LAr TPC Detectors Research Articles

Unpaired Image Translation to Mitigate Domain Shift in Liquid Argon Time Projection Chamber Detector Responses

Abstract Deep learning algorithms often are developed and trained on a training dataset and deployed on test datasets. Any systematic difference between the training and a test dataset may severely degrade the final algorithm performance on the test dataset -- what is known as the domain shift problem. This issue is prevalent in many scientific domains where algorithms are trained on simulated data but applied to real-world datasets. Typically, the domain shift problem is solved through various domain adaptation methods. However, these methods are often tailored to a specific downstream task and may not easily generalize to different tasks. This work explores the feasibility of using an alternative way to solve the domain shift problem that is not specific to any downstream algorithm. The proposed approach relies on modern Unpaired Image-to-Image translation techniques, designed to find translations between different image domains in a fully unsupervised fashion. In this study, the approach is applied to a domain shift problem commonly encountered in Liquid Argon Time Projection Chamber detector research when seeking a way to translate samples between two differently distributed LArTPC detector datasets deterministically. This translation allows for mapping real-world data into the simulated data domain where the downstream algorithms can be run with much less domain-shift-related performance degradation. Conversely, using the translation from the simulated data in a real-world domain can increase the realism of the simulated dataset and reduce the magnitude of any systematic uncertainties. We adapted several popular UI2I translation algorithms to work on scientific data and demonstrated the viability of these techniques for solving the domain shift problem with LArTPC detector data. To facilitate further development of domain adaptation techniques for scientific datasets, the "Simple Liquid-Argon Track Samples" (SLATS) dataset used in this study also is published.

Directional neutrino searches for Galactic Center dark matter at large underground LArTPCs

We investigate the sensitivity of a large, underground LArTPC-based neutrino detector to dark matter in the Galactic Center annihilating into neutrinos. Such a detector could have the ability to resolve the direction of the electron in a neutrino scattering event, and thus to infer information about the source direction for individual neutrino events. We consider the improvements on the expected experimental sensitivity that this directional information would provide. Even without directional information, we find a DUNE-like LArTPC detector is capable of setting limits on dark matter annihilation to neutrinos for dark matter masses above 30 MeV that are competitive with or exceed current experimental reach. While currently-demonstrated angular resolution for low-energy electrons is insufficient to allow any significant increase in sensitivity, these techniques could benefit from improvements to algorithms and the additional spatial information provided by novel 3D charge imaging approaches. We consider the impact of such enhancements to the resolution for electron directionality, and find that where electron-scattering events can be distinguished from charged-current neutrino interactions, limits on dark matter annihilation in the mass range where solar neutrino backgrounds dominate ($\lesssim 15$ MeV) can be significantly improved using directional information, and would be competitive with existing limits using $40$ kton$\times$year of exposure.

A hybrid 3D/2D field response calculation for liquid argon detectors with PCB based anode plane

Liquid Argon Time Projection Chamber (LArTPC) technology is commonly utilized in neutrino detector designs. It enables detailed reconstruction of neutrino events with high spatial precision and low energy threshold. Its field response (FR) model describes the time-dependent electric currents induced in the anode-plane electrodes when ionization electrons drift nearby. An accurate and precise FR is a crucial input to LArTPC detector simulations and charge reconstruction. Established LArTPC designs have been based on parallel wire planes. It allows accurate and computationally economic two-dimensional (2D) FR models utilizing the translational symmetry along the direction of the wires. Recently, novel LArTPC designs utilize electrodes formed on printed circuit board (PCB) in the shape of strips with through holes. The translational symmetry is no longer a good approximation near the electrodes and a new FR calculation that employs regions with three dimensions (3D) has been developed. Extending the 2D models to 3D would be computationally expensive. Fortuitously, the nature of strips with through holes allows for a computationally economic approach based on the finite-difference method (FDM). In this paper, we present a new software package pochoir that calculates LArTPC field response for these new strip-based anode designs. This package combines 3D calculations in the volume near the electrodes with 2D far-field solutions to achieve fast and precise field response computation. We apply the resulting FR to simulate and reconstruct samples of cosmic-ray muons and 39Ar decays from a Vertical Drift (VD) detector prototype operated at CERN. We find the difference between real and simulated data within 5%. Current state-of-the-art LArTPC software requires a 2D FR which we provide by averaging over one dimension and estimate that variations lost in this average are smaller than 7%.

