アイテム詳細

要旨

The Stereo experiment is one of the pioneering efforts to test the light sterile neutrino
hypothesis at short baselines from nuclear reactors. Placed at ~ 10m from the
Institut-Laue-Langevin research reactor in Grenoble, France, Stereo is observing ¯ν_e signals since 2016. Given its cell-wise segmented volume, Stereo can perform spectral analyses at different baselines. This allows to test the compatibility of the observed
flux with different oscillatory hypotheses, provided by a dedicated Monte Carlo simulation
of the detector and the physics within. This thesis addresses the process of fine
tuning performed on the simulation framework of Stereo. In particular, the production,
transport and quenching of scintillation light in the detector has been adjusted
to match calibration data, including the characterization of the light yield, attenuation
length and fluor quantum yields of the liquid scintillator components. A new optical
model for the separation walls has been implemented, successfully accounting for the
increased light cross-talk between cells observed. Energy non-linearities in the response
of the detector have also been investigated and reproduced in the simulation to the
subpercent level. The process of tuning has lead to an excellent agreement of the reconstructed
energy signal between calibration data and simulations, allowing Stereo
to exclude a considerable portion of the allowed oscillation parameter space.