The role of low-energy electrons in the charging process of LISA test masses

Abstract

The estimate of the total electron yield is fundamental for our understanding of the test-mass charging associated with galactic cosmic rays in the 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 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 Monte Carlo simulations carried out with the GEANT4-DNA toolkit.

Monte Carlo simulations and machine learningmodels for cosmic-ray short-term variations andtest-mass charging on board LISA

“…and the Sakata cross section is adopted for electrons and positrons (Sakata et al, 2016;Grimani et al, 2022) in LEI. Our program also implements the electron kinetic emission (i.e., the emission of low-energy electron from a surface bombarded by keV electrons) using the yield reported in Taioli et al (2023). Finally, due to the very low-energy of the propagated electrons, quantum mechanics effects, such as quantum diffraction, cannot be neglected and have been therefore 1 Galactic cosmic-ray variations observed with LPF and with polar NMs.…”

High-Precision Inertial Sensor Charge Management Based on Ultraviolet Discharge: A Comprehensive Review

“…There are two mechanisms by which these charged particles promote TM charging [ 50 ]: one is that the charged particles accumulate directly on the TM (direct charging); the other is that the charged particles interact with the internal material of the spacecraft to produce secondary particles which then accumulate on the TM (indirect charging). Research indicates that indirect charging has a more pronounced effect on TM charging [ 51 ].…”

Electronic cross section, stopping power and energy-loss straggling of metals for swift protons, alpha particles and electrons

“…Θ(E − E j th,nl ) is a Heaviside step function with the threshold at the ionization energy E j th,nl of the nl-shell of the atom j. The ELF describing the excitation of the outer-shell electrons can be obtained either from optical experiments (k = 0) extended to finite momentum transfer by appropriate models (Garcia-Molina et al, 2012), or alternatively by means of time-dependent density functional theory (TDDFT) calculations (Nguyen-Truong, 2017;Pedrielli et al, 2021;Taioli et al, 2021;Taioli et al, 2023). While the latter approach allows a totally ab initio calculation of the excitation spectrum (which could be very convenient for targets that are difficult to study experimentally, such as nanostructured materials), the description of bulk matter has typically relied on the use of optical experimental data, which is usually rather reliable (Raether, 1965;Egerton, 2011).…”

“…Ref. (Taioli et al, 2023)], and that the current assignment may be subject to revision in future work. The fitting parameters are given in Supplementary Tables S2, S3 in the Supplementary Material.…”