MicroBooNE is a neutrino experiment that utilizes a liquid argon time projection chamber (LArTPC) located on-axis in the Booster Neutrino Beam (BNB) at Fermilab. One of the experiment's main goals is to search for excess low-energy electromagnetic-like events as seen by the MiniBooNE experiment, located just downstream of MicroBooNE in the BNB. As MicroBooNE nears the completion of its first single-electron-like and single-photon-like searches, these proceedings present the status of MicroBooNE's low-energy excess search as of early summer 2020. In addition to presenting an overview of the approach to the analysis, we showcase results from $π^0$ calibrations and e/$γ$ separation, and sample results from sidebands aimed at validating the analysis' progress outside the low-energy signal region.
The MicroBooNE experiment is an upcoming liquid argon TPC experiment which will pursue a program of short baseline neutrino physics in the Fermilab Booster Neutrino Beam, starting in early 2014. I give a description of the experiment and review the current status of various aspects of the MicroBooNE detector.
Recently, MiniBooNE observed an electromagnetic excess at low energy. What is the nature of this excess? What about the nature of the low-energy excess at LSND 20 years ago? The MicroBooNE detector will see neutrinos from the same Booster beam at Fermilab as used by MiniBooNE. MicroBooNE's design will enable us to discriminate photons from electrons elucidating the MiniBooNE and LSND low-energy electromagnetic excesses. MicroBooNE is a 170 ton liquid argon time projection chamber (LArTPC) capable of imaging neutrino interactions with the detail of a bubble chamber, but with electronic data acq…
This thesis describes an analysis developed for the MicroBooNE experiment to investigate an anomalous excess of electron-like events observed in the MiniBooNE detector. The hypothesis investigated here is that the MiniBooNE anomaly represents appearance of electron neutrinos. Using an amalgam of novel Deep Learning and standard algorithmic techniques this analysis reconstructs and identifies a highly pure sample of charged current quasi-elastic muon neutrino and electron neutrino interactions. This thesis describes the steps in the analysis chain and provides data-to-simulation comparisons for…
MicroBooNE (the Micro Booster Neutrino Experiment) is a liquid argon time-projection chamber (TPC) experiment designed for short-baseline neutrino physics, currently running at Fermilab. It aims to address the anomalous excess of low-energy events observed by the MiniBooNE experiment. Recent progress towards the search for the low-energy events have brought to develop fully automated event selection algorithm to identify charged-current electron neutrino event candidates with no pions and at least one proton in the final state ($ν_e~\text{CC} 0π\text{N}p$) using the Pandora multi-algorithm pat…
MicroBooNE is a neutrino experiment based at Fermilab which consists of a liquid argon time-projection chamber in the Booster Neutrino Beam (BNB). The experiment aims to investigate the excess of electron-neutrino-like events seen by the MiniBooNE experiment, also located in the BNB, which is potential evidence for new non-Standard Model physics such as sterile neutrinos. I discuss the status of a search for low-energy electron-neutrino interactions within the MicroBooNE detector. This analysis features a hybrid approach of traditional reconstruction methods along with the use of convolutional…
A new generation of neutrino experiments is testing the $4.8σ$ anomalous excess of electron-like events observed in MiniBooNE. This is of huge importance for particle physics, astrophysics, and cosmology, not only because of the potential discovery of physics beyond the Standard Model, but also because the lessons we will learn about neutrino-nucleus interactions will be crucial for the worldwide neutrino program. MicroBooNE has recently released results that appear to disfavor several explanations of the MiniBooNE anomaly. Here, we show quantitatively that MicroBooNE results, while a promisin…
MicroBooNE is a liquid-argon-based neutrino experiment, which began collecting data in Fermilab's Booster neutrino beam in October 2015. Physics goals of the experiment include probing the source of the anomalous excess of electron-like events in MiniBooNE. In addition to this, MicroBooNE is carrying out an extensive cross section physics program that will help to probe current theories on neutrino-nucleon interactions and nuclear effects. These proceedings summarise the status of MicroBooNE's neutrino cross section analyses.
MicroBooNE is a neutrino experiment located on axis in the Booster Neutrino Beamline, at Fermi National Accelerator Laboratory, scheduled to begin data collection in 2014. The MicroBooNE detector consists of two main components: a large liquid argon time projection chamber (LArTPC), and a light collection system. Thirty two 8-inch diameter cryogenic photomultiplier tubes (PMTs) will detect the scintillation light generated in the liquid argon. In this article, we describe the basic features of the system and current status of MicroBooNE light collection system.
