the daya bay experiment kam-biu luk (uc berkeley & lbnl) for the daya bay collaboration p5...

The Daya Bay Experiment

Kam-Biu Luk (UC Berkeley & LBNL)

forThe Daya Bay Collaboration

P5 Review, Fermilab, April 18, 2006

April 18, 2006 P5 Review (Kam-Biu Luk) 2

?

13The Last Unknown Neutrino Mixing Angle

2345

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?• Ue3 is a gateway to CP violation in neutrinos:

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,Accelerator

Reactor,accelerator

0SNO, solar SK,KamLAND

12 ~ 32° 23 = ~ 45° 13 = ?

P( e) - P( e) sin(212)sin(223)cos2(13)sin(213)sin


Current Knowledge of 13

Direct search

At m231 = 2.5 103 eV2,

sin22 < 0.15

allowed region

Experimentalallowed at 3

Nu

mb

er

of

pre

dic

tion

s

Theoretical predications


Recommendations

• APS Neutrino Study Group:

• Neutrino Scientific Assessment Group:


Limitations of Past and CurrentReactor Neutrino Experiments

Palo Verde, CHOOZTypical precision is 3-6%due to• limited statistics• reactor-related systematic

errors:

- energy spectrum of e

(~2%)

- time variation of fuel

composition (~1%)• detector-related systematic

error (1-2%)• background-related error

(1-2%)


How To Reach A Precision of 0.01 ?

• Utilize a powerful nuclear power plant • Use large detectors to reduce statistical error • Use near and far detectors to minimize reactor-

related errors• Optimize baseline to have best sensitivity and further reduce any residual reactor-related

errors• Interchange near and far detectors to cancel

some of the detector systematic uncertainty• Use sufficient shielding to reduce background• Carry out comprehensive calibration to reduce

detector systematic error• Build almost identical detectors to reduce

detector-related systematic error


Goals And Approach• Utilize the Daya Bay nuclear power facilities to:

- determine sin2213 with a sensitivity of 1%- measure m2

31

• Adopt horizontal-access-tunnel scheme:

- mature and relatively inexpensive technology- flexible in choosing overburden- relatively easy and cheap to add experimental halls- easy access to underground experimental facilities - easy to move detectors between different

locations with good environmental control.


Where To Place The Detectors ?

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

0.1 1 10 100

Nos

c/Nn

o_os

c

Baseline (km)

P(e e ) 1 sin2 213 sin2 m312 L

4E

cos413 sin2 212 sin2 m21

2 L

4E

Large-amplitudeoscillation due to

12

Small-amplitudeoscillation due to 13

• Place near detector(s) close to reactor(s) to measure raw flux and spectrum of e, reducing reactor-related systematic

• Position a far detector near the first oscillation maximum to get the highest sensitivity, and also be less affected by 12

Sin2() = 0.1m2

31 = 2.5 x 10-3 eV2

Sin2() = 0.825m2

21 = 8.2 x 10-5 eV2

• Since reactor e are low-energy, it is a disappearance experiment:


Detecting Low-energy e

e p e+ + n (prompt)

+ p D + (2.2 MeV) (delayed) + Gd Gd*

Gd + ’s(8 MeV) (delayed)

• Time- and energy-tagged signal is a good tool to suppress background events.

• Energy of e is given by:

E Te+ + Tn + (mn - mp) + m e+ Te+ + 1.8

MeV 10-40 keV

• The reaction is the inverse -decay in Gd-doped liquid scintillator:

Arb

itra

ry

Flux Cross

Sectio

n

Observable Spectrum

From Bemporad, Gratta and Vogel

0.3b

50,000b


The Daya Bay Collaboration: China-Russia-U.S.

