Multiplicity and Energy of Neutrons from 233U(nth,f) Fission Fragments
Katsuhisa NISHIO
Japan Atomic Energy Agency (JAEA)
Japan Atomic Energy Research Institute
Tokai InstituteJapan Atomic Energy Agency (JAEA),
Tokai Campus
Tokyo
Tokai
J-PARC
Tandem
Contents
(1) Neutron multiplicity and energy spectrum measurement ➢ 235U(nth,f), 233U(nth,f), 239Pu(nth,f)
(2) Experiment at J-PARC
➢ n + actinide
➢ μ ー + actinide
Research Reactor, Kyoto University
Contents
(1) Neutron multiplicity and energy spectrum measurement ➢ 235U(nth,f), 233U(nth,f), 239Pu(nth,f)
(2) Experiment at J-PARC
➢ n + actinide
➢ μ ー + actinide
TokyoKyoto
Tokai
Supermirror Neutron Guide Tube
1964 First Criticality 5 MW Operation
Kyoto University Reactor
Research Reactor Institute, Kyoto University
5×107 neutrons/cm2/s
Osaka
Fission Neutron Measurement at KURRI
Fission Fragment ( mass and kinetic energy ) ➢ Si-detector : Pulse height Analysis ➢ Parallel Plate Avalanche Counter : Time-of-Flight analysis
Prompt Fission Neutron (neutron energy) ➢ Flight path = 76.5 cm ➢ Liquid Scintillator NE213 ( Φ 5 ” × 2 ”)
K. Nishio et al., J. Nucl.Sci.Technol., 35, 631 (1998).
Neutron Spectra
FWHM = 1.5 ns
For neutrons energy Spectra in the c.m. Frame ➢ Vn >= Vf1 / cos θ
Assumption : All the neutrons are emitted from the fully accelerated fragments
Calculated Neutron yields
Fragment 1 Fragment 2 Neutron detector
θ < 18o
Light Fragment Heavy Fragment
Fission Fragment Yield
233U(nth,f)
Tota
l Kin
etic
Ene
rgy
[MeV
]
Fragment Mass [u]
Q-value
80 90 100 110 120 130 140 150
140
160
180
200
220
Neutron energy spectra from fragments in c.m. frame for 233U(nth,f)
Average neutron energy from FFs for 233U(nth,f)
Neutron multiplicities for 233U(nth,f)
ν L = 1.49
νH = 1.01
Total Neutron multiplicity as function of TKE for 233U(nth,f)
Neutron multiplicity from fragment as function of TKE for 233U(nth,f)
-d
/ dT
KE
(M
eV-1
)
Fragment Mass [u]
Yie
ld
(%)
132102
80 100 120 140 1600.00
0.02
0.04
0.06
0.08
0.10
0.12
0
1
2
3
4
5
6
7
8
Scission configuration
233U(nth,f)132 u102 u
Tot
al K
inet
ic E
nerg
y [M
eV]
Fragment Mass [u]
Q-value
80 90 100 110 120 130 140 150
140
160
180
200
220
Neutron multiplicity ;
132 u
102 u
0 1 2 3 4 5
- d
/ dT
KE
[1/
MeV
] 132102
TKEFragment Mass [u]
Yie
ld [
%]
80 100 120 1400.00
0.02
0.04
0.06
0.08
0.10
0
1
2
3
4
5
6
7
Level density parameters of fission fragments
Neu
tron
M
ulti
plic
ity
Mas
s Y
ield
(%
)
0
1
2
3
4
0
2
4
6
T (
MeV
)a
(M
eV -
1)
1.0
1.5
2.0
2.5
Fission FragmentStable Nuclei
E*=aT2
0
10
20
Fission Fragment
Stable Nuclei
132Sn78Ni
She
ll C
orre
ctio
n E
nerg
y
(MeV
)
Fragment Mass [u]80 100 120 140 160
-10
-5
0
5
Total excitation energy of the fragments
Total neutron multiplicity for each TKE
TKE (MeV)
233U(nth,f)
Tota
l Kin
etic
Ene
rgy
[MeV
] Fragment Mass [u]
Q-value
80 90 100 110 120 130 140 150
140
160
180
200
220
Contents
(1) Neutron multiplicity and energy spectrum measurement ➢ 235U(nth,f), 233U(nth,f), 239Pu(nth,f)
(2) Experiment at J-PARC
➢ n + actinide
➢ μ ー + actinide
J – PARC ( Japan Proton Accelerator Research Complex )
3 GeV
Linac
Materials & LifeExperimental Hall
Hadron Experimental Hall
Materials & LifeExperimental Hall
NeutrinoTargetArea
J - PARC
Energy (GeV)
Cur
rent
(μ
A)
Now 100 kW (300 kW)
MLF Building MLF Materials and Life Science Facility
Mercury Target and Its Container
Shutter on the Top of the Source
ProtonBeam
Neutron Beam Lines
Summer of 2007
MLF Materials and Life Science Facility
MLF Materials and Life Science Facility
Proton
Neutron Time-of-flight cource
Neutron TOF course
Undergoing measurement ➜ Neutron capture cross-sections for 244,245Cm, 129I, 99Tc, 93Zr ➜ Fission experiments can be proposed !
Flight path = 22 - 29 mNeutron energy = 0.01 eV – 100 keV
Neutron induced Fission
➢ Prompt neutron multiplicity and energy spectra Mass – TKE correlations (Cm244,Cm245, …) Pre-scission neutron ?
I. Tsekhanovich et al., Phys.Rev.C 70 , 044610 (2004)
Investigation for the Fission Neutrons
Neutron Detectors
Fission Fragment Detectors
Prompt Fisssion Neutron
Target
FragmentNeutron form J-PARC
Energy of prescission neutron ?
Neutron induced Fission
➢ Fragment mass distribution and angular distributions from each resonances.
➢ Resonance tunneling through the collective states in the 2nd minimum ( mass distributions )
Contents
(1) Neutron multiplicity and energy spectrum measurement ➢ 235U(nth,f), 233U(nth,f), 239Pu(nth,f)
(2) Experiment at J-PARC
➢ n + actinide
➢ μ ー + actinide
muon course
•Positive or negative muons slower than 120 MeV/c are available. •Beam intensity (@ 100kW proton beam): 1.0×106/s
3 GeV proton
μ - induced Fission
V.E. Oberacker et al., Phys.Rev.C 48, 1297 (1993).
Delayed Fission (78 ns in 238U)
Prompt Fission : muon stays at the fissioning nucleus
1s
2p
3d
?
E1(2p->1s) 238U = 6.6 MeVE2(3d ->1s) 238U = 9.6 MeV
H L