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\begin{center}
  \LARGE
  Statement of Research Interests\\
  % \large
  % Nam Tran
\end{center}

\bigskip

My work centers in an experimental search for charged lepton flavor violation
(CLFV) with muons, namely the COMET experiment at J-PARC. COMET is a new
experiment that aims to find the neutrinoless decay of muon to electron in
a nuclear field, or
muon to electron conversion, at a single event sensitivity of $10^{-17}$. The
experiment has high impact as a positive result would provide an unambiguous
evidence of new physics beyond the Standard Model (BSM); and a negative result
will place stringent limits on theoretical models. The search is part of the
Intensity Frontier in particle physics, which will provide a window to probe
physics at energy scales far beyond the reach of the most powerful accelerator
currently exists. I was inspired to join the COMET experiment because of its
elegance: 
\begin{itemize}
  \itemsep-0.5em
  \item the overall idea is simple;
  \item the signal is clean and distinctive; 
  \item and many novel technologies and solutions are needed to realize its goal.
\end{itemize}

% One issue had arisen in the preparation for COMET experiment is our knowledge
% on the products of the nuclear muon capture process on aluminum target was not
% sufficient. 
One issue that arose during the preparation for COMET is that our knowledge of
the products of the nuclear capture process on aluminum was not sufficient.
Protons are expected to be a significant source of hits in the tracking
detector of COMET, but there was no direct measurement of the proton rate and
spectrum in the relevant energy range. Neutrons could cause serious problem for
the front-end electronics. Therefore, COMET and its counterpart, Mu2e at
Fermilab, jointly carried out a series of measurements, in the so-called AlCap
experiment, of the products emitted after nuclear muon capture on aluminum and
titanium at Paul Scherer Institute (PSI), Switzerland. I did a Monte Carlo
study that showed the feasibility of the experiment, and contributed to DAQ
developement, and hardware and electronics works on silicon and germanium
detectors.

My initial analysis of proton data in 2013 showed that the proton emission rate
is low enough for the tracking detector of COMET to operate normally. The
smallness of proton emission rate was later confirmed by another independent
analysis on a larger dataset. However, there are still discrepancies between
the two analyses. Therefore we have had another run for the  proton measurement
in 2015. The data analysis for this run is ongoing.

Since November 2014, I have been assigned as a subproject leader of COMET,
responsible for monitoring the number of muons that stop in the muon stopping
target. The number is evidently necessary for calculation of branching ratio
and single event sensitivity of the experiment. There have been several
ideas on how to achieve the goal: online measurement of muonic X-rays and
delayed gamma rays from activated $^{27}$Mg; measurement of the spectrum of
decay-in-orbit electrons, and the rate of protons emitted after nuclear muon
capture. I have proposed another activation measurement: measure population of
a long-lived activation product, namely $^{24}$Na ($T_{1/2} = 14.96$~h). The
measuring scheme will be:
\begin{itemize}
  \itemsep-0.5em
  \item irradiation with muon beam for 2 days,
  \item beam off,
  \item measure delayed gammas from $^{24}$Na (1368 and 2574 keV) for 2 hours,
  \item continue irradiating, then repeat the cycle.
\end{itemize}
All these methods could be used simultaneously for cross-checking and
reducing systematic uncertainties.

% I also involve in other works, such as Monte Carlo simulation of cosmic ray
% background in COMET Phase-I, and magnetic field map calculation for both COMET
% Phase-I and Phase-II. 

Having been working in COMET for 5 years, I have been able to work together
with great collaborators, and have gained a wide range of skills
needed for an experimental physicist, including simulation, detector
development, data acquisition, and data analysis.  Now I would like to broaden
my perspective and earn more experience by joining the Muon $g-2$ experiment.
I am attracted by the ambitious goal of measuring the muon anomalous magnetic
moment at an unprecedented precision, its impact of the measurement in
establishing a signal for new physics beyond the Standard Model, as well as the
synergy between $g-2$ and $\mu-e$ conversion experiments. My areas of
contribution could be Monte Carlo simulation, detector and DAQ development.
Besides, I am eager to learn new skills including accelerator-related
techniques, FPGA development, and data analysis using machine learning.  

% moving to another position.
% The
% transition to Mu2e would be smooth since the two
% experiments have many things in common. 
% Personally, I would like to strengthen
% my data analysis skill with a new technique: machine learning. I believe
% machine learning will be used extensively as I continue working in the
% Intensity Frontier.
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