Reactor Neutrino Experiments

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Reactor Neutrino Experiments

Jun Cao

[email protected]

Institute of High Energy Physics

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2 Outline

_Outline

Past Reactor Neutrino Experiments

Ö

Palo Verde

Ö

Chooz

Ö

KamLAND

Theta13 experiments

Ö

Angra

Ö

Daya Bay

Ö

Double Chooz

Ö

RENO

Search for neutrino magnetic moment

Ö

TEXONO

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3 Past Reactor Neutrino Experiments

_{Past Reactor Neutrino Experiments}

Reactor anti-neutrino experiments have played a critical role in the 50-

year-long history of neutrinos.

The first neutrino observation in

1956 by Reines and Cowan.

Determination of the upper limit

of mixing angle theta13 to

sin

2

2θ

13

<0.17 (Chooz, Palo Verde)

The first observation of reactor

anti-neutrino disappearance at

KamLAND in 2003.

Now reactor neutrino experiments become prominent again for measuring mixing angle θ₁₃precisely.

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4 Savannah River Experiment

_{Savannah River Experiment}

The first neutrino observation in 1956 by Reines and Cowan.

Ö

Inverse beta decay in CdCl

₃

water solution Æ coincidence of prompt and

delayed signal

Ö

Liquid scintillator + PMTs

Ö

Underground

A modern experiment is still quite similar, except

Ö

Larger, better detector

Ö

Deeper underground, better passive and active shielding

Ö

Now we know how to load Gd into liquid scintillator

e

p

e

n

ν

_{+ →}

+

₊

2 e

+

e

−

→

γ

Capture on H, or Gd, Cd, etc. Delayed signal Prompt signal

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5 Reactor Neutrino Spectra

_{Reactor Neutrino Spectra}

235

_U,

239

_Pu,

241

_Pu

_{beta spectra were measured at}

_ILL

_.

238

_U

_{spectrum is}

calculated theoretically.

Counting rate and spectra were verified by

Bugey

and

Bugey-3

Power fluctuation <1%, counting rate precision ~2% with burn-up evolution.

Spectra precision ~2%

Rate and spectra precision are less important for next theta13 experiments.

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6 CHOOZ

_CHOOZ

Baseline 1.05 km 1997-1998, France 8.5 GWth 300 mwe 5 ton 0.1% Gd-LS Bad Gd-LS

Parameter Relative error

Reaction cross section 1.9 %

Number of protons 0.8 %

Detection efficiency 1.5 %

Reactor power 0.7 %

Energy released per fission 0.6 %

Combined 2.7 %

R=1.01±2.8%(stat) ±2.7%(syst), sin

2

2θ

13

<0.17

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7 Palo Verde

Palo Verde

1998-1999, US 11.6 GWth Segmented detector 12 ton 0.1% Gd-LS Shallow overburden 32 mwe Baseline 890m & 750m R=1.01±2.4%(stat) ±5.3%(syst) Palo Verde Gd-LS Chooz Gd-LS 1st year 12%, 2nd year 3% 60%/year Phys.Rev.D64, 112001(2001)

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8 KamLAND

KamLAND

2002-now, Japan 53 reactors, 80 GWth 1000 ton normal LS 2700 mwe

Radioactivity Æ fiducial cut, Energy threshold

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9 KamLAND

KamLAND

The first observation of reactor anti

The first observation of reactor anti--neutrino neutrino disappearance

disappearance

Confirmed antineutrino disappearance at

99.998% CL

Excluded neutrino decay at 99.7% CL Excluded neutrino decay at 99.7% CL Excluded

Excluded decoherence decoherence at 94% CLat 94% CL

R=0.658±0.044(stat) ±0.047(syst) Phys.Rev.Lett. 94, 081801 (2005)

2 0 .6 5 2 1 2 0 .5 2 0 .1 0 1 2 0 .0 7

7 .9

1 0

t a n

0 .4 0

m

e V

θ

+ − − + −

Δ

=

×

=

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10 Neutrino Oscillation

_{Neutrino Oscillation}

Neutrino Mixing: PMNS Matrix

13 13 1 13 13 2 12 12 1 23 23 2 23 23 cos 0 si 1 0 0 0 cos s n 0 1 0 cos sin 0 sin cos 0 sin in

