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The estimate of the total electron yield is fundamental for our understanding of the test-mass charging associated with cosmic rays in the Laser Interferometer Space Antenna (LISA) Pathfinder mission and in the forthcoming gravitational wave observatory LISA. To unveil the role of low energy electrons in this process owing to galactic and solar energetic particle events, in this work we study the interaction of keV and sub-keV electrons with a gold slab using a mixed Monte Carlo (MC) and ab-initio framework. We determine the energy spectrum of the electrons emerging from such a gold slab hit by a primary electron beam by considering the relevant energy loss mechanisms as well as the elastic scattering events. We also show that our results are consistent with experimental data and MC simulations carried out with the GEANT4-DNA toolkit. [ABSTRACT FROM AUTHOR]

High-energy particles of galactic and solar origin will charge the test-masses on board laser interferometer space antenna (LISA) and other interferometers for gravitational-wave detection in space. The stochastic noise associated with this charging process is estimated to limit the sensitivity of space interferometers at low frequencies. In a previous paper we have reported a detailed study of low-energy electromagnetic processes affecting the LISA test-mass charging. In particular, we have discussed ionization and electron kinetic emission due to electrons and ions, while the role of plasmons in generating low-energy electrons has been deemed as negligible. Recently, the decay of plasmons has been observed to modify the energy distribution of electrons emitted by ions incident on foils of carbon and gold. Our work is consolidated here accordingly. The contribution of plasmon decay will be considered in future Monte Carlo simulations of LISA test-mass charging in the energy range of a few eV in addition to electron quantum diffraction and backscattering. [ABSTRACT FROM AUTHOR]

Galactic cosmic rays and solar energetic particles charge gold-platinum, free-falling test masses (TMs) on board interferometers for the detection of gravitational waves in space. The charging process induces spurious forces on the test masses that affect the sensitivity of these instruments mainly below 10−3 Hz. Geant4 and FLUKA Monte Carlo simulations were carried out to study the TM charging process on board the LISA Pathfinder mission that remained into orbit around the Sun–Earth Lagrange point L1 between 2016 and 2017. While a good agreement was observed between simulations and measurements of the TMs net charging, the shot noise associated with charging fluctuations of both positive and negative particles resulted 3–4 times higher that predicted. The origin of this mismatch was attributed to the propagation of electrons and photons only above 100 eV in the simulations. In this paper, low-energy electromagnetic processes to be included in the future Monte Carlo simulations for LISA and LISA-like space interferometers TM charging are considered. It is found that electrons and photons below 100 eV give a contribution to the effective charging comparable to that of the whole sample of particles above this energy. In particular, for incident protons ionization contributes twice with respect to low energy kinetic emission and electron backscattering. The other processes are found to play a negligible role. For heavy nuclei only sputtering must be considered. [ABSTRACT FROM AUTHOR]