tof spectrometers for measurement of n d /n t ratios k.okada, t.nishitani 2, k. ochiai 2, k.kondo 2,...
Post on 14-Dec-2015
213 Views
Preview:
TRANSCRIPT
TOF spectrometers for measurement of nd/nt ratios
K.Okada, T.Nishitani2, K. Ochiai2, K.Kondo2, M.Sasao, M. Okamoto, K.Shinto, S.Kitajima
Tohoku Univ. 2JAEA
OUTLINE
Concept Neutron Spectrum in a collimator-optimaization with MCNP Time-of-flight (TOF) spectrometer designTime-of-flight (TOF) spectrometer design High-counting-rate TOF electronics POP experiment of High-counting-rate TOF electronics Future work and Summary
2/1310th ITPA diagnostics meeting , Moscow 10-14/04/06 M. Sasao
Neutron Spectrum in a collimator - optimaization with MCNP(1)
H areaBlanket
SUS 316LNVacuum vessele
20 deg.
10 m
Collimatorradius:10 cm
Reflection of all particle
First wall
Estimation of scattered/energy-degraded neutrons originated DT neutrons
The fuel ratio in center of plasma
line of sight on center of plasma
3/1310th ITPA diagnostics meeting , Moscow 10-14/04/06 M. Sasao
Neutron Spectrum in a collimator - optimaization with MCNP(2)
In a neutronics calculation on the model of ITER, the possibility of separating the DD component from that of the DT reaction was examined. The separation in a neutron spectrum is possible at an appropriate measurement position with a collimator 1–10 cm in diameter.
4/1310th ITPA diagnostics meeting , Moscow 10-14/04/06 M. Sasao
Neutron Spectrum in a collimator - optimaization with MCNP(2)
0 1 2 3 4 5 6 7 8 9 10111213141516170.0
5.0x10-13
1.0x10-12
1.5x10-12
2.0x10-12
2.0 2.5 3.0 3.5 4.0 4.50.0
1.0x10-15
2.0x10-15
3.0x10-15
4.0x10-15
5.0x10-15
Energy [MeV]
total DD DT
(distance from center of plasma : 10 m, collimator radius : 10 cm)
Ti=25 keV
0.5 MeV
The energy resolution demanded is below 0.5 MeV grade.
Neu
tron
flu
x
[
/0.1
MeV
/cm
2/s
our
ce] 2.0
1.5
1.0
0.5
5/1310th ITPA diagnostics meeting , Moscow 10-14/04/06 M. Sasao
Time-of-flight (TOF) spectrometer designTime-of-flight (TOF) spectrometer design
a
0.000E+005.000E-041.000E-031.500E-032.000E-032.500E-033.000E-033.500E-034.000E-034.500E-035.000E-03
0 0.2 0.4 0.6 0.8 1
Energy resolution [MeV]
neutron flux [/source]
0.2cm0.5 cm1 cm2 cmd2
d1d
L
n
n’
The second detector
R
W
The optimization is on going using MCNP calculationfor both high detection efficiency for interesting events (2-3 MeV) and the energy resolution.
> 35 [deg.]70~ [cm]
5 ×10×~1 [cm]30×60×2 [cm]
scatter angle q distance Ld1 sized2 size
Optimal value
6/1310th ITPA diagnostics meeting , Moscow 10-14/04/06 M. Sasao
High-counting-rate TOF electronics(1)
• Number of interesting events is only ~1/1000 of total e
vents.
• Fast rejection of DT neutrons and gamma events in th
e D1 detector is essential.
• The TOF geometry defines the energy loss (pulse heig
ht) of DD neutrons in the D1 detector.
• We propose fast selection of interesting events by puls
e height discrimination.