0 sin cos 0 cos 0 0 1

i i e e δ δ

θ

− ⎛ ⎞⎛ ⎞ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎝− ⎜ ⎟ ⎜ ⎟ ⎜ ₋ ⎟ ⎝ ⎠ ⎛ ⎞ ⎜₋ ⎟ ⎜ ⎟ ⎜ ⎝ ⎠ ⎠ ⎟

Atmospheric,

K2K, MINOS, T2K, etc.

θ

₂₃

~ 45º

Solar

KamLAND

θ

₁₂

~ 30º

Reactor

Accelerator

θ

₁₃

< 12º

Known: |Δm

2 32

|, sin

2

2θ

23

, Δm

221

, sin

2

2θ

12

Unkown:

sin

2

2θ

13,

δ

CP

, Sign of Δm

232

“We recommend, as a high priority, …, An

expeditiously deployed multi-detector reactor

experiment with sensitivity to

⎯ν

_e

disappearance

down to sin

2

₂

θ

13

=0.01”

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11 Precisely Measuring theta13

_{Precisely Measuring theta13}

Parameter Relative error By Near/far configuration Reaction cross section 1.9 % Cancel out

Number of protons 0.8 % Reduced to ~0.3% Detection efficiency 1.5 % Reduced to 0.2~0.6%

Reactor power 0.7 % Cancel out or reduced to ~0.1% Energy released per fission 0.6 % Cancel out

Chooz Combined 2.7 % Major sources of uncertainties:

Reactor related ~2% Detector related ~2% Background subtraction Lessons from past experience: Need near and far detectors Chooz: Good Gd-LS

Palo Verde: Go deeper

KamLAND: No fiducial cut, lower threshold

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12 Proposals for measuring

_{Proposals for measuring}

θ

13 13

Angra, Brazil

Diablo Canyon, USA

Braidwood, USA

Double Chooz, France

Krasnoyarsk, Russia

KASKA, Japan

Daya Bay, China

RENO, Korea

8 proposals

4 cancelled

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13 Angra

_Angra

Goal: sin

2

₂

θ

13

~ 0.006 @ 90% CL.

Site: Rio de Janeiro, Brazil

30 researchers from 11 institutions.

Budget for Very Near (prototype) detector for Safeguards study approved by

FINEP in March 2007 (~$0.5M)

High precision theta13 experiment in Angra around 2013?

Participation of the Brazilian group in Double Chooz

experiment

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14 Daya Bay

_{Daya Bay}

Goal:

LA: 40 ton Baseline: 500m Overburden: 112m Muon rate: 0.73Hz/m2 Far: 80 ton 1600m to LA, 1900m to DYB Overburden: 350m Muon rate: 0.04Hz/m2 DYB: 40 ton Baseline: 360m Overburden: 98m Muon rate: 1.2Hz/m2 Access portal 8% slope 0% slope 0% slope 0% slope

Goal: sin

2

₂

θ

13

< 0.01 @ 90% CL in 3 years.

Site: Shen Zhen, China

Power Plant

4 cores 11.6 GW

6 cores 17.4 GW from 2011 Three experimental halls

Multiple detectors at each site Side-by-side calibration

Horizontal Tunnel

Total length 3200 m Movable Detector

All detectors filled at the

filling hall, w/ the same batch of Gd-LS, w/ a reference tank Event Rate: ~1200/day Near ~350/day Far Backgrounds B/S ~0.4% Near B/S ~0.2% Far

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15 Daya Bay Detector

_{Daya Bay Detector}

RPC

Water Cherenkov

Antineutrino detector

Eight 3-layer cylindrical anti-neutrino detectors, 5mx5m

_{Target mass 20 ton. Stable 0.1% Gd-LS by IHEP&BNL: [Gd+carboxylic]+LAB+fluor} Gamma catcher ~ 42cm, LAB+fluor

Oil Buffer ~ 50 cm, 192 8-in PMTs + reflective panels. Energy resolution ~12%/sqrt(E) Water shield (2 layer water cherenkov) ~ 250 cm, ~2000 ton. 4 layer RPC at top.

