This PhD work was carried out within the framework of the n2EDM experiment at the Paul Scherrer Institute (PSI) in Switzerland. The goal of the experiment is to measure the neutron electric dipole moment (nEDM) with an unprecedented sensitivity of 1×10−27 e⋅cm.

The work conducted over these three years focuses on the development, characterization, and optimization of the simultaneous spin analyzers (USSAs), as well as on the improvement of the GADGET neutron detectors, which are essential for counting ultracold neutrons (UCN) and for background discrimination.

In the first phase, COMSOL simulations were performed to optimize the magnetic field in the spin flipper (SF) region in order to ensure a high adiabaticity factor. These simulations made it possible to predict the resonance frequencies of the SFs within the prototype. Once the prototype was tested and validated, two units were built at LPC. Further simulations in the final n2EDM experimental environment were carried out to fine-tune the positioning of the USSAs and to predict the operational point of the spin flippers.
Currently, both polarization analyzers and detectors are operational. However, the experimental characterization of the USSAs revealed performance differences between the two systems (top and bottom) and a variation of the measured asymmetry over the year 2024. The best performance was achieved with a maximum asymmetry of 96.6%.
An empirical model based on eight parameters (SF efficiency, reflection rate, spin-flip probability, etc.) was developed to explain these results. Solved using a Monte Carlo Markov Chain (MCMC) approach, this model showed that the spin flipper efficiency of the upper USSA can still be improved.

This work contributes to the understanding of USSA performance within the n2EDM experiment and provides perspectives for their future optimization, which is crucial for achieving the final experimental sensitivity.