Double Chooz Near Detector Guillaume MENTION CEA Saclay, DAPNIA/SPP Workshop AAP 2007 Friday, December 14 th, 2007

Double Chooz Double Chooz Near DetectorNear Detector

Guillaume MENTION

CEA Saclay, DAPNIA/SPP

Workshop AAP 2007Friday, December 14th, 2007

http://doublechooz.in2p3.fr/

http://doublechooz.in2p3.fr/

Double ChoozDouble Choozdetector capabilities detector capabilities

- Double Chooz experiment- The site- The 2 identical detectors- The reactors: powerful anti-neutrino sources

- Expected performance- Detection of reactor anti-neutrinos: e+ and neutron- Anti-neutrino spectrum measurement (Far and Near detectors)- Thermal power measurement- Burn-up detection

-Conclusions

Chooz power plant mapChooz power plant map

Near site: D~380 m, overburden 120 mwe Far site: D~1.05 km, overburden 300 mwe

Type PWR (N4)

# Cores 2

Th. Power 8.5 GWth

Operating since 1996/1997

Load Factor 78%

The experiment siteThe experiment site

ν ν ννννν

ν 1051 m380 m

Double Chooz: 2 phasesDouble Chooz: 2 phases

Double Chooz phase 1: far detector only may help to reach a higher precision on anti-e spectrum…

Double Chooz phase 2: higher precision on anti- e spectrum~ 2 105 events in 3 years

Timeline

Site Proposal Construction FarDesign

2004 2005 2006 2007 2008 2009 2010 2011 2012Data Taking (Phase I)

Cstr. Near Data Taking (Phase II)

Reactors are abundant Reactors are abundant antineutrino sourcesantineutrino sources

235U239Pu

Days

235U

239Pu

238U 241PuFi

ssio

n pe

rcen

tage

s

235U 239Pu

Energy released per fission

201.7 MeV 210.0 MeV

Average energy of e 2.94 MeV 2.84 MeV

# e per fission > 1.8 MeV 1.92 1.45

More than 1021 fissions/second

νe identification: using coïncidences (allows strongly reducing backgrounds)

(1) 0,5 < Eprompt < 10 MeV

(2) 6 < Edelayed < 10 MeV

(3) 1 μs < Δt < 100 μs

―

Σ ≃ 8 MeV

Ee+

+ 1 MeV

Δt < 100 μs

te+ n

ννee Detection technique Detection technique50 years of Physics50 years of Physics

Detector structureDetector structure

Far detector

Double Chooz: 2 identical detectors

CalibrationGlove-Box

Outer Veto:plastic scintillator panels

-Target: 10.3 m3 liquid scintillator doped with 0.1% of Gd

γ-Catcher:22.6 m3 liquid scintillator

Buffer: 114 m3 mineral oilwith ~400 PMTs

Inner Veto: 90 m3 liquid scintillatorwith 80 PMTs

Shielding: 15 cm steel

4 LiquidVolumes

9

BackgroundsBackgroundsfast neutrons

Gdγ ~ 8 MeV

proton recoils

μ → (9Li, 8He) → β-n

γPM + rocks

+ neutron-lik

e event

Acc

iden

tals

~~~~~

~~~~~~

~~~ ~ ~

~~~~

Cor

rela

ted

(CHOOZ data)

Far detector capabilitiesFar detector capabilities• Far site: phase I of Double Chooz• Anti-neutrino spectrum measurement over 1.5 years. (~ 22 000 anti-neutrinos):

– Require the knowledge of the average power over 1.5 years– Require the knowledge of the average fuel composition over 1.5 years

• Would allow to measure the antineutrino rate at a statistical precision of 0.7%(in case of no systematics)

• But also the shape of the spectrum,with a statistical precision of 2 to 3%per energy bin (with 8 bins between1.5 and 5.5 MeV).

• Systematical uncertainties reduce thispotential which is limited by the knowledgeon the detector normalization (~ 2%) andon the reactor powers (~ 2%).

• Backgrounds also lead to some systematicalsubtraction error around 1% per energy bin

• The measured spectrum will include the oscillationeffect.

Evis in MeV

# an

ti- e

in 1

.5 y

ears stat

stat”+” syst

Map of the near siteMap of the near site(Preliminary, still under study)(Preliminary, still under study)

• Distance to reactor cores: 456 m & 340 m 385 m (1 R. with 2Pth)

• Neutrino fluxes: w/o eff. 496 anti-e/day 2.5 105 events in 3 years (all eff. included)

• Depth: 120 m.w.e. ( flux: ~ 3-4 /m-2s-1)

456 m

340

m

160 m

Cho

oz N

PP

, mas

s m

ap Near sitelocation

Accesstunnel

Huber &

Schw

etz hep-ph/0407026Thermal power measurementThermal power measurement

with the near detectorwith the near detector

1 error on thermalpower

measurement

~ 10 000 events/month@ Double Chooz Near

• Thermal power is measured at ~2% (?) by the nuclear power companies• Current measurement at reactor 3% but possibility of improvement

• What can only neutrino do: • Independent method looking directly at the nuclear core, from outside• Cross calibration of different power plants from different sites

With Double Chooz NearAverage power measurement

of both reactors: 5-6% over 3 weeks

Fig: Chooz cooling tubes

= Assuming no knowledge on reactor (neither power nor fuel composition)

Following up the burn-upFollowing up the burn-up

Days

235U

239Pu

238U 241PuFiss

ion

perc

enta

ges

Evis in MeV

# an

ti- e

in 1

0 da

ys

Detector efficiency included.