Parameterization of electron attachment rate constants for impurities in LArTPC detectors

The ability of free electrons to drift long distances at high velocities in pure liquid argon under an applied electric field has been exploited for the past forty years to implement detectors with increasingly larger volumes for high energy physics research. The attachment of free electrons to impurities in the LAr is an important limit on the free instrumented volume of these extremely large detectors, and impurity concentrations as small as 100 ppt can reduce their resolution and efficiency. In this paper, we summarize the electron attachment rate constants as a function of the applied electric field, for common impurities in LArTPCs, obtained from data in the literature. We further provide analytical functions to parameterize the data, which are useful to compare with new measurements, to model and analyze the performance of existing detectors, and to predict the performance of new detectors.

Neural-network-driven proton decay sensitivity in the p \u2192 overline{nu} K+ channel using large liquid argon time projection chambers

We report on an updated sensitivity for proton decay via p → overline{nu} K+ at large, dual phase liquid argon time projection chambers (LAr TPCs). Our work builds on a previous study in which several nucleon decay modes have been simulated and analyzed [1]. At the time several assumptions were needed to be made on the detector and the backgrounds. Since then, the community has made progress in defining these, and the computing power available enables us to fully simulate and reconstruct large samples in order to perform a better estimate of the sensitivity to proton decay. In this work, we examine the benchmark channel p → overline{nu} K+, which was previously found to be one of the cleanest channels. Using an improved neutrino event generator and a fully simulated LAr TPC detector response combined with a dedicated neural network for kaon identification, we demonstrate that a lifetime sensitivity of τ /Br (p → overline{nu} K+) > 7 × 1034 years at 90% confidence level can be reached at an exposure of 1 megaton · year in quasi-background-free conditions, confirming the superiority of the LAr TPC over other technologies to address the challenging proton decay modes.

Neutrino identification with scintillation light in MicroBooNE

MicroBooNE is a neutrino experiment which employs a liquid argon (LAr) time projection chamber (TPC) to record neutrino interactions from Fermilab's neutrino beamlines. The experiment's primary objective is to study low-energy νe interactions from the Booster Neutrino Beamline (BNB). Located on the surface, the detector is affected by a continuous rate of cosmic-rays. This leads to one neutrino interaction for every 104 cosmic rays observed in the TPC, making it difficult to isolate neutrino interactions in the detector using charge alone. MicroBooNE's trigger makes use of prompt scintillation light and plays an essential role in both performing strong background rejection and significantly reducing data-rates. Furthermore, a series of novel techniques relying on scintillation light are used to isolate beam-induced activity. This document briefly presents MicroBooNE's scintillation-light based trigger and novel Flash-Matching pattern recognition techniques for cosmic-rejection. This work serves as the foundation of neutrino analyses in LArTPC detectors and is therefore of interest to the broader short- and long-baseline neutrino programs being launched at Fermilab.

Ion transport model for large LArTPC

High single photoelectron (SPE) rates have been recently observed in several large LArTPC detectors operating at the surface. These single photons are background that could limit the LArTPC capability for low energy physics. To understand the origin of the high SPE rate, we developed a model focusing on the slowly moving positive and negative ions (space charge) induced by the ionization of cosmic rays and electron attachment to impurities in LAr. Our model can predict the electric field distortion due to the presence of space charge that is well matched to measurements. More importantly, the model contains two new processes that contribute to producing photons from the interactions of the ions, which provide a plausible explanation for the observed high single PE rate.

