  A statistical analysis of interstellar He+ pickup ion measurements from
SOHO/CTOF combined with magnetic field data from WIND/MFI enable quantitative
study of wave-particle interactions in the inner heliosphere for the first
time. Magnetic field vector measurements with a time resolu-tion of 3 seconds
are used to determine power spectrum char-acteristics of interplanetary
magnetic turbulence. These spec-tral characteristics are then compared in
superposed epoch and correlation analyses with He+ fluxes and spectra. The
observed pickup ion velocity distributions can be explained consistently as a
consequence of pitch angle scattering of the interstellar pickup ions by
Alfvenic fluctuations.
