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The Daya Bay Experiment. Motivation Reactor anti- n e Daya Bay Experiment Collaboration/BNL involvement. Steve Kettell BNL. The U.S. should mount one multi-detector reactor experiment sensitive to  e disappearance down to sin 2 2θ 13 ~ 0.01. Neutrinos.

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The daya bay experiment

The Daya Bay Experiment

  • Motivation

  • Reactor anti-ne

  • Daya Bay Experiment

  • Collaboration/BNL involvement

Steve Kettell



The U.S. should mount one multi-detector reactor experiment

sensitive to edisappearance down to sin22θ13 ~ 0.01.


  • Connecting Quarks to the Cosmos: One of the eleven `profound questions’ addresses the mass and mixing of neutrinos. (2003)

  • Quantum Universe: “Detailed studies of the properties of neutrinos  their masses, how they mix, and whether they are Majorana particles will tell us whether neutrinos conform to the patterns of ordinary matter or whether they are leading us to the discovery of new phenomena.” (2004)

    recommendation of the APS  Study Group (11/04)

    NuSAG (2/28/06)

Steve Kettell, BNL DOE HEP Review

Bnl pac


  • BNL High Energy Nuclear Physics Program Advisory Committee meeting 3/23/06

  • The BNL neutrino group's presentation of the Daya Bay experiment and their involvement in it was very well received. In particular, the committee noted the crucial role BNL plays in R&D work for the Daya Bay experiment. In conjunction with the BNL Chemistry department, the group studies solubility of Gd in scintillator, and attenuation of light in the Gd doped scintillator. These R&D issues are at the heart of the potential success of both the Daya Bay and Braidwood reactor efforts. The committee recognizes and encourages the great synergy between the BNL physicists and chemists in the reactor program.

  • PAC Membership: Stanley Brodsky, Donald Geesaman, Miklos Gyulassy, Barbara Jacak, Peter Jacobs, Bob Jaffe, Takaaki Kajita, James Nagle, Jack Sandweiss, Yannis Semertzidis, (Bonnie Fleming, Frank Sculli)

Steve Kettell, BNL DOE HEP Review

The last unknown neutrino mixing angle 13

The Last Unknown Neutrino Mixing Angle: 13


reactor and accelerator

atmospheric, K2K

SNO, solar SK, KamLAND


13 = ?

23 = ~ 45°

12 ~ 32°


UMNSP Matrix

Maki, Nakagawa, Sakata, Pontecorvo

What ise fraction of 3?

Is there  symmetry in neutrino mixing?

Ue3 is the gateway to CP violationin neutrinos.

Steve Kettell, BNL DOE HEP Review

Measuring 13 with reactor neutrinos

Measuring 13 with Reactor Neutrinos




Distance (km)

Search for 13 in oscillation experiment


detector 1

nuclear reactor

detector 2

~1.8 km

~ 0.3-0.5 km

Pure measurement of 13.

Daya Bay, China

Steve Kettell, BNL DOE HEP Review

Detection of antineutrinos in liquid scintillator

Detection of antineutrinos in liquid scintillator

e  p  e+ + n(prompt)


 + p  D + (2.2 MeV) (delayed)


  • + Gd  Gd*

     Gd + ’s(8 MeV) (delayed)

From Bemporad, Gratta and Vogel

  • Time- and energy-tagged signal is a good

  • tool to suppress background events.


Observable n Spectrum

  • Energy ofe is given by:

ETe+ + Tn + (mn - mp) + me+ Te+ + 1.8 MeV

Cross Section


10-40 keV

  • The reaction is inverse -decay in 0.1% Gd-doped liquid scintillator:

Steve Kettell, BNL DOE HEP Review

The daya bay experiment

Current Knowledge of 13




At m231 = 2.4  103 eV2,

sin22 < 0.15

allowed region

Established technique (e.g. Chooz)

 with improvements for Daya Bay

Limit on q13 from Chooz

2.7% without near detectors

  • 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%)

Steve Kettell, BNL DOE HEP Review

Requirements for improving the sensitivity to sin 2 2 13 0 01

Requirements for improving the sensitivity to sin2213 0.01

  • Higher statistics:

  • More powerful reactor cores

  • Larger target mass

  • Better control of systematic errors:

  • Utilize multiple detectors at different baselines (near and far)

