34 Search Results

Inter-channel mis-synchronisation can be a limiting factor to the time resolution of high performance timing detectors with multiple readout channels and independent electronics units. In these systems, time calibration methods employed must be able to efficiently correct for minimal mis-synchronisation between channels and achieve the best detector performance. We present an iterative time calibration method based on Markov Chains, suitable for detector systems with multiple readout channels. Starting from correlated hit pairs alone, and without requiring an external reference time measurement, the method solves for fixed per-channel offsets, with precision limited only by the intrinsic single-channel resolution. A mathematical proofmore » that the method is able to find the correct time offsets to be assigned to each detector channel in order to achieve inter-channel synchronisation is given, and it is shown that the number of iterations to reach convergence within the desired precision is controllable with a single parameter. Numerical studies are used to confirm unbiased recovery of true offsets. Finally, the application of the calibration method to the Super Fine-Grained Detector (SuperFGD) and the Time of Flight (TOF) detector at the upgraded T2K near detector (ND280) shows good improvement in overall timing resolution, demonstrating the effectiveness in a real-world scenario and scalability.« less

Abstract The T2K experiment presents new measurements of neutrino oscillation parameters using $$$$19.7(16.3)\times 10^{20}$$$$ $19.7\left(16.3\right)\times {10}^{20}$ protons on target (POT) in (anti-)neutrino mode at the far detector (FD). Compared to the previous analysis, an additional $$$$4.7\times 10^{20}$$$$ $4.7\times {10}^{20}$ POT neutrino data was collected at the FD. Significant improvements were made to the analysis methodology, with the near-detector analysis introducing new selections and using more than double the data. Additionally, this is the first T2K oscillation analysis to usemore » NA61/SHINE data on a replica of the T2K target to tune the neutrino flux model, and the neutrino interaction model was improved to include new nuclear effects and calculations. Frequentist and Bayesian analyses are presented, including results on $$$$\sin ^2\theta _{13}$$$$ ${sin}^2{\theta }_{13}$ and the impact of priors on the $$$$\delta _{\textrm{CP}}$$$$ ${\delta }_{\text{CP}}$ measurement. Both analyses prefer the normal mass ordering and upper octant of $$$$\sin ^2\theta _{23}$$$$ ${sin}^2{\theta }_{23}$ with a nearly maximally CP-violating phase. Assuming the normal ordering and using the constraint on $$$$\sin ^2\theta _{13}$$$$ ${sin}^2{\theta }_{13}$ from reactors, $$$$\sin ^2\theta _{23}=0.561^{+0.021}_{-0.032}$$$$ ${sin}^2{\theta }_{23}=0.{561}_{-0.032}^{+0.021}$ using Feldman–Cousins corrected intervals, and $$$$\varDelta {}m^2_{32}=2.494_{-0.058}^{+0.041}\times 10^{-3}~\text {eV}^2$$$$ $\Delta m_{32}^2=2.{494}_{-0.058}^{+0.041}\times {10}^{-3}{\text{eV}}^2$ using constant $$$$\varDelta \chi ^{2}$$$$ $\Delta {\chi }^2$ intervals. The CP-violating phase is constrained to $$$$\delta _{\textrm{CP}}=-1.97_{-0.70}^{+0.97}$$$$ ${\delta }_{\text{CP}}=-1.{97}_{-0.70}^{+0.97}$ using Feldman–Cousins corrected intervals, and $$$$\delta _{\textrm{CP}}=0,\pi $$$$ ${\delta }_{\text{CP}}=0,\pi$ is excluded at more than 90% confidence level. A Jarlskog invariant of zero is excluded at more than $$$$2\sigma $$$$ $2\sigma$ credible level using a flat prior in $$$$\delta _{\textrm{CP}},$$$$ ${\delta }_{\text{CP}},$ and just below $$$$2\sigma $$$$ $2\sigma$ using a flat prior in $$$$\sin \delta _{\textrm{CP}}.$$$$ $sin{\delta }_{\text{CP}}.$ When the external constraint on $$$$\sin ^2\theta _{13}$$$$ ${sin}^2{\theta }_{13}$ is removed, $$$$\sin ^2\theta _{13}=28.0^{+2.8}_{-6.5}\times 10^{-3},$$$$ ${sin}^2{\theta }_{13}=28.0_{-6.5}^{+2.8}\times {10}^{-3},$ in agreement with measurements from reactor experiments. These results are consistent with previous T2K analyses.« less

The T2K experiment widely uses plastic scintillator as a target for neutrino interactions and an active medium for the measurement of charged particles produced in neutrino interactions at its near detector complex. Over 10 years of operation the measured light yield recorded by the scintillator based subsystems has been observed to degrade by 0.9–2.2% per year. Extrapolation of the degradation rate through to 2040 indicates the recorded light yield should remain above the lower threshold used by the current reconstruction algorithms for all subsystems. This will allow the near detectors to continue contributing to important physics measurements during the T2K-IImore » and Hyper-Kamiokande eras. Additionally, work to disentangle the degradation of the plastic scintillator and wavelength shifting fibres shows that the reduction in light yield can be attributed to the ageing of the plastic scintillator. The long component of the attenuation length of the wavelength shifting fibres was observed to degrade by 1.3–5.4% per year, while the short component of the attenuation length did not show any conclusive degradation.« less

Abstract DUNE is a dual-site experiment for long-baseline neutrino oscillation studies, neutrino astrophysics and nucleon decay searches. ProtoDUNE Dual Phase (DP) is a 6  $$$$\times $$$$ $\times$  6  $$$$\times $$$$ $\times$  6 m $$^3$$ ${}^3$ liquid argon time-projection-chamber (LArTPC) that recorded cosmic-muon data at the CERN Neutrino Platform in 2019–2020 as a prototype of the DUNE Far Detector. Charged particles propagating through the LArTPC produce ionization and scintillation light. The scintillation light signal in these detectors can provide the trigger for non-beam events. In addition, it adds precise timing capabilities andmore » improves the calorimetry measurements. In ProtoDUNE-DP, scintillation and electroluminescence light produced by cosmic muons in the LArTPC is collected by photomultiplier tubes placed up to 7 m away from the ionizing track. In this paper, the ProtoDUNE-DP photon detection system performance is evaluated with a particular focus on the different wavelength shifters, such as PEN and TPB, and the use of Xe-doped LAr, considering its future use in giant LArTPCs. The scintillation light production and propagation processes are analyzed and a comparison of simulation to data is performed, improving understanding of the liquid argon properties.« less

The ProtoDUNE-SP detector is a single-phase liquid argon time projection chamber (LArTPC) that was constructed and operated in the CERN North Area at the end of the H4 beamline. This detector is a prototype for the first far detector module of the Deep Underground Neutrino Experiment (DUNE), which will be constructed at the Sandford Underground Research Facility (SURF) in Lead, South Dakota, U.S.A. The ProtoDUNE-SP detector incorporates full-size components as designed for DUNE and has an active volume of 7 × 6 × 7.2 m$$^{3}$$. The H4 beam delivers incident particles with well-measured momenta and high-purity particle identification. ProtoDUNE-SP's successful operation between 2018 andmore » 2020 demonstrates the effectiveness of the single-phase far detector design. This paper describes the design, construction, assembly and operation of the detector components.« less