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4. September 2013 PSI, 4. September 2013 PSI,
Paul Scherrer Institut
Comparison of the Tricarb and Hidex 300 SL technique using
measurements for 241Pu and 90Sr for diverse samples
Maya Jäggi
Comparison
Hidex 300 SL with guard-
function and Anti-Coincidence
LSC-Detector with BGO-Anti-
Coincidence
Outline
-90Sr activity determination using the Two-window method (Tricarb/Hidex)
-soil samples
-sediment samples
-241Pu activity determination using the / separation mode (Tricarb/Hidex)
-radioactive slurry samples
-IAEA-375 soil sample
-Summary
Two-window LSC technique for 90Sr
-Two windows are set for Hidex 300 SL using the tracers 85Sr and 90Sr (also for Tricarb)
-90Sr is in equilibrium with 90Y and must be separated by Sr-resin (Triskem) and measured
separately
-The figure below shows the three necessary radionuclides and the blank to determine the two
windows
0
100
200
300
400
500
600
700
800
900
1000
0
41
82
123
164
205
246
287
328
369
410
451
492
533
574
615
656
697
738
779
820
861
902
943
984
Counts
Channel
Beta-Backgr
Beta-S-90
Beta-Y-90
Beta-Sr-85
260 705 853
Three-window LSC technique for 90Sr
-The efficiencies per radionuclide and window are determined by dividing the counts per
second (total counts minus background) by the total activity [Bq]
efficiency Sr-85 Sr-90 Y-90
(normal count m.)
window A 0.605 0.103 0.016
window B+C 0.077 0.910 0.963
Hidex
0.995 0.913 0.077 window B+C
0.002 0.071 0.580 window A
(normal count m.)
Y-90 Sr-90 Sr-85 efficiency
Tricarb
E2/B
FOM
440 440/423 429/412 Tricarb: window A+B+C: sed/soil
505/496 540/534 Hidex: window A+B+C: sed/soil
Y-90 Sr-90 E2/B
4. September 2013 PSI,
90Sr in soil samples
4. September 2013 PSI, Seite 7
0.00
1.00
2.00
3.00
4.00
5.00
6.00
Act
ivit
yco
nce
ntr
atio
n [
Bq
/kg]
Soilsamples
Soilsamples: Tricarb - Hidex
Sr-90-Tricarb
Sr-90-Hidex
4. September 2013 PSI,
90Sr in soil samples
4. September 2013 PSI, Seite 8
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
Act
ivit
yco
nce
ntr
atio
n [
Bq
/kg]
Samples
Soilsamples: Tricarb-Hidex
Sr-90 Tricarb
Sr-90 Hidex
4. September 2013 PSI,
90Sr in sediment samples
4. September 2013 PSI, Seite 9
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
5.00
KL10-5-24 KL10-5-25 KL10-5-29 KL10-5-30 KL10-5-36 KL10-5-40 KL10-5-44 KL10-5-45 KL10-5-51 KL10-5-52
Act
ivit
yco
nce
ntr
atio
n [
Bq
/kg]
Sedimentsamples
Sedimentsamples: Hidex - TriCarb
Sr-90-TriCarb
Sr-90-Hidex
Tschernobyl
The 70ties
Bomb fallout 60ties
* * * * * * * * *
* The value is below the calculated detection limit
4. September 2013 PSI,
90Sr in sediment samples
4. September 2013 PSI, Seite 10
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
5.00
Act
ivit
yco
nce
ntr
atio
n [
Bq
/kg]
Sedimentsamples
Sedimentsamples: Hidex - TriCarb
Sr-90-TriCarb
Sr-90-Hidex
Tschernobyl
The 70ties
Bomb fallout 60ties
* * * * * * * * *
Thoughts about the difference in 90Sr activities:
-aging of the cocktail between two measurments (first Tricarb, then Hidex)
-not optimized window-settings (however the background must also be adjusted)
-Tricarb values seem to be ok, since another lab (ICPMS) found also 4 Bq/kg 90Sr for the fallout
samples
-The FOM is higher for the Hidex, thus the instrument should be more sensitive
4. September 2013 PSI,
Hidex/Tricarb-241Pu: /-Separation – pulse shape – discriminator
4. September 2013 PSI, Seite 11
20 40 60 80 100 120 140 1600
200
400
600
800
1000
1200
alpha-pulse
beta-pulse
rela
tive inte
nsity
pulse decay time [ns]100 110 120 130 140 1500
2
4
6
8
10
12
14
in in
sp
illove
r [%
]
discriminator setting [ns]
Scintillator: Ultima Gold A/B – optimises the difference in alpha-pulse/beta-pulse.