Average spectra (analytical estimations), no statistical fluctuations here

Question: How far can we see two different burn-up?

Try to answer with non-parametric statistical test: Kolmogorov-Smirnov

Days

235U

239Pu

238U 241PuFiss

ion

perc

enta

ges

Evis in MeV

# an

ti- e

in 3

wee

ks

- 9980 events- 9370 events

Two extreme burn-up inTwo extreme burn-up in3 weeks3 weeks (identical reactors)(identical reactors)

Preliminary

2 fixed fuel compositions (in fraction of fission per isotope) 235U=0.66 239Pu=0.24 238U=0.08 241Pu=0.02 235U=0.47 239Pu=0.37 238U=0.08 241Pu=0.08

Kolmogorov-Smirnov Test on Burn-up:Null hypothesis H0: the two “burn-up” induce identical anti-e spectra

• Shape only: PKS = 0.81 (Max Distance = 0.0093) Shapes are very close!!!

• Rate and shape: PKS = 1.3 x 10-4 Rates are very different (~7% diff. on # of anti-e)

Evis in MeV

# an

ti- e

in 1

0 da

ys


Two extreme Burn-up inTwo extreme Burn-up in10 days10 days (identical reactors)(identical reactors)OR OR 16 days 16 days with R1with R1 ONON R2R2 OFF OFFOROR 29 days 29 days with R1with R1 OFF OFF R2R2 ONON

Days

235U

239Pu

238U 241PuFiss

ion

perc

enta

ges

Preliminary



• Shape only: PKS = 0.99 (Max Distance = 0.0093) Shapes look identical!!!

• Rate and shape: PKS = 1.8 x 10-2 Rates are different (~7% diff. on # of anti-e)

Evis in MeV

# an

ti- e

in 3

wee

ks


Two closer burn-up inTwo closer burn-up in3 weeks3 weeks (identical reactors)(identical reactors)

Days

235U

239Pu

238U 241PuFiss

ion

perc

enta

ges

Preliminary



• Shape only: PKS = 0.997 (Max Distance = 0.006) Shapes look identical!!!

• Rate and shape: PKS = 4.2 10-2 Rates are different (~4 % diff. on # of anti-e)

Evis in MeV

# an

ti- e

in 3

wee

ks


Two still closer burn-up inTwo still closer burn-up in3 weeks3 weeks (identical reactors)(identical reactors)

Days

235U

239Pu

238U 241PuFiss

ion

perc

enta

ges

Preliminary



• Shape only: PKS = 1.00 (Max Distance = 0.002) Looks identical!!!

• Rate and shape: PKS = 0.55 Rates are too close, spectra match (~2 % diff. on # of anti-e)

Conclusion & OutlookConclusion & Outlook

- Neutrinos could “take a picture” of the nuclear cores Thermal power measurement & non proliferation applications

- Thermal power measurement will rely on the absolute normalization (but time-relative measurement of interest for burn-up, cross calibration)

- Non proliferation applications will rely on time-relative measurements (try to detect an ‘abnormal’ burn-up)

- Double Chooz Near detector will provide an unrivalled anti-e spectrum measurement. These data will be an incredibly rich source of information in order to look for power, burn-up correlations with anti-e spectra as a first step toward isotopic core composition.

- However more precise determination of reactor power and some hints of isotopic composition might be obtained only with a closer detector to a single reactor.

Thank you for your attention!

It’s time for lunch now!

SystematicsSystematics

(Total ~0.45% without contingency ….)

(see next slide)

Measured with several methods

‘’identical’’ Target geometry & LS

Same scintillator batch + Stability

Accurate T control (near/far)

Same weight sensor for both det.

Distance measured @ 10 cm + monitor core barycenter

Two ‘’identical’’ detectors, Low bkg

< 0.6 %2.7 %Total

0.2 - 0.3 %1.5 %From 7 to 3 cutsAnalysis

<0.1 %1.0 %Spatial effects

<0.2%1.2 %H/C ratio & Gd concentration

<0.1 %0.3 %Density

<0.1 %0.3 %Solid angle

0.25 %few %Live time

0.2 %0.3 %Target MassDetector - induced

<0.1 %0.6 %Energy per fission

<0.1 %0.7 %Reactor power

<0.1 %1.9 % flux and Reactor-induced

Double Chooz (relative)Chooz

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Double Chooz Near Detector Guillaume MENTION CEA Saclay, DAPNIA/SPP Workshop AAP 2007 Friday, December 14 th, 2007