  •  measure RATIOS

  • Make detectors as nearly IDENTICAL as possible

  • Careful and thorough calibration and monitoring of each detector

  • Optimize baseline for best sensitivity and small residual reactor-related errors

  • Interchange detectors to cancel most detector systematics

Steve Kettell, BNL DOE HEP Review

Goals and approach

Goals And Approach

  • Utilize the Daya Bay nuclear power facilities to:

  • - determine sin2213 with a sensitivity of 1%

  • - measure m231

  • Employ horizontal-access-tunnel scheme:

  • - mature and relatively inexpensive technology

  • - flexible in choosing overburden and baseline

  • - 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.

  • Adopt three-zone antineutrino detector design.

Steve Kettell, BNL DOE HEP Review

Daya bay china

Daya Bay, China

45 km

55 km

Steve Kettell, BNL DOE HEP Review

The daya bay nuclear power facilities

The Daya Bay Nuclear Power Facilities

  • Powerful facilities (total thermal power):

  • 11.6 GW (now)  17.4 GW (2011)

  • comparable to Palo Verde, the most

  • powerful nuclear power plant in U.S.

  • Adjacent to mountain, easy to

  • construct tunnels to 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

Daya Bay NPP:

2  2.9 GWth

Steve Kettell, BNL DOE HEP Review

The daya bay experiment

Far site

1600 m from Ling Ao

2000 m from Daya

Overburden: 350 m

910 m

Mid site

~1000 m from Daya

Overburden: 208 m

570 m

230 m

(15% slope)

730 m

290 m

(8% slope)

Daya Bay Near

360 m from Daya Bay

Overburden: 97 m

Empty detectors: moved to underground halls through access tunnel.

Filled detectors: swapped between underground halls via horizontal tunnels.

Ling Ao Near

500 m from Ling Ao

Overburden: 98 m

Ling Ao-ll NPP

(under const.)

Ling Ao


Entrance portal

Daya Bay


Total length: ~2700 m

Steve Kettell, BNL DOE HEP Review

Antineutrino detector

20 tonnes



gamma catcher

Antineutrino Detector

  • Antineutrinos are detected via inverse -decay

  • in Gd-doped liquid scintillator (LS)

  • Description:

  • 3 zones: Gd-LS target (20 tonnes),

  • LS gamma catcher, oil buffer

  • 2 nested acrylic vessels, 1 stainless vessel

  • 200 8” PMT’s on circumference of 5m  5m cylinder

  • reflective surfaces on endplates of cylinder

  • energy resolution is 14%/E

Steve Kettell, BNL DOE HEP Review

Conceptual design of muon veto

Conceptual Design of Muon Veto


muon tracker


2m of


a conceptual design


Neutron background vs.

thickness of water

  • Detector modules enclosed by 2m of water to shield neutrons (and gamma-rays)

  • Water shield also serves as a Cherenkov veto

  • Augmented with a muon tracker: scintillator or RPC's

  • Combined efficiency of Cherenkov and tracker > 99.5%

Steve Kettell, BNL DOE HEP Review

Findings of geotechnical survey

Chris Laughton (FNAL)

Pat Dobson


Joe Wang


Yanjun Sheng


Borehole drilling

Findings of Geotechnical Survey

U.S. experts in geology and

tunnel construction assist

geotechnical survey:

  • No active or large faults

  • Earthquakes are infrequent

  • Rock: massive and blocky granite

  • Rock mass: slightly weathered or fresh

  • Groundwater: low flow at tunnel depth

  • Quality of rock: stable and hard

Good geotechnical conditions for tunnel construction

Steve Kettell, BNL DOE HEP Review

Tunnel construction

7.2 m

Tunnel construction

  • The total tunnel length is ~3 km

  • Preliminary civil construction design: ~$3K/m

  • Construction time is ~24 months (5 m/day)

  • A similar tunnel already exists on site

7.2 m

Steve Kettell, BNL DOE HEP Review



  • Accidental Background:

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

    • Neutrons

  • Correlated Background:

    • Fast neutronsNeutrons produced in rock and water shield (99.5% veto efficiency)

    • Cosmic Ray production of 8He/9Li which can decay via -n emission

For reference, 560(80) neutrino events per detector per day at the near(far) site

