Speaker
Description
The existence of baryon number violating processes is one of the Sakharov conditions considered necessary to explain the matter-antimatter asymmetry in the universe, but is yet to be observed. The NNBAR experiment, planned to be housed at the European Spallation Source (ESS) will perform a
search with free neutrons for neutron-antineutron oscillations with a gain in sensitivity of three orders of magnitude compared to the most recent search with free neutrons. To achieve this, a detector is needed to reconstruct multi-pion final states with an invariant mass < 2 GeV from neutron-antineutron annihilations and discriminate against spallation and non-spallation backgrounds. The key component in the detector is the calorimeter. The energy regime for calorimetry at the experiment is challenging due to large fluctuations in energy deposition in the showers which disfavour a sampling calorimeter solution. The NNBAR collaboration has developed a novel hadronic range followed by full absorption calorimeter concept. Simulation and construction of a prototype calorimeter is underway. The prototype is planned to be deployed at testbeams in 2021, and ultimately installed at the ESS testbeam area in 2023 for in-situ studies of neutron backgrounds from the ESS beamline. This talk will present the novel NNBAR calorimeter concept, as well as ongoing work towards a prototype calorimeter at Stockholm University.