The MicroBooNE experiment is a 170 ton Liquid Argon Time Projection Chamber (LArTPC) that will begin running at Fermilab in 2013. Its primary physics goal is to explore the low energy excess of events seen by the MiniBooNE experiment and it is the next step in the R&D to make LAr a viable option for future large neutrino detectors. This talk presented an overview of the MicroBooNE experiment with an emphasis on the light collection system and recent technical advances.
The strong statistical significance of an observed electron-like event excess in the MiniBooNE (MB) experiment, along with an earlier similar excess seen in the Liquid Scintillator Neutrino Detector (LSND), when interpreted in conjunction with recent MicroBooNE results may have brought us to the cusp of new physics discoveries. This has led to many attempts to understand these observations, both for each experiment individually and in conjunction, via physics beyond the Standard Model (SM). We provide an overview of the current situation, and discuss three major categories under which the many…
A good understanding of the cross sections for neutrino interactions with nucleons and nuclei is crucial for neutrino oscillation studies, in addition to providing a tool for the exploration of nucleon and nuclear structures. The MicroBooNE liquid-argon time-projection-chamber (LArTPC) experiment has been taking neutrino data with the Booster Neutrino Beam at Fermilab since 2015. The LArTPC capabilities in track reconstruction, energy measurement, and particle identification allow us to probe interesting regions of neutrino-argon scattering cross sections and to probe the quark composition of …
Implications for new physics solutions to the LSND and MiniBooNE anomalies after MicroBooNE results
Cairo University（开罗大学）；Harish-Chandra Research Institute（哈里什-昌德拉研究所）；Amity School of Engineering and Technology, Amity University Hyderabad（海德拉巴阿米蒂大学工程与技术学院）；School of Physics, University of Hyderabad（海德拉巴大学物理学院）
The MicroBooNE Experiment at the Fermi National Accelerator Laboratory, an 89-ton active mass liquid argon time projection chamber, affords a unique opportunity to observe low-$Q^2$ neutral-current neutrino-proton scattering events. Neutral-current neutrino-proton scattering at $Q^2 < 1$ GeV$^2$ is dominated by the proton's axial form factor, which can be written as a combination of contributions from the up, down, and strange quarks: $G_A(Q^2) = \frac{1}{2}[-G_A^u(Q^2)+G_A^d(Q^2)+G_A^s(Q^2)]$. The contribution from up and down quarks has been established in past charged-current measurements. …
This article presents a measurement of $ν_e$ interactions without pions in the final state using the MicroBooNE experiment and an investigation into the excess of low-energy electromagnetic events observed by the MiniBooNE collaboration. The measurement is performed in exclusive channels with (1$e$N$p$0$π$) and without (1$e$0$p$0$π$) visible final-state protons using 6.86$\times 10^{20}$ protons on target of data collected from the Booster Neutrino Beam at Fermilab. Events are reconstructed with the Pandora pattern recognition toolkit and selected using additional topological information from …
MicroBooNE (the Micro Booster Neutrino Experiment) is a short-baseline neutrino experiment based on the technology of a liquid-argon time-projection chamber (LArTPC), and has recently completed its first year of data-taking in the Fermilab Booster Neutrino Beam. It aims to address the anomalous excess of events with an electromagnetic final state in MiniBooNE, to measure neutrino-argon interaction cross sections, and to provide relevant R\&D for the future LArTPC experiments, such as DUNE. In these proceedings, we present the first reconstructed energy spectrum of Michel electrons from cosmic …
We present a measurement of the $ν_e$-interaction rate in the MicroBooNE detector that addresses the observed MiniBooNE anomalous low-energy excess (LEE). The approach taken isolates neutrino interactions consistent with the kinematics of charged-current quasi-elastic (CCQE) events. The topology of such signal events has a final state with 1 electron, 1 proton, and 0 mesons ($1e1p$). Multiple novel techniques are employed to identify a $1e1p$ final state, including particle identification that use two methods of deep-learning-based image identification, and event isolation using a boosted deci…
The MiniBooNE experiment reported results from the analysis of $ν_e$ and $\overlineν_e$ appearance searches, which showed an excess of signal-like events at low reconstructed neutrino energies with respect to the expected background. A proposed explanation for this anomaly is based on the existence of a heavy ($\sim 50$~MeV) sterile neutrino. These $ν_h$ would be produced by $ν_μ$ electromagnetic and neutral current interactions. A fraction of them decays radiatively inside the detector. The emitted photon is misidentified as an electron or positron in MiniBooNE. We have investigated the $ν_h$…
