Charged current quasi-elastic muon neutrino interactions in the Baby MIND detector

[摘要] The T2K long-baseline neutrino experiment in Japan is designed to study neutrino oscillations, to determine the mixing angles and mass-squared difference of the neutrino mass eigenstates and, potentially, to discover CP violation in neutrinos by comparing neutrino to antineutrino oscillations. In the near detector complex 280 m downstream of the produc- tion target at the Japanese Particle Accelerator Research Centre (J-PARC), the WAGASCI experiment will measure the ratio of cross sections from neutrinos interacting with a water and scintillator targets, in order to constrain neutrino cross sections essential for the T2K neutrino oscillation measurements. A prototype Magnetised Iron Neutrino Detector, called Baby MIND, has been constructed at CERN and will act as a magnetic spectrometer behind the main WAGASCI target. The Baby MIND spectrometer was installed between February and March 2018 in the near detector complex, behind WAGASCI and is able to measure the charge and momentum of the outgoing muon from neutrino charged current interactions inside the WAGASCI target, to be able to perform full neutrino event reconstruction. Baby MIND collected data in the reverse horn focussed antineutrino beam between April and May 2018. In this thesis, the Baby MIND spectrometer is described in detail along with the performance from initial beam tests performed with the Proton Synchrotron (PS) charged particle beam at the T9 test beam facility at CERN. The test beam was used to perform measurements of track reconstruction efficiency and charge reconstruction efficiency, using dedicated reconstruction programmes, SaRoMaN and SAURON. The software environment used to perform event reconstruction in the complex detector geometry of Baby MIND is described in this thesis. Furthermore, a machine learning multi-variate analysis was used to perform particle identification between muons and hadrons, allowing for a pure selection of muons in the test beam. NuSTORM is a novel type of neutrino beam from the decay of muons in a storage ring. This type of facility produces well defined beams of $\nu_\mu$ and $\bar{\nu_e}$ neutrinos. A study is performed in the thesis to determine the expected sensitivity of mea- suring neutrino interactions in a fully active scintillator neutrino target, with a magnetised iron detector downstream. This analysis also benefited from an identification of the different event types by using a machine learning multi-variate approach. Finally, results are presented on charged current quasi-elastic neutrino and antineutrino interactions in iron reconstructed with the Baby MIND detector during the 2018 neutrino data taking at J-PARC.

[发布机构] University:University of Glasgow;Department:School of Physics and Astronomy

[关键词] QC Physics