Neutron Capture and the Production of 60-Fe in Stellar Environments (open access)

Neutron Capture and the Production of 60-Fe in Stellar Environments

The observation of gamma rays associated with the decay of {sup 26}Al and {sup 60}Fe can provide important information regarding ongoing nucleosynthesis in our galaxy. The half-lives of these radioisotopes (7.2 x 10{sup 5} y and 1.5 x 10{sup 6} y, respectively) are long compared to the interval between synthesis events such as supernovae, so they build up in a steady state in the interstellar medium (centered on the galactic plane, where massive stars reside), yet short enough that gamma radiation from their decay may be detected. Additionally, these half-lifes are short compared to the period of galactic revolution, so that observable abundances remain in the proximity of their production sites. Predicted abundances of {sup 26}Al and {sup 60}Fe vary widely between several calculations in the last decade. In 2004, the first observation of the gamma ray flux from {sup 60}Fe decay was reported, with a {sup 60}Fe/{sup 26}Al flux ratio in good agreement with nucleosynthesis modeling from 1995. However, recent calculations that include well motivated updates to the stellar and nuclear physics, predict a flux ratio as much as six times higher than the observed value. It is desirable to understand the discrepancy between the latest calculation, which in …
Date: August 23, 2005
Creator: Kelley, K
Object Type: Thesis or Dissertation
System: The UNT Digital Library
JPAT - Economic Impact - Base ROI Assignment Data (open access)

JPAT - Economic Impact - Base ROI Assignment Data

JPAT - Economic Impact - Base ROI Assignment Data
Date: June 23, 2005
Creator: United States. Department of Defense.
Object Type: Text
System: The UNT Digital Library
Texas Register, Volume 30, Number 38, Pages 5991-6134, September 23, 2005 (open access)

Texas Register, Volume 30, Number 38, Pages 5991-6134, September 23, 2005

A weekly publication, the Texas Register serves as the journal of state agency rulemaking for Texas. Information published in the Texas Register includes proposed, adopted, withdrawn and emergency rule actions, notices of state agency review of agency rules, governor's appointments, attorney general opinions, and miscellaneous documents such as requests for proposals. After adoption, these rulemaking actions are codified into the Texas Administrative Code.
Date: September 23, 2005
Creator: Texas. Secretary of State.
Object Type: Journal/Magazine/Newsletter
System: The Portal to Texas History