Study of neutrino-induced neutral current neutral pion production in the T2K near detector
Author(s)
Short, Samantha
Type
Thesis
Abstract
The T2K experiment is a long baseline neutrino oscillation experiment. The
most intense accelerator muon neutrino beam ever built is produced at the
J-PARC facility in Tokai, located on the east coast of Japan, and directed
(2.5 [degrees] off -axis) toward the Super-Kamiokande water Cherenkov detector, located
295 km away in the mountains of western Japan.
For the current T2K [Symbol appears here. To view, please open pdf attachment]e appearance analysis, 23% of the background at Super-
Kamiokande is from neutral current interactions that produce one π0 in the final state (NC 1π0). This study uses ND280 Run 2 data totalling 7.832 x 10 [to the power of 19] POT
and selects neutrino-induced NC 1π0 interactions in FGD1 and FGD2 where
both π0 decay photons convert in the barrel and downstream ECAL.
Overall, neglecting photon reconstruction efficiency, an efficiency of 22% and
purity of 16% is obtained. For the case where both π0 decay photons convert in
the downstream (barrel) ECAL an efficiency of 33% (12%) and purity of 43%
(9%) is achieved. When one photon converts in the barrel ECAL and the other
in the downstream ECAL the efficiency (purity) is 29% (16%).
Systematic uncertainties arising from cross-section model parameters and final state interactions, the neutrino flux prediction and the shape discrepancy between
ECAL variables in data and MC are evaluated. The predicted total number
of events when both photons convert in the downstream and barrel ECAL is
7.1± 2.3 (syst)± 0.5 (stat) and 31.6± 8.9 (syst) ±1.2 (stat), respectively. Whereas
when one decay photon is reconstructed in the barrel ECAL and the other in the
downstream ECAL the expected number of events is 38.1± 8.7 (syst) ±1.3 (stat).
The selected number of events in data is 5, 22 and 31, respectively, which agrees
with the prediction within errors.
The calibration of the time offsets for the barrel and downstream ECAL is
also presented in this thesis. The application of this calibration reduces the
timing resolution from 9 ns to approximately 2.5 ns, for high charge hits.
most intense accelerator muon neutrino beam ever built is produced at the
J-PARC facility in Tokai, located on the east coast of Japan, and directed
(2.5 [degrees] off -axis) toward the Super-Kamiokande water Cherenkov detector, located
295 km away in the mountains of western Japan.
For the current T2K [Symbol appears here. To view, please open pdf attachment]e appearance analysis, 23% of the background at Super-
Kamiokande is from neutral current interactions that produce one π0 in the final state (NC 1π0). This study uses ND280 Run 2 data totalling 7.832 x 10 [to the power of 19] POT
and selects neutrino-induced NC 1π0 interactions in FGD1 and FGD2 where
both π0 decay photons convert in the barrel and downstream ECAL.
Overall, neglecting photon reconstruction efficiency, an efficiency of 22% and
purity of 16% is obtained. For the case where both π0 decay photons convert in
the downstream (barrel) ECAL an efficiency of 33% (12%) and purity of 43%
(9%) is achieved. When one photon converts in the barrel ECAL and the other
in the downstream ECAL the efficiency (purity) is 29% (16%).
Systematic uncertainties arising from cross-section model parameters and final state interactions, the neutrino flux prediction and the shape discrepancy between
ECAL variables in data and MC are evaluated. The predicted total number
of events when both photons convert in the downstream and barrel ECAL is
7.1± 2.3 (syst)± 0.5 (stat) and 31.6± 8.9 (syst) ±1.2 (stat), respectively. Whereas
when one decay photon is reconstructed in the barrel ECAL and the other in the
downstream ECAL the expected number of events is 38.1± 8.7 (syst) ±1.3 (stat).
The selected number of events in data is 5, 22 and 31, respectively, which agrees
with the prediction within errors.
The calibration of the time offsets for the barrel and downstream ECAL is
also presented in this thesis. The application of this calibration reduces the
timing resolution from 9 ns to approximately 2.5 ns, for high charge hits.
Version
Open Access
Date Issued
2013-03
Date Awarded
2013-07
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Advisor
Wascko, Morgan
Nash, Jordan
Publisher Department
Physics
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)