ダブルショー実験　概要およびその準備状況

川崎健夫（新潟大学）

ニュートリノ研究会、宇宙線研　２０１０年２月１０日

・ Double Chooz:　　 Collaboration, Experimental concept, Detector, Physics Prospect, Status & Schedule, ・ Summary

Small q13

leptonic CP phase d

Neutrino oscillations

3

2

1

1212

1212

1313

1313

2323

2323

100

0

0

0

010

0

0

0

001

cs

sc

ces

esc

cs

sci

ie

atmospheric n solar nReactor n

Super-K+K2K+MINOS P(nm→nm)

Solar+KAMLAND P(ne→nx)CHOOZsin2(2q13)<0.2

sin2 23 0.50 0.070.08

m232 2.5 0.25

0.20 10 3eV 2

sin2 12 0.30 0.030.02

m122 7.90.3 10 5eV 2

@1hep-ph/0606060

(ne,nm,nt)T = U (n1,n2,n3)T :U=MNS Matrix

,,,,, 132312223

212 mm

sij sinij , cij cosij

(2 mass differences, 3 angles,1complex phase)

6 parameters can be accessible from neutrino oscillation.

Remains

Reactor neutrino experiment

L=1.05km

D=300mwe

CHOOZ reactor experiment

Reactor Neutrino Oscillation

0

0.2

0.4

0.6

0.8

1

1.2

0.1 1 10 100 1000

L(km)

P(e

-->

e )

e e (disappearance experiment)

Pth= 4.5 GWth, L = 1.050 km, M = 5 toverburden: 300 mwe

Chooz B reactor

2 cores

P e e 1 sin2 213sin2 m132 L

4E

sin2213=0.1

E=4MeV

Measure very small deficit

e 　

ne Detection

CHOOZ hep-ex/0301017v1

Chooz dataGd doped liquid scintillator

E=1~8MeV E=8MeV

~30s

e+ n

sin2(213)=0.04 sin2(213)=0.1 sin2(213)=0.2

(0.511MeV)

(0.511MeV)

Egå ~ 8MeV

30μs

Prompt signal

Delayed signal

Ee = E+ 1.8 MeV + O(Ee/mn)

Gd

The next quest for 13

Chooz Result

sin22<0.15 @m2=2.5x10-3eV2

CHOOZ : Rosc = 1.01 ± 2.8% (stat) ± 2.7% (syst)

World best constraint

E

Lm.

P e

420502

2232

13132

232

sinsinsinsinsin

)(

E

Lm

P ee

421

2132

132

sinsin

No effect from dSmall Matter effectAccelerator Reactor

Complementary

Double ChoozDetecctor Design/Physics Prospects

How to improve CHOOZ result?

CHOOZ Result :sin2(2q13)<0.2

Rosc = 1.01 ± 2.8% (stat) ± 2.7% (syst)

Double Chooz Experiment

Reactor Neutrino Oscillation

0

0.2

0.4

0.6

0.8

1

1.2

0.1 1 10 100 1000

L(km)

P(e

-->

e )

FarNear

~1.05km

~0.4km

Ardennes, FranceCHOOZ B ReactorPower = 4.27GWth x 2

Far SiteOverhaul CHOOZ Exp. Hall300 m.w.e70n/day©2009 Google

Near Site115 m.w.e500n/day

Double Chooz Collaboration

~150 people35 institutes, 8 countries

JapanTohoku UTokyo Metropolitan UNiigata UTokyo Institute of Tech.Kobe UTohoku Gakuin UHiroshima Inst. of Tech.

FranceSaclayAPC (collège de France)Subatech NantesIPHC Strasbourg

GermanyMax planck HeidelbergMunich TUHamburg UTubingen UAachen U

SpainCIEMAT Madrid

EnglandSussex Univ

RussiaKurchatov instSc. Acad.

BrasilCBPFUNICAMP

Very Experienced members: Chooz, Bugey, KamLAND, Super-Kamiokande, SNO, Borexino

USALivermore nat labArgonneColumbia UnivChicago UnivKansas UNotre Dame UTennesse UAlabama UDrexel UIllinois Inst techMIT

Double Chooz: 2 phasesTimeline

Construction FarDesign

2007 2008 2009 2010 2011 2012

Data Taking (Phase 1)

Cstr. Near Data Taking (Phase 2)

2013

We are here now!

