AUTHOR=da Silva D. E. , Elkington S. R. , Li X. , Hudson M. K. , Boyd A. J. , Jaynes A. N. , Wiltberger M. TITLE=Radiation belt phase space density: calculation analysis and model dependence JOURNAL=Frontiers in Astronomy and Space Sciences VOLUME=11 YEAR=2024 URL=https://www.frontiersin.org/journals/astronomy-and-space-sciences/articles/10.3389/fspas.2024.1423545 DOI=10.3389/fspas.2024.1423545 ISSN=2296-987X