X. Guo, N. Wang, R. WangBeijing Normal University, Beijing

L. Hou, B. Xing, Z. ZhouChina Institute of Atomic Energy, Beijing

M.C. Chu, W.K. NgaiChinese University of Hong Kong, Hong Kong

J. Cao, H. Chen, J. Fu, J. Li, X. Li, Y. Lu, Y. Ma, X. Meng, R. Wang, Y. Wang, Z. Wang, Z. Xing, C. Yang, Z. Yao, J. Zhang, Z. Zhang, H. Zhuang, M. Guan, J. Liu, H. Lu, Y. Sun, Z. Wang, L. Wen, L. Zhan, W. ZhongInstitute of High Energy Physics, Beijing

X. Li, Y. Xu, S. JiangNankai University, Tianjin

Y. Chen, H. Niu, L. NiuShenzhen University, Shenzhen

S. Chen, G. Gong, B. Shao, M. Zhong, H. Gong, L. Liang, T. XueTsinghua University, Beijing

K.S. Cheng, J.K.C. Leung, C.S.J. Pun, T. Kwok, R.H.M. Tsang, H.H.C. WongUniversity of Hong Kong, Hong Kong

Z. Li, C. ZhouZhongshan University, Guangzhou

Yu. Gornushkin, R. Leitner, I. Nemchenok, A. OlchevskiJoint Institute of Nuclear Research, Dubna, Russia

V.N. VyrodovKurchatov Institute, Moscow, Russia

B.Y. HsiungNational Taiwan University, Taipei

M. Bishai, M. Diwan, D. Jaffe, J. Frank, R.L. Hahn, S. Kettell, L. Littenberg, K. Li, B. Viren, M. YehBrookhaven National Laboratory, Upton, New York, U.S.

R.D. McKeown, C. Mauger, C. JillingsCalifornia Institute of Technology, Pasadena, California, U.S.

K. Whisnant, B.L. Young Iowa State University, Ames, Iowa, U.S.

W.R. Edwards, K. Heeger, K.B. LukUniversity of California and Lawrence Berkeley National Laboratory, Berkeley, California, U.S.

V. Ghazikhanian, H.Z. Huang, S. Trentalange, C. Whitten Jr.University of California, Los Angeles, California, U.S.

M. Ispiryan, K. Lau, B.W. Mayes, L. Pinsky, G. Xu,L. LebanowskiUniversity of HoU.S.ton, HoU.S.ton, Texas, U.S.

J.C. PengUniversity of Illinois, Urbana-Champaign, Illinois, U.S.

20 institutions, 89 collaborators


QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

Ling Ao II NPP:2 2.9 GWth

Ready by 2010-2011

Ling Ao NPP:2 2.9 GWth

55 k

m

45 km

The Daya Bay Nuclear Power Facilities

Daya Bay NPP:2 2.9 GWth

1 GWth generates 2 × 1020 e per sec

• 12th most powerful in the world• Top five most powerful by 2011• Adjacent to mountain, easy to construct tunnels to reach underground labs with sufficient overburden to suppress cosmic rays


Daya BayNPP

Ling AoNPP

Ling Ao-ll NPP(under const.)

Entrance portal

Empty detectors: moved to underground halls through access tunnel.Filled detectors: swapped between underground halls via horizontal tunnels.

Total length: ~2700 m

230 m(15% slope)290 m

(8% slope) 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

Mid site~1000 m from DayaOverburden: 208 m


A Versatile Site

• Rapid deployment:- Daya near site + mid site - 0.7% reactor systematic error

• Full operation: (1) Two near sites + Far site (2) Mid site + Far site (3) Two near sites + Mid site + Far site Internal checks, each with different systematic


Geotechnical Survey

far

Dayanear

Lingaonear

midTopological survey:

Length: 2.5 km (S-N) Width: 450 m ~ 1.3 km (E-W) Area: 1.839 km2

Scale: Along tunnel 1:2000 Portal area 1:500

• Topological survey - complete• Geophysical survey

- complete• Bore drilling - complete


Planned tunnel

fault

Lingaonear

Dayanear

mid

mid

far

Weathering bursa

Geophysical Survey

Electrical Resistivitymethod

mid Lingaonear


bursa

Bore Drilling

LocationDrill

Depth (m)

ZK1 211

ZK2 210

Zk3 127

Zk4 133


(in the weathering bursa)


Findings of Geotechnical Survey

• No active or large fault

• Earthquake is infrequent

• Rock structure: massive and blocky granite

• Rock mass: most is slightly weathered or fresh

• Groundwater: low flow at the depth of the tunnel

• Quality of rock mass: stable and hard

Good geotechnical conditions for tunnel construction

Pat Dobson(LBL)