Steve Kettell, BNL DOE HEP Review

Systematic uncertainty

Systematic Uncertainty

Statistical Error (3 years): 0.2%2.8% (Chooz)

Residual systematic error: ~ 0.2%2.7%

Steve Kettell, BNL DOE HEP Review


Far (80t)

Antineutrino detector

modules, each with

20 tonne target mass

Ling Ao

near (40t)

Horizontal tunnel

Daya Bay

near (40t)




3-year run with 80 t at far site

Steve Kettell, BNL DOE HEP Review

The daya bay collaboration china russia u s

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

20 institutions, 89 collaborators

Yu. Gornushkin, R. Leitner, I. Nemchenok, A. Olchevski

Joint Institute of Nuclear Research, Dubna, Russia

V.N. Vyrodov

Kurchatov Institute, Moscow, Russia

B.Y. Hsiung

National Taiwan University, Taipei

M. Bishai, M. Diwan, D. Jaffe, J. Frank, R.L. Hahn, S. Kettell,

L. Littenberg, K. Li, B. Viren, M. Yeh

Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.

R.D. McKeown, C. Mauger, C. Jillings

California Institute of Technology, Pasadena, CA 91125, U.S.

K. Whisnant, B.L. Young

Iowa State University, Ames, Iowa 50011, U.S.

W.R. Edwards, K. Heeger, K.B. Luk

University of California and Lawrence Berkeley National Laboratory, Berkeley, CA 94720, U.S.

V. Ghazikhanian, H.Z. Huang, S. Trentalange, C. Whitten Jr.

University of California, Los Angeles, CA 90095, U.S.

M. Ispiryan, K. Lau, B.W. Mayes, L. Pinsky, G. Xu,

L. Lebanowski

University of Houston, Houston, Texas 77204, U.S.

J.C. Peng

University of Illinois, Urbana-Champaign, Illinois 61801, U.S.

X. Guo, N. Wang, R. Wang

Beijing Normal University, Beijing

L. Hou, B. Xing, Z. Zhou

China Institute of Atomic Energy, Beijing

M.C. Chu, W.K. Ngai

Chinese 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. Zhong

Institute of High Energy Physics, Beijing

X. Li, Y. Xu, S. Jiang

Nankai University, Tianjin

Y. Chen, H. Niu, L. Niu

Shenzhen University, Shenzhen

S. Chen, G. Gong, B. Shao, M. Zhong, H. Gong, L. Liang,

T. Xue

Tsinghua University, Beijing

K.S. Cheng, J.K.C. Leung, C.S.J. Pun, T. Kwok,

R.H.M. Tsang, H.H.C. Wong

University of Hong Kong, Hong Kong

Z. Li, C. Zhou

Zhongshan University, Guangzhou

Steve Kettell, BNL DOE HEP Review

The daya bay experiment

Steve Kettell, BNL DOE HEP Review

Accomplishments at feb collaboration meeting

Accomplishments at Feb Collaboration Meeting

  • Bylaws were ratified by the collaboration.

  • Institutional board, with one representative from each member institution and two spokespersons, was established.

  • Executive board was established:

    Y. Wang (China)A. Olshevski (Russia)

    C. Yang (China)K.B. Luk (U.S.)

    M.C. Chu (Hong Kong)R. McKeown (U.S.)

    Y. Hsiung (Taiwan)

  • Scientific spokespersons were chosen:

    Y. Wang (China), K.B. Luk (U.S.)

  • Project management in China and U.S. werecompared.

  • Initial discussions of construction project management.

  • Task forces were set up. Each task is led by at least one member from China and one from U.S.

Steve Kettell, BNL DOE HEP Review

Collaboration communications

Collaboration Communications

  • Weekly collaboration phone meetings

  • Weekly U.S. Daya Bay phone meetings

  • LBL serves as the hub for both phone meetings

  • BNL provides web archive for phone meetings

  • Several face-to-face collaboration meetings have been held in Beijing, Shenzhen, Hong Kong, and Berkeley. The most recent one was held at IHEP in February 2006.

  • Next collaboration meeting in Beijing, June 9-12, 2006.

Steve Kettell, BNL DOE HEP Review

Joint u s china task forces

Joint U.S.-China Task Forces

International working groups with U.S.-China co-leadership for main detector systems and R&D issues established at the February collaboration meeting.

