resolve™ filters for alpha source preparation charleston, sc may 4, 2004
TRANSCRIPT
Resolve™ Filtersfor alpha source preparation
Charleston, SC
May 4, 2004
Resolve™ Filters
0.1μ polypropylene
25mm disks
Uniform pore size distribution
Quality control appropriate for α-spectrometry
Product Development/Validation
• Evaluation of Resolve Filters – Comparison with commercially available filters
• Supplier #1
• Supplier #2
– Evaluate performance (alpha spec) and appearance (SEM)
• Validate lot-to-lot variability of supplier
• Assurance of filter quality
Reported Lot-to-lot VariabilityFilter Supplier #1, 1500x
Known “poor” performing lot Known “well” performing lot
SEM Comparison
Supplier #1: 1500 X Supplier #2: 1500 X
Eichrom Filter: 1500 X
Various Lots of Eichrom Filters
Eichrom lot A Eichrom lot B
Eichrom lot D Eichrom lot C
1500x
Compared to “Poor Performing” Lot
Eichrom lot A Eichrom lot B
Eichrom lot D Eichrom lot C
Known “poor” performing lot
1500x
Compared to “Well Performing” Lot
Eichrom lot A Eichrom lot B
Eichrom lot D Eichrom lot C
Known “well” performing lot
1500x
Filter Blank Comparison1000 minute direct count
Measured activity (pCi) in the U-232 region
Supplier #1 Supplier #2 Eichrom Filter
<0.0155 <0.0040 <0.0259
<0.0321 <0.0022 <0.033
<0.0031 <0.0019 <0.0017
Alpha Spectra – lot 292218
Am-243FWHM: 32 keV
Am-241FWHM: 31 keV
U-232FWHM: 23 keV
Alpha Spectra: Lot 264825
Am-243FWHM:28 keV
Am-241FWHM: 32 keV
U-232FWHM:29 keV
Quality Assurance Program
• Screening of filter material roll stock
• SEM– Visual evaluation
– Pore size uniformity: subjective determination
• Alpha Spectrometry– Am-241/243; 50µg Ce
– FWHM each peak <= 50 keV
A little background on filters
• Design and specification set on “removal” of particles from liquids.
• Nominal “pore size” related to the size of particles removed from the liquid.
• In alpha spec source prep the major consideration should be a uniform pore size to give the best source.
• “Shiny side” apparent on some types of filters indicating different performance each side.
“0.1 micron” pore size filter
1µSurface pores > 0.1µ
will occur
Designed to remove 99.98% of particles >0.1µ
Goal of Eichrom product is uniform pore size
15,000x
Resolve “0.1 micron” pore size filter
1µ
15,000x
Two sides of the filter“Inside” and “Outside” of the Roll Stock
(5,000x magnification)
Inside Lot 292218 Outside Lot 292218
Peak Resolution EvaluationFWHM (keV)
Am-243
Outside
Am-243
Inside
Am-241
Outside
Am-241
Inside
36 29 41 26
28 22 33 37
31 38 32 45
32 35 37 44
43 42 37 42
43 41
Ave =34 Ave =33 Ave = 36 Ave = 39
Std dev = 7 Std dev = 8 Std dev = 4 Std dev = 8
External Product Evaluation
• Barry Stewart, Carlsbad EMRC– “These filters are superb for use in making sources for alpha
spectroscopy.”
• Am 241/243
• With and without substrate
• ASTM C1163-98, LaF3 ppt., 50 µg La carrier
• “Glossy side” up and down
External Results
Sample Substrate Orientation FWHM keV
Am-243 recovery
Am-241 recovery
1 No Glossy down 28 98.4% 98.4%
2 No Glossy down 25 95.7% 95.5%
3 No Glossy up 22 101.9% 97.6%
4 No Glossy up 26 100.2% 99.3%
5 Yes Glossy down 25 100.5% 96.1%
6 Yes Glossy down 23 98.6% 97.0%
7 Yes Glossy up 25 95.1% 94.8%
8 Yes Glossy up 26 97.6% 95.0%
Summary
• Eichrom now supplies a 0.1µ polypropylene filter for alpha spec source prep
• Pore size uniformity is monitored by SEM analysis and performance is measured by FWHM of Am-243/241 (specification <= 50 keV.)
• Performance demonstrated at Eichrom and externally.
• Both sides of filter are equivalent: no need to “put the shiny side up.”