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Title: Determination of rain age via {gamma} rays from accreted radon progeny

Abstract

The relative {gamma} ray activities from {sup 214}Pb and {sup 214}Bi condensed from precipitation are used to determine its 'age', the average time the accreted activity has been removed from secular equilibrium. A verifiable assumption that radon progeny on/in the surface/volume of droplets mostly remains in secular equilibrium until they begin their descent, enables estimates of their transit times to ground of typically a few tens of minutes. This agrees well with the time expected for the activity on the surface of droplets to reach the ground from heights of a few kilometers. The half lives of {gamma} activities from {sup 214}Bi and {sup 214}Pb, 19.7 and 26.9 min, respectively, are on the same scale as transit time to ground and close enough to each other to measure ratios of activities from secular equilibrium (1.00) to transient equilibrium (3.88) within a few hundreds of minutes. The ratio of {gamma} count rates is independent of knowledge of either initial activity or any systematic errors and thus limited only by the uncertainty from counting statistics, which from condensates of 5-30 l of rain viewed with 2{pi} solid angle by a 50% efficient, high-resolution Ge detector is only a few percent. These ratiosmore » fit extremely well to known theoretical curves, which cannot only be used to date rain but can also be extrapolated backward to determine radon progeny activities in rain prior to its descent, knowledge of which may facilitate further studies using radon progeny as tracers.« less

Authors:
; ; ; ;  [1];  [2]
  1. International Christian University, Mitaka, Tokyo 1818585 (Japan)
  2. Low Level Radioactivity Laboratory, Kanazawa University, Ishikawa 923122 (Japan)
Publication Date:
OSTI Identifier:
21182681
Resource Type:
Journal Article
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 104; Journal Issue: 7; Other Information: DOI: 10.1063/1.2990773; (c) 2008 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-8979
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; AIR POLLUTION; ATMOSPHERIC CHEMISTRY; BISMUTH 214; COUNTING RATES; DROPLETS; ENERGY-LEVEL TRANSITIONS; GAMMA RADIATION; GE SEMICONDUCTOR DETECTORS; HALF-LIFE; LEAD 214; RADON; RAIN

Citation Formats

Greenfield, M B, Ito, N, Iwata, A, Kubo, K, Ishigaki, M, and Komura, K. Determination of rain age via {gamma} rays from accreted radon progeny. United States: N. p., 2008. Web. doi:10.1063/1.2990773.
Greenfield, M B, Ito, N, Iwata, A, Kubo, K, Ishigaki, M, & Komura, K. Determination of rain age via {gamma} rays from accreted radon progeny. United States. https://doi.org/10.1063/1.2990773
Greenfield, M B, Ito, N, Iwata, A, Kubo, K, Ishigaki, M, and Komura, K. 2008. "Determination of rain age via {gamma} rays from accreted radon progeny". United States. https://doi.org/10.1063/1.2990773.
@article{osti_21182681,
title = {Determination of rain age via {gamma} rays from accreted radon progeny},
author = {Greenfield, M B and Ito, N and Iwata, A and Kubo, K and Ishigaki, M and Komura, K},
abstractNote = {The relative {gamma} ray activities from {sup 214}Pb and {sup 214}Bi condensed from precipitation are used to determine its 'age', the average time the accreted activity has been removed from secular equilibrium. A verifiable assumption that radon progeny on/in the surface/volume of droplets mostly remains in secular equilibrium until they begin their descent, enables estimates of their transit times to ground of typically a few tens of minutes. This agrees well with the time expected for the activity on the surface of droplets to reach the ground from heights of a few kilometers. The half lives of {gamma} activities from {sup 214}Bi and {sup 214}Pb, 19.7 and 26.9 min, respectively, are on the same scale as transit time to ground and close enough to each other to measure ratios of activities from secular equilibrium (1.00) to transient equilibrium (3.88) within a few hundreds of minutes. The ratio of {gamma} count rates is independent of knowledge of either initial activity or any systematic errors and thus limited only by the uncertainty from counting statistics, which from condensates of 5-30 l of rain viewed with 2{pi} solid angle by a 50% efficient, high-resolution Ge detector is only a few percent. These ratios fit extremely well to known theoretical curves, which cannot only be used to date rain but can also be extrapolated backward to determine radon progeny activities in rain prior to its descent, knowledge of which may facilitate further studies using radon progeny as tracers.},
doi = {10.1063/1.2990773},
url = {https://www.osti.gov/biblio/21182681}, journal = {Journal of Applied Physics},
issn = {0021-8979},
number = 7,
volume = 104,
place = {United States},
year = {Wed Oct 01 00:00:00 EDT 2008},
month = {Wed Oct 01 00:00:00 EDT 2008}
}