  The Earth is constantly hit by energetic particles originating from galactic
sources. The flux of these particles is altered by the magnetized solar wind in
the heliosphere and the Earth's magnetic field. For this reason, the ability of
a particle to approach a spacecraft in LEO depends on its energy and the
position of the spacecraft within the Earth' magnetosphere. Moreover, there are
some areas (radiation belts) where the particles are trapped for a long time,
and therefore the flux of energetic particles is particularly high.
Occasionally, SEP contribute to the energetic particle flux too. DOSTEL is one
of the instruments aboard the \ac{ISS} that monitors the radiation field within
the European module Columbus. Because being installed inside the \ac{ISS},
particles produced by the interaction between the "primary" radiation and the
ISS materials are also measured. To describe the observations in such a complex
radiation field, we follow the method by Caballero-Lopez and Moraal (2012) in
order to compute the so-called yield function using precise measurements of the
proton and Helium energy spectra obtained by AMS and the systematic variation
of the DOSTEL measurements within the Earth's magnetosphere
