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A Trial of Neutrino Detection from Joyo Fast Research Reactor

F.SuekaneResearch Center for Neutrino Science

Tohoku Universitysuekane@awa.tohoku.ac.jp

JAEA-IAEA Workshop on Advanced Safeguards Technology for the Future Nuclear Fuel Cycle

13-16 November 2007, Tokai-mura, Ibaraki, Japan

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Collaborating Institutes and Gratitude

Tohoku Univ., Kobe Univ., Tokyo Inst. of Tech., KEK, Niigata Univ., Hiroshima Inst. of Tech.Tokyo Metropolitan Univ., Miyagi Univ. of EducationTohoku Gakuin Univ., and JAEA O-arai Reseach and Development Center.

This work has been supported by grants in aid for the scientific research,

by Japanese Ministry of Education, Culture, Sports, Science and Technology.

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What is neutrino(ν)?

!"

#$%&

'$$()&

*+

,-./"

01

23

2!1020456

2!1038456

6!10554

6.6!101045s/cm2

2!1016456

2!1024456

789:;<=>?@ABCDBE

the sun

Super Nova

Nuclear Reactor

Cosmic-ray hitting Atmosphere

the earth

ν is an elementary particle which is produced in nuclear reactions.ν is the 2nd most abundant particle in the universe (next to the photon). We are living in ν sea.

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Nuclear Reactor Produces a huge number of ν

~6ν's are produced per fission

~ 6 !1020" e/ s / reactor

n U235

U236*

n n

Zr94140

Cs

I140

Te140

Xe140

Rb94

Sr94

Y94

e-

e-

e-

e-

e-

e-

νe

νe

νe

νe

νe

νe

Reactor ν's are produced in β-decays of fission products.

An example of β-decay chain

Chooz data

ν energy spectrum

6% of fission energy is carried away by neutrinos.

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ν for SafeguardsNuclear reactor produces a huge huge # of (~1021/s) ν's <= ν carries direct information of nuclear fuel.

The # of produced ν is proportional to the thermal power. <= ν may be used as a power monitor.

The energy spectrum and # of ν depends on fuel component. <= ν may be used as real time Pu monitor.

ν is impossible to stop. <= ν can not be hidden.

Nuclear explosion also produces a huge huge # of ν's instantaneously. <= ν may be used as nuclear testing monitor.

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ν for SafeguardsNuclear reactor produces a huge huge # of (~1021/s) ν's <= ν carries direct information of nuclear fuel.

The # of produced ν is proportional to the thermal power. <= ν may be used as a power monitor.

The energy spectrum and # of ν depends on fuel component. <= ν may be used as real time Pu monitor.

ν is impossible to stop. <= ν can not be hidden.

Nuclear explosion also produces a huge huge # of ν's instantaneously. <= ν may be used as nuclear testing monitor.

However, it is extremely difficult to detect ν

and such application has not been realized yet.

ν detection technique has progressed much recently in the field of elementary particle physics.

<= Now it may be the time to seriously think about its possibility.

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How to measure Pu/U ratio by ν

!

Pth = q nU + nPu( )

N" = anU +bnPu

# $ %

!

nPu

nU=1" ar

br "1; r =

Pth

qN#

0

5

10

15

20

0 1 2 3 4 5 6 7 8 9 10

E!(MeV)

#ev

ent/

MeV

/GW

th/1

030 p

roto

n/d

ay

@ 1

km

235U

239Pu

a

b

nU, nPu: Fission rate of U and Puq: Energy release per fission (~200MeV)Pth: Thermal powerNν: # of νa, b: # of ν generation per U, Pu fission (a/b~1.5)

(simplified discussion)

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Activity of ν physicists.

1st: Feb. 5-7, 2004 @Univ. of Hawaii, USA2nd: Dec.14-16, 2005 @Univ. of Hawaii, USA3rd: Sept.24-26, 2006 @ Laurence Livermore National Lab., USA

And 4th: Dec. 23-24, 2007 @ Saclay, France

= Applied Antineutrino Physics Workshops =

Next Slide

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ν detection from San-Onofre Nuclear Reactor

San-OnofreNuclear Reactor

Burn-up effect=> Change of U/Pu ratio

FromN.S.Bowden et al. N.I.Meth.A572:985-998,2007& Talk slide from AAP2006

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!

