SEARCH FOR ALUMINUM-26 IN DUST FROM THE GREENLAND ICE SHEET
Large volumes of approximately 250-year-old Greenland glacier ice were filtered. Approximately 20,000 liters passed through 0.45 micron retention paper with a 2.5 ft surface area, and approximately 200,000 1. passed through 3 micron retention paper. Less than 4 x 10/> dpm/1. of aluminum-26 was fo...
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ftdtic:AD0613750 2023-05-15T16:21:13+02:00 SEARCH FOR ALUMINUM-26 IN DUST FROM THE GREENLAND ICE SHEET Fireman,Edward L. Langway,Chester C. ,Jr. SMITHSONIAN ASTROPHYSICAL OBSERVATORY CAMBRIDGE MASS 1964-07-29 text/html http://www.dtic.mil/docs/citations/AD0613750 http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=AD0613750 en eng http://www.dtic.mil/docs/citations/AD0613750 APPROVED FOR PUBLIC RELEASE DTIC AND NTIS (*GEOCHEMISTRY GREENLAND) (*ALUMINUM GEOCHEMISTRY) (*GREENLAND METEORITES ISOTOPES EXTRATERRESTRIAL TOPOGRAPHY DUST ICE COLLECTING METHODS GEOLOGIC AGE DETERMINATION RADIATION MEASURING INSTRUMENTS ASTROPHYSICS GEOPHYSICS SILICATES THALLIUM THORIUM Text 1964 ftdtic 2016-02-18T18:13:25Z Large volumes of approximately 250-year-old Greenland glacier ice were filtered. Approximately 20,000 liters passed through 0.45 micron retention paper with a 2.5 ft surface area, and approximately 200,000 1. passed through 3 micron retention paper. Less than 4 x 10/> dpm/1. of aluminum-26 was found in the 3 micron collections, and less than 3 x 10/6 dpm/1. in the 0.45 micron collection. These limits are significant for determinations of the exposure age, the chemical composition, and the accretion rate of extraterrestrial dust. For an accretion rate for the Earth of a million tons per year of silicates, the limit of 4 x 10/> dpm/1. corresponds to an exposure age of 4000 years. Although the filter collections do not contain aluminum-26, they do contain radioactivities. The principal one is thallium208, a thorium decay product attributed to terrestrial material in the collection. There is also a small positron activity, which disappeared with the purification of aluminum. (Author) Pub. in Geochimica et Cosmochimica Acta (Netherlands) v29 p21-7 1965 (Copies available only to DDC users). Text glacier Greenland Ice Sheet Defense Technical Information Center: DTIC Technical Reports database Greenland |
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Defense Technical Information Center: DTIC Technical Reports database |
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English |
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(*GEOCHEMISTRY GREENLAND) (*ALUMINUM GEOCHEMISTRY) (*GREENLAND METEORITES ISOTOPES EXTRATERRESTRIAL TOPOGRAPHY DUST ICE COLLECTING METHODS GEOLOGIC AGE DETERMINATION RADIATION MEASURING INSTRUMENTS ASTROPHYSICS GEOPHYSICS SILICATES THALLIUM THORIUM |
spellingShingle |
(*GEOCHEMISTRY GREENLAND) (*ALUMINUM GEOCHEMISTRY) (*GREENLAND METEORITES ISOTOPES EXTRATERRESTRIAL TOPOGRAPHY DUST ICE COLLECTING METHODS GEOLOGIC AGE DETERMINATION RADIATION MEASURING INSTRUMENTS ASTROPHYSICS GEOPHYSICS SILICATES THALLIUM THORIUM Fireman,Edward L. Langway,Chester C. ,Jr. SEARCH FOR ALUMINUM-26 IN DUST FROM THE GREENLAND ICE SHEET |
topic_facet |
(*GEOCHEMISTRY GREENLAND) (*ALUMINUM GEOCHEMISTRY) (*GREENLAND METEORITES ISOTOPES EXTRATERRESTRIAL TOPOGRAPHY DUST ICE COLLECTING METHODS GEOLOGIC AGE DETERMINATION RADIATION MEASURING INSTRUMENTS ASTROPHYSICS GEOPHYSICS SILICATES THALLIUM THORIUM |
description |
Large volumes of approximately 250-year-old Greenland glacier ice were filtered. Approximately 20,000 liters passed through 0.45 micron retention paper with a 2.5 ft surface area, and approximately 200,000 1. passed through 3 micron retention paper. Less than 4 x 10/> dpm/1. of aluminum-26 was found in the 3 micron collections, and less than 3 x 10/6 dpm/1. in the 0.45 micron collection. These limits are significant for determinations of the exposure age, the chemical composition, and the accretion rate of extraterrestrial dust. For an accretion rate for the Earth of a million tons per year of silicates, the limit of 4 x 10/> dpm/1. corresponds to an exposure age of 4000 years. Although the filter collections do not contain aluminum-26, they do contain radioactivities. The principal one is thallium208, a thorium decay product attributed to terrestrial material in the collection. There is also a small positron activity, which disappeared with the purification of aluminum. (Author) Pub. in Geochimica et Cosmochimica Acta (Netherlands) v29 p21-7 1965 (Copies available only to DDC users). |
author2 |
SMITHSONIAN ASTROPHYSICAL OBSERVATORY CAMBRIDGE MASS |
format |
Text |
author |
Fireman,Edward L. Langway,Chester C. ,Jr. |
author_facet |
Fireman,Edward L. Langway,Chester C. ,Jr. |
author_sort |
Fireman,Edward L. |
title |
SEARCH FOR ALUMINUM-26 IN DUST FROM THE GREENLAND ICE SHEET |
title_short |
SEARCH FOR ALUMINUM-26 IN DUST FROM THE GREENLAND ICE SHEET |
title_full |
SEARCH FOR ALUMINUM-26 IN DUST FROM THE GREENLAND ICE SHEET |
title_fullStr |
SEARCH FOR ALUMINUM-26 IN DUST FROM THE GREENLAND ICE SHEET |
title_full_unstemmed |
SEARCH FOR ALUMINUM-26 IN DUST FROM THE GREENLAND ICE SHEET |
title_sort |
search for aluminum-26 in dust from the greenland ice sheet |
publishDate |
1964 |
url |
http://www.dtic.mil/docs/citations/AD0613750 http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=AD0613750 |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
glacier Greenland Ice Sheet |
genre_facet |
glacier Greenland Ice Sheet |
op_source |
DTIC AND NTIS |
op_relation |
http://www.dtic.mil/docs/citations/AD0613750 |
op_rights |
APPROVED FOR PUBLIC RELEASE |
_version_ |
1766009233286889472 |