Scattering cross section set for electrons in CH3OCH3

Summary form only given. Scattering cross section set for electrons in CH₃OCH₃ (dimethyl ether, DME) is developed by using the standard swarm procedure. Our work was motivated by the interest for this molecule as it is one of the largest organic molecule in the interstellar space, with the wide industrial use and application in particle detectors, especially in micro-strip gas chambers [1]. Therefore, there was a need for accurate and reliable collision and transport data that can be used in plasma models.The first objective of our analysis was to examine how well the available and the most commonly used cross sections [2] reproduced experimental transport data [3]. In order to achieve that goal we started from that set and we calculated electron drift velocity (W) and the density normalized ionization coefficient (α/N) over a wide range of reduced electric fields (E/N), for pure gas and its mixtures with Ar and Ne. Calculations were made by two term approximation of the Boltzmann equation, and also by using our Monte Carlo simulation code. Comparison of calculated and experimental data showed that some modifications in the starting cross section set need to be made to fit the available experimental data [4-6]. In particular the elastic momentum transfer and electronic excitation energy dependences (with the threshold energy of εth=7.7 eV) were modified both in their magnitude and shape as well as the vibrational excitation (εth=0.349 eV). The process of cross section modifications was performed in iterations, for pure gas and mixtures simultaneously until a consistent set was developed. The alterations in calculated W appear to be small and only for the low electron energies. At the same time, the α/N is now much more accurate in comparison to the experimental data, over the entire investigated electron energy range. That fact justifies our revision of the cross section set, especially having in mind the signif- cance of the ionization coefficient from the application point of view.