Christian Buck, MPIK Heidelberg

LAUNCH 09

November, 11th 2009

The Double Chooz reactor neutrino

experiment

Neutrino oscillations

3

2

1

321

321

321

UUU

UUU

UUU eeee

Δmsol2 ~ 7.6∙10-5 eV2, sin2(2Θ12) ~ 0.85

Δmatm2 ~ 2.4∙10-3 eV2, sin2(2Θ23) ~ 1

ν2

Δmatm2

Δmsol2

ν1

ν3

sin2Θ13

sin2Θ23

sin2Θ12

νe

νμ

ντ

E

LmPee 4

sin2sin12

13213

2

Why Double Chooz?

Improved knowledge of mixing matrix

Key experiment to unveil leptonic CP violation

Discovery potential: hint given by global analysis

Fogli et al., arXiv:0905.3549 (2009)

Complementarity to beam experiments

- Degeneracies + parameter correlations

- Optimize future accelerator experiments

Discrimination power of 0νββ

Safeguard applications,…

)1(04.008.02sin 132

Reactor neutrino experiments

1956: First observation (Nobel Prize 1995)

1990s: Chooz, Palo Verde (sin22Θ13< 0.2)

2002: KamLand

Δm12, Θ12

Reactor neutrinos: Pure νe - beam Intense flux (~2% precision) Detection: inverse β-decay Energy: few MeV

Double Chooz collaboration

Spokesman: H. de Kerret (APC) France: CEA Saclay, APC Paris, Subatech Nantes, IPHC Strasbourg Germany: MPIK Heidelberg, TU München, EKU Tübingen, Universität Hamburg,

RWTH Aachen USA: Univ. of Alabama, Argonne Nat. Lab., Chicago, Drexel, Kansas State, LLNL,

Notre Dame, Tennessee, Columbia Univ., Davis, MIT, Sandia Spain: CIEMAT Madrid Japan: Tohoku University, Kobe University, Tokyo Inst. of Tech., Niigata

University, Tokyo Metropolitan University, Hiroshima Inst. of Tech. England: University of Sussex Russia: RAS Moskau, Kurchatov Institute Brasil: CBPF Rio de Janeiro, UNICAMP

The Double Chooz principle

Survival probability

G. Mention (APC)

Dnear Dfar

E

Lm

E

LmPee 4

sin2sincos4

sin2sin12

12212

213

42

13213

2

Survival probability assuming sin2(2Θ13) = 0.2 for different Δm13

Current proposals

Angra

Double-Chooz

KaskaDaya bay

RENO

Neutrino signal

n

ep

511 keV511 keV e+

~ 8 MeV

Gd

Target: Gadolinium loaded liquid scintillator

Neutrino rates: - far: ~50/day- near: ~300/day

235U

ββ

236U

n pure e source

Eν ~ MeV

Emin ~ 1.8 MeV

> 1020 /(s∙GW) Chooz: ~ 7.4 GWth

prompt

delayed (30 µs)

Background

Accidentals

n

~ 8 MeV

+

E ≥ 1 MeV

Gd

n

~ 8 MeV

Gd

fast neutrons

β-n-cascades: 9Li,8He

Chooz data:

far detector: ca. 1.4/day

Long lived!

Detector Design

TARGET (2.3m)- Acrylic vessel (8mm)- 10,3 m3 LS (1 g/l Gd)

γ-catcher (0.55m) - Acrylic vessel (12mm)

- 22,6 m3 LS

Buffer (1.05m) -Steel (3 mm)- 110 m3 oil

Inner Veto (0.5m) -Steel (10 mm)

- 80 m3 LS

7m

Calibration systems

Target

GC

Buffer

Articulated arm

z-axis system (glove box)

Guide tube / wire sources

LED system / multi-wavelength

Buffer tube

Comparison with Chooz

Fehler Chooz DC

Statistical 2.8% 0.4%

Flux, σ 1.9 % <0.1 %

E/fission 0.6 % <0.1 %

power 0.7 % <0.1 %

# protons 0.8 % 0.2 %

Det.eff. 1.5 % 0.5 %

Σ System. 2.7 % ~ 0.6%

Best limit: CHOOZ

sin2(2θ13) < 0.15 (90% CL)

for m2atm = 2.5·10-3 eV2

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

Reactor

Detector

Sensitivity

2010

Sensitivity 2010 – 2015 (near detector starts < 2 y after far) for m2

atm = 2.8·10-3 eV2

Far detector filling early 2010!

Far detector installation

Lab cleaning

Installation Veto and Veto-PMTs Installation Buffertank

PMT installation

Acrylic vessel installation

Arrival Gamma Catcher on-site Acrylic vessels in lab

Gamma Catcher installationGamma Catcher transport

Status October ‘09

Status near detector

Tunnel (155 m), 12%

Site engineering study completed excavate 2010

r = 415 m (115 m w.e.)

Myons (Veto): 250 Hz reactors

near detector

LaboratoryOpen ramp (85 m), 14%

Liquid storageData taking: 2011

Scintillator development (MPIK)

Requirements:

Gd-solubility > 1 g/l

Stability (5 years)

Transparency

Material compatibility

Radiopurity

Target – Gamma catcher matching (optics + density)

Large scale (multi tons)

Light yield

PXE conc,

PPO conc.

Scintillator properties

400 420 440 460 480 500 520 540 560 580 6000,000

0,005

0,010

0,015

0,020

0,025

0,030

2.5m

5m

abso

rban

ce (1

0 cm

cel

l)

wavelength [nm]

30Aug2006 04Feb2009

10m

Target

Gamma Catcher candidates

Event localization by pulse shape analysis

Transparency in ROI stable in 10 m range!

Time [ns]

Eve

nts

All components (40 tons) delivered to MPIK Purifications finalized, prepare for mixing Scintillator production starts

Large scale production

PMT activities at MPIK

Testing / Calibration Assembly / Installation Implementation of data in Double Chooz software Current upgrade: full detector segment

PMT calibration

Calibration program: HV scans Single photon electron (P/V) Transit time Dark rate Quantum efficiency

Summary

Goal of Double Chooz reactor neutrino experiment: Determination of mixing angle Θ13 (sin2(2θ13) ~ 0.03)

2-detector concept to reduce systematical error

Detection via inverse β-decay in Gadolinium loaded liquid scintillator

Schedule:

– Data taking far detector: Spring 2010

– Near detector: end of 2011

MPIK: scintillators, PMTs, Analysis

Θ13 and 0νββ

Normal hierarchy: discrimination power of 0νββ-exp. depends on sin2(2Θ13) !

M.Lindner, A.Merle, W.Rodejohann, Phys.Rev.D73:073012 (2006)

Positron spectrum

Far/Near ratio

sin2(213)=0.12

e+ spectrum

Far DetetectorStat. Errors

Sensitivity (rate vs shape)

Robustness