Chris Laughton (FNAL)

Joe Wang(LBL) Yanjun Sheng

(IGG)

U.S. experts in geology andtunnel construction assistgeotechnical survey:


Tunnel construction

• The total tunnel length is ~3 km• Preliminary cost estimate by professionals:

~$3K/m• Construction time is ~24 months• A similar tunnel exists on site as a reference

7.2 m

7.2 m


~350 m

~97 m

~98 m~210 m

Cosmic-ray Muon

• Apply modified Geiser parametrization for cosmic-ray flux at surface• Use MUSIC and mountain profile to estimate muon flux & energy

DYB LA Mid Far

Elevation (m) 97 98 208 347

Flux (Hz/m2) 1.2 0.73 0.17 0.045

Mean Energy (GeV)

55 60 97 136


What Target Mass Should Be?

Systematic error (per site): Black : 0.6% Red : 0.25% Blue : 0.12%

Solid lines : near+farDashed lines : mid+far

DYB: B/S = 0.5% LA: B/S = 0.4% Mid: B/S = 0.1% Far: B/S = 0.1%

m231 = 2 10-3 eV2

tonnes


Design of Antineutrino Detectors• Three-layer structure:

I. Target: Gd-loaded liquid scintillatorII. Gamma catcher: liquid scintillator, 45cmIII. Buffer shielding: mineral oil, ~45cm

• Possibly with diffuse reflection at ends. For ~200 PMT’s around the

barrel:vertex

14%~ , 14cm

(MeV)

E E

buffer

20t

Gd-doped

LS

gamma catcher

IsotopesPurity

(ppb)

20cm

(Hz)

25cm

(Hz)

30cm

(Hz)

40cm

(Hz)

238U(>1MeV) 50 2.7 2.0 1.4 0.8

232Th(>1MeV) 50 1.2 0.9 0.7 0.4

40K(>1MeV) 10 1.8 1.3 0.9 0.5

Total 5.7 4.2 3.0 1.7

Oil buffer thickness


3 zone

cut

Why three zones ?• Three zones:

- Construction of acrylic vessels is more involved - More background coming from the walls - Less fiducial mass

• Two zones:– Neutrino energy spectrum is distorted – Error of neutron efficiency due to energy scale and resolution: two zones: 0.4%, three zones 0.2%

2 zone

cut

– Using 4 MeV cut can reduce the error by a factor of two, but backgrounds from do not allow us to do so

CHOOZ


Design of Shield-Muon Veto

• Detector modules enclosed by 2m of water to shield neutrons and

gamma-rays from surrounding rock• Water shield also serves as a Cherenkov veto• Augmented with a muon tracker: scintillator or RPCs• Combined efficiency of Cherenkov and tracker > 99.5%

2m ofwater

~0.05

Neutron background vs thickness of water


Background

Near Site Far Site

Radioactivity (Hz) <50 <50Accidental B/S <0.05% <0.05%

Fast neutron background B/S

0.15% 0.1%

8He/9Li B/S 0.55% 0.25%

• Natural Radioactivity: PMT glass, Rock, Radon in the air, etc

• Slow neutron, and fast neutron

- Neutrons produced in rock and water shield (99.5% veto efficiency)

• Cosmogenic isotopes: 8He/9Li which can -n decay

- Cross section measured at CERN (Hagner et. al.)

- Can be measured in-situ, even for near detector with muon rate ~ 10 Hz.

• Use a modified Palo-Verde-Geant3-based

MC to model response of detector:

The above number is before shower-muon cut.

20t module


Systematic Uncertainty

Systematic error Chooz Daya Bay

Reaction Cross Section 1.9% 0, near-far cancellation

Energy released per fission 0.6% 0, near-far cancellation

Reactor Power 0.7% 0.06%, near-far cancellation

Number of Protons 0.8% 0, detector swapping

Detection efficiency* 1.5% ~0.2%, fewer cuts, detector swapping

Total 2.75% ~0.2%

Statistical Error (3 years): 0.2% Residual systematic error: ~ 0.2%

*• No Vertex cut.• Residual detection error is dominated by the neutron energy cut at 6 MeV arises mainly from the energy-scale uncertainties. (It is ~0.2% for a 1% energy-scale error at 6 MeV.• Positron energy cut is negligible.


