Thesis: Experimental Work for the Direct Measurement of Interstellar Neutral Gas

My Master Thesis written at the Philosophisch-naturwissenschaftlichen Fakultät at the University of Bern.

Abstract

To study neutral gas in the heliosphere, e.g. interstellar neutral gas, a sensitive neutral particle imaging detector is needed. Surface ionization is a new technique for neutral particle imaging instruments with the potential for sufficient detection efficiency in the energy range of 10eV-1000eV inaccessible by other means. This method is currently employed by the LENA instrument on the IMAGE mission. In this work, mainly insulating surfaces for two different instruments were investigated: start- and stop surfaces for use in the NPD sensor of the ASPERA-3 instrument and ionization surfaces for use in the prototype of NICE. A brief overview of these two sensor types is given. The experimental setup used to investigate the surface properties is described. Data about the secondary electron yield upon reflection of a particle, angular scattering and the resulting reflection efficiencies, and the ionization efficiency of different surfaces is presented with an emphasis on a polished magnesium oxide surface. In the final chapter first laboratory results obtained from a next generation prototype of a neutral particle instrument are presented.

See online: http://www.iapetus.ch/doc/diploma