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Abstract  

Semiconductor particle detectors are ideal for alpha spectroscopy due to their compact size, low noise, and high resolution. This paper describes the construction and testing of an automatic sample changer for use with such a detector. The changer was constructed from locally available services and materials. It holds up to 24 samples of alpha emitting material deposited on 22 mm stainless steel counting planchets. The vacuum chamber can be evacuated to less than 10 μm mercury in 10 to 15 minutes. Once the chamber has been evacuated and detector bias has been applied, any sample in the chamber may be selected for analysis, either automatically or manually. Continuous automatic analysis of up to 24 samples is possible. Variation in efficiency from position to position was found to be 3.25% at the detector-sample spacing of 4.8 mm, and 2.31% at 27 mm. Shielding between the adjacent samples not under analysis and the detector was acceptable.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: N. Stradling, G. Etherington, A. Hodgson, M.R. Bailey, S. Hodgson, P. Pellow, A.L. Shutt, A. Birchall, E. Rance, D. Newton, and K. Fifield

Abstract  

Due to the paucity of human data after inhalation of different chemical forms of radionuclides, the implications for human exposure are often based on animal studies. This paper describes biokinetic studies of plutonium nitrate and gadolinium oxide in human volunteers and rats. The results, together with information from other studies with radionuclides, suggests that animal studies can be used with advantage for assessing the biokinetic behavior in humans, and for providing guidance on the assessment of intake and optimal monitoring regimens.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: N. Stradling, M. Bailey, A. Birchall, G. Etherington, A. Hodgson, P. Fritsch, J.-L. Poncy, D. Newton, W. Kreyling, E. Ansoborlo, and R. Guilmette

Abstract  

Due to the diversity of the chemical forms of radionuclides inhaled in industry and the environment, the assessment of intake and dose is based frequently on biokinetic studies of the materials in laboratory animals. The ICRP respiratory tract and systemic models provide an effective framework for extrapolating the results of such studies to humans, but there is a paucity of data concerning the crucial assumption that the absorption rates from lungs into blood for a given material are independent of the mammalian species. To address this uncertainty, biokinetic studies involving five chemical compounds and four mammalian species are being conducted. The compounds, with the species in parenthesis, are Pu-nitrate (man, primate, rat), Gd-oxide (man, primate, dog, rat), Np- oxide and nitrate (primate, rat), and U-octoxide (primate, dog, rat). This paper describes progress to date.

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