Periodic Reporting for period 3 - SENSE (Sterile neutrino search in tritium beta decay)
Reporting period: 2022-05-01 to 2023-10-31
Despite the remarkable success of the Standard Model of Particle physics, we know today that it cannot be complete. One of the most fundamental open questions is the nature of dark matter, which makes up 25% of the content of our universe. One minimal extension of the Standar Model of Particle physics is the introduction of a new type of neutrino, the so-called sterile neutrino. With a mass in the kilo-electron-volt (keV) range, such neutrino would be a viable dark matter candidate. With a mass in the electron-volt (eV) regime, such neutrino could resolve long-standing anomalies in neutrino oscillation experiments.
A promising way to search for eV to keV sterile neutrinos is via the kinematics of beta decay, where this new particle would manifest itself as characteristic spectral deformation. The Karlsruhe Tritium Neutrino (KATRIN) experiment operates one of the strongest tritium sources for scientific research. Its primary goal is a direct measurement of the absolute neutrino mass scale. It has recently published a world-leading direct limit on the neutrino mass of m < 0.8 eV.
The aim of the SENSE project is to extend the KATRIN experiment to search for eV and keV-scale sterile neutrinos. The former can be searched for with the data that is currently being recorded for the neutrino mass measurement. However, a keV-scale sterile neutrino search requires an upgrade of the focal plane detector system in the 70-m long KATRIN beamline. In the framework of SENSE we develop a beyond-the-state-of-the art multi-pixel Silicon Drift Detector focal plane array to be installed in the beamline after the completion of the neutrino mass program of KATRIN.
A promising way to search for eV to keV sterile neutrinos is via the kinematics of beta decay, where this new particle would manifest itself as characteristic spectral deformation. The Karlsruhe Tritium Neutrino (KATRIN) experiment operates one of the strongest tritium sources for scientific research. Its primary goal is a direct measurement of the absolute neutrino mass scale. It has recently published a world-leading direct limit on the neutrino mass of m < 0.8 eV.
The aim of the SENSE project is to extend the KATRIN experiment to search for eV and keV-scale sterile neutrinos. The former can be searched for with the data that is currently being recorded for the neutrino mass measurement. However, a keV-scale sterile neutrino search requires an upgrade of the focal plane detector system in the 70-m long KATRIN beamline. In the framework of SENSE we develop a beyond-the-state-of-the art multi-pixel Silicon Drift Detector focal plane array to be installed in the beamline after the completion of the neutrino mass program of KATRIN.
A major achievement of the first funding period were two eV-scale sterile neutrino searches based on the first two data taking campaigns of KATRIN. These outcomes are leading in the field and are complementary to other oscillation-based searches. The results are published in PRL and PRD.
The second major achievement of the first funding period is the completion of the design of the multi-pixel Silicon Drift Detector array. We succeeded in operating a 166-pixel monolithic SDD array, which is the largest array that was ever built. Our tests show an excellent performance of the system with respect to energy resolution and stability. For the final installation in KATRIN, prospectiveley in 2026, nine 166-pixel arrays will be combined.
The second major achievement of the first funding period is the completion of the design of the multi-pixel Silicon Drift Detector array. We succeeded in operating a 166-pixel monolithic SDD array, which is the largest array that was ever built. Our tests show an excellent performance of the system with respect to energy resolution and stability. For the final installation in KATRIN, prospectiveley in 2026, nine 166-pixel arrays will be combined.
In this first funding period unchartered parameter space for light eV-scale sterile neutrinos could be explored, which helps to shed light on long-standing anomalies in neutrino physics. A novel detector system was developed which will allow to perform beta-spectroscopy with unprecedented precision and will enable a search for keV-scale sterile neutrinos in beta decays.
We except to largely improve our eV-scale sterile neutrino sensitivity with the upcoming KATRIN data sets. The next publication based on the first five data taking campaigns in planned for 2023. The full statistics will be collected by the end of 2025. The new detector system will be integrated thereafter in 2026. By the end of 2024, i.e. in the scope of the SENSE project, we expect to achieve the final construction of the full Silicon Drift Detector system, consisting of 9 arrays and a complete read-out and data acquisition chain.
We except to largely improve our eV-scale sterile neutrino sensitivity with the upcoming KATRIN data sets. The next publication based on the first five data taking campaigns in planned for 2023. The full statistics will be collected by the end of 2025. The new detector system will be integrated thereafter in 2026. By the end of 2024, i.e. in the scope of the SENSE project, we expect to achieve the final construction of the full Silicon Drift Detector system, consisting of 9 arrays and a complete read-out and data acquisition chain.