Neutrinos

Thorsten Lux

For more than a decade, IFAE has been contributing to several key experiments in the field of neutrino physics. Currently, it participates in the long-baseline neutrino oscillation experiment T2K and the next-generation experiment Hyper-Kamiokande which will start data-taking in 2027.

In 2023, the T2K ND280 upgrade entered its final phase. The ND280 upgrade consists of the installation of three new subdetector systems, a novel scintillator tracker (SuperFGD), two high-angle time project chambers (HAT) and a time of flight (TOF) detector, in the existing ND280 detector. The effort was coordinated by the PI of the IFAE group who, together with other group members, stayed for this reason for the first half of 2023 at CERN where the first HAT and the TOF were assembled and commissioned before being shipped to J-PARC (Japan). In the 2nd half of 2023, the installation work at J-PARC started and the first neutrino beam data was taken with the SuperFGD, one of the HAT and a part of the TOF system. The rest of the detectors will be installed in the first half of 2024.

Figure 1: ND280 upgrade detector with bottom HAT, SuperFGD and 4 out of 6 TOF panels installed.

Figure 2: One of the first neutrino beam events with the detector configuration shown in Fig. 1.

Furthermore, members of the group are working on event reconstruction for Water Cherenkov detectors in the context of Hyper-Kamiokande.

Analysis of test beam data taken with a prototype of TPC with resistive Micromegas

The new TPCs will use a novel readout technology, Encapsulated Resistive Anode Micromegas (ERAM). This technology is highly interesting for future experiments with TPCs as the main tracker detector. This required an intensive R&D program studying in detail the different possible ERAM configurations. For this purpose a TPC prototype resembling the final TPCs was built at NEXUS Projects SL (Martorell), Fig. 3, and used to test single ERAM modules in testbeams at CERN and DESY. It could be shown that the required spatial resolution of 600 μm can be safely achieved even for long drift distances (Fig. 4).

Figure 4: Spatial resolution as a function of the drift distance for two different electronics settings.

Figure 2: Production of the TPC prototype at NEXUS which was accompanied by members of the IFAE Neutrino group

Figure 5: The three 2D views from the SuperFGD - classification of the reconstructed cubes. One can clearly see that a short track out ghosts cubes would have been taken for real without classification.

Figure 6: The three 2D views from the SuperFGD - the raw reconstructed 3D event