Identical detectors cancel systematics on.Neutrino flux/Reactor powerAcceptance, Cross section and etc..

Improve statistics Large target volume Longer stable operation

Improve systematics Better detector design

Low BG PMT/materialBuffer oil/Gamma catcher Improved Cosmic-Veto detectors

Phase 1:Far Detector Only Phase 2:Far + Near Detector

Better understand of Background and Energy scale is important for the further reduction of systematic errors

CHOOZ Result :sin2(2q13)<0.2

Rosc (=Observe/Expect)= 1.01 ± 2.8% (stat) ± 2.7% (syst)

Ele

ctro

nics

&

DA

QC

EA

-DS

M-I

RF

U (

thec

hnic

al c

oord

ina

tion)

Outer Veto: plastic scintillator strips (400 mm)

-Target: 10,3 m3 scintillator doped with 4.5g/l of Gd compound in an acrylic vessel (8 mm)

-Catcher: 22,3 m3 scintillator in an acrylic vessel (12 mm)

Buffer: 110 m3 of mineral oil in a stainless steel vessel (3 mm) viewed by 390 PMTs

Inner Veto: 90m3 of scintillator in a steel vessel equipped with 78 PMTs

Veto Vessel (10mm) & Steel Shielding

Detector DesignNew 4-region large detector concept

Muon Inner-VETO: LS

PMT support structure: steel tank, optical insulation target/veto

The detector design

7 m

Shielding: steel 17 cm: >7

7 m

-catcher: Extra-volume for -interaction 80% dodecane + 20% PXE + PPO + Bis-MSB

n -target: Volume for -interaction 80% dodecane + 20% PXE + PPO + Bis-MSB + 0.1% Gd

n

ep

Gd

~ 8 MeV

511 keV

511 keVe+

Non-scintillating buffer: Mineral Oil Isolate PMTs from target area

Muon Outer-VETO: Scintillators　 Panels

Acrylic vessels «hardware» definition of fiducial volume

Improved background reduction

How much can we improve?

@CHOOZ: R = 1.01 2.8%(stat) 2.7%(syst)

CHOOZ-far : 50,000/3 y

CHOOZ-near: ~2.5x105/3 y2700Event rate

3-5 yearsFew monthsData taking period

0.5%2.8%Statistical error

6.82 1028 H/m36.77 1028 H/m3 Target composition

10.2 m35.55 m3Target volume

Double-ChoozCHOOZ

– Statistical error –

Luminosity incerase L = t x P(GW) x Np

Large detection volume & Long stable operation are necessary

Gd doped scintillator

• Solvent: 20% PXE – 80% Dodecane• Gd loading: being developed @MPIK

• 0.1% Gd loading of Gd-BDK (Beta Diketonate)• Long term Stability promising• LY ~7000 ph/MeV: 6 g/l PPO + 50 mg/l Bis-MSB• Attenuation length: 5-10 m meters at 420 nm• Radiopurity U: 10-12 g/g - Th: 10-12 g/g - K: 10-9 g/g

UV

-VIS

-IR

sci

nti

llat

or

tran

sm

issi

on

-All liquids are on site.

MPI-K product and purify scintillators

Gd(dpm)3

Stable@20-40 for 2 years℃

e+Energy

Systematic on Analysis/Selection

ne

p Gde+

1.5% syst. err. (Efficiency ~70% )

• 2 layer design (no fiducial cut)• Low BG PMT/Material• Improve Veto detector ⇒　 Reduce # of cuts in Analysis

@CHOOZ:

Goal Double Chooz:

Efficiency is INSENSITIVE to the energy scale errorIn total, 0.2~0.3% syst. err.:Better Energy calibration (depends on position) realize further reduction

Neutron Energy Dt

BackgroundsEstimated with CHOOZ OFF data & Simulation ( represent CHOOZ data well)

Spallation fast

neutron

μ capture

Recoil p n capture on Gd

Gd

Gd

Recoil p n from capture

μμ

Nbkg = ~1.6 evts/day (Far) 2% of n signal 　　　　　　　　　　　　　　⇒ 0.7% syst err.　　　　　 =10~20evts/day (Near) 0.5% ⇒ 0.2% syst err.

