Fusion Crust and the Measurement of Surface Ages of Antarctic Ordinary Chondrites
Natural thermoluminescence (TL) reflects radiation exposure and storage temperature. Meteorites generally exhibit thermoluminescence acquired during their long exposure to galactic cosmic rays in space. During atmospheric passage, temperatures are high enough to completely drain the TL, in the first...
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ftnasantrs:oai:casi.ntrs.nasa.gov:19980107901 2023-05-15T13:47:44+02:00 Fusion Crust and the Measurement of Surface Ages of Antarctic Ordinary Chondrites Akridge, Jannette M. C. Benoit, Paul H. Sears, Derek W. G. Unclassified, Unlimited, Publicly available 1997 application/pdf http://hdl.handle.net/2060/19980107901 unknown Document ID: 19980107901 http://hdl.handle.net/2060/19980107901 No Copyright CASI Astrophysics NASA/CR-97-207735 NAS 1.26:207735 1997 ftnasantrs 2019-08-31T23:06:09Z Natural thermoluminescence (TL) reflects radiation exposure and storage temperature. Meteorites generally exhibit thermoluminescence acquired during their long exposure to galactic cosmic rays in space. During atmospheric passage, temperatures are high enough to completely drain the TL, in the first mm of material under the fusion crust. We therefore refer to this surface layer as "fusion crust" although it does include some unmelted material just below the crust. When the meteorite lands on earth this drained layer will begin to build up natural TL once again due to radiation from cosmic rays and internal radionuclides. Cosmic ray annual dose is estimated to be between 0.04 and 0.06 rad/yr on the earth's surface in Antarctica while the internal radionuclides contribute only about 0.01 rad/yr. Therefore the total annual dose received by the meteorite while it is on the surface is between 0.05 and 0.07 rad/yr. If the meteorite is buried deeply in the ice it is effectively shielded from most cosmic rays and thus only internal radioactivity contributes to the annual dose. Other/Unknown Material Antarc* Antarctic Antarctica NASA Technical Reports Server (NTRS) Antarctic |
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Open Polar |
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NASA Technical Reports Server (NTRS) |
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ftnasantrs |
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unknown |
topic |
Astrophysics |
spellingShingle |
Astrophysics Akridge, Jannette M. C. Benoit, Paul H. Sears, Derek W. G. Fusion Crust and the Measurement of Surface Ages of Antarctic Ordinary Chondrites |
topic_facet |
Astrophysics |
description |
Natural thermoluminescence (TL) reflects radiation exposure and storage temperature. Meteorites generally exhibit thermoluminescence acquired during their long exposure to galactic cosmic rays in space. During atmospheric passage, temperatures are high enough to completely drain the TL, in the first mm of material under the fusion crust. We therefore refer to this surface layer as "fusion crust" although it does include some unmelted material just below the crust. When the meteorite lands on earth this drained layer will begin to build up natural TL once again due to radiation from cosmic rays and internal radionuclides. Cosmic ray annual dose is estimated to be between 0.04 and 0.06 rad/yr on the earth's surface in Antarctica while the internal radionuclides contribute only about 0.01 rad/yr. Therefore the total annual dose received by the meteorite while it is on the surface is between 0.05 and 0.07 rad/yr. If the meteorite is buried deeply in the ice it is effectively shielded from most cosmic rays and thus only internal radioactivity contributes to the annual dose. |
format |
Other/Unknown Material |
author |
Akridge, Jannette M. C. Benoit, Paul H. Sears, Derek W. G. |
author_facet |
Akridge, Jannette M. C. Benoit, Paul H. Sears, Derek W. G. |
author_sort |
Akridge, Jannette M. C. |
title |
Fusion Crust and the Measurement of Surface Ages of Antarctic Ordinary Chondrites |
title_short |
Fusion Crust and the Measurement of Surface Ages of Antarctic Ordinary Chondrites |
title_full |
Fusion Crust and the Measurement of Surface Ages of Antarctic Ordinary Chondrites |
title_fullStr |
Fusion Crust and the Measurement of Surface Ages of Antarctic Ordinary Chondrites |
title_full_unstemmed |
Fusion Crust and the Measurement of Surface Ages of Antarctic Ordinary Chondrites |
title_sort |
fusion crust and the measurement of surface ages of antarctic ordinary chondrites |
publishDate |
1997 |
url |
http://hdl.handle.net/2060/19980107901 |
op_coverage |
Unclassified, Unlimited, Publicly available |
geographic |
Antarctic |
geographic_facet |
Antarctic |
genre |
Antarc* Antarctic Antarctica |
genre_facet |
Antarc* Antarctic Antarctica |
op_source |
CASI |
op_relation |
Document ID: 19980107901 http://hdl.handle.net/2060/19980107901 |
op_rights |
No Copyright |
_version_ |
1766247783769047040 |