TOTAL NEUTRON CROSS SECTION MEASUREMENT ON HYDROCARBON WITH A NOVEL 3D-PROJECTION SCINTILLATOR DETECTOR

Next generation long-baseline experiments such as T2HK aim to measure neutrino oscillation parameters with higher precision that would help in search of CP violation in the lepton sector and determination of neutrino mass hierarchy. To achieve the required precision in the measurement of neutrino oscillation parameters, an accurate estimation of (anti)neutrino energy is pivotal. In such pursuit, the modeling of neutrino-nuclear interactions needs to be well understood as it represents one of the dominant source of systematic uncertainty in (anti)neutrino energy reconstruction. This is particularly challenging when the kinematics of all final state particles from a (anti)neutrino interaction are not reconstructed. Neutrons being neutral particles cannot be detected through electromagnetic process and thus can escape detectors without visible energy deposition. As such, neutrons present a challenge in anti(neutrino) reconstruction when they're part of the outgoing particles from the (anti)neutrino interaction. To address this challenge, the main target in T2K's near detector complex is upgraded to a 3-dimensional projection scintillator tracker known as SuperFGD. This novel detector design enables the detection of neutrons and reconstruction of neutron kinematics on an event-by-event basis using the time-of-flight method. This provides an additional handle in the estimation of the incoming (anti)neutrino energy. To better understand the performance of such a detector, prototypes were built and deployed in various test beams to characterize detector performance. One such test beam is the neutron test beam conducted in Los Alamos National Laboratory. Using data collected from the neutron test beam, a neutron total cross section on hydrocarbon measurement is performed to demonstrate the neutron detection capability of such a detector. The prototype detector has a size of $24\times8\times48$ cm$^3$ and consists of 9216 1 cm$^3$ plastic scintillator cubes instrumented with Multi-Pixel Photon Counters. The prototype is exposed to a neutron beam with kinetic energies between 0 and 800 MeV with beam bunches separated by 1.8 $\mu$s. The neutron total cross section on hydrocarbon measurement is presented in this thesis. The integrated cross section of neutron kinetic ranges from 98 to 688 MeV is $0.36\pm0.05$ barn.