  • 1. Antineutrino Detector

  • Co-Chairs: S. Kettell (BNL, U.S.)

  • Y. Wang (IHEP, China)

  • 2. Calibration

  • Co-Chairs: R.D. McKeown (Caltech, U.S.)

  • X. Biao (CIAE, China)

  • 3. Communications

  • Co-Chairs: J. Cao (IHEP, China)

  • K.M. Heeger (LBNL, U.S.)

  • W. Ngai (CUHK, Hong Kong)

  • 4. Liquid Scintillator

  • Co-Chairs: R.L. Hahn (BNL, U.S.)

  • Z. Zhang (IHEP, China)

  • I. Nemchenok (Dubna, Russia)

  • 5. Muon Veto

  • Co-Chairs: L. Littenberg (BNL, U.S.)

    • K. Lau (Houston, U.S.)

  • Y. Changgen (IHEP, China)

    • 6. Offline Data Distribution and Processing

    • Co-Chairs: J. Cao (IHEP)

    • B. Viren (BNL)

    • 7. Project Management and Integration

    • Co-Chairs: B. Edwards (LBNL, U.S.)

      • S. Kettell (BNL, U.S.)

      • Y. Wang (IHEP, China)

      • H. Zhuang (IHEP, China)

  • 8. Simulation

  • Co-Chairs: J. Cao (IHEP, China)

    • C. Jillings (Caltech, U.S.)

  • 9. Tunneling and Civil Construction

  • Lead: C. Yang (IHEP, China)

  • U.S. Consultant: C. Laughton (FNAL, U.S.)

  • Steve Kettell, BNL DOE HEP Review

    Why bnl

    Why BNL?

    • The Physics is compelling! and a critical step to CP

    • BNL provides a strong National Laboratory presence to assure the success of the experiment.

    • BNL has a rich and storied tradition in n physics: in both the Physics and Chemistry departments

    • BNL Chemistry has been involved in liquid scintillator research for Daya Bay for 3 years

    • This experiment provides a bridge from the current Physics Department effort on MINOS to a long-baseline effort to measure CP violation in the neutrino sector.

    Steve Kettell, BNL DOE HEP Review

    Bnl involvement in daya bay

    BNL involvement in Daya Bay

    • Formally joined collaboration at Feb. 2006 meeting in Beijing

    • Member of Institutional Board (Kettell)

    • Lead of liquid scintillator task force (Hahn,Yeh)

    • Lead of muon veto task force (Littenberg, Diwan, Bishai)

    • Central detector task force (Kettell)

    • Simulations task force (Jaffe)

    • Project and other engineering resources available

    Steve Kettell, BNL DOE HEP Review

    Bnl in daya bay

    BNL in Daya Bay

    • BNL is deeply involved in the muon tracker design

    • BNL is working with engineer from LBNL on antineutrino detector design and project management

    • BNL is looking to incorporate additional BNL engineering

    • One third of R&D request for BNL projects

    • As MINOS analysis effort matures, more effort directed to Daya Bay construction project and later to DB analysis




    Steve Kettell, BNL DOE HEP Review

    U s r d plan

    U.S. R&D Plan

    Primary R&D Goals:

    • Ensure a strong U.S. contribution to the Daya Bay experiment.

    • Match the schedule of Chinese R&D and design.

      • Don’t let U.S. slow project down!

    • Optimize U.S. scope while minimizing cost.

      Full R&D funding in FY06 (and FY07):

    • Enable U.S. input to experiment design.

    • Timely technology choices.

    • Early determination of project cost and schedule.

    • Finalize preparations for CD-1 in about six months.

    DOE-HEP Daya Bay

    FY06 R&D Request

    1/23/06, revised 1/31/06

    Steve Kettell, BNL DOE HEP Review

    Gd loaded liquid scintillator

    Gd-Loaded Liquid Scintillator

    BNL lead role: substantial R&D at BNL on metal loaded LS (funded by ONP + LDRD)

    • Avoid the chemical/optical degradation problems encountered in the Chooz and Palo Verde experiments

      Primary R&D Goals:

    • Study alternatives to PC (Low flashpoint: 48oC, health/environmental issues, attack acrylic)

      • For example, mixture of 20% PC and 80% dodecane

      • Current R&D is with Linear Alkyl Benzene, LAB, which is very attractive (high flashpoint:130o, biodegradable and environmentally friendly, readily available with tons produced by industry for detergents)

    • Successfully prepared Gd-LS in 100% LAB, with favorable properties (over Gd in PC)

    • Further studies needed to determine stability over time

    • Develop mass-production techniques to go from the current bench-top scale of kg (several liters) to tonnes (thousands of liters)

    Require stable (~years) Gd-LS with high light yield, long attenuation length.