• Daya Bay site Daya Bay site - baseline = 360 m- baseline = 360 m

- target mass = 40 tonne- target mass = 40 tonne

- B/S = ~0.5%- B/S = ~0.5%

• LingAo site LingAo site - baseline = 500 m- baseline = 500 m


- B/S = ~0.5%- B/S = ~0.5%

• Far site Far site - baseline = 1900 m to DYB cores- baseline = 1900 m to DYB cores

1600 m to LA cores1600 m to LA cores


- B/S = ~0.2%- B/S = ~0.2%

• Three-year run (0.2% Three-year run (0.2% statistical error)statistical error)

• Detector residual error = Detector residual error = 0.2%0.2%

• Use rate and spectral shapeUse rate and spectral shape

90% confidence level90% confidence level

Sensitivity of sin2213

2 n

ear +

far

near (4

0t) +

mid

(40 t)

1 year

Near-mid


Precision of m231

sin2213 = 0.02

sin2213 = 0.1


Major Items of U.S. Project Scope

• Muon tracking system (veto system)• Gd-loaded liquid scintillator• Calibration systems• PMT’s, base’s & control• Readout electronics & daq/trigger hardware

(partial)• Acrylic vessels (antineutrino detector)• Detector integration activities• Project management activities


U.S. Project Scope & Budget TargetsBudget

Institution WBS element Lead? target ($K) Comments

BNL Muon tracker system Y 5,000 joint with university groupsGd-loaded liquid scintillator Y 1,500 may include LS purification system

California Institute Techology Calibration systems Y 2,000 joint with univ groups & LBNL

University of Houston DAQ hardward & software 1,000 joint with univ groups & LBNL

LBNL Project management Y 1,700System integration Y 1,700 joint with BNLPMT's, bases & control Y 3,000 joint with university groupsLocomotion & cranes Y 600 joint with BNLReadout & trigger electronics 1,000 joint with univ groups & BNLAcrylic Vessels Y 2,000

U. Ill at Urbana-Champaign, addn'l university-based scope 4,200 see next slide for detailsIowa State University,UCLA + other universities

Other Necessary ItemsCommon fund 2,000Project contingency ~30% 7,000

Total:Total: 32,700


Details of Additional U.S. Scope

There are opportunities for the U.S. in other areas also:

These are items for which additional U.S. collaborators could participate

Details of additional university-based scopesoftware architecture 1000Offline computing architecture 1000Addn'l system test stands 700Water purification system 500Simulation 1000

Sub total: 4200


Overall Project Schedule


Prelim. Civil Construction Sched.


Project Development

• Schedule/activities over next several months:

Determine scale of detector for sizing halls:

Continue building strong U.S. team - key people:

Conceptual design, scale & technology choices:

Firm up U.S. scope, schedule & cost range:

Write CDR, prepare for CD-1:

now – June

now – summer

now – Aug

July – Nov

Aug – Nov


Funding Profile

Begin construction in China March 2007

CD-1 in U.S. November 2006

CD-2 in U.S. September 2007

Begin data collection January 2010

Measure sin2213 to 0.01 March 2013

FY06 U.S. R&D $2M FY07

$3.5MFY08 U.S. Construction

$8MFY09

$14MFY10

$8M


Synergy of Reactor and Accelerator Experiments

Δm2 = 2.5×10-3 eV2 sin2213 = 0.05

Reactor experiments can help in Resolving the 23 degeneracy

(Example: sin2223 = 0.95 ± 0.01)

90% CL

Reactor w 100t (3 yrs) + Nova Nova only (3yr + 3yr) Reactor w 10t (3yrs) + Nova

90% CL

McConnel & Shaevitz, hep-ex/0409028

90% CL

Reactor w 100t (3 yrs) +T2K T2K (5yr,-only) Reactor w 10t (3 yrs)+T2K

Reactor experiments providea better determination of 13


Daya Bay

Ling Ao~1700 m


Sensitivity

For 3 years

With four 20-t modules at the far site and two 20-t modules at each near site:

the daya bay experiment kam-biu luk (uc berkeley & lbnl) for the daya bay collaboration p5...

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