If you read the article @JonCuster linked, Multiyear Measurements of Radiation Belt Electrons: Acceleration, Transport, and Loss by Baker, et al., and scroll down to the end, you will find this:
Van Allen Probes REPT data used in this paper are available from the
ECT Science Operations and Data Center (http://www.rbsp-ect.lanl.gov).
Van Allen Probes Solar wind data and geomagnetic indices are provided
by OMNIWeb (http://omniweb.gsfc.nasa.gov/).
This first of those leads through https://www.rbsp-ect.lanl.gov/science/DataDirectories.php to a long list of files in CDF format. Search results that say CDF means "content definition file" or "computable document format" are not relevant here, since these are Common Data Format, as often with NASA data. Download some of those files, learn to use a CDF-aware tool (what are you doing your data science in? it should know.) to read first their explanatory headers and then the contents, and you should be good to go.