    Explore alternatives to pseudocumene, PC.

    Evaluate chemical compatibility of Gd-LS with acrylic (detector vessel).

    Steve Kettell, BNL DOE HEP Review

    Optical attenuation of bnl gd ls

    Absorbance at 430 nm

    Calendar Date

    Optical Attenuation of BNL Gd-LS

    Stable for ~500 days so far

    Gd-LS under UV light

    (in 10 cm cells)

    Steve Kettell, BNL DOE HEP Review

    Muon veto tracker

    Muon Veto/Tracker

    Understanding muon and spallation backgrounds:

    • High efficiency, redundant muon vetoes.

    • Tracking ability for systematic studies and event identification.

    • Primary R&D Goals:

      • Evaluate candidate technologies for muon tracker:

      • Plastic scintillator strips

      • Resistive Plate Chambers

      • Liquid scintillator modules

  • Evaluate candidate technologies for muon veto:

    • Water pool Cherenkov

    • Modular water Cherenkov

  • BNL Role

  • Subsystem in which U.S. is likely to take the lead  BNL has extensive experience in both plastic and liquid scintillator.

  • Steve Kettell, BNL DOE HEP Review

    The daya bay experiment

    Antineutrino Detector

    • Measurement of sin2213  0.01 requires detector systems designed to

    • minimize systematic uncertainties.

    • Identical detector modules:

      • identical scintillator volumes, optical transparency.

      • facilitate calibration/monitoring system.

    • Moveable detectors:

      • design detectors for identical performance at all sites.

      • engineer support and movement structures.

      • time critical due to close interface with tunnel/cavern design.

    Primary R&D Goals:

    • Mechanical design of central detector.

    • Design of transportation and installation systems for detectors.

    • Identify vendors for fabricating acrylic vessels.

    BNL Role:

    • Engineering and leadership experience at LBNL and BNL.

    On the critical path (civil construction design contract).

    KamLAND 2005

    Steve Kettell, BNL DOE HEP Review

    The daya bay experiment

    Site Development

    • Analyze core samples: input for detailed civil construction design studies.

    • Define surface building and underground halls (space and infrastructure).

    • Define liquid scintillator purification and handling (space and infrastructure).

    • Primary R&D Goals:

    • Define underground hall specifications in order to proceed to final civil design contract.

    • Interface between experiment design and hall design.

    • BNL Role:

    • Engineering and physics design experience

    • Specification of civil design is on the critical path; minimize delay and reduce risk for civil construction.

    KamLAND 2005

    Steve Kettell, BNL DOE HEP Review

    The daya bay experiment

    Project Definition

    • Develop complete project scope and schedule (joint with China).

    • Define U.S. and Chinese deliverables (joint with China).

    • Develop U.S. cost and schedule ranges.

    • Build U.S. project team and organization.

    • Primary R&D Goals:

    • Develop the U.S. project scope, cost and schedule.

    • Coordinate with China on total project scope, cost and schedule.

    • BNL Role:

    • U.S. responsibility. Exploit project experience at LBNL and BNL.

    • Continue to develop coordination with Chinese effort.

    • Develop baseline project.

    • Develop overall experiment design.

    KamLAND 2005

    Steve Kettell, BNL DOE HEP Review

    Initial definition of project scope

    Initial definition of Project Scope

    U.S.-China primary responsibilities

    U.S. Scope

    • Muon tracking system (veto system)

    • Gd-loaded liquid scintillator

    • Calibration systems

    • Antinu Detector (Acrylic, PMT’s)