U(1) ′ mediated decays of heavy sterile neutrinos in MiniBooNE

The MiniBooNE low-energy excess is a longstanding problem which has received further confirmation recently with a reanalysis using newly collected data, with the anomaly now at the $4.8\sigma$ level. In this letter we propose a novel explanation which advocates a low-energy sector containing $Z^\prime$ bosons with GeV-scale masses and sterile neutrinos with masses around $100$-$500$ MeV. We show that this scenario can provide an excellent spectral agreement with the MiniBooNE low-energy excess in the form of $Z^\prime$-mediated neutral current production of heavy sterile states, a fraction of whose subsequent decay to $e^+e^-$ pairs are misidentified as single electron-like electromagnetic showers. Our model inscribes itself in the broad class of models in which sterile neutrinos are charged under novel interactions, allowing new couplings to hidden-sector physics. Alongside the electron-like MiniBooNE signature this model also predicts a novel, low-background, signal in LArTPC detectors such as MicroBooNE consisting of two distinguishable electron-like electromagnetic showers originating from a single vertex with no associated hadronic activity.

The Feasibility Study of the Long-baseline Neutrino Oscillation Experiment at the SUNLAB Laboratory in Poland

The feasibility study of an underground laboratory in the Polkowice -Sieroszowice mine in Poland (SUNLAB) as a host of a far detector in a long-baseline neutrino oscillation experiment was performed. The SUNLAB location was previously studied under the LAGUNA FP7 project as a location for the underground multipurpose laboratory. The complementary study of the long-baseline neutrino experiment presented in this paper was performed as a continuation of this idea. A neutrino beam produced at CERN and a far LAr-TPC detector hosted in the SUNLAB laboratory were simulated. The sensitivity of such an experiment for the determination of the CP symmetry violation in the neutrino sector was calculated. The experiment at SUNLAB equipped with the 100 kton LAr TPC detector after 10 years of data taking can give the coverage of {\delta}CP parameter space of 58% (60%) for the normal (inverted) neutrino mass hierarchy at 3{\sigma} level in both cases reaches 5{\sigma} level in case of the maximal violation.

The Pandora multi-algorithm approach to automated pattern recognition in LAr TPC detectors

The development and operation of Liquid Argon Time Projection Chambers (LAr TPCs) for neutrino physics has created a need for new approaches to pattern recognition, in order to fully exploit the superb imaging capabilities offered by this technology. The Pandora Software Development Kit provides functionality to aid the process of designing, implementing and running pattern recognition algorithms. It promotes the use of a multi-algorithm approach to pattern recognition: individual algorithms each address a specific task in a particular topology; a series of many tens of algorithms then carefully builds-up a picture of the event. The input to the Pandora pattern recognition is a list of 2D Hits. The output from the chain of over 70 algorithms is a hierarchy of reconstructed 3D Particles, each with an identified particle type, vertex and direction.

Simulations of the Long Baseline Neutrino Experiment for the Sieroszowice Underground Laboratory (SUNLAB)

The Sieroszowice Underground Laboratory in Poland, SUNLAB, had been studied in the years 2008-2011 within the framework of the FP7 LAGUNA design study as an option for the realization of a next generation large volume neutrino observatory in Europe. However, in order to fully understand its physics capabilities, the feasibility studies of the SUNLAB laboratory have continued after 2011, including sensitivity calculations focused on the delta CP measurement for a large LArTPC detector at a distance of 950 km from CERN in a long baseline neutrino experiment. For this purpose the neutrino beam based on the SPS proton accelerator at CERN was simulated and the LAr data used to simulate the detector response.

The photomultiplier tube calibration system of the MicroBooNE experiment

We report on the design and construction of a LED-based fiber calibration system for large liquid argon time projection detectors. This system was developed to calibrate the optical systems of the MicroBooNE experiment. As well as detailing the materials and installation procedure, we provide technical drawings and specifications so that the system may be easily replicated in future LArTPC detectors.