Fast neutrons

Gd ~ 8 MeV

proton recoils

μ → (9Li, 8He) → β-n

γPM + rocks

+ neutron-like event

Cor

rela

ted

Acc

iden

tals

Due to the different overburden, BG is not fully canceled.

Better understand of BG reduces sys. errors. (To be measured within a few tens of percent If we can take ~a few weeks reactor OFF data.)

“Positron” Energy spectrum

How much can we improve?

Systematic error CHOOZ Dobule Chooz

Reactor Cross section 1.9% -

Number of protons 0.8% 0.2%

Detection efficiency 1.5% 0.5%

Reactor power 0.7% -

Energy per fission 0.6% -

Total systematic error 2.7% <0.6%

@CHOOZ: R = 1.01 2.8%(stat) 2.7%(syst)

– Systematic errors –

Double Chooz Goal in Phase 2 (Far+Near)Thanks to improved detector design and 2 detectors concept

Achievable sensitivity of sin22θ13

5 times better than current limit(5 year measurement)

Achievable sensitivity of sin22θ13(90%CL)

2010 2011 2012 2013 2014

m2atm = 2.5x10-3 eV2 (20% uncertainty by MINOS)

CHOOZ: sin22θ13 < 0.15(0.12@global) Far/Near ratio

e+ spectrum

Spectrum Analysis is necessary for confidence

Status of construction/Schedule in the future

Material Status of installation

Steel shield Complete ✔

Inner veto tank Complete ✔

Inner veto PMT (8” 78PMTs) Complete ✔

Buffer tank Complete ✔

Buffer tank PMT(10” 390PMTs) Complete ✔

Gamma catcher and Target vessels Complete ✔

Close Lids Complete ✔

Electronics/DAQ installation On going

Liquid filling Soon

・・・・・・・ ・・・・

Far detector construction

Far site construction

Lab cleaning

Installation Veto and Veto-PMTs Installation Buffertank

February 2009

Overhaul CHOOZ Exp. Hall

PMT installation400High performance low background 10" PMTs(Oil proof)(HAMAMATSU R7081MOD-ASSY)

May 2009

TestAssembly

Final test at Exp. site

Installation to detector

PMT installation report

July 2009

Buffer PMT complete

Acrylic vessel installation

Acrylic vessels in lab

Gamma Catcher installation

Gamma Catcher transport

Sept 2009

Acrylic vessels in buffer tank Oct 2009

Current status

Construction Far

2009 2010 2011

Data Taking (Phase 1)

In parallel, start filling of Liquid Scintillator to Acrylic Vessels, Buffer and Inner Veto.

DAQ/Electronics installation will start in the Next week!

DAQ/Electronics: Deadtime less Splitter(Installed), PMT HV

supplies Trigger electronics 500MHz FADC, DAQ PCs Run control PCs

Dec 2009

Lid closedStart Data taking!!!

Soon..

Construction Far

2009 2010 2011

Data Taking (Phase 1)

Outer veto: Panels of strips of coextruded plastic scintillator with wavelength shifting fiber.

Calibration: - Target fish-line & articulated arm - -catcher and buffer guide tubes - Embedded LEDs (Installed)

Cstr. Near Data Taking (Phase 2)

Data taking start.Then….

Improve data quality and reduce systematic errors.

Status of the Near site

Tunnel (155 m),12% slope

• Site engineering study completed ⇒Start excavation 2010 Site will be ready 2011

• Neutrino fluxes: 2.5 x105 events in 3 years

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

1)

Laboratory

Open ramp (85 m), 14% slope

Liquid storage

456m

160m

340m

Summary for Double Chooz • The Double Chooz experiment

– Double Chooz will be the first of a new generation of reactor neutrino experiments. It is the one of the best experimental concept to measure 13

• The status of DoubleChooz Experiment– Detector Construction are close to the final stages.

• Installation of DAQ/Electronics starts in the next week.• Filling of Liquid Scintillator follows.

– We should observe the neutrino from reactor in this year!– Construction of the near site/detector will be started soon.

• Prospects for the future– First data taking expected to start in 2010 with far detector only ⇒sin2(213) < 0.06 in 1.5 year – From year 2011~, take data with the both near and far detectors ⇒sin2(213) < 0.03 in 3 years