    • Electronics/DAQ/trigger hardware

    • Detector integration activities

    • Project management activities

    other contributions

    • Russia: liquid scintillator, calibration, and plastic scintillator

    • Taiwan: acrylic vessels and trigger

    • Hong Kong: calibration and data storage

    Steve Kettell, BNL DOE HEP Review

    U s project scope budget

    U.S. Project Scope & Budget

    Steve Kettell, BNL DOE HEP Review

    Overall project schedule

    Overall Project Schedule

    Steve Kettell, BNL DOE HEP Review

    Project development

    Project Development

    • Schedule/activities over next several months:

    now – June

    now – summer

    now – Aug

    July – Nov

    Aug – Nov

    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:

    Steve Kettell, BNL DOE HEP Review

    Funding profile

    Funding Profile

    FY06U.S. R&D $2M

    FY07 $3.5M

    FY08U.S. Construction $10M

    FY09 $14M

    FY10 $8M

    CD-1 reviewNovember 2006

    Begin construction in ChinaMarch 2007

    CD-2 reviewSeptember 2007

    Begin data collection January 2010

    Measure sin2213 to 0.01March 2013

    Steve Kettell, BNL DOE HEP Review

    Summary and prospects

    Summary and Prospects

    • The Daya Bay nuclear power facility in China and the mountainous topology in the vicinity offer an excellent opportunity for carrying out a measurement of sin2213 at a sensitivity of 0.01.

    • The Chinese funding agencies have agreed in principle to a request of RMB 150M to fund civil construction and ~half of the detector.

    • NuSAG endorsed U.S. participation in a 13 experiment, P5 is evaluating 13 experiments as part of the Roadmap, and we are hopeful for a positive decision by DOE.

    • BNL/LBNL submitted R&D request to DOE for FY06 in January 2006.

    • Have begun to form project leadership team with China: progress on organization, scope and cost.

    • Will complete a conceptual design of detectors, tunnels and underground facilities in 2006, aiming for CD1 review this year and a CD2 review in 2007.

    • In the ~3 months since BNL joined the Daya Bay collaboration we have made huge strides in defining and understanding the project and the U.S. scope.

    • Plan to commission a Fast Deployment plan in 2009, with full operation in 2010.

    Steve Kettell, BNL DOE HEP Review



    Steve Kettell, BNL DOE HEP Review

    A versatile site

    A Versatile Site

    • Full operation:

    • (A) Two near sites + Far site

    • (B) Mid site + Far site

    • (C) Two near sites + Mid site + Far site

    • Internal checks, each with different

    • systematic

    • Rapid deployment:

      • - Daya Bay near site + mid site

      • - 0.7% reactor systematic

      • error

    Steve Kettell, BNL DOE HEP Review

    Cosmic ray muon

    ~350 m

    ~98 m

    ~208 m

    ~97 m

    Cosmic-ray Muon

    • Apply a modified Gaisser parameterization for cosmic-ray flux at surface

    • Use MUSIC and mountain profile to estimate muon flux & energy

    near site

    far site

    Steve Kettell, BNL DOE HEP Review

    Science goals experiment design r d

    Science Goals → Experiment Design → R&D

    • Reduce and control systematic errors:

    • “Identical” detectors at multiple sites

    • → detector design/construction, side-by-side comparisons

    • Detector performance - well-understood, stable

    • → materials/construction, calibration/monitoring

    • Reduce radioactivity background

    • → materials/construction, Gd-loaded scintillator

    • Reduce and measure cosmogenic backgrounds

    • → shielding, muon veto and tracking, DAQ system

    • Swap detectors

    • → horizontal tunnel system, locomotion equipment

    U.S. R&D tasks focused on achieving these goals

    Steve Kettell, BNL DOE HEP Review

    Background estimated by geant mc simulation

    Background estimated by GEANT MC simulation

    Steve Kettell, BNL DOE HEP Review

    Detector related uncertainties

    Detector-related Uncertainties


    → 0

    → 0.006

    → 0

    → 0.06%

    Swapping: canreduce relative uncertainty further





    Baseline: currently achievablerelativeuncertainty without R&D

    Goal: expectedrelativeuncertainty after R&D

    Steve Kettell, BNL DOE HEP Review

    Experimental parameters

    Experimental Parameters

    Steve Kettell, BNL DOE HEP Review

    H c ratio

    H/C ratio

    • CHOOZ claims 0.8% absolute based on multiple lab analyses (combustion)

    • We need only relative measurement

    • Double-CHOOZ claims 0.2%

    • Adopt 0.2% baseline

    • Adopt 0.1% goal

    R&D: measure via NMR or neutron capture

    Steve Kettell, BNL DOE HEP Review

    Target volume

    Target Volume

    • KamLAND: ~1%

    • CHOOZ: 0.02%?