ICARUS-NESSiE: a sensitive search for sterile neutrinos at CERN SPS

A new experimental search for sterile neutrinos beyond the Standard Model at a new CERN-SPS neutrino beam aiming at measuring the electron and muon neutrino events with a Near and Far detectors (1600 and 330 m from the proton target) is presented. The project will exploit the ICARUS T600 LAr-TPC moved from LNGS to the CERN Far position and a new additional LAr-TPC detector, 1/4 of the T600, located in the Near position. Two magnetic spectrometers will be placed downstream of the two LAr-TPC detectors to greatly complement the physics capabilities. Comparing the two detectors, in absence of oscillations, all cross sections and experimental biases cancel out. Any difference of the event distributions at the two locations should be attributed to the possible existence of oscillations, presumably due to additional neutrinos with a mixing angle sin2(2θnew) and a mass squared difference Δm2new larger than the measured for the standard neutrinos. The superior quality of the LAr imaging TPC, in particular its unique electron-π0 discrimination allows for full rejection of backgrounds and offers a lossless νe detection capability. The determination of the muon charge with the spectrometers allows for the full separation of νμ from ν̄μ and therefore controlling systematics from muon mis-identification mainly at high momenta.

ICARUS+NESSiE: A proposal for short baseline neutrino anomalies with innovative LAr imaging detectors coupled with large muon spectrometers

The proposal for an experimental search for sterile neutrinos beyond the Standard Model with a new CERN-SPS neutrino beam is presented. The experiment is based on two identical LAr-TPCʼs followed by magnetized spectrometers, observing the electron and muon neutrino events at 1600 and 300 m from the proton target. This project will exploit the ICARUS T600, moved from LNGS to the CERN “Far” position. An additional 1/4 of the T600 detector will be constructed and located in the “Near” position. Two spectrometers will be placed downstream of the two LAr-TPC detectors to greatly complement the physics capabilities. Comparing the two detectors, in absence of oscillations, all cross sections and experimental biases cancel out. Any difference of the event distributions at the locations of the two detectors might be attributed to the possible existence of ν-oscillations, presumably due to additional neutrinos with a mixing angle sin2(2θnew) and a larger mass difference Δmnew2. The superior quality of the LAr imaging TPC, in particular its unique electron-π0 discrimination allows full rejection of backgrounds and offers a lossless νe detection capability. The determination of the muon charge with the spectrometers allows the full separation of νμ from anti-νμ and therefore controlling systematics from muon mis-identification largely at high momenta.

A proposed search for sterile neutrinos with the ICARUS detector at the CERN-PS

An experiment to search for sterile neutrinos beyond the Standard Model with the CERN-PS 19.2 GeV beam and the technology of imaging in ultra-pure cryogenic liquid Argon is proposed. The superior quality of the LAr-TPC, now widely demonstrated experimentally and in particular its unique e/π0 discrimination allows a full rejection of backgrounds, offers the possibility to explore the neutrino conversion into sterile components as recently suggested by the analysis of different observed neutrino anomalies.The experiment is based on two identical LAr-TPC detectors observing the electron-neutrino signal in the Near and Far positions, the first of about 150 tons at 127 m from the proton target, the second one of about 600 tons placed 850 m away. This project will exploit the largest LAr-TPC ever built, ICARUS T600 now running underground at LNGS exposed to CNGS neutrino beam, by moving it from Gran Sasso to the CERN Far position. An additional 150 t detector will be constructed in the Near position. The intrinsic νE beam spectra are expected practically identical in the two positions; in addition all cross-sections and experimental biases cancel out in the comparison of the two detector signals allowing to perform a sensitive search for neutrino oscillations in the presence of sterile neutrinos.

ICARUS-T600 and beyond: LAr-TPC for neutrino physics and proton decay search

Liquid Argon TPCs are performing detectors for neutrino and astroparticle physics thanks to their high granularity, good energy resolution and 3D imaging, allowing a precise event reconstruction. At the end of May 2010 the ICARUS-T600, the first underground large mass LAr-TPC devoted to the experimental study of neutrinos, matter stability and, more generally, rare phenomena, recorded the first CNGS neutrino interaction and is presently taking data at INFN Gran Sasso Laboratory. ICARUS-T600 represents also an important step of the Liquid Argon technique towards the realization of much larger LAr-TPC detectors for future neutrino and matter stability projects.