7/1310th ITPA diagnostics meeting , Moscow 10-14/04/06 M. Sasao
DD 65 nsDL1
d1 PMT
HV
LinearFAN-in/out
LinearFAN-in/out
Discri
Discri
Discri
Coin
GDG TAC
Delay
ADC
MCA
Delay TAC
ADC MCA
d2
HV
PMTLinearFAN-in/out
Discri
-2300 V
-1300 V
DT
Anti
65 ns
Gate
start
stop
start
stop
DL2
DL3
Target room
Target room
d1~ DD stop
d1~ DT stop
start
DL5
Control room
High-counting-rate TOF electronics(2) Experiment circuitExperiment circuit
8/1310th ITPA diagnostics meeting , Moscow 10-14/04/06 M. Sasao0 200 400 600 800 10000.00
0.02
0.04
0.06
0.08
0.10
ch
POP experiment of High-counting-rate TOF electronics at FNS, JAEA
DTDD
-ray
Total TOF spectrum
Time (ch)
Using contaminated deuterium in the tritium target, the principle has been tested at FNS.D1 - 0.5 cm t NE102A (active divider had a trouble) , D2-NE201A, 60 cm apart, 0.35 deg.
cps
9/1310th ITPA diagnostics meeting , Moscow 10-14/04/06 M. Sasao
POP experiment of High-counting-rate TOF electronics(2)
0 200 400 600 800 10000.00
0.02
0.04
0.06
0.08
0.10
ch0 200 400 600 800 10000.00
0.02
0.04
0.06
0.08
0.10
ch
DTDD
-ray
Total TAC spectrum
DT spectrum
Separation by a circuit
0 20 40 60 80 100 1200.0
5.0x10-7
1.0x10-6
1.5x10-6
2.0x10-6
2.5x10-6
3.0x10-6
3.5x10-6
time [ns]
DT time spectrum
conversionDT spectrum is separated from total spectrum by fast Discri.
10/1310th ITPA diagnostics meeting , Moscow 10-14/04/06 M. Sasao
0 200 400 600 800 10000.0
1.0x10-3
2.0x10-3
3.0x10-3
4.0x10-3
5.0x10-3
6.0x10-3
7.0x10-3
ch
DD peak
DT peak
g-ray
12C(n,n’g)12C
16.7 ns44.3 ns
POP experiment of High-counting-rate TOF electronics- DD output of TAC DD output of TAC (3)
0 200 400 600 800 10000.00
0.02
0.04
0.06
0.08
0.10
ch
DTDD
-ray
Total TAC spectrum
DD separation is not perfect due to the active devider trouble, but the DT component is reduced more than factor 10, by fast Discri.
Separation by a circuit
11/1310th ITPA diagnostics meeting , Moscow 10-14/04/06 M. Sasao
POP experiment of High-counting-rate TOF electronics(3)
DD energy spectrumDD energy spectrum
0 1 2 3 4 5
1.0x10-6
2.0x10-6
3.0x10-6
4.0x10-6
5.0x10-6
6.0x10-6
Energy [MeV]
DD peak
DD spectrum is separated from total spectrum
12/1310th ITPA diagnostics meeting , Moscow 10-14/04/06 M. Sasao
Future work and Summary (1)
• In a neutronics calculation on the model of ITER, the possibility of
separating the DD component from that of the DT reaction was
examined. The separation in a neutron spectrum is possible at an
appropriate measurement position with a collimator 1–10 cm in
diameter and a spectrometer with energy resolution better than 0.5
MeV. • The optimization TOF spectrometer design is on going using MCNP ca
lculationfor both high detection efficiency for interesting events (2-3
MeV) and the energy resolution. High detection capability with 0.5 MeV
energy resolution can be realized with a single D2 detector. • We proposed a high counting rate TOF electronics using fast selectio
n of interesting events by fast pulse height discrimination (<10 ns).• FNS experiment showed the POP of the high counting rate TOF electro
nics.
13/1310th ITPA diagnostics meeting , Moscow 10-14/04/06 M. Sasao
Future work and Summary (2)
• After changing the PMT of D1, the experiment will be repeated.
• The experiment with a full size D2 detector is scheduled.
• In order to have larger dynamic range, multi-layer D1 detecors,
and multi D2 detectors are necessary.
• The measurement with present machines is desired.
top related