20 t Gd-LS Gamma Catcher

Oil Buffer

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16 Civil Construction

_{Civil Construction}

Underground Filling in hall 5Æ

Significantly reduce detector

systematic uncertainties.

Ö Same batch of Gd-LS and LS Æ H/Gd ratio, H/C ratio, light

properties

Ö A reference tank with load cell to fill all detectors Æ Target mass 0.1-0.2%

Site Survey, bore hole 2005.5-2006.6 Conceptual Design 2006.6-2006.8 Preliminary Design 2007.1-2007.3 Engineering Design 2007.3-2007.7

Civil Bidding 2007.8-2007.9 Start civil construction 2007.9 Complete civil construction 2009.6

Hall 5: LS mixing and filling

200t Gd-LS

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17 Daya Bay Status

_{Daya Bay Status}

~180 collaborators, 34 institutes from China (Taiwan, Hong Kong), Czech,

Russia, and United States.

All funding from China (all civil and ~50% detector) is secured.

Passed US DOE physics review (2006.10) and CD1 review (2007.4).

R&D

funding approved.

CD2/3a review scheduled in 2007.11.

Detector

construction funding (~50% detector) expected shortly after CD2/3a

.

Funding from Taiwan, Czech, Russia is secured.

Schedule

Start Tunnel Construction ……… 2007. 09

Surface Assembly Building ready ……… 2008. 06

DB Near Hall civil complete ……… 2008. 07

DB Near Site ready to take data ………. 2009. 06

LA Near Site ready to take data ……… 2010. 05

All Sites Ready to take Data……… 2010. 10

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18 Daya Bay R&D

_{Daya Bay R&D}

A 2-layer prototype running at IHEP for 1.5 years. Outer detector: 2mx2m,

Inner acrylic vessel: 1mx1m.

Ö Phase-I with 800 liters normal LS for 1 year.

Ö Phase-II with 800 liters 0.1% Gd-LS has been running for 7 months.

A 2-layer prototypes is under construction in Hong Kong. (underground)

3-m and 4-m Acrylic Vessel prototype will be completed before 2007.11

All critical detector components are being prototyped, e.g. water system,

reflectors, RPC chamber, electronics, PMT base and seal, etc.

245 255 265 275 285 1 ₁₃ ₂₅ ₃₇ ₄₉ ₆₁ ₇₃ ₈₅ ₉₇ 109 121 133 145 157 days P.E./MEV Cs137 Co60 Prototype with 45 8” PMTs

Stability monitoring of 800-L 0.1% Gd-LS in IHEP prototype. No visible attenuation length degradation.

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19 Double Chooz

_{Double Chooz}

Goal: sin

2

₂

θ

13

< 0.03 @ 90% CL in 3 years

Ardennes, France

Far detector (1050 m) 300 m.w.e. Near detector (~280 m) ~80 m.w.e.

νν

ν

Â 2 reactors - 8.5 GW

_th

Â 2 identical detectors:

►Target: 2 x 8.3 t

Â Comparison of neutrino

rate & energy spectrum

Â Civil work:

► 1 near lab is foreseen

► 1 far lab is available

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20 Double Chooz Detector

_{Double Chooz Detector}

3-layer cylindrical detector

Target mass 8.3 ton. Stable Gd-LS by Heidelberg: [Gd+Beta-Dikotonates]+[20% PXE+80% dodecane]+fluor

Gamma catcher ~ 54cm, normal LS Oil Buffer ~ 100 cm, 390 10-in PMTs Veto ~ 50 cm, shielding 15cm

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21 Double Chooz Status

_{Double Chooz Status}

Proposal

of the experiment (hep-ex/0606025)

Technical Design Report

almost finished

Funding has been established

in Europe

Ö

NSF groups in US funded

Ö

Japan and US DOE groups pending

The experiment is

moving forward

Schedule

:

Ö

2007-2008

: Detector construction and integration

Ö

2008

: Far detector data taking starts, sin

2

2θ

13

< 0.06 (90% CL)

Ö

2010

: Near detector starts

~100 scientists, 32 institutions from Brazil, France, Germany, Japan, Russia, Spain, UK, and US.

