S. Kettell WIN09 9/13/09 Daya Bay Experiment Steve Kettell BNL On Behalf of the Daya Bay...

S. Kettell WIN09 9/13/09

Daya Bay Experiment

Steve Kettell

BNLOn Behalf of the Daya Bay Collaboration

2S. Kettell WIN09 9/13/09

The Last Mixing Angle: 13

UMNSP MatrixMaki, Nakagawa, Sakata, Pontecorvo

1 0 0

0 cos23 sin23

0 sin23 cos23

cos13 0 e iCP sin13

0 1 0

e iCP sin13 0 cos13

cos12 sin12 0

sin12 cos12 0

0 0 1

1 0 0

0 e i / 2 0

0 0 e i / 2i

• What ise fraction of 3?• Is there symmetry in neutrino mixing?• Will we be able to observe CP violation?

• Ue3 is the gateway to leptonic CP violation.

?

U Ue1 Ue2 Ue3

U1 U2 U 3

U1 U 2 U 3

0.8 0.5 Ue3

0.4 0.6 0.7

0.4 0.6 0.7

?

atmospheric, K2K reactor and accelerator 0SNO, solar SK, KamLAND

12 ~ 32° 23 = ~ 45° 13 = ?


Detection of e

• Calibrate with 68Ge, neutron, and 60Co • additional calibration with LED and spallation neutrons

Inverse -decay in Gd-doped liquid scintillator:

Prompt Energy Signal

.

1 MeV6 MeV 10 MeV

•Ee+ = [1,8] MeV•En (delayed) = [6,10] MeV•tdelayed-tprompt = [0.3,200] s

n-p n-Gd

e p e+ + n (prompt)

+ p D + (2.2 MeV) (delayed)

+ Gd Gd* Gd + ’s(8 MeV) (delayed)

0.3b

50kb

Delayed Energy Signal


Measuring 13 at a Reactor

~1.8 km

~ 0.3-0.5 km

Pee 1 sin2 213 sin2 m312L

4E

cos4 13 sin2 212 sin2 m21

2L

4E

Distance (km)

Pe e

nuclear reactor

detector 1detector 2

13

• Precise measurement• No dependence on CP or matter effects

Gd-LS

LSMO

• near detectors measure e flux and spectrum to reduce reactor-related systematic uncertainties• far detector at the oscillation maxprovides the highest sensitivity

Disappearance Probability


MeasuredRatio of Rates

DetectorEfficiency

Ratio

DetectorMass Ratio,

H/C

Measure ratio of interaction rates in multiple detectors

near far

νe

distance L ~ 1.5 km

Measurement Concept

mass measurement calibration

sin2213

± 0.3% ± 0.2%

Gd-LS Storage Tank

FarNear

6S. Kettell WIN09 9/13/09Daya Bay NPP:2 2.9 GWth

Ling Ao II:2 2.9 GWth

2010-11

Ling Ao:2 2.9 GWth

1 GWth generates 2 × 1020 e /s

Total tunnel length: ~2700 m

73

0 m

570 m

910 m

Daya Bay Near360 m from Daya BayOverburden: 97 m

Ling Ao Near500 m from Ling AoOverburden: 98 m

Far site1600 m from Ling Ao2000 m from DayaOverburden: 350 m

Water hall

Filling hall

Total PowerNow: 11.6 GWth

2011: 17.4 GWth


Daya Bay Detectors

Ancillary Rooms- Gas- DAQ- Water

• 8 Antineutrino detectors• 4 in far hall, 2 in each near hall• 20t target mass per AD• Muon Veto system


Muon Veto System

Multiple muon detectors: Water pool Cherenkov counter:

inner/outer regions, 2.5m shield RPC muon tracker Combined efficiency (99.5

0.25)%

1m outer water veto1.5m inner water veto

WaterCerenkov(2 layers) RPC

960 8”PMTs(3 pools)

AD


Gd-LS

LS

MO

5 m

1.55 m

1.99 m

2.49 m

Calibration System

Reflectors

Anti-neutrino Detector (AD) Design

E/E = 12%/E 12% / E1/2

AcrylicVessels

PMT

Total Weight = 110t

Eight identical 3-zone detectors: I. Target: 20t Gd-LSII. -catcher: 20t LS III. Buffer shielding: 40t mineral oil Top/bottom reflectors 192 8”PMT/module


(Gd) Liquid Scintillator

500L fluor-LABTwo 1000L 0.5% Gd-LAB 5000L 0.1% Gd-

LS

0.1% Gd-LS in 5000L tank

Daya Bay experiment uses 185 ton 0.1% gadolinium-loaded liquid scintillator (Gd-LS). Gd-TMHA + LAB + 3g/L PPO + 15mg/L bis-MSB

4-ton test batch production in March 2009.

Gd-LS will be produced in multiple batches but mixed in reservoir on-site to ensure identical detectors.

Gd-LS stability in 4T test


Daya Bay Background

9Li

signal

backgrounds from beta-delayed neutron emission isotopes 8He and 9Li will have to be measured and subtracted

840

4 near detectors


Systematic Uncertainties

Absolutemeasurement

Relativemeasurement

O(0.2-0.3%) precision for relative measurement between detectors at near and far sites

Detector-Related Uncertainties

Ref: Daya Bay TDR

CHOOZ: R=1.012.8%(stat) 2.7%(syst), sin2213<0.17


Daya Bay Sensitivity

Sensitivity:

sin22θ13 < 0.01 @ 90% CL after 3 years of data taking

Steps to Physics:• Dry-Run• near site operations• Full operations

0 1 2 3 4 5

0.05

0.04

0.03

0.02

0.01

0.

Number of years of data taking

Sensi

tivit

y in s

in22

13 (

90

%C

L)

0.38% relative detector syst. uncertaintym2

31 = 2.5 103 eV2

Source Uncertainty

Reactor power 0.13%

Detector (per module) 0.38% (baseline)

Signal statistics 0.2%


August 2009

Daya Bay Project Status

• CD-0 (DOE Mission Need): 11/2005• Daya Bay proposed at OHEP Briefing 4/2006• Successful Physics Review 10/16/06• CD-1 site selection approved 9/2007• Groundbreaking for civil construction 10/2007• CD-2 Baseline approved 3/2008• CD-3b Construction start 8/2008• Occupancy of SAB 3/2009• Occupancy of first underground halls, fall 2009• Expected start of first operations, summer 2010 • Full operations start, summer 2011

Far hall

Daya Bay hall

Ling Ao hall

LS hall


Civil ConstructionControl Room

Surface Assembly Building

Entrance

Daya Bay Near Hall - July 09


Detector Assembly

4-m vessel in the U.S.3-m acrylic vessel in Taiwan

SS Vessel delivery to SAB Reflector Prototype assembly in SAB

0.1% Gd-LS in 5000-L tank


Summary and Conclusions

The Daya Bay experiment is the most sensitive reactor θ13

experiment under construction and is designed to measure sin22θ13 < 0.01 at 90% CL with 3 years of data taking.

• Daya Bay will use eight “identical” antineutrino detectors to achieve a relative detector systematic error < 0.38%. The 3-zone detector design allows the observation of the antineutrino signal without fiducial cuts.• Civil and detector construction are progressing well. Data taking at the near site is scheduled to begin in summer 2010 with 2 detectors, which will allow extensive studies of systematics.• The full experiment will begin in summer 2011. • Detectors are movable. Swapping can be considered after some running to further reduce systematic uncertainties but is not required to reach the baseline sensitivity.


Daya Bay Collaboration

Europe (3) (9)JINR, Dubna, Russia

Kurchatov Institute, RussiaCharles University, Czech Republic

Asia (19) (~135)IHEP, Beijing Normal U., Chengdu U. of Sci. and Tech.,

CGNPG, CIAE, Dongguan Polytech. U., Nanjing U., Nankai U., Shandong U., Shanghai Jiaotong U.,

Shenzhen U., Tsinghua U., USTC, Zhongshan U., U. of Hong Kong, Chinese U. of Hong Kong,

National Taiwan U., National Chiao Tung U., National United U.

United States (15)(~89)BNL, Caltech, U. Cincinnati, George Mason U,

LBNL, Iowa State U, Illinois Inst. Tech., Princeton, RPI, UC-Berkeley, UCLA,

U. of Houston, U. of Wisconsin, Virginia Tech., U. of Illinois-Urbana-Champaign

~ 230 collaborators


Backup


Phase-I, started in 2006, ended in Jan. 2007


IHEP Prototype (0.1% Gd-LS)Gd-TMHA complex synthesis

Phase-II, filled with half-ton 0.1% Gd-LS, started in Jan. 2007 and keep running until now.

The prototype is also used for the FEE and Trigger boards testing.

Gd-TMHA complex synthesis


Calibration system

automated calibration system

Automated calibration system→ routine weekly deployment of sources

LED light sources → monitoring optical properties

e+ and n radioactive sources (=fixed energy)→ energy calibration

• 68Ge source• Am-13C + 60Co source• LED diffuser ball


Daya Bay Antineutrino Detectors3-Zone Designno position reconstruction, no fiducial cut for event identification

Gd-LS(20 tons)

= 5m (tunnel limitations)

oil buffer (MO) thickness

> 15cm buffer between PMT and OAV

gamma catcher (LS) thickness

thickness= 42.3 cm

det. efficiency> 91.5%

LS

MO

Eff

icie

ncy

(%)

24S. Kettell WIN09 9/13/09 24

Detector Top/Bottom Reflectors

z (cm)z (cm)

reflector flattens detector response

specular reflectors consist of ESR® high reflectivity film on acrylic panels

tota

l p.e

without reflector

with reflector


Antineutrino Detector ResponseDetector Uniformity

along radial R direction along vertical symmetry axis (z-direction)

Gd-LS boundary Gd-LS boundary

- GEANT4-based simulations

- idealized 3-zone detector plus reflectors

- developing realistic geometry in simulations


Detector Calibration

z(cm

)

automated calibration system

automated calibration system→ routine weekly deployment of sources

LED light sources → monitoring optical properties

e+ and n radioactive sources (=fixed energy)→ energy calibration

R(cm)

/E = 0.5% per pixel requires:1 day (near), 10 days (far)

tagged cosmogenic background (free) → fixed energy and time

68Ge sourceAm-C + 60Co sourceLED diffuser ball


Energy calibrationPrompt Energy Signal

1 MeV 8 MeV

6 MeV 10 MeV

Delayed Energy Signal

e+ threshold: stopped positron signal using 68Ge source (2x0.511 MeV)e+ energy scale: 2.2 MeV neutron capture signal (n source, spallation)

1 MeV cut for prompt positrons: >99%, uncertainty negligible

6 MeV cut for delayed neutrons: 91.5%,uncertainty 0.22% assuming 1% energy uncertainty

6 MeV threshold: n capture signals at 8 and 2.2 MeV (n source, spallation)

efficiency 78%efficiency 98%

e + p → e+ + n


Target mass measurementfilling platform with clean room

ISO Gd-LS weighing tank

pump stations

detector

load cell accuracy < 0.02%

Coriolis mass flowmeters < 0.1%

200-ton Gd-LS reservoir

20-ton ISO tank

filling “pairs” of detectors

Gd-LS MOLS


• Fission process in nuclear reactor produces huge number of low-energy antineutrino

• A typical commercial reactor, with 3 GW thermal power, A typical commercial reactor, with 3 GW thermal power, produces 6×10produces 6×102020ννee/s/s

• Daya Bay reactors produce 11.6 GWDaya Bay reactors produce 11.6 GWthth now, 17.4 GW now, 17.4 GWthth in 2011 in 2011

Nuclear reactors as antineutrino source

Arbi

trar

y

Flux Cross Secti

on

From Bemporad, Gratta and Vogel

• The observable The observable antineutrino antineutrino spectrum is the product of the spectrum is the product of the flux flux and the and the cross sectioncross section

Antineutrino spectrum


Proposed Reactor Experiments

Angra,

Brazil

R&D phase

Diablo Canyon, USA

Braidwood, USA

Double Chooz, France

sin2213~0.03

Krasnoyarsk, Russia

KASKA, Japan

Daya Bay, China

sin2213~0.01

RENO, Korea

sin2213~0.03

8 proposals

4 cancelled

4 in progress

Advantages of Daya Bay:1)very high antineutrino flux; 2) mountains to suppress cosmic-ray-induced backgrounds

S. Kettell WIN09 9/13/09 Daya Bay Experiment Steve Kettell BNL On Behalf of the Daya Bay...

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