Reconstruction of neutrino induced neutral current neutral pion events with the T2K ND280 Tracker and ECAL
Author(s)
Guzowski, Pawel
Type
Thesis
Abstract
T2K is a long baseline neutrino oscillation experiment in Japan. One of
the goals is to search for electron neutrino appearance at the far detector
(Super Kamiokande) in a muon neutrino beam produced 295 km away, to
make a measurement of the unknown neutrino oscillation angle [Symbol appears here. To view, please open pdf attachment]13. A
major background to this appearance search is neutral pions (π0) produced
in neutral current (NC) neutrino interactions. The π0s decay to photons,
which can in cases mimic the electron appearance signal.
The near detector of the experiment (ND280) has the capability of measuring
the rates of NCπ0 production processes. NCπ0 interactions in the
Tracker of the detector (plastic scintillator targets, and time projection
chambers for tracking charged particles) can be detected through photon
conversions in the electromagnetic calorimeter that surrounds the Tracker.
For these types of events, the photon reconstruction in the calorimeter has
to have good energy and angular resolutions.
This thesis describes the T2K experiment, the ND280 detector and its
offline software, and gives details on the ECal reconstruction of photons.
The performance of the reconstruction in relation to the π0 decay photons,
their energy and angular resolutions, is studied.
An analysis is presented for the reconstruction of NC π0s produced in
the trackers, with both photons converting in the downstream calorimeter, developed purely with Monte Carlo (with GENIE as the interaction generator),
and then applied to the first-year data from ND280. The Monte Carlo
expectation is 17.7 ± 1.1(stat) ± 4.9(syst) events, with 37 ± 4% NCπ0 purity;
21 events are seen in the first year data. The MC is consistent with data at
the 0.5σ level.
As a crosscheck, the same analysis is applied to a different Monte Carlo
production (using NEUT as the generator). The expectation from this
production is 16.8 ± 1.0(stat) ± 4.7(syst) events, with 30 ± 4% purity. This
is consistent with data at the 0.7σ level.
the goals is to search for electron neutrino appearance at the far detector
(Super Kamiokande) in a muon neutrino beam produced 295 km away, to
make a measurement of the unknown neutrino oscillation angle [Symbol appears here. To view, please open pdf attachment]13. A
major background to this appearance search is neutral pions (π0) produced
in neutral current (NC) neutrino interactions. The π0s decay to photons,
which can in cases mimic the electron appearance signal.
The near detector of the experiment (ND280) has the capability of measuring
the rates of NCπ0 production processes. NCπ0 interactions in the
Tracker of the detector (plastic scintillator targets, and time projection
chambers for tracking charged particles) can be detected through photon
conversions in the electromagnetic calorimeter that surrounds the Tracker.
For these types of events, the photon reconstruction in the calorimeter has
to have good energy and angular resolutions.
This thesis describes the T2K experiment, the ND280 detector and its
offline software, and gives details on the ECal reconstruction of photons.
The performance of the reconstruction in relation to the π0 decay photons,
their energy and angular resolutions, is studied.
An analysis is presented for the reconstruction of NC π0s produced in
the trackers, with both photons converting in the downstream calorimeter, developed purely with Monte Carlo (with GENIE as the interaction generator),
and then applied to the first-year data from ND280. The Monte Carlo
expectation is 17.7 ± 1.1(stat) ± 4.9(syst) events, with 37 ± 4% NCπ0 purity;
21 events are seen in the first year data. The MC is consistent with data at
the 0.5σ level.
As a crosscheck, the same analysis is applied to a different Monte Carlo
production (using NEUT as the generator). The expectation from this
production is 16.8 ± 1.0(stat) ± 4.7(syst) events, with 30 ± 4% purity. This
is consistent with data at the 0.7σ level.
Date Issued
2011-09
Date Awarded
2013-03
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Advisor
Wascko, Morgan
Publisher Department
Physics
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)