Aerosol nucleation induced by a high energy particle beam

We have studied sulfuric acid aerosol nucleation in an atmospheric pressure reaction chamber using a 580 MeV electron beam to ionize the volume of the reaction chamber. We find a clear contribution from ion-induced nucleation and consider this to be the first unambiguous observation of the ion-effect on aerosol nucleation using a particle beam under conditions that resemble the Earth's atmosphere. By comparison with ionization using a gamma source we further show that the nature of the ionizing particles is not important for the ion-induced component of the nucleation. This implies that inexpensive ionization sources - as opposed to expensive accelerator beams - can be used for investigations of ion-induced nucleation. Citation: Enghoff, M. B., J. O. P. Pedersen, U. I. Uggerhoj, S. M. Paling, and H. Svensmark (2011), Aerosol nucleation induced by a high energy particle beam, Geophys. Res. Lett., 38, L09805, doi:10.1029/2011GL047036.