Scintillator: Ultima Gold F – optimises the peak resolution of the /-emitters.
Discriminator
4. September 2013 PSI,
Hidex: /-Separation – PLI – ygain
4. September 2013 PSI, Seite 13
PLI
(Pulse length index)
ygain
Background
HL-slurry sample
Alpha
Beta
3D
Plot
4. September 2013 PSI,
241Pu: Efficiency-Curve-Hidex, Quench-Curve-Tricarb, E2/B
4. September 2013 PSI, Seite 14
y = 1.0017x - 0.0395 R² = 0.9967
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0 0.1 0.2 0.3 0.4
Eff
icie
ncy
Pu
-241
TDCR
Efficiency
y = -7E-07x2 + 0.001x - 0.0139 R² = 0.9988
0.25
0.26
0.27
0.28
0.29
0.3
0.31
0.32
0.33
0.34
0.35
350 450 550 650
Eff
icie
ncy P
u-2
41
tSIE
Efficiency Pu-241
Samples
Parameter
Rad. Slurry
Hidex (n=10)
Rad. Slurry
Tricarb (n=10)
Soil-samples
Hidex (n=6)
Soil-samples
Tricarb (n=6)
Efficiency [%] 47 34 36 34
Background CPM 9.6 3.2 9.7 3.6
E2/B - FOM 239 ± 36 362 ± 1 134 ± 8 312 ± 1
4. September 2013 PSI,
241Pu in radioactive slurry samples 1
4. September 2013 PSI, Seite 15
0
200
400
600
800
1000
1200
1400
1600
1800
2000
HL-1 HL-2 HL-3 HL-4 HL-5 HL-6 HL-7 HL-8 HL-9 HL-10
Pu
-24
1 A
ctiv
ityc
on
cen
trat
ion
[B
q/k
g]
Radioactive slurry samples
Pu-241: TriCarb - Hidex
Tricarb 1
Tricarb 2
Hidex 300 SL
4. September 2013 PSI, 4. September 2013 PSI, Seite 16
0
20
40
60
80
100
120
140
160
180
200
HL-1 HL-2 HL-3 HL-4 HL-5 HL-6 HL-7 HL-8 HL-9 HL-10
Pu
-24
1 A
ctiv
ityc
on
cen
trat
ion
[B
q/k
g]
Radioactive slurry samples
Pu-241: TriCarb - Hidex
Tricarb 1
Tricarb 2
Hidex 300 SL
241Pu in radioactive slurry samples 2
4. September 2013 PSI,
241Pu for the IAEA-375 soil sample
4. September 2013 PSI, Seite 17
0.00
2.00
4.00
6.00
8.00
10.00
12.00
14.00
16.00
1 2 3 4 5 6
Pu
-24
1 A
ctiv
ityc
on
cen
trat
ion
[B
q/k
g]
IAEA-375 samples
IAEA-375: TriCarb - Hidex
IAEA-375-Tricarb
IAEA-375-Hidex
-The activityconcentrations were backcalculated to 1991 (sampling of the IAEA-standard)
4. September 2013 PSI, 4. September 2013 PSI, Seite 18
Summary
- 90Sr shows good agreement, even at low level measurments (sample weight 30 g; low
detection limit).
- The lower the sample weights of the sediments (6 – 8 g) the higher the fluctuations between
the single 90Sr measurements and the higher the detection limits.
- The Hidex 300 SL is not an absolute low level instrument, however, what really accounts for
the discrepancies of 90Sr activities in the sediments, could not be found.
- For the measured 241Pu samples we find very good agreement for both instruments. All
samples have been corrected for Quench and thus the efficiency has been adjusted.
- The FOM for 90Sr is 22%, and for 90Y 14% higher for the Hidex compared to theTricarb.
- The FOM of 241Pu is 34% (radioactive slurry) and 57% (soil samples) lower for the Hidex,
compared to the Tricarb. Eventhough the Hidex shows higher efficiencies in both cases, the
high beta-background (three times higher than the Tricarb) causes this difference.
Question
-Can we use the Hidex 300 SL for routine measurements, concerning 241Pu and 90Sr
Answer: Yes!
But…low weight, low level measurements might be
excluded
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