2.1% - O(0.1%)
2 detectors cancellation of the reactor physical uncertainties
T.L. (Saclay) - NuFact04 -
Detector induced systematics
systematics Error type CHOOZFuture
Experiment
Sim.Monte-Carlo
2 identical detectorLow backgrounds
Detector
Scintillator density 0.3% 0.3% O(0.1%)
% H 1.2% 1.2% O(0.1%)
Target volume 0.3% 0.2% 0.2%
« Spill in/out » effect 1.0% 1.0% X O(0.1%)
Live time ? 0.25% 0.25%
M. Apollonio et. al., Eur.Phys.J. C27 (2003) 331-374
A single scintillator batch will be prepared to fill both detectors with the same apparatus
T.L. (Saclay) - NuFact04 -
Relative Normalisation: Analysis
@CHOOZ: 1.5% systematic error - 7 analysis cuts- Efficiency ~70%
Sélection cuts - positron energy [energy threshold]
- e+ position/géode (30cm) [position reconstruction] - neutron energy [energy cut - calibration] - n pos./géode (30 cm) [position reconstruction] - distance e+ - n [position reconstruction] - t e+ - n [neutron capture on Gd] - n multiplicity [level of accidental background]
Goal Double-CHOOZ: <0.5% systematic error - 2 to 3 analysis cut
Sélection cuts - neutron energy
(- distance e+ - n ) [level of accidentals] - t e+ - n
T.L. (Saclay) - NuFact04 -
Attempt to compare Double-Chooz with T2K (3σ discovery potential)
sin22θ13 = 0.14 sin22θ13 = 0.08 Sin2(2θ13) = 0.04
Double-CHOOZ starts with two detectors in January 2008T2K starts at FULL intensity in January 2010Assumption
From Huber, Lindner, Schwetz (hep/0405032) 90% C.L.
3σ C.L.
T.L. (Saclay) - NuFact04 -
Letter of Intent
Th. Lasserre
+ Univ. Alabama - Univ. Louisiana - Univ. Tennessee - Univ. Drexel – Argonne
T.L. (Saclay) - NuFact04 -
Double-Chooz & IAEA IAEA :Intenational Agency for Atomic Energy
Missions: Safety & Security, Science & Technology, Safeguard & Verification Control that member states do no use civil installations with military goals (production of plutonium !)
•Control of the nuclear fuel in the whole fuel cycle *•Fuel assemblies, rods, containers * (*Anti-neutrinos could play a role!)•Distant & unexpected controls of the nuclear installations *
Why IAEA is interested to antineutrino ? •IAEA wants the « state of the art »methods for the future !•Cost issue … 10,000$/day/inspector …
AIEA wants a feasibility study on antineutrinos•Monitoring of the reactors with a Double-Chooz like detector ?•Monitoring a country – new reactors “à la KamLAND”
Double-CHOOZ-IAEA: CEA/Saclay + Subatech Nantes + Kurchatov
•Perform new antineutrino spectrum @ILL reactor•Use Double-Chooz near as a ‘prototype’ for nuclear reactor monitoring•Other studies like large and very large underwater antineutrino detectors …
T.L. (Saclay) - NuFact04 -
Towards evidence of non vanishing
H. M
inakata
& H
. Sugiy
am
a, h
ep-p
h/0
30
93
23
• T2K: 10 years running (0.75MW beam & Super-Kamiokande)• Reactor (second generation): 103 104 GWth.ton.year
Regions consistent with the hypothesis =0 (90% CL)
By the reactor-LBL combined measurement
Reactor [103 GW.t.y]@ ~1km200 tons10 GWth
5 years
T.L. (Saclay) - NuFact04 -
Single reactor core P=4.1 GWth A new core is being built (2006)
Civil construction Near: 6x6x60m tunnel + 10x10x12m exp. hall Far: 6x6x450m tunnel + 10x10x12m exp. hall + emergency shafts
Two >100 tons detector Near: 300 m – 50 mwe ? Far: 1.35 km - 600 mwe Non movable detectors concept
Sensitivity 5 years >103 GWth.t.y
sin2(213) < 0.01 (90% C.L.) 1% systematic error Shape only analysis
2nd generation project: Angra (Brazil)Argonne + Brazil : CBPF, UNICAMP, USP, PUC-
RIO
T.L. (Saclay) - NuFact04 -
Conclusion & outlook A new reactor neutrino experiment could provide an evidence
of the oscillation in the (1,3) sector in 2009
Reactor & LBL programs provide independent and complementary measurements of 13. But current proposals have low synergy …
Of course reactor experiments won’t replace the rich LBL program. However, a preliminary value of 13 might help to design the best CP- detector:
Several projects of reactor experiment & strong world momentum First generation : sensitivity sin2(213)~0.02-0.03 - Rate + Shape
Motionless detectors: Double-Chooz (funded in France), KASKA Movabledetectors: Daya-bay, Braidwood
Second generation : sensitivity sin2(213)<0.01 - Shape only (>103
GWth.tons.years): Motionless detectors: Angra
)()()2sin(
1
)2sin(
)sin(1.0
)()(
)()(2/1
1313
syststatNPP
PPA
ee
eecp