Experimental Neutrino Physics and Dark Matter Search

My past research work has mainly focused on experimental studies on neutrino properties, this includes measuring the neutrino oscillation parameters and searching for the fourth type neutrino, the sterile neutrino. Although the Standard Model of particle physics has proved to be a remarkably resilient theory, we know that it does not give a complete description of the observable universe. For my dissertation work, I have been testing models which describe the physics beyond the standard model. In the next step of my research career, I would like to gain experience in designing precision experiments to test our knowledge of the universe, to extend the present knowledge and make new discoveries.

Standard three-flavor neutrino oscillations have been well explained by a wide range of neutrino experiments. But there are anomalous results, such as electron-antineutrino excesses seen by LSND and MiniBooNE which do not fit the three-flavor paradigm. This can possibly be explained by an additional fourth sterile neutrino at a larger mass scale than the existing three flavor neutrinos. The NOvA experiment at Fermilab consists of two finely segmented, liquid scintillator detectors, a near and a far detector, operating 14.6 mrad off-axis from the Neutrinos at Main Injector (NuMI) muon-neutrino beam. The Near Detector is located on the Fermilab campus, 1 km from the NuMI target, while the Far Detector is located at Ash River, MN, 810 km from the NuMI target. The NOvA experiment is primarily designed to measure electron-neutrino appearance at the Far Detector using the Near Detector to control systematic uncertainties; however, the Near Detector with L/E in the range 0.1 -1 is well suited for searching for anomalous short-baseline oscillations.

My PhD research is on the NOvA experiment where I performed a search for anomalous τ neutrino appearance due to sterile neutrino oscillations in the NOvA Near Detector. This was the first time this search has been performed at NOvA. I performed the full analysis which includes, developing particle identifiers for the hadronic decay mode of ν_τ Charged Current interactions, optimizing the signal event selection for maximum background rejection and detailed systematic studies for this first analysis of its type. As mentioned before, NOvA is located 14.6 mrad off-axis to NuMI beam axis, where the beam energy peaks at 2 GeV, with neutrinos mainly coming from pions. The NOvA beam has also a second energy peak in which neutrinos are mainly coming from kaons, whose energy is greater than the τ production threshold. I used these high energy neutrinos for this analysis. The main challenge of this analysis comes from the identification of high energy ν_τ Charged Current (CC) signal from a huge ν_μ, ν_e CC and Neutral Current background in the detector. It is not practically possible to identify the τ particle directly since the spatial and time resolution of the detector is much larger than the τ decay length. However, it is possible to identify the τ decay products in the detector. The other challenge is to optimize the sensitivity when including the huge systematic uncertainty arising from various detector and simulation effects. To identify the signal in this analysis, the hadronic τ decay, I developed 3 discriminants using the ROOT toolkit for multivariate data analysis(TMVA).

This work has been presented in major international conferences like Neutrino ‘16 (London, 2016 - poster), International Neutrino Summer School (Fermilab, 2017 - received 2-nd place poster award), Neutrino ‘18 (Germany, 2018 - poster), April Meeting of American Physical Society (Washington DC, January 2016 - talk) and Meeting of Division of Particles and Fields of American Physical Society (Fermilab, April 2017 - poster).

I am an expert in monte-carlo production in NOvA. I have made a significant contributions to the production of data files corresponding to 8×10²⁰ POT needed for the various analyses in NOvA including 2016 and 2017 ν_e appearance, ν_μ disappearance and 2017 Neutral Current disappearance analyses.

In addition to this research work I have also had the opportunity to participate in hardware projects. I have a significant contribution in the quality analysis of the avalanche photodiodes (APDs) used for the replacement of malfunctioning APDs. I am a trained expert in the replacement of malfunctioning electronics on the detector. Additionally I participated in the operation of the experiment by taking control room shifts.

My Post-doctoral research at Vrije Universitiet of Brussels (VUB) was mainly focused on the sterile neutrino hypotheses tests using the neutrinos produced in the BR2 nuclear reactor at Mol, Belgium. Anti–electron neutrinos produced at nuclear reactors also greatly help to shed light on sterile neutrino hypothesis. I am currently working as a post-doctoral fellow in SoLid neutrino experiment located in BR2 nuclear reactor in Belgium. Primary goals of the SoLid experiment are to search for sterile neutrino oscillations and measure the anti-electron neutrino flux and energy spectrum. I was contributing to the sterile neutrino analysis by leading the background studies using the entire reactor–off Phase–1 data of the experiment for simulation tuning. I was mostly working on oscillation fit and sensitivity studies for this analysis. Additionally, I have a significant contribution in the heavy neutral lepton analysis in the experiment. I have implemented Machine Learning (ML) based signal discriminant for the first time in that analysis. I have also had the opportunity to participate in the calibration of the electromagnetic scintillation signal in the detector.

Currently, as a postdoctoral fellow in Virginia Tech I am mostly focusing on the DarkSIDE 20K experiment. My research primarily focuses on the hardware aspect of the project. DarkSIDE 20K is a cutting-edge experiment designed to detect dark matter through the use of liquid argon as a target material. Within this context, my work involves developing and optimizing the intricate hardware components essential for the experiment's functioning, ensuring their precise calibration and effective integration within the larger experimental setup.

Future Research Interests

The next few years are pivotal with a range of experiments being conceived to improve the understanding and make new discoveries. Working on the future neutrino experiment would be an ideal opportunity to make my contribution. I am more excited than ever to put my skills to any present or future experiment and help the field strive to reach a better understanding of the laws of nature.

During my time at Fermilab, as a member in one of the world leading long-baseline neutrino experiments, I became aware of the exciting neutrino physics programs at the Lab and I would love the opportunity to expand my horizon in this area. The neutrino sector is one of the aspects of the Standard Model (SM) and Beyond Standard Model (BSM) where there are still many unanswered questions and puzzles.