double-ch 13 13 z: a search for 13

Double-CH1313Z:

A search for 13

Thierry Lasserre (CEA/Saclay)On behalf the Double-Chooz collaboration

NuFact04, Osaka, JapanJuly 28th 2004

T. L. (Saclay) - NuFact04 -

Letter of Intent


CHOOZ site &

Detector Overview


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, Ardennes, France


The CHOOZ-far site

September 2003


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)


Full detector simulation

~500 PMTs/detector


The CHOOZ-near site

250 m

125 m

Near detector @100-200 m from the coresExact position under study, in collaboration with EDF


The CHOOZ-near laboratory

@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


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

Event rate 2700CHOOZ-far : 60 000/3 yCHOOZ-near: >3 106/3 y

Statistical error 2,7% 0,4%


Decreasing systematical error

1. Improve the detector concept2. Two identical detectors towards σrelative~0,6%3. Backgrounds – improve S/B>100 error<1%

Improving CHOOZ – Systematical error -

@CHOOZ : σsys=2.7%


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


Relative Normalisation: Detector

Solid angle- Distance measured @10cm + Monitoring of the source

barycenter …

Target volume- @CHOOZ : 0.3% [simple measurement]- Goal ~0.2% [same apparatus for both detectors] - Not trivial

…

Density- 0.1% achievable, but accurate temperature control mandatory

H/C ratio & Gd concentration- Absolute measurement is difficult : 1% error @CHOOZ- Plan: use the same batch to fill both detectors

Boundary effect at the inner vessel interface (spill in/out)

- Neutron transport slightly different due to solid angle effect- MC study to be done to check that it is negligible

Live time to be measured accurately by several methods


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

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

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


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 bkg]

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

e+

n

t

e+


Systematics uncertainties


Backgrounds


- CHOOZ: N/S ~ 4%

- Double-CHOOZ-Far (300 mwe): 12.7 tons Signal x 3

-Modification of the detector design + expensive

-Uncorrelated: N/S(chooz) ~ 4% : Double-Chooz: Sx3 & N/3 < 0.5%

-Correlated events: N/S < 1%CHOOZ : ~<1 recoil proton per day Double-CHOOZ: liquid active buffer +30cm ~0.3 events per day

- Double-CHOOZ-near (50 mwe): Signal x 50-100 S(CHOOZ-Far)

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

-Uncorrelated: CHOOZ-Far backgrounds x 50 N/S < 1%

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

(but not a comprehensive list of backgrounds …)

Backgrounds Estimates


Neutron Induced Background

Surrounded by 100 mwe rock shielding

Cosmic muons create fast neutrons through spallation and muon capture in the rock surrounding the detector

Fast neutron slowns 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.)


Overview of Scintillator developement

& 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)


Scintillator liquid baselineVolume

[m3]Type

-target 12,7 0,1% Gd loaded scintillator

-Catcher 28,1 Unloaded scintillator

Buffer 100 Non scintillating oil

Veto 110 Scintillating oil

Reference recipe- PC (C9H12), PXE (C16H18) attack acrylics- Dodécane + PXE more resistant …- R&D Saclay+MPIK+Gran Sasso (08/2004)Baseline: 80% dodecane + 20% PXE + 6 g/l PPO + 20 mg/l BisMSB + 0.1% Gd

LY~8000 /MeV , L = 5-10 m

Fluors concentration- Match scintillation light to PMTs - PPO : 6g/l- BisMSB: 20mg/l

Vtot = 250 m3 (200 tons)


Acrylic vessels

4m

2m

2.4m

3.6m

2.8m

Gamma catcher Target

Final assembly on Chooz’s site Assembly at the manufacturer

Target

Gamma catcher

•Empty weight:– Target = 220kg– Gamma catcher = 470kg

Maximum stress: 12 MPa

Thickness: 6 mm


Sensitivity &

Discovery Potential


Spectrum deformation @Double-CHOOZ

sin2(213)=0.15


90% C.L. sensitivity if sin2(213)=0

m2=2.4 10-3 eV2

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


Attempt to compare Double-Chooz with Beams & Superbrams

Th. Lasserre

P. Huber et. al. hep/0403068

Double-CHOOZ starts with two detectors in January 2008T2K starts at FULL intensity in January 2010

m2=2.0 10-3 eV2


Attempt to compare Double-Chooz with T2K (3σ discovery potential)

sin22θ13 = 0.14 sin22θ13 = 0.08 sin22θ13 = 0.04


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 (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


Strong Support for the EDF power company & local authorities to perform a 2nd

experiment at Chooz (castle available again for physicists !!!)Double-CHOOZ sensitivity: sin2(213)<0.025-0.03, 90% C.L. (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: Saclay, APC, Subatech, TUM, MPIK, Tubingen Univ. Hamburg Univ., Kurchatov, Univ. Alabama, Univ. Tennessee, Univ. Lousiana, Univ. Drexel, Argonne, + Italian groups soon … (maxi-)letter of intent (May 2004) final proposal end of 2004

Approved in France. Detector cost ~7 Million euros (Civil engineering cost not included)

Our Goal @Double- CHOOZ: Construction starts end of 2005 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

double-ch 13 13 z: a search for 13

Documents

saclay nufact04

chooz plan

chooznear laboratory

chooznear sitenear detector

choozfar siteseptember

chooz site detector

mwe choozfarchooz

detector simulation