a trial of neutrino detection from joyo fast research · pdf file · 2007-11-14a...
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07.11.14 suekane JAEA-IAEA 1
A Trial of Neutrino Detection from Joyo Fast Research Reactor
F.SuekaneResearch Center for Neutrino Science
Tohoku [email protected]
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
!"
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'()*
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
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!"#MNKL
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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.