preview

What Is The Measurement Of The Electron Anti-Neutrino?

Decent Essays

\chapter{Event Selection}\label{Ch:BDTSelection}

The measurement of the intrinsic electron anti-neutrino ($\overline{\nu}_e$) component in the muon anti-neutrino $\overline{\nu}_{\mu}$ T2K beam is crucial for the oscillation analysis, as it represents the largest irreducible background for the ($\overline{\nu}_{\mu} \rightarrow \overline{\nu}_e $) appearance measurement at Super-Kamiokande.
Furthermore, the near detector number of $\overline{\nu}_e$ events $\text{N}_{\text{ND}}$ is used to constrain the flux $\phi$(E) times cross-section $\sigma$(E) given detector efficiency $\epsilon$(E), as described in~\cref{sec:ImpactXsecOsc}.

The $\overline{\nu}_e$ event selection will be summarized in this chapter. This work is based …show more content…

\subsection{TPC Number of Tracks Cut}\label{subsec:nbTracksTPC}
The selected event must have at least one TPC segment, as the track's momentum and charge are measured using the TPC.
\subsection{TPC Quality Cut}
The TPC segment should consist of at least 18 hits if the track had an ECAL segment, and 36 hits otherwise.
The number of hits in the TPC segment balances the TPC performance with its systematic uncertainties, and was chosen based on previously done studies~\cite{NueSel}.
\subsection{Momentum Cut}
As mentioned in~\cref{sec:SigDef}, one of the major background is the electron coming from gammas. The low momentum region of the phase space is highly contaminated with these electrons. hence, a momentum cut was introduced, as shown in~\cref{fig:EvtSel_MomCut}.
\begin{figure}[H]
\centering
\includegraphics[scale = 0.25]{./Include/EvtSel_MomCut.png}
\caption{Introduced momentum cut to reduce the gamma background contamination. {\color{red} reproduce with MC only at this stage.}} \label{fig:EvtSel_MomCut}
\end{figure}
\subsection{BDT Cut}
The BDT works as an optimized cut in a multi-dimensional feature space, and uses the correlation between different features to improve the separation power between signal and background.
First, it calculates the test statistic (tBDT) for each track then checks if it is higher than a certain value (tBDT\_cut), it will be considered as a

Get Access