skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: ORIGIN OF EXCESS {sup 176}Hf IN METEORITES

Abstract

After considerable controversy regarding the {sup 176}Lu decay constant ({lambda}{sup 176}Lu), there is now widespread agreement that (1.867 {+-} 0.008) x 10{sup -11} yr{sup -1} as confirmed by various terrestrial objects and a 4557 Myr meteorite is correct. This leaves the {sup 176}Hf excesses that are correlated with Lu/Hf elemental ratios in meteorites older than {approx}4.56 Ga meteorites unresolved. We attribute {sup 176}Hf excess in older meteorites to an accelerated decay of {sup 176}Lu caused by excitation of the long-lived {sup 176}Lu ground state to a short-lived {sup 176m}Lu isomer. The energy needed to cause this transition is ascribed to a post-crystallization spray of cosmic rays accelerated by nearby supernova(e) that occurred after 4564.5 Ma. The majority of these cosmic rays are estimated to penetrate accreted material down to 10-20 m, whereas a small fraction penetrate as deep as 100-200 m, predicting decreased excesses of {sup 176}Hf with depth of burial at the time of the irradiation event.

Authors:
; ;  [1]; ;  [2]
  1. Geological Museum, University of Copenhagen, Oester Voldgade 5-7, DK-1350 (Denmark)
  2. Department of Physics and Astronomy, Clemson University, Clemson, SC 29634-0978 (United States)
Publication Date:
OSTI Identifier:
21457123
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 717; Journal Issue: 2; Other Information: DOI: 10.1088/0004-637X/717/2/861; Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COSMIC RADIATION; CRYSTALLIZATION; HAFNIUM 176; LUTETIUM 176; METEORITES; NUCLEAR DECAY; BETA DECAY RADIOISOTOPES; BETA-MINUS DECAY RADIOISOTOPES; DECAY; EVEN-EVEN NUCLEI; HAFNIUM ISOTOPES; HOURS LIVING RADIOISOTOPES; INTERMEDIATE MASS NUCLEI; INTERNAL CONVERSION RADIOISOTOPES; IONIZING RADIATIONS; ISOTOPES; LUTETIUM ISOTOPES; NUCLEI; ODD-ODD NUCLEI; PHASE TRANSFORMATIONS; RADIATIONS; RADIOISOTOPES; RARE EARTH NUCLEI; STABLE ISOTOPES; YEARS LIVING RADIOISOTOPES

Citation Formats

Thrane, Kristine, Connelly, James N, Bizzarro, Martin, Meyer, Bradley S, and The, Lih-Sin. ORIGIN OF EXCESS {sup 176}Hf IN METEORITES. United States: N. p., 2010. Web. doi:10.1088/0004-637X/717/2/861.
Thrane, Kristine, Connelly, James N, Bizzarro, Martin, Meyer, Bradley S, & The, Lih-Sin. ORIGIN OF EXCESS {sup 176}Hf IN METEORITES. United States. doi:10.1088/0004-637X/717/2/861.
Thrane, Kristine, Connelly, James N, Bizzarro, Martin, Meyer, Bradley S, and The, Lih-Sin. Sat . "ORIGIN OF EXCESS {sup 176}Hf IN METEORITES". United States. doi:10.1088/0004-637X/717/2/861.
@article{osti_21457123,
title = {ORIGIN OF EXCESS {sup 176}Hf IN METEORITES},
author = {Thrane, Kristine and Connelly, James N and Bizzarro, Martin and Meyer, Bradley S and The, Lih-Sin},
abstractNote = {After considerable controversy regarding the {sup 176}Lu decay constant ({lambda}{sup 176}Lu), there is now widespread agreement that (1.867 {+-} 0.008) x 10{sup -11} yr{sup -1} as confirmed by various terrestrial objects and a 4557 Myr meteorite is correct. This leaves the {sup 176}Hf excesses that are correlated with Lu/Hf elemental ratios in meteorites older than {approx}4.56 Ga meteorites unresolved. We attribute {sup 176}Hf excess in older meteorites to an accelerated decay of {sup 176}Lu caused by excitation of the long-lived {sup 176}Lu ground state to a short-lived {sup 176m}Lu isomer. The energy needed to cause this transition is ascribed to a post-crystallization spray of cosmic rays accelerated by nearby supernova(e) that occurred after 4564.5 Ma. The majority of these cosmic rays are estimated to penetrate accreted material down to 10-20 m, whereas a small fraction penetrate as deep as 100-200 m, predicting decreased excesses of {sup 176}Hf with depth of burial at the time of the irradiation event.},
doi = {10.1088/0004-637X/717/2/861},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 717,
place = {United States},
year = {2010},
month = {7}
}