33118
The isotope Am ( half-life 141 years ) has the largest cross sections for absorption of thermal neutrons ( 5,700 barns ) , that results in a small critical mass for a sustained nuclear chain reaction .
 Am
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Am