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.”