投影片 1 - Virginia Tech Department of Physics
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Transcript 投影片 1 - Virginia Tech Department of Physics
Daya Bay Reactor Neutrino
Experiment
On behalf of the DayaBay collaboration
Virginia Polytechnic Institute and State University
Joseph ykHor
1
YuenKeung, Hor
Virginia Tech.
Daya Bay collaboration
APS SouthEast meeting 2009
Table of Content
Physics Goal
Relative measurement & disappearance probability
Baseline & detector design
Sensitivity
Current status, schedule and dates
Background and energy cut
YuenKeung, Hor
Virginia Tech.
Daya Bay collaboration
APS SouthEast meeting 2009
2
Physics Goal
Krasnoyarsk, Russia
Braidwood, USA
Diablo Canyon, USA
RENO, Korea
sin2213~0.03
Double Chooz, France
sin2213~0.03
KASKA, Japan
Daya Bay, China
sin2213~0.01
8 proposals
Angra, Brazil
R&D phase
4 cancelled
3 in progress
YuenKeung, Hor
Virginia Tech.
Daya Bay collaboration
APS SouthEast meeting 2009
3
Physics Goal
Determine θ13 better than any past experiments
1
0
0 cos13
0 ei CP sin 13 cos12 sin 12 0 1 0
0
i / 2
0 cos 23 sin 23
0
1
0
sin
cos
0
0
12
12
0 e
i CP
i / 2i
0
0
sin
cos
e
sin
0
cos
0
1
0 0 e
23
23
13
13
θ23 ~ 45o
θ12 ~ 35o
Super K + Accelerator
+ atmospheric
CP-phase + small θ13
DayaBay
Double Chooz
KamLand + Solar
Neutrinoless
double beta
decay
PMNS Matrix Parameterization:
YuenKeung, Hor
Virginia Tech.
Daya Bay collaboration
APS SouthEast meeting 2009
4
Relative measurement &
disappearance probability
2
m
L
2
2
31
Pee 1 sin 213 sin
4
E
•near detectors
measure e flux and
spectrum to reduce
reactor-related systematic
uncertainties
• far detector at the
oscillation maximum
provides the highest
sensitivity
YuenKeung, Hor
Virginia Tech.
Daya Bay collaboration
APS SouthEast meeting 2009
5
Relative measurement &
disappearance probability
Ratio of
measured
event
rate from
far and
near site
detectors
Ratio of
number of
protons in GdLS.
Obtained by
mass flow
measurements
νe
~ 0.4 km
YuenKeung, Hor
Virginia Tech.
Ratio of
the
detector
efficiency
Obtained
by
calibration
Probability
ratio
determine
sin2 (2θ13 )
distance L ~ 1.8 km
Daya Bay collaboration
APS SouthEast meeting 2009
6
Baseline & detector design
• currently running at 11.6 GW
• one of the top five most powerful
by 2011 (17.4 GW)
• Adjacent to mountain, easy to
construct tunnels to reach
underground labs with sufficient
overburden to suppress cosmic rays
Ling Ao II NPP:
2 2.9 GWth
Ready by 2010-2011
Ling Ao NPP:
2 2.9 GWth
1 GWth generates 2 × 1020 e per sec
YuenKeung, Hor
Virginia Tech.
Daya Bay collaboration
APS SouthEast meeting 2009
7
Baseline & detector design
Far site
1615 m from Ling Ao
1985 m from Daya Bay
Overburden: 350 m
Ling Ao Near site
~500 m from Ling Ao
Overburden: 112 m
Deep down the mountain
to suppress cosmogenic
background
Deploy identical
detectors in all sites to
isolate systematic
uncertainties
Daya Bay Near site
363 m from Daya Bay
Overburden: 98 m
YuenKeung, Hor
Virginia Tech.
Daya Bay collaboration
Optimize baseline
distance for
disappearance oscillation
APS SouthEast meeting 2009
8
Baseline & detector design
Antineutrino Detector(AD)
Automatic calibration system
Top and bottom reflectors
192 8” PMTs
5m
Three-zone design:
Gd-doped LS, 20 tons
Inner acrylic vessel
LS as Gamma Catcher, 20 tons
Outer acrylic vessel
5m
YuenKeung, Hor
Virginia Tech.
Mineral oil as buffer, 40 tons
Stainless steel tank
Daya Bay collaboration
APS SouthEast meeting 2009
9
Baseline & detector design
2.5m
water
shield
Resistive plate
chambers
(RPC)
AD
Muon tagging
8” PMTs 289 PMTs in near site
384 PMTs in far site
Shielding of background radiation
RPC as muon veto on top of
water Cherenkov
YuenKeung, Hor
Virginia Tech.
Daya Bay collaboration
APS SouthEast meeting 2009
10
Sensitivity
0.05
sin22θ
< 0.008 @ 90% CL
after 3 years of data taking
Sensitivity in sin2213 (90%CL)
0.04
0.03
Rapid convergence
0.02
0.01
Δm312 =2.5 x 10-3 eV2
0.
0
13
YuenKeung, Hor
Virginia Tech.
Daya Bay collaboration
1
2
3
4
5
Number of years of data taking
APS SouthEast meeting 2009
11
Sensitivity
sin22θ13 < 0.008 @ 90% CL
after 3 years of data taking
YuenKeung, Hor
Virginia Tech.
Daya Bay collaboration
APS SouthEast meeting 2009
12
Current status, schedule and dates
• 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 & 3a Baseline approved 3/2008
• CD-3b Construction start 8/2008
• Occupancy of SAB 3/2009
• Occupancy of first underground halls, 2009
• Expected start of first operations, 2010
• Full operations start, 2011
YuenKeung, Hor
Virginia Tech.
Daya Bay collaboration
APS SouthEast meeting 2009
13
Current status, schedule and dates
YuenKeung, Hor
Virginia Tech.
Daya Bay collaboration
APS SouthEast meeting 2009
14
Current status, schedule and dates
Red
indicates
current
construction
progress
YuenKeung, Hor
Virginia Tech.
Daya Bay collaboration
APS SouthEast meeting 2009
15
Summary
DayaBay experiment is the most sensitive θ13 experiment
under construction
Specifically designed to achieve the sensitivity of sin2 (2θ13 )
down to 0.01(goal) at 90% C.L. and 0.008(projected) in
three years of data taking
It is now on track to take initial data in the next year and
become fully operational in 2 years
YuenKeung, Hor
Virginia Tech.
Daya Bay collaboration
APS SouthEast meeting 2009
16
The End
Thank You
YuenKeung, Hor
Virginia Tech.
Daya Bay collaboration
APS SouthEast meeting 2009
17
Back up
YuenKeung, Hor
Virginia Tech.
Daya Bay collaboration
APS SouthEast meeting 2009
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Back up
Accidental coincidence:
Correlated events:
natural radioactivity
neutrons from cosmic muons
YuenKeung, Hor
Virginia Tech.
Fast neutron capture + recoil proton
Beta + neutron decay from Helium
& Lithium
Daya Bay collaboration
APS SouthEast meeting 2009
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Back up
Prompt Energy Signal
1 MeV
Delayed Energy Signal
8 MeV
6 MeV
e p e+ + n (prompt)
0.3b
50,000b
+ p D + (2.2 MeV)
(delayed)
10 MeV
Energy spectrum of
two processes in
inverse-beta decay
+ Gd Gd* Gd + ’s(8 MeV) (delayed)
YuenKeung, Hor
Virginia Tech.
Daya Bay collaboration
APS SouthEast meeting 2009
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