Swift heavy ion irradiation of water ice from MeV to GeV energies: Approaching true cosmic ray compaction

• Published in: Astronomy and astrophysics (Berlin) 2013-09, Vol.557, p.np-np
• Main Authors: Dartois, E, Ding, J J, de Barros, A LF, Boduch, P, Brunetto, R, Chabot, M, Domaracka, A, Godard, M, Lv, X Y, Guaman, C F Mejia, Pino, T, Rothard, H, da Silveira, E F, Thomas, J C
• Format: Article
• Language: English
• Subjects: Astrophysics; Chemical bonds; Cosmic rays; Cross sections; Electronics; Galactic Astrophysics; Ion irradiation; Mantles; Physics; Sciences of the Universe; Stopping power; Thresholds
• ISSN: 0004-6361; 1432-0746; 1432-0756
• DOI: 10.1051/0004-6361/201321636

Cosmic ray ion irradiation affects the chemical composition of and triggers physical changes in interstellar ice mantles in space. Previously, ice compaction was monitored at low to moderate ion energies. The existence of a compaction threshold in stopping power has been suggested. In this article we experimentally study the effect of heavy ion irradiation at energies closer to true cosmic rays. This minimises extrapolation and allows a regime where electronic interaction always dominates to be explored, providing the ice compaction cross section over a wide range of electronic stopping power. The presence of a threshold in compaction at low stopping power suggested in some previous works seems not to be confirmed for the high-energy cosmic rays encountered in interstellar space. Ice mantle porosity or pending bonds monitored by the OH dangling bonds is removed efficiently by cosmic rays. As a consequence, this considerably reduces the specific surface area available for surface chemical reactions.