We report results from a search for neutrino-induced neutral current (NC) resonant $Δ$(1232) baryon production followed by $Δ$ radiative decay, with a $\langle0.8\rangle$~GeV neutrino beam. Data corresponding to MicroBooNE's first three years of operations (6.80$\times$10$^{20}$ protons on target) are used to select single-photon events with one or zero protons and without charged leptons in the final state ($1\gamma1p$ and $1\gamma0p$, respectively). The background is constrained via an in-situ high-purity measurement of NC $π^0$ events, made possible via dedicated $2\gamma1p$ and $2\gamma0p$…
We report a search for an anomalous excess of inclusive charged-current (CC) $ν_e$ interactions using the Wire-Cell event reconstruction package in the MicroBooNE experiment, which is motivated by the previous observation of a low-energy excess (LEE) of electromagnetic events from the MiniBooNE experiment. With a single liquid argon time projection chamber detector, the measurements of $ν_μ$ CC interactions as well as $π^0$ interactions are used to constrain signal and background predictions of $ν_e$ CC interactions. A data set collected from February 2016 to July 2018 corresponding to an expo…
Heavy neutral leptons ($N$) below the kaon mass are severely constrained by cosmology and lab-based searches for their decays in flight. If $N$ interacts via an additional force, $N\toνe^+e^-$ decays are enhanced and cosmological limits can be avoided. We show that the T2K and MicroBooNE neutrino experiments provide the best limits on the mixing of $N$ with muon-neutrinos, outperforming past-generation experiments, previously thought to dominate. We constrain models with electromagnetically-decaying and long-lived $N$, such as in a transition-magnetic-moment portal and in a leptophilic axion-l…
Inclusive Search for Anomalous Single-Photon Production in MicroBooNE
Tufts University（塔夫茨大学）；Illinois Institute of Technology (IIT)（伊利诺伊理工学院）；The University of Manchester（曼彻斯特大学）；University of Texas, Arlington（德克萨斯大学阿灵顿分校）；Tel Aviv University（特拉维夫大学）；Fermi National Accelerator Laboratory (FNAL)（费米国家加速器实验室）；University of Oxford（牛津大学）；University of Minnesota（明尼苏达大学）；Imperial College London（伦敦帝国学院）；Michigan State University（密歇根州立大学）；University of Chicago（芝加哥大学）；Brookhaven National Laboratory (BNL)（布鲁克海文国家实验室）；Lancaster University（兰卡斯特大学）
We propose the addition of scintillator to the existing MiniBooNE detector to allow a test of the neutral-current/charged-current (NC/CC) nature of the MiniBooNE low-energy excess. Scintillator will enable the reconstruction of 2.2 MeV $γ$s from neutron-capture on protons following neutrino interactions. Low-energy CC interactions where the oscillation excess is observed should have associated neutrons with less than a 10% probability. This is in contrast to the NC backgrounds that should have associated neutrons in approximately 50% of events. We will measure these neutron fractions with $ν_μ…
The Short-Baseline Neutrino (SBN) Program is a short-baseline neutrino oscillation experiment in the Booster Neutrino Beam-line (BNB) at Fermilab. It consists of three Liquid Argon Time Projection Chambers (LArTPCs) from the Short-Baseline Near Detector (SBND), Micro Booster Neutrino Experiment (MicroBooNE), and Imaging Cosmic And Rare Underground Signals (ICARUS) experiments. The SBN Program will definitively search for short-baseline neutrino oscillations in the 1 eV mass range, make precision neutrino-argon interaction measurements, and further develop the LArTPC technology. The physics pro…
The low-noise operation of readout electronics in a liquid argon time projection chamber (LArTPC) is critical to properly extract the distribution of ionization charge deposited on the wire planes of the TPC, especially for the induction planes. This paper describes the characteristics and mitigation of the observed noise in the MicroBooNE detector. The MicroBooNE's single-phase LArTPC comprises two induction planes and one collection sense wire plane with a total of 8256 wires. Current induced on each TPC wire is amplified and shaped by custom low-power, low-noise ASICs immersed in the liquid…
Reactor neutrinos have been an intense field of investigation for the last decade. Two anomalies are discussed in this document. First, a status of the sterile neutrino searches by STEREO, PROSPECT and DANSS is presented. The best-fit parameters of active-to-sterile oscillations from the Reactor Antineutrino Anomaly are strongly rejected by these experiments. Second, the analyses of the shape anomaly ("5 MeV bump") by STEREO and PROSPECT, both using a virtually pure-$^{235}$U neutrino flux, are detailed. Results show a significant excess of events at 5-6 MeV and indicate that the bump observed…
