Search

Wire-Cell is a 3D event reconstruction package for liquid argon time projection chambers. Through geometry, time, and drifted charge from multiple readout wire planes, 3D space points with associated charge are reconstructed prior to the pattern recognition stage. Pattern recognition techniques, including track trajectory and dQ/dx (ionization charge per unit length) fitting, 3D neutrino vertex fitting, track and shower separation, particle-level clustering, and particle identification are then applied on these 3D space points as well as the original 2D projection measurements. A deep neural network is developed to enhance the reconstruction of the neutrino interaction vertex. Compared to traditional algorithms, the deep neural network boosts the vertex efficiency by a relative 30% for charged-current νe interactions. This pattern recognition achieves 80–90% reconstruction efficiencies for primary leptons, after a 65.8% (72.9%) vertex efficiency for charged-current νe (νμ) interactions. Based on the resulting reconstructed particles and their kinematics, we also achieve 15-20% energy reconstruction resolutions for charged-current neutrino interactions.

This article presents the reconstruction of the electromagnetic activity from electrons and photons (showers) used in the MicroBooNE deep learning-based low energy electron search. The reconstruction algorithm uses a combination of traditional and deep learning-based techniques to estimate shower energies. We validate these predictions using two $\nu_{\mu}$-sourced data samples: charged/neutral current interactions with final state neutral pions and charged current interactions in which the muon stops and decays within the detector producing a Michel electron. Both the neutral pion sample and Michel electron sample demonstrate agreement between data and simulation. Further, the absolute shower energy scale is shown to be consistent with the relevant physical constant of each sample: the neutral pion mass peak and the Michel energy cutoff., Comment: 27 pages; matches published version

Employing an 800 MeV, high-intensity proton beam, the LSND experiment performed a sensitive search for neutrino oscillations and obtained evidence for ν μ → ν e flavor change. Although the KARMEN experiment observed no such evidence, a joint analysis of the two experiments shows that the data sets are compatible with neutrino oscillations occurring either in a band from 0.2 to 1 eV 2 or in a region around 7 eV 2. The MiniBooNE experiment at Fermilab was designed to test the LSND evidence for neutrino oscillations [C. Athanassopoulos et al., Phys. Rev. Lett. 75, 2650 (1995); 77, 3082 (1996); 81, 1774 (1998); A. Aguilar et al., Phys. Rev. D 64, 112007 (2001)]. The MiniBooNE oscillation result in neutrino mode [A. Aguilar-Arevalo et al., Phys. Rev. Lett. 98, 231801 (2007); A. Aguilar-Arevalo et al. arXiv:0812.2243 ] shows no significant excess of events at higher energies ( E ν > 475 MeV ), although a sizeable excess is observed at lower energies ( E ν 475 MeV ). The lack of a significant excess at higher energies allows MiniBooNE to rule out simple 2 − ν oscillations as an explanation of the LSND signal. However, the low-energy excess is presently unexplained. Additional antineutrino data and NuMI data may allow the collaboration to determine whether the excess is due, for example, to a neutrino neutral-current radiative interaction or to neutrino oscillations involving sterile neutrinos and whether the excess is related to the LSND signal. If the excess is consistent with being due to sterile neutrinos or other new physics, then future experiments at FNAL (MicroBooNE & BooNE) or ORNL (OscSNS) or with the Low-Energy Neutrino Spectrometer (LENS) detector could confirm their existence.

The LSND experiment at Los Alamos has conducted searches for {anti {nu}}{sub {mu}} {r_arrow} {anti {nu}}{sub e} oscillations using {anti {nu}}{sub {mu}} from {mu}{sup +} decay at rest and for {nu}{sub {mu}} {r_arrow} {nu}{sub e} oscillations using {nu}{sub {mu}} from {pi}{sup +} decay in flight. For the {anti {nu}}{sub {mu}} {r_arrow} {anti {nu}}{sub e} search, a total excess of 51.8{sub {minus}16.9}{sup +18.7} {+-} 8.0 events is observed with e{sup +} energy between 20 and 60 MeV, while for the {nu}{sub mu} {r_arrow} {nu}{sub e} search, a total excess of 18.1 {+-} 6.6 {+-} 4.0 events is observed with e{sup {minus}} energy between 60 and 200 MeV. If attributed to neutrino oscillations, these excesses correspond to oscillation probabilities (averaged over the experimental energies and spatial acceptances) of (0.31 {+-} 0.12 {+-} 0.05)% and (0.26 {+-} 0.10 {+-} 0.05)%, respectively. For the future, the BooNE experiment at Fermilab could prove that neutrino oscillations occur and make precision measurements of {Delta}m{sup 2} and sin{sup 2}2{theta}.

A search for {anti v}{sub {mu}} {yields} {anti v}{sub e} oscillations has been made by the Liquid Scintillator Neutrino Detector experiment at LAMPF after an initial month and a half run. The experiment observes eight events consistent with the reaction {anti v}{sub e}p {yields} e{sup +}n followed by np {yields} d{gamma} (2.2 MeV). The total estimated background is 0.9{plus_minus}0.2 events.

Dilute scintillation mixtures emit isotropic light for both fast and slow particles, but retain the Cherenkov light cone from fast particles. Large volume detectors using photomultipliers to reconstruct relativistic tracks will also be sensitive to slow particles if they are filled with these mixtures. Our data show that 0.03 g/l of b-PBD in mineral oil has a 2.4:1 ratio (in the first 12 ns) of isotropic light to Cherenkov light for positron tracks. The light attenuation length is greater than 15 m for wavelength above 400 nm, and the scintillation decay time is about 2 ns for the fast component. There is also a slow isotropic light component that is larger (relative to the fast component) for protons than for electrons. This effect allows particle identification by a technique similar to pulse shape discrimination. These features will be utilized in LSND, a neutrino detector at LAMPF.

The Liquid Scintillator Neutrino Detector (LSND), located at the LANSCE (formerly LAMPF) linear accelerator at Los Alamos National Laboratory, has seen evidence for the oscillation of neutrinos, and hence neutrino mass. That discovery was the impetus for this LDRD project, begun in 1996. The goal of this project was to define the appropriate technologies to use in a follow up experiment and to set in place the requirements for such an experiment.

In the past several years, a number of experiments have searched for neutrino oscillations, where a neutrino of one type (say {bar {nu}}{sub {mu}}) spontaneously transforms into a neutrino of another type (say {bar {nu}}{sub e}). For this phenomenon to occur, neutrinos must be massive and the apparent conservation law of lepton families must be violated. In 1995 the LSND experiment published data showing candidate events that are consistent with {bar {nu}}{sub {mu}} oscillations. Additional data are reported here which provide stronger evidence for neutrino oscillations.