    • Flowmeters – 0.02% repeatability

    • Baseline = 0.2%

    • Goal = 0.02%

    Steve Kettell, BNL DOE HEP Review

    Energy cuts

    Energy Cuts

    • CHOOZ = 0.8% absolute

    • Baseline 0.2%

    • Goal = 0.05% for

    • 2% energy calibration

    Steve Kettell, BNL DOE HEP Review

    Energy cuts1

    Energy Cuts

    KamLAND calibration data:

    Steve Kettell, BNL DOE HEP Review

    Time cuts

    Time Cuts

    Neutron time window uncertainty:

    • Dt = 10 ns g 0.03% uncertainty

    • Use common clock for detector modules

    • Baseline = 0.1%

    • Goal = 0.03%

    Steve Kettell, BNL DOE HEP Review

    H gd ratio

    H/Gd ratio

    Measure neutron capture time

    CHOOZ measured t to ±0.5ms gDe=0.01% for t1=0.2ms

    Steve Kettell, BNL DOE HEP Review



    • Measure relative livetimes using accurate common clock

    • Should be negligible error (note SNO livetime error of ~10-5

    Steve Kettell, BNL DOE HEP Review

    The daya bay experiment

    What Have We Learned From Chooz?

    P = 8.4 GWth

    L = 1.05 km

    D = 300 mwe

    5 t Gd-loaded liquid scintillator

    to detect


    ~5 events/day/t (full power)

    including 0.2-0.4 bkg/day/t

    ~3000 ecandidates

    (included 10% bkg) in

    335 days

    e + p  e+ + n

    e+ + e-  2 x 0.511 MeV 

    n + Gd  8 MeV of s;  ~ 30 s

    Steve Kettell, BNL DOE HEP Review

    Reactor anti e

    Reactor anti-e

    For 235U, for instance, an

    average of 6 esare producedper fission (~200 MeV).



    3 GWthgenerates 61020 ne per sec

    Steve Kettell, BNL DOE HEP Review

    Time variation of fuel composition

    Time Variation of Fuel Composition





    0 0.5 1 1.5 2 2.5 3 3.5

    normalized flux times cross section (arbitrary units)

    2 3 4 5 6 7 8 9 10

    E (MeV)

    Typically known to ~1%

    Steve Kettell, BNL DOE HEP Review



    • Radioactive Source

      137Cs, 22Na, 60Co, 54Mn, 65Zn , 68Ge, Am-Be

      252Cf, Am-Be

    • Gamma generator

      p+19F→ α+16O*+6.13MeV; p+11B→ α+8Be*+11.67MeV

    • Backgrounds

      40K, 208Tl, cosmic-induced neutrons, Michel’s electrons, …

    • LED calibration

    KI & CIAE

    Hong Kong

    Steve Kettell, BNL DOE HEP Review

    What target mass should be

    What Target Mass Should Be?

    (3 year run)

    DYB: B/S = 0.5%

    LA: B/S = 0.4%

    Far: B/S = 0.1%

    m231 = 2  10-3 eV2


    Systematic error

    Black : 0.6%

    Red : 0.25% (baseline goal)

    Blue : 0.12%

    Steve Kettell, BNL DOE HEP Review



    For 3 years

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

    Steve Kettell, BNL DOE HEP Review

    The daya bay experiment

    sin2213 = 0.02

    sin2213 = 0.1

    Precision of m231

    Steve Kettell, BNL DOE HEP Review

    Synergy of reactor and accelerator experiments

    Synergy of Reactor and Accelerator Experiments

    90% CL

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

    Reactor experiments can help in

    Resolving the23 degeneracy

    (Example: sin2223 = 0.95 ± 0.01)

    Δm2 = 2.5×10-3 eV2sin2213 = 0.05

    Reactor w 100t (3 yrs) +T2K

    T2K (5yr,n-only)

    Reactor w 10t (3 yrs)


    90% CL

    90% CL

    Reactor experiments provide

    a better determination of 13

    McConnel & Shaevitz, hep-ex/0409028

    Steve Kettell, BNL DOE HEP Review

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