THE EFFECT OF PARTICLE SIZE AND DUST LOADING ON THE SHAPE OF ALPHA PULSE- HEIGHT SPECTRA OF AIR SAMPLE FILTERS
The effects of particle size andd total dust loading on the shape of alpha pulse height spectra obtained by direct measurement of dust collected on membrane filters (Millipore), glass fibre filters (Whatmand AGF/A), and cellulose fibre filters (Fourstones Sample A) were studied using uranyl acetate and uranium oxide aerosols. Large active particles of diameter comparable with the range of the alpha emission in the particles ( approximates 5 mu for uranium oxide) are the most serious cause of alpha energy degradation and result in almost complete loss of resolution. The alpha pulse-height spectra from small dust particles ( approximates 1 mu ) collected on membrande filters are comparable with that obtained from a standard thin' source. When glsss fibre filters are used, some broadening of the peaks of the spectra occurs due to the penetration of the particles into the surface fibres but this is not excessive and it is generally possible to identify the commonly occurring nuclides. A large proportion (50 to 80%) of the alpha emission from fine dust particles is completely absorbed in the fibres of the cellulose filters but the quality of the pulse height spectra obtained is similar to that obtained with glass fibre filters. Resolution is not seriously reduced by the presence of inactive dust on membrane or glass fibre filters until the dust loading is about 0.4 mg/cm/sup 2/. (auth)
- Research Organization:
- United Kingdom Atomic Energy Authority. Research Group. Atomic Energy Research Establishment, Harwell, Berks, England
- NSA Number:
- NSA-18-001940
- OSTI ID:
- 4144537
- Report Number(s):
- AERE-R-4249
- Country of Publication:
- United Kingdom
- Language:
- English
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