The status of the solar axion search with the CERN Axion Solar Telescope (CAST) will be discussed. Results from the first part of CAST phase II where the magnet bores were filled with 4He gas at variable pressure in order to scan axion masses up to 0.4 eV will be presented. From the absence of excess X-rays when the magnet was pointing to the Sun, we set a typical upper limit on the axion-photon coupling of g < 2.17 x 10^10 GeV$-1 at 95% CL for axion masses lower than 0.4 eV, the exact result depending on the pressure setting. Our search for axions with masses up to about 1.2 eV using 3He as a…
The status of the solar axion search with the CERN Axion Solar Telescope (CAST) will be discussed. Results from the first part of CAST phase II where the magnet bores were filled with \hefour gas at variable pressure in order to scan \ma up to 0.4 eV will be presented. From the absence of excess X-rays when the magnet was pointing to the Sun, we set a typical upper limit on the axion-photon coupling of $\gag \lesssim 2.17 \times10^{-10}$GeV$^{-1}$ at 95% CL for \ma$<0.4$ eV, the exact result depending on the pressure setting. Our search for axions with masses up to about 1.2 eV using \hethree …
The MiniBooNE Experiment has contributed substantially to beyond standard model searches in the neutrino sector. The experiment was originally designed to test the $Δm^2$~1 eV$^2$ region of the sterile neutrino hypothesis by observing $ν_e$ ($\barν_e$) charged current quasi-elastic signals from a $ν_μ$ ($\barν_μ$) beam. MiniBooNE observed excesses of $ν_e$ and $\barν_e$-candidate events in neutrino and anti-neutrino mode, respectively. To date, these excesses have not been explained within the neutrino Standard Model ($ν$SM), the Standard Model extended for three massive neutrinos. Confirmatio…
We present a search for the decays of a neutral scalar boson produced by kaons decaying at rest, in the context of the Higgs portal model, using the MicroBooNE detector. We analyze data triggered in time with the Fermilab NuMI neutrino beam spill, with an exposure of $1.93\times10^{20}$ protons on target. We look for monoenergetic scalars that come from the direction of the NuMI hadron absorber, at a distance of 100 m from the detector, and decay to electron-positron pairs. We observe one candidate event, with a Standard Model background prediction of $1.9\pm0.8$. We set an upper limit on the …
A number of short baseline neutrino oscillation experiments have observed an anomalous excess of neutrinos in the low energy range. This may hint towards the existence of additional neutrino mass splittings. If true, additional sterile (non-interacting) neutrino states above the current 3 neutrino model would be required. On the other hand, many parameters of the allowed space are limited by experiments that have seen no anomaly. We will introduce models which accommodate these additional neutrinos, and then discuss our work towards fitting these models to the available global high $Δm^{2}$ os…
First application of a liquid argon time projection chamber for the search for intranuclear neutron-antineutron transitions and annihilation in $^{40}$Ar using the MicroBooNE detector
In this paper, we study the extended Standard Model (SM) with an extra Higgs doublet and right-handed neutrinos. If the symmetry to distinguish the two Higgs doublets is not assigned, flavor changing neutral currents (FCNCs) involving the scalars are predicted even at the tree level. We investigate the constraints on the FCNCs at the one-loop level, and especially study the semileptonic $B$ meson decays, e.g. $B \to D^{(*)} τν$ and $B \to K^{(*)} ll$ processes, where the SM predictions are more than $2 σ$ away from the experimental results. We also consider the flavor-violating couplings invol…
This article summarises a talk given at the 2014 Palermo workshop on Astrophysics. It covers a short review on the neutrino physics status and the potential physics opportunities of future experiments. During the last year our knowledge on the neutrino oscillation parameter $\sin^2θ_{13}$ improved dramatically, and the large value opened the way to oscillation experiments sensitive to possible CP-violation. The first high-energetic neutrinos in the TeV range were detected in the IceCube experiment, while the Planck collaboration set further limits on the number of active neutrinos from cosmolo…
The excess of electron-like events measured by MiniBooNE challenges our understanding of neutrinos and their interactions. We review the status of this open problem and ongoing efforts to resolve it. After introducing the experiment and its results, we consider the main experimental backgrounds and the related physics of neutrino interactions with matter such as quasielastic-like scattering and weak pion production on nucleons and nuclei. Special attention is paid to single photon emission in neutral current interactions and, in particular, its coherent channel. The difficulties to reconcile t…