The experiment has been approved by most of the respective Scientific Councils

90% C.L. Δm2

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22 RENO

_RENO

YongGwang NPP, Korea

6 cores, 16.4 GW

Goal: sin

2

₂

θ

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23 RENO Detector

_{RENO Detector}

Target 15-t 0.1% Gd-LS,

[Gd+CBX or BDK] +

[20%PC+80% dodecane] + fluor,

R&D by INR/IPCE group

Gamma Catcher ~60 cm

Oil Buffer ~70 cm, 537 8-in PMTs,

7.7%/sqrt(E)

Water veto ~1 m, PMT number

undetermined.

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24 RENO Status

_{RENO Status}

Experiment site usage has been approved.

Geological survey completed in 2007.05

Issue tunnel construction contract in

2007.10

Detector Construction begin in 2007.10

Data taking expected to start in early

2010.

43 collaborators, 13 institutes from Korea, Russia

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25 RENO R&D

_{RENO R&D}

Small prototype running

Working on “mock-up” detector

Gd-LS R&D

4-L Gd-LS 140-L gamma catcher

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26 ¾ TEXONO Collaboration

– Academia Sinica-based and run, with groups from

China, Turkey & India, close partnership with KIMS group in Korea.

¾ Facilities

–

Kuo-Sheng Reactor Neutrino Laboratory in Taiwan

;

YangYang

Underground Laboratory in South Korea.

¾ Program

– Low Energy Neutrino and Astroparticle (Dark Matter) Physics.

Neutrino Magnetic Moments

,

Neutrino Radiative Decays,

Axions

Y2L

TEXONO

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27 Reactor Neutrino Interaction Cross

_{Reactor Neutrino Interaction Cross}

-

_-

Sections

_Sections

R&D

(ULEGe)

:

¾

Coh. (

νN)

¾

T < 1 keV

Results

(HPGe):

¾

μ

_ν

(

ν

_e

)

¾

T ~ 1-100 keV

On-Going

Data Taking

& Analysis

[CsI(Tl)]

:

¾

SM

σ(νe)

¾

T > 2 MeV

mass

quality

Detector requirements

Bkg level at O(10 keV)~ 1 counts / kg-keV-day

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28 TEXONO 2007 Highlights

_{TEXONO 2007 Highlights}

Improved Limits in

Neutrino Magnetic

Moments

(PRL-03, PRD-07)

μ

ν

(ν

e

)

< 7.4 X 10

-11

μ

B

@ 90% CL

Bounds on neutrino radiative decays.

Reactor Axion (PRD-07):

Improved laboratory limits axion mass 102_-106 _eV

Exclude DFSZ/KSVZ Models for axion mass 104 -106 _eV

On-Going – measurements of neutrino-electron scattering cross-sections (i.e. sin2θ

w at MeV) Future – develop 100 eV threshold + 1 kg mass detector for

Ö First observation of neutrino-nucleus coherent scattering Ö Dark matter searches for WIMP-mass less then 10 GeV

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29 Summary

_Summary

Precisely measuring θ

₁₃

is one of the highest priority in neutrino oscillation

study. Sensitivity to sin

2

2θ

13

< 0.01 is achievable based on experiences of

past reactor neutrino experiments.

Four theta13 experiments are in progress. Three of them project similar

timeline, full operation starting in 2010. Double Chooz will get 0.06 before

2010 using a single far detector.

Luminosity in 3 year (ton·GW·y) Overburden near/far (mwe) Projected Sensitivity Projected Full operation date

Daya Bay 4200 270/950 <0.01 End of 2010

Double Chooz 210 80/300 0.02~0.03 2010

RENO 740 90/440 ~0.02 Early 2010

Limit on neutrino magnetic moment is improved to be < 7.4 X 10

-11

μ

B

by

TEXONO. Many interesting physics topics can be carried out at very near

neutrino scattering experiment.

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