Double-Chooz A search for 13 Guillaume MENTION (PCC-Collège de France/APC) On behalf of the...

Double-ChoozA search for 13

Guillaume MENTION (PCC-Collège de France/APC)

On behalf of the Double-Chooz collaboration

NOW 2004 Conca Specchiulla, Italy

September 14th 2004

G. Mention (PCC/APC) -NOW04-

In this presentation

1. Current 13 physical context

2. Chooz site and detector

3. Improving Chooz

4. Backgrounds

5. Detector design

6. Sensitivity and discovery potential

7. Safeguard applications


Best current constraint: Chooz

World best constraint !

@m2atm = 2 10-3 eV2

sin2(2θ13) < 0.2

(90% C.L)

e x

M. Apollonio et. al., Eur.Phys.J. C27 (2003) 331-374

e e (disappearance experiment)

Pth= 8.4 GWth, L = 1.050 km, M = 5 toverburden: 300 mwe

R = 1.01 2.8%(stat)2.7%(syst)


1 3 oscillations

Near detector Far detector


The Double-Chooz concept

8.4 GWth

Chooz power station Near detector Far detector

e e,,

anti-e flux (uranium 235, 238 & plutonium 239, 241) Reaction: e + p e+ + n, <E>~ 4 MeV, Ethreshold =1.8 MeV Disappearance experiment: search for a departure from the 1/D2

behavior and shape distortion

D1 = 100-200 m D2 = 1,050 m

Improve the detector concept and backgrounds rejection

improve Chooz sensitivity 0.03


Letter of Intent (hep-ex/0405032)

ANDDrexel, Argonne and Universities ofAlabama, Louisiana and Tennessee


Chooz site &

Detector Overview


Near site: D~100-200 m, overburden 50-80 mweFar site: D~1.1 km, overburden 300 mwe

2Cores

EDFOperator

FramatomeConstructor

66, 57(%, in 2000)

1996/1997Couplage

8.4 GWthPower

PWRType

Chooz-Far

Chooz-Near

Double-Chooz, Ardennes, France


Two detectors


Far detector laboratory


Near laboratory outlines

@DAPNIA

Distance Reactor-detector Required overburden (m.w.e)

100 45-53

150 55-65

200 67,5-80

~10m

60 m.w.e. overburden• 12 m compacted earth• 3 meter high density material

5m

15m


Detectors design

7 m

Shielding: 0,15 m steel

7 m

Muon VETO: scintillating oil (r+0.6 m – V = 110 m3)

Non-scintillating buffer: same liquid (+ quencher?)(r+0.95m, , V = 100 m3)

-catcher: 80% dodecane + 20% PXE (acrylic, r+0,6m – V = 28,1 m3)

PMTs supporting structure

target: 80% dodecane + 20% PXE + 0.1% Gd (acrylic, r = 1,2 m, h = 2,8 m, 12,7 m3)

n

ep

Gd

~ 8 MeV

511 keV

511 keVe+


How to improve Chooz:statistics & systematics


Improving Chooz – Statistical error –

Luminosity increase L = t x P(GW) x Vtarget

Chooz : R = 1.01 2.8% (stat) 2.7% (syst)

Chooz Double-Chooz

Target volume 5.55 m3 12,67 m3

Target composition 6.77 1028 H/m3 6.82 1028 H/m3

Data taking period Few months 3-5 years

Number of events 2700Chooz-far : 60 000/3 y

Chooz-near: > 3 106/3 y

Statistical error 2.7% 0.4%


Decreasing systematical error

1. Improve the detector concept

2. Two identical detectors towards σrelative~ 0.6%

3. Backgrounds – improve S/N>100 error < 1%

Improving Chooz – Systematical error –

@Chooz : σsys = 2.7%


Reactor induced systematics

systematics Error type Chooz

2 identical detector

Low 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


Detector induced systematics

systematics Error type Chooz

2 identical detector

Low backgrounds

Detector

Scintillator density 0.3% O(0.1%)

% H 1.2% O(0.1%)

Target volume 0.3% 0.2%

Boundary effects 1.0% O(0.1%)

Live time n.g. 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

http://babbage.sissa.it/find/hep-ex/1/au:+Apollonio_M/0/1/0/all/0/1


Main works on systematic errors

Solid angle- Reactor cores to near detector distance to be measured @10 cm- Monitoring of the source barycenter…

Target volume- @Chooz : 0.3% [simple measurement]- Goal ~ 0.2% [same apparatus for both detectors] – feasible but not

trivial…

Live time to be measured accurately by several methods KamLAND : dead-time 10% and σsyst = 0.6%

Double-Chooz: dead-time(near) 25% and goal: σsyst ~ 0.25%


Relative Normalization: Analysis @Chooz: 1.5% syst. err.

- 7 analysis cuts- Efficiency ~70%

Goal Double-Chooz: ~0.3% syst. err. - 2 to 3 analysis cuts

Selection cuts - neutron energy

(- distance e+ - n ) [level of accidentals] - t (e+ - n)

e+

n

t

ne

p Gde+


Systematics uncertainties


Backgrounds


Uncorrelated and correlated backgrounds

n

ep

Gd

~ 8 MeV

511 keV

511 keVe+

neutrino identification (signal)

n Gd

~ 8 MeV

n deposits energy

correlated background

accidental background (uncorrelated)

prompt signal + n capture on Gd

n

Gd

~ 8 MeV

+

E >~ 1 MeV

+-n cascades


- Chooz: N/S ~ 4%

- Double-Chooz-Far (300 mwe): 12.7 m3 Signal x 2.4

- Uncorrelated (, + n capt. on Gd):N/S(Chooz) ~ 4% : Double-Chooz: Sx3 & N/3 can be measured and

subtracted

- Correlated events (neutrons):Chooz : ~<1 recoil proton per day Double-Chooz: liquid active buffer +30 cm

~0.3 events per day N/S<1%

- Double-Chooz-near (50 mwe): Signal x 50-100 SFAR

- Key advantage: Dnear ~ 100-200 m Signal x 50-100 !

