| dc.description.abstract | The goal of this thesis is to measure the coherent + production cross section on carbon
and oxygen nuclei, induced by muon neutrinos from the T2K beamline. This is performed
using the tracker system of the off-axis near detector which consists of three argon gas
Time Projection Chambers between which two Fine-Grained Detectors (FGD) are located.
While the first FGD is made of plastic scintillator, the second one has alternate layers of
scintillator and water which allows a measurement on oxygen target. The measurement on
carbon target is reported as a function of the muon and pion momentum and angle, the
sum of the pion and muon energies and the coplanarity angle between the muon and the
pion. The statistics for the oxygen measurement remains too low and therefore an upper
limit is set on both the differential cross sections and total flux-integrated cross section.
The phase space considered is 0.2 < pμ− < 5 GeV/c , cos μ− > 0.7, 0.15 < p + < 1.5 GeV/c
, cos + > 0.45, 0.5 < E + + Eμ− < 6.5 GeV, +μ− > 90 .
The values found for the flux-integrated cross section in the reduced phase-space are:
< C >= 3.23 ± 0.67(stat.) ± 0.82(syst.) × 10−40cm2 per carbon nucleus
O 9.57 × 10−40cm2 per oxygen nucleus, with 95% probability
It was found that the 95% upper limit on oxygen is always smaller than the Rein-Sehgal
predictions, making this model unreliable for low neutrino energies. On the other hand, the
limit remains compatible with the Berger-Sehgal model in every differential variables. The
data for carbon target agree, within the systematic errors, with the Berger-Sehgal model
except for pion momentum below 0.35 GeV/c and coplanarity angle below 155 degrees. In
the latter cases an excess is observed in the data. | en_US |
