We report the first double-differential cross section measurement of
neutral-current neutral pion (NC$\pi^0$) production in neutrino-argon
scattering, as well as single-differential measurements of ...the same channel in
terms of final states with and without protons. The kinematic variables of
interest for these measurements are the $\pi^0$ momentum and the $\pi^0$
scattering angle with respect to the neutrino beam. A total of 4971 candidate
NC$\pi^0$ events fully-contained within the MicroBooNE detector are selected
using data collected at a mean neutrino energy of $\sim 0.8$ GeV from
$6.4\times10^{20}$ protons on target from the Booster Neutrino Beam at the
Fermi National Accelerator Laboratory. After extensive data-driven model
validation to ensure unbiased unfolding, the Wiener-SVD method is used to
extract nominal flux-averaged cross sections. The results are compared to
predictions from commonly used neutrino event generators, which tend to
overpredict the measured NC$\pi^0$ cross section, especially in the 0.2-0.5
GeV/c $\pi^0$ momentum range, at forward scattering angles, and when at least
one proton is present in the final state. These measurements show sensitivity
to a variety of features that complicate the description of NC$\pi^0$
production including the form factors describing the elementary neutrino
interaction and the final state interactions of the outgoing particles in the
residual argon nucleus. This data will help improve the modeling of NC$\pi^0$
production, which represents a major background in measurements of
charge-parity violation in the neutrino sector and in searches for new physics
beyond the Standard Model.
A detailed understanding of inclusive muon neutrino charged-current
interactions on argon is crucial to the study of neutrino oscillations in
current and future experiments using liquid argon time ...projection chambers. To
that end, we report a comprehensive set of differential cross section
measurements for this channel that simultaneously probe the leptonic and
hadronic systems by dividing the channel into final states with and without
protons. Measurements of the proton kinematics and proton multiplicity of the
final state are also presented. For these measurements, we utilize data
collected with the MicroBooNE detector from 6.4$\times10^{20}$ protons on
target from the Fermilab Booster Neutrino Beam at a mean neutrino energy of
approximately 0.8 GeV. We present in detail the cross section extraction
procedure, including the unfolding, and model validation that uses data to
model comparisons and the conditional constraint formalism to detect
mismodeling that may introduce biases to extracted cross sections that are
larger than their uncertainties. The validation exposes insufficiencies in the
overall model, motivating the inclusion of an additional data-driven
reweighting systematic to ensure the accuracy of the unfolding. The extracted
results are compared to a number of event generators and their performance is
discussed with a focus on the regions of phase-space that indicate the greatest
need for modeling improvements.
The liquid argon time projection chamber (LArTPC) detector technology has an excellent capability to measure properties of low-energy neutrinos produced by the sun and supernovae and to look for ...exotic physics at very low energies. In order to achieve those physics goals, it is crucial to identify and reconstruct signals in the waveforms recorded on each TPC wire. In this paper, we report on a novel algorithm based on a one-dimensional convolutional neural network (CNN) to look for the region-of-interest (ROI) in raw waveforms. We test this algorithm using data from the ArgoNeuT experiment in conjunction with an improved noise mitigation procedure and a more realistic data-driven noise model for simulated events. This deep-learning ROI finder shows promising performance in extracting small signals and gives an efficiency approximately twice that of the traditional algorithm in the low energy region of \(\sim\)0.03-0.1 MeV. This method offers great potential to explore low-energy physics using LArTPCs.
Phys. Rev. Lett. 132, 151801 Published 10 April 2024 We present a measurement of $\eta$ production from neutrino interactions on
argon with the MicroBooNE detector. The modeling of resonant neutrino
...interactions on argon is a critical aspect of the neutrino oscillation physics
program being carried out by the DUNE and Short Baseline Neutrino programs.
$\eta$ production in neutrino interactions provides a powerful new probe of
resonant interactions, complementary to pion channels, and is particularly
suited to the study of higher-order resonances beyond the $\Delta(1232)$. We
measure a flux-integrated cross section for neutrino-induced $\eta$ production
on argon of $3.22 \pm 0.84 \; \textrm{(stat.)} \pm 0.86 \; \textrm{(syst.)}$
$10^{-41}{\textrm{cm}}^{2}$/nucleon. By demonstrating the successful
reconstruction of the two photons resulting from $\eta$ production, this
analysis enables a novel calibration technique for electromagnetic showers in
GeV accelerator neutrino experiments.
MicroBooNE is a neutrino experiment located in the Booster Neutrino Beamline
(BNB) at Fermilab, which collected data from 2015 to 2021. MicroBooNE's liquid
argon time projection chamber (LArTPC) is ...accompanied by a photon detection
system consisting of 32 photomultiplier tubes used to measure the argon
scintillation light and determine the timing of neutrino interactions. Analysis
techniques combining light signals and reconstructed tracks are applied to
achieve a neutrino interaction time resolution of $\mathcal{O}(1\,\text{ns})$.
The result obtained allows MicroBooNE to access the ns neutrino pulse structure
of the BNB for the first time. The timing resolution achieved will enable
significant enhancement of cosmic background rejection for all neutrino
analyses. Furthermore, the ns timing resolution opens new avenues to search for
long-lived-particles such as heavy neutral leptons in MicroBooNE, as well as in
future large LArTPC experiments, namely the SBN program and DUNE.
Phys. Rev. Lett. 127, 121801 (2021) A search for Heavy Neutral Leptons has been performed with the ArgoNeuT
detector exposed to the NuMI neutrino beam at Fermilab. We search for the decay
signature ...$N \to \nu \mu^+ \mu^-$, considering decays occurring both inside
ArgoNeuT and in the upstream cavern. In the data, corresponding to an exposure
to $1.25 \times 10^{20}$ POT, zero passing events are observed consistent with
the expected background. This measurement leads to a new constraint at 90\%
confidence level on the mixing angle $\left\vert U_{\tau N}\right\rvert^2$ of
tau-coupled Dirac Heavy Neutral Leptons with masses $m_N =$ 280 - 970 MeV,
assuming $\left\vert U_{eN}\right\rvert^2 = \left\vert U_{\mu N}\right\rvert^2
= 0$.
We present the first measurement of the cross section of Cabibbo-suppressed
$\Lambda$ baryon production, using data collected with the MicroBooNE detector
when exposed to the neutrinos from the Main ...Injector beam at the Fermi National
Accelerator Laboratory. The data analyzed correspond to $2.2 \times 10^{20}$
protons on target of neutrino mode running and $4.9 \times 10^{20}$ protons on
target of anti-neutrino mode running. An automated selection is combined with
hand scanning, with the former identifying five candidate $\Lambda$ production
events when the signal was unblinded, consistent with the GENIE prediction of
$5.3 \pm 1.1$ events. Several scanners were employed, selecting between three
and five events, compared with a prediction from a blinded Monte Carlo
simulation study of $3.7 \pm 1.0$ events. Restricting the phase space to only
include $\Lambda$ baryons that decay above MicroBooNE's detection thresholds,
we obtain a flux averaged cross section of $2.0^{+2.2}_{-1.7} \times 10^{-40}$
cm$^2/$Ar, where statistical and systematic uncertainties are combined.
In this letter we present the first measurements of an exclusive electron
neutrino cross section with the MicroBooNE experiment using data from the
Booster Neutrino Beamline at Fermilab. These ...measurements are made for a
selection of charged-current electron neutrinos without final-state pions.
Differential cross sections are extracted in energy and angle with respect to
the beam for the electron and the leading proton. The differential cross
section as a function of proton energy is measured using events with protons
both above and below the visibility threshold. This is done by including a
separate selection of electron neutrino events without reconstructed proton
candidates in addition to those with proton candidates. Results are compared to
the predictions from several modern generators, and we find the data agrees
well with these models. The data shows best agreement, as quantified by
$p$-value, with the generators that predict a lower overall cross section, such
as GENIE v3 and NuWro.
A search for millicharged particles, a simple extension of the standard model, has been performed with the ArgoNeuT detector exposed to the Neutrinos at the Main Injector beam at Fermilab. The ...ArgoNeuT Liquid Argon Time Projection Chamber detector enables a search for millicharged particles through the detection of visible electron recoils. We search for an event signature with two soft hits (MeV-scale energy depositions) aligned with the upstream target. For an exposure of the detector of \(1.0\) \(\times\) \(10^{20}\) protons on target, one candidate event has been observed, compatible with the expected background. This search is sensitive to millicharged particles with charges between \(10^{-3}e\) and \(10^{-1}e\) and with masses in the range from \(0.1\) GeV to \(3\) GeV. This measurement provides leading constraints on millicharged particles in this large unexplored parameter space region.
We report the first electron neutrino cross section measurements on argon, based on data collected by the ArgoNeuT experiment running in the GeV-scale NuMI beamline at Fermilab. A flux-averaged ...\(\nu_e + \overline{\nu}_e\) total and a lepton angle differential cross section are extracted using 13 \(\nu_e\) and \(\overline{\nu}_e\) events identified with fully-automated selection and reconstruction. We employ electromagnetic-induced shower characterization and analysis tools developed to identify \(\nu_e/\overline{\nu}_e\)-like events among complex interaction topologies present in ArgoNeuT data (\(\langle E_{\bar{\nu}_e} \rangle = 4.3\) GeV and \(\langle E_{\nu_e} \rangle = 10.5\) GeV). The techniques are widely applicable to searches for electron-flavor appearance at short- and long-baseline using liquid argon time projection chamber technology. Notably, the data-driven studies of GeV-scale \(\nu_e/\overline{\nu}_e\) interactions presented in this Letter probe an energy regime relevant for future DUNE oscillation physics.