- Uncorrelated: Chooz-Far backgrounds x 50 can be measured and subtracted

- Correlated events: Chooz-Far x <30 N/S < 1%

(but not a comprehensive list of backgrounds …)

Backgrounds Estimates


Neutron Induced BackgroundCosmic muons create fast neutrons through spallation and muon capture in the rock surrounding the detector

Fast neutron slows down by scattering into the scintillator; it could deposit between 1-8 MeV and be later captured on Gd !

Full simulation – Geant + Fluka

Old Chooz simulation: 300 m.w.e. 31hours – MC is reliable !• Simulated: Nb<1.6 evts/day (90% C.L.)• Measured in-situ: Nb=1.1 evts/day

Double-Chooz simulation:• 338 106 tracked – 580 103 neutrons tracked• 1 neutron created a muon event• Far detector: Nb<0.5 evt/day (90% C.L.)• Near detector: Nb<3.2 evts/day (90%C.L.)

n Gd

~ 8 MeV


Overview of Scintillator development

& Acrylic vessel design


Gd-Acac

3+Gd

Goal: 0.1% Gd loaded scintillator (follow up of LENS R&D)

Light yield ~8000 /MeV + attenuation length > 5m STABLE & Compatible with acrylic

Gd doped scintillator development

3+Gd(R-C

OO

H)

x R

-CO

O-

R-COO- -O

OC-R

Carboxylate

Ongoing: 1/ Long term stability 2004 2/ scintillator-acrylic compatibility

~80 days Ageing test @40-50o [x2-4 each 100] Material compatibility test + acrylic design

70

75

80

85

90

95

100

105

300 350 400 450 500 550 600l [nm]

T [

%]

Gd(2MVA)3 inPC(35%)+Dod(65%)[2MVA]=0.05M [Gd]=2g/ laf ter 1 month

af ter T-test (6 days @ 40°C)

af ter T-test (14 days@40°C)

af ter T-test (20 days @50°C)


DAPNIAta

rget

: 2

.8 m

-ca

tche

r:

4.0

m

-catcher: 1.8 m

target: 1.2 m

Acrylic vessels (preliminary)

single acrylic pieceintegration (-target + -catcher set)


Sensitivity &

Discovery Potential


Spectrum deformation @Double-Chooz1σ statistical errors only

rate info:

no-osc excluded@ 2.66σ

shape info:

flat shape excluded@ 5.98σ


Global normalization: 2%

Detector N Detector F

σabs=2%


σrel=0.6%

Relative normalization: 0.6%


σshape=2%

Spectrum shape uncertainty: 2%


σbkg=1%

Backgrounds subtraction: 1%

Systematical errors influence on spectra


Potential limit if sin2(213)=0

• Efficiencies included

• 1% of background in Near & Far detectors

• Syst. uncert.:σabs = 2.0%σrel = 0.6%σscl = 0.5%σshp = 2.0%σΔm

2= 20% m2=2.4 10-3 eV2

3 years (efficiencies included) sin2(213)<0.024

Det. Bins k

2

k

k

2

kk

2

σ

α

Error Uncor.

BiasesαTheoryDataχ

FN,A

N

1i

K

1k

2

Ak

Aki,

2

Ai

K

1k

Aki,

Aki,

Ai

Ai

2bins

σ

α

U

SαTOχ


Discovery potential1 d.o.f.


Complementarity of Double-Chooz with T2K (3σ discovery potential)

sin22θ13 = 0.08

Double-Chooz 1 year 3 years 7 yearsJ-Parc / 1 year 5 years

m2 = 2.0 10-3 eV2

Lindner et al.


Double-Chooz & IAEA IAEA: International Agency for Atomic Energy

Missions: Safety & Security, Science & Technology, Safeguard & Verification Control that member states do not 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 !

IAEA 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:

• Perform new antineutrino spectrum measurement @ILL reactor (Mini-Inca + -spectrometer)• Use Double-Chooz near as a ‘prototype’ for nuclear reactor monitoring• Other studies like large and very large underwater antineutrino detectors …

Mini-Inca


Double-Chooz sensitivity:can set sin2(213)<0.025-0.03, 90% C.L. (if m2 = 2.0-2.5 10-3 eV2)& can see sin2(213)>0.04-0.05, 3σ C.L. (if m2 = 2.0-2.5 10-3 eV2)Current limit: Chooz : sin2(213)<0.2 discovery potential !

Technology / design well known (Chooz, BOREXINO, KamLAND,…) few R&D needed : Gd loading (stability) + material compatibility (Started, to be completed in half a year)

Collaboration: APC Paris, Saclay, Subatech, TU Munich, MPIK Heidelberg, Tubingen Univ. Hamburg Univ., Kurchatov, RAS Moscow, Univ. Alabama, Univ. Tennessee, Univ. Louisiana, Univ. Drexel, Argonne, + Italian groups discussing… (maxi-)letter of intent (May 2004) final proposal end of 2004

Approved in France. Our Goal @Double-Chooz: Construction starts in 2006

Start data taking in 2007 (far) & 2008 (near + far)

Summary & outlook

2003 2004 2005 2006 2007 2008 2009Site Data takingProp. Construction ?design

in 2009 sin2(213) < 0.05

in 2011sin2(213) < 0.025

Far detector starts Near detector starts

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Double-Chooz A search for 13 Guillaume MENTION (PCC-Collège de France/APC) On behalf of the...

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