Resolve filters for alpha source preparation
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Resolve ™ Filters for 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

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Resolve ™ Filters for alpha source preparation

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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

Known “poor” performing lot

Known “well” performing lot

Reported Lot-to-lot VariabilityFilter Supplier #1, 1500x

Supplier #1: 1500 X

Supplier #2: 1500 X

Eichrom Filter: 1500 X

SEM Comparison

Eichrom lot A

Eichrom lot B

Eichrom lot D

Eichrom lot C

Various Lots of Eichrom Filters


Eichrom lot B

Known “poor” performing lot

Eichrom lot D

Eichrom lot C

Compared to “Poor Performing” Lot


Eichrom lot A

Eichrom lot A

Eichrom lot B

Known “well” performing lot

Eichrom lot D

Eichrom lot C

Compared to “Well Performing” Lot


Filter Blank Comparison1000 minute direct countMeasured activity (pCi) in the U-232 region


FWHM: 32 keV


FWHM: 31 keV


FWHM: 23 keV

Alpha Spectra – lot 292218


FWHM:28 keV


FWHM: 32 keV


FWHM:29 keV

Alpha Spectra: Lot 264825

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


Designed to remove 99.98% of particles >0.1µ

Surface pores > 0.1µ will occur

Goal of Eichrom product is uniform pore size

Resolve “0.1 micron” pore size filter


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)

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


  • 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.”

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