The single-phase liquid argon time projection chamber (LArTPC) provides a large amount of detailed information in the form of fine-grained drifted ionization charge from particle traces. To fully ...utilize this information, the deposited charge must be accurately extracted from the raw digitized waveforms via a robust signal processing chain. Enabled by the ultra-low noise levels associated with cryogenic electronics in the MicroBooNE detector, the precise extraction of ionization charge from the induction wire planes in a single-phase LArTPC is qualitatively demonstrated on MicroBooNE data with event display images, and quantitatively demonstrated via waveform-level and track-level metrics. Improved performance of induction plane calorimetry is demonstrated through the agreement of extracted ionization charge measurements across different wire planes for various event topologies. In addition to the comprehensive waveform-level comparison of data and simulation, a calibration of the cryogenic electronics response is presented and solutions to various MicroBooNE-specific TPC issues are discussed. This work presents an important improvement in LArTPC signal processing, the foundation of reconstruction and therefore physics analyses in MicroBooNE.
We report the first measurement of monoenergetic muon neutrino charged current interactions. MiniBooNE has isolated 236 MeV muon neutrino events originating from charged kaon decay at rest ...(K^{+}→μ^{+}ν_{μ}) at the NuMI beamline absorber. These signal ν_{μ}-carbon events are distinguished from primarily pion decay in flight ν_{μ} and νover ¯_{μ} backgrounds produced at the target station and decay pipe using their arrival time and reconstructed muon energy. The significance of the signal observation is at the 3.9σ level. The muon kinetic energy, neutrino-nucleus energy transfer (ω=E_{ν}-E_{μ}), and total cross section for these events are extracted. This result is the first known-energy, weak-interaction-only probe of the nucleus to yield a measurement of ω using neutrinos, a quantity thus far only accessible through electron scattering.
We describe a method used to calibrate the position- and time-dependent response of the MicroBooNE liquid argon time projection chamber anode wires to ionization particle energy loss. The method ...makes use of crossing cosmic-ray muons to partially correct anode wire signals for multiple effects as a function of time and position, including cross-connected TPC wires, space charge effects, electron attachment to impurities, diffusion, and recombination. The overall energy scale is then determined using fully-contained beam-induced muons originating and stopping in the active region of the detector. Using this method, we obtain an absolute energy scale uncertainty of 2% in data. We use stopping protons to further refine the relation between the measured charge and the energy loss for highly-ionizing particles. This data-driven detector calibration improves both the measurement of total deposited energy and particle identification based on energy loss per unit length as a function of residual range. As an example, the proton selection efficiency is increased by 2% after detector calibration.
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 argon. The digitization of the signal waveform occurs outside the cryostat. Using data from the first year of MicroBooNE operations, several excess noise sources in the TPC were identified and mitigated. The residual equivalent noise charge (ENC) after noise filtering varies with wire length and is found to be below 400 electrons for the longest wires (4.7m). The response is consistent with the cold electronics design expectations and is found to be stable with time and uniform over the functioning channels. This noise level is significantly lower than previous experiments utilizing warm front-end electronics.
We present an extended problem appropriate for students in a semester-long introductory elementary particle physics class. This problem requires them to synthesize concepts and investigative ...approaches learned throughout the class, directed toward answering the question of why muon-to-electron conversion experiments are proposed, but not electron-to-muon experiments. Although direct electron-to-muon decays are kinematically forbidden, the production of muons via the interaction of electron and photon beams is kinematically allowed, so why not propose such an experiment? In the analysis presented here, we set forth a model approach that guides students through exploration of the design of such a proposed experiment. As part of the discussion, we identify an obstacle that makes doing an experiment of this kind prohibitively difficult.
We present an extended problem appropriate for students in a semester-long introductory elementary particle physics class. This problem requires them to synthesize concepts and investigative ...approaches learned throughout the class, directed toward answering the question of why muon-to-electron conversion experiments are proposed, but not electron-to-muon experiments. Although direct electron-to-muon decays are kinematically forbidden, the production of muons via the interaction of electron and photon beams is kinematically allowed, so why not propose such an experiment? In the analysis presented here, we set forth a model approach that guides students through exploration of the design of such a proposed experiment. As part of the discussion, we identify an obstacle that makes doing an experiment of this kind prohibitively difficult.
Liquid argon time projection chambers (LArTPCs) are now a standard detector technology for making accelerator neutrino measurements, due to their high material density, precise tracking, and ...calorimetric capabilities. An electric field (E-field) is required in such detectors to drift ionization electrons to the anode where they are collected. The E-field of a TPC is often approximated to be uniform between the anode and the cathode planes. However, significant distortions can appear from effects such as mechanical deformations, electrode failures, or the accumulation of space charge generated by cosmic rays. The latter effect is particularly relevant for detectors placed near the Earth's surface and with large drift distances and long drift time. To determine the E-field in situ, an ultraviolet (UV) laser system is installed in the MicroBooNE experiment at Fermi National Accelerator Laboratory. The purpose of this system is to provide precise measurements of the E-field, and to make it possible to correct for 3D spatial distortions due to E-field non-uniformities. Here we describe the methodology developed for deriving spatial distortions, the drift velocity and the E-field from UV-laser measurements.
Cosmic ray (CR) interactions can be a challenging source of background for neutrino oscillation and cross-section measurements in surface detectors. We present methods for CR rejection in ...measurements of charged-current quasielastic-like (CCQE-like) neutrino interactions, with a muon and a proton in the final state, measured using liquid argon time projection chambers (LArTPCs). Using a sample of cosmic data collected with the MicroBooNE detector, mixed with simulated neutrino scattering events, a set of event selection criteria is developed that produces an event sample with minimal contribution from CR background. Depending on the selection criteria used a purity between 50 and 80% can be achieved with a signal selection efficiency between 50 and 25%, with higher purity coming at the expense of lower efficiency. While using a specific dataset and selection criteria values optimized for the MicroBooNE detector, the concepts presented here are generic and can be adapted for various studies of exclusive
ν
μ
CCQE interactions in LArTPCs.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
An accurate and efficient event reconstruction is required
to realize the full scientific capability of liquid argon time
projection chambers (LArTPCs). The current and future neutrino
...experiments that rely on massive LArTPCs create a need for new ideas
and reconstruction approaches. Wire-Cell, proposed in recent years,
is a novel tomographic event reconstruction method for LArTPCs. The
Wire-Cell 3D imaging approach capitalizes on charge, sparsity, time,
and geometry information to reconstruct a topology-agnostic 3D image
of the ionization electrons prior to pattern recognition. A second
novel method, the many-to-many charge-light matching, then pairs the
TPC charge activity to the detected scintillation light signal, thus
enabling a powerful rejection of cosmic-ray muons in the MicroBooNE
detector. A robust processing of the scintillation light signal and
an appropriate clustering of the reconstructed 3D image are
fundamental to this technique. In this paper, we describe the
principles and algorithms of these techniques and their successful
application in the MicroBooNE experiment. A quantitative evaluation
of the performance of these techniques is presented. Using these
techniques, a 95% efficient pre-selection of neutrino
charged-current events is achieved with a 30-fold reduction of
non-beam-coincident cosmic-ray muons, and about 80% of the selected
neutrino charged-current events are reconstructed with at least 70%
completeness and 80% purity.
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![Why not an e [arrow right] ...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/0002-9505/small "Why not an e [arrow right] [mu] experiment? An extended exercise for students studying introductory particle physics")