P

L2"

observed ν rate

KamLAND experiment (JAPAN); ν detection from reactors180km away

ν target=1kton of liquid scintillator

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How ν is detected

p

e+

nν

scintillation light

positron

!"

#$$$%&

'()*

Reaction probability=10−18%with 1ton of scintillator.

neutirno

Photomultiplier(photo sensor)

Chemical component of scintillator ~ CxHyOz

!

" + p# e+

+ n

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KASKA Experimentν detectorν detectorν detector

Kashiwazaki-Kariwa Nuclear Power Station

ν detector

ΣP=24.3GWth(world's highest Power)

R&D 2003-2006

Purpose is to detect the last neutrino oscillationand measure mixing angle θ13

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KASKA Prototype:for ν Detector R&D

in Tohoku Univ.

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Prototype@Joyo(JAEA) research reactor

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()*+, ()-.,

/0123

4567

89:;<=>?@A

BCDE*+'

F9:;<=>?@ABGHIJ1

!"#KL

!"#MNKL

!"#&'

#O

PQR4567

STU>?VW-'

>2JXYZU[U\

Fast Reactor (Pu rich)Pth=140MWFrequent ON/OFFL~25m~150 νp−>e+n reaction/day

KASKA Prototype

25m

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Why Joyo?

* Practical Reason:Research Reactor is easier to access.

* Scientific Interest: ν from fast reactor has not been measured. * Technological Interest ν spectum from U and Pu can be measured separately by combining with the data from Light Water Reactor

However, the thermal power is small (1/20 of San-Onofre) and it is

challenging to detect ν at Joyo.

U

Pu#

of ν

# of

νU

LWR

Fast Reactor

Pu

Measured

Not measured

(Does not scale)

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Prototype@Joyo research reactor

Not to scale

0.05% Gd Liquid Scintillator (900L)

Lead Shields

Cosmic-ray anti-counters

Light shield

Paraffin Blocks

N2

* 0.05% Gd LS(10%BC521+15%PC+75%isoParaffin oil)* Lead shield,* Cosmic-ray anti counter* Paraffin Blocks* n/γ pulse shape discrimination(PSD)

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Acrylic sphere & Liquid Scintillator

Cosmic veto counter

Paraffin blocks

Electronics

In Joyo Building

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Neutrino Detection

! e + p" e+

+ n

Then

e+ + e! " 2# 2 $ 0.511MeV( )

n +Gd! Gd' +" ' s E"# ~ 8MeV( )!

"#

#$

#%

&'()*++,#-.

&'()*++,#-.

/

01

&

&&

&

E!" ~ 8MeV

2(34

!567!894:;/<=

>#=<?#194:;/<=

!"#$

%&'(

)*!"#$

+

,-./0123456#4+7

=> use Gd

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Energy Correlation of Prompt and Delayed Signals

1

10

104

105

1

10

102

103

104

Background (/day/0.4MeV/0.4MeV) AmBe + Background (/day/0.4MeV/0.4MeV)105

1

10

102

103

104

105

Del

ayed

Ede

p(M

eV)

0 2 4 6 8 10 12 14 16 18 20Prompt Edep(MeV)

0 2 4 6 8 10 12 14 16 18 20Prompt Edep(MeV)

20

18

16

14

12

10 8 6

4

2

0

20

18

16

14

12

10

8

6

4

2

0

Del

ayed

Ede

p(M

eV)

simulated ν signal(Am/Be source)

Back grounds: * γ-rays from U, Th, K, Rn * cosmic-rays

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Energy Spectrum in ν windowOn:20days, Off:20days

13 ± 4

163 ± 3

150 ± 3

Total events

135 ± 315 ± 0.01Reactor OFF

7 ± 46 ± 0.01ON - OFF

142 ± 321 ± 0.01Reactor ON

Correlated eventsAccidental BG

- Reactor ON- Reactor Off- Accidental (Reactor ON)- Accidental (Reactor OFF)

Rate

(/day

/Mev

)

E(Mev)

Preliminary

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ν candidate（Data vs MC）

・ Dataー　MCPreliminary

Expected

Nν=NON-NOFF

So far no significant positive result yet.

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Possible Future improvements

More Statistics,Pusle Shape neutron-e+ separation,Better Fiducial cuts,Use Timing inforamtion, :

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Summary

*In this talk, our effort to detect ν from Joyo research reactor was presented. * There are similar activities in worldwide and this kind of ν detector may be able to be used as a monitor of nuclear reactor operation in the future.