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LAr RD for neutrino physics

Final Report Summary - NULARD (LAr RD for neutrino physics)

The MicroBooNE experiment, 170ton Liquid Argon detector, is located at Fermilab in the US and allows to study properties of the elusive particles, the neutrinos. The experiment was designed to give an answer to an anomalous excess of events previously observed by the MiniBooNE experiment. This anomaly could be explained by a hypothetical particle – sterile neutrino – which would be proof of physics beyond the Standard Model. The detector construction and commissioning was completed in 2015 and neutrino data have been recorded since October 2015. MicroBooNE is an essential milestone in the development of these state-of-the-art detectors for the next generation of neutrino experiments. We have been focusing on data analyses for MicroBooNE since the start of data taking. After performing some technical analyses to understand and calibrate the new MicroBooNE detector, with my group of 1 PDRA and 3 PhD students, we are now performing neutrino oscillation searches and neutrino cross-sections measurements. The UK is now more widely involved in this project and I was the UK spokesperson for MicroBooNE for the whole period of this grant.

In more details, my group has performed several studies and analyses of cosmic rays in the MicroBooNE experiment. The first project was to provide a robust simulation framework to perform cosmic-ray studies. My PDRA implemented a new cosmic-ray generator and performed my studies to assess the performance of the simulations [MICROBOONE-NOTE-1005-PUB]. My group has also looked at selected event samples, recorded with a small muon counter system on top of the MicroBooNE detector, to study the reconstruction efficiencies of through-going muons in the detector [arXiv:1707.09903]. In addition to providing reconstruction efficiencies, this study allowed to validate the method for the future analyses using a recently added cosmic-ray tagger system for MicroBooNE. The student performing this analysis also contributed to the installation of that system, gaining valuable hardware experience. The analysis was submitted to a peer-reviewed journal and is currently under review. Both of these projects are crucial to the MicroBooNE experiment, since the detector location on the surface leads to a large number of cosmic-ray interactions and will be a dominant background in all the analyses.

We are also working on the measurement of the inclusive muon-neutrino charged-current interactions on Argon. One student has been developing the selection of these events and many technical methods to improve the selection, such as using optical information. His work has been central to many direct improvement in the whole reconstruction software of MicroBooNE. The first selection results were shown at the Neutrino conference in July 2016 [MICROBOONE-NOTE-1004-PUB ]. He also led the study of certain systematic uncertainties linked to the theoretical models used in the simulations. His work was also presented at the conference []. He is now focusing on finalizing this analysis with anticipated results and publication by Spring 2018. This analysis will be very important for the MicroBooNE collaboration and for the scientific community since it will be the first physics result from the collaboration that will impact the whole neutrino community.

Finally, we have also started to lead a new effort in the search for the low-energy excess using the Pandora reconstruction framework. One student has recently demonstrated that this method is viable for the search and we are now performing the analysis, with results anticipated for Summer 2018. This is the flagship analysis for MicroBooNE and our group has been playing a significant role. This will have a major impact on the scientific community since an excess could lead to the discovery of sterile neutrinos.

MicroBooNE alone cannot demonstrate definitively the presence of sterile neutrinos, and we have proposed a new experiment (SBND), adding a near detector to MicroBooNE to identify a potential excess observed by MicroBooNE. This new project is unique and has unprecedented sensitivity to the discovery of this new particle, which would revolutionize the entire field of Physics. The proposal was approved in February 2015 and the SBND detector is currently under construction. I played a major role in the proposal and I am now leading the Physics and Analysis Tool group for SBND. We are currently developing the simulation and analysis software for the experiment.

The large-scale LBNE project, originally proposed to build a 40 kiloton Liquid Argon detector to study long-baseline neutrino oscillation, has been restructured and renamed DUNE (the Deep Underground Neutrino Experiment). This now much larger (now over 1000 collaborators) and more international collaboration has been dedicating its efforts on designing the experiment for optimal scientific impact. I was the Deputy Convener for the Installation and Integration of the Far Detector until a recent restructuring of the collaboration, where I am now leading the Installation effort for the readout plane consortium. DUNE will have unprecedented sensitivity to the neutrino mass hierarchy and to CP violation and will have a great impact on the scientific community. DUNE will offer many opportunities for groundbreaking discoveries.

Finally, one student in my group has developed a smartphone application to visualize, in 3D, neutrino interaction in the neutrino detector. He designed, developed, tested and launched the VENu app [] and there are now more than 2000 downloads world-wide. This app is now used for outreach activities across the UK, EU and USA.