Neutrinos are the second most abundant known particle in the Universe but our understanding about them is still lacking many important neutrino properties. One of the most intriguing mysteries is their tiny mass, which is at least a million times lighter than an electron. A possible explanation for such a small value is the existence of new heavier particles known as heavy neutral leptons (HNLs for short), which are connected to the neutrinos like in a seesaw, making the neutrinos masses appear very light. The mass of the HNLs can take a large range of values, and therefore they must be sought in different experiments sensitive to different mass values.
The liquid argon (LAr) detector is a technology that has gained relevance because it has been selected for the future DUNE experiment that will investigate other mysteries such as if neutrinos and antineutrinos behave differently as they propagate, which could be connected to the dominance of matter over antimatter in our Universe. In this project we proposed to use SBND, a LAr detector located very close to the origin of the Booster Neutrino Beam at Fermilab, to search for HNLs and advance our expertise with this technology.
The overall objectives were 1) contribute to the data acquisition of the scintillating light produced in LAr when the particles excite it, 2) develop the simulation and analysis of this light which is used to reject fake signals that mimic the HNL signature, 3) develop the search for HNLs in SBND. Through this research program, the fellow was trained in LAr scintillation light in which the CIEMAT Neutrino Group is a reference, and the fellow was reintegrated in the European Union, becoming an independent researcher and bringing his previous expertise in LAr detectors and Beyond Standard Model physics to the host.