Solving the octant degeneracy with the silver channel

We study the potential of the combination of the golden (νe→νμ) and silver (νe→ντ) channels to solve the octant degeneracy affecting the measurement of θ13 and δ at future neutrino factories. To search for τ leptons produced in ντ charged-current interactions, we consider two different detectors: the Emulsion Cloud Chamber detector (ECC) and the Liquid Argon Time Projection Chamber (LAr TPC). We show that, when using similar detector masses, the upgraded version of the ECC detector (sensitive also to hadronic τ decay modes) and the LAr TPC detector have comparable sensitivities to the octant of θ23, being able to discriminate the two solutions for sin2(2θ13)≳10−3 at 3σ level if θ23=40°. We also show that the same setups are able to see deviation from maximal mixing as small as ∼ (4–6)% (at 3σ) if θ13 is close to its upper bound.

A new, very massive modular Liquid Argon Imaging Chamber to detect low energy off-axis neutrinos from the CNGS beam (Project MODULAr)

The paper is considering an opportunity for the CERN/GranSasso (CNGS) neutrino complex, concurrent time-wise with T2K and NOvA projects, with the aim of improving the sensitivity on ν μ ↔ ν e θ 13 mixing angle by nearly an order of magnitude with respect to T2K expectations. The experiment is based on a ≈20 kt fiducial volume LAr-TPC, following very closely the technology developed for the ICARUS-T600. The present preliminary proposal, called MODULAr, is focused on the following three main activities, for which we seek an extended international collaboration: (1) The neutrino beam from the CERN 400 GeV proton beam and an optimized horn focussing, eventually with an increased intensity in the framework of the LHC accelerator improvement programme. (2) A new experimental area LNGS-B, of at least 50,000 m 3 at 10 km off-axis from the main laboratory, eventually upgradable to larger sizes. A location is under consideration at about 1.2 km equivalent water depth. The bubble chamber like imaging and the very fine calorimetry of the LAr-TPC detector will ensure the best background recognition not only from the off-axis neutrinos from the CNGS but also for proton decay and cosmic neutrinos. (3) A new LAr Imaging detector, at least initially with about 20 kt fiducial mass, realised with a modular set of four identical, but independent units, each of about 5 kt, “cloning” the basic technology of the T600. Further phases may foresee extensions of MODULAr to a mass required by the future physics goals. Compared with large water Cherenkov (T2K) and fine grained scintillators (NOvA), the LAr-TPC offers a higher detection efficiency for a given mass and lower backgrounds, since virtually all channels may be unambiguously recognized. In addition to the search for θ 13 oscillations and CP violation, it would be possible to collect a large number of accurately identified cosmic ray neutrino events and perform search for proton decay in the exotic channels.

Ideas for future liquid Argon detectors

We outline a strategy for future experiments on neutrino and astroparticle physics based on the use, at different detector mass scales (100 ton and 100 kton), of the liquid Argon Time Projection Chamber (LAr TPC) technique. The LAr TPC technology has great potentials for both cases with large degree of interplay between the two applications and a strong synergy. The ICARUS R&D programme has demonstrated that the technology is mature and that one can built a large ($\sim$ 1 kton) LAr TPC. We believe that one can conceive and design a very large mass LAr TPC with a mass of 100 kton by employing a monolithic technology based on the use of industrial, large volume cryogenic tankers developed by the petro-chemical industry. We show a potential implementation of a large LAr TPC detector. Such a detector would be an ideal match for a Superbeam, Betabeam or Neutrino Factory, covering a broad physics program that could include the detection of atmospheric, solar and supernova neutrinos, and search for proton decays, in addition to the rich accelerator neutrino physics program. In parallel, physics is calling for another application of the LAr TPC technique at the level of 100 ton mass, for low energy neutrino physics and for use as a near station setup in future long baseline