S. Kettell WIN09 9/13/09 Daya Bay Experiment Steve Kettell BNL On Behalf of the Daya Bay...
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Transcript of 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 = ?
3S. Kettell WIN09 9/13/09
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
4S. Kettell WIN09 9/13/09
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
5S. Kettell WIN09 9/13/09
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
7S. Kettell WIN09 9/13/09
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
8S. Kettell WIN09 9/13/09
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
9S. Kettell WIN09 9/13/09
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
10S. Kettell WIN09 9/13/09
(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
11S. Kettell WIN09 9/13/09
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
12S. Kettell WIN09 9/13/09
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
13S. Kettell WIN09 9/13/09
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%
14S. Kettell WIN09 9/13/09
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
15S. Kettell WIN09 9/13/09
Civil ConstructionControl Room
Surface Assembly Building
Entrance
Daya Bay Near Hall - July 09
16S. Kettell WIN09 9/13/09
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
17S. Kettell WIN09 9/13/09
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.
18S. Kettell WIN09 9/13/09
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
19S. Kettell WIN09 9/13/09
Backup
20S. Kettell WIN09 9/13/09
Phase-I, started in 2006, ended in Jan. 2007
21S. Kettell WIN09 9/13/09
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
22S. Kettell WIN09 9/13/09
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
23S. Kettell WIN09 9/13/09
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
25S. Kettell WIN09 9/13/09
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
26S. Kettell WIN09 9/13/09
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
27S. Kettell WIN09 9/13/09
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
28S. Kettell WIN09 9/13/09
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
29S. Kettell WIN09 9/13/09
• 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
30S. Kettell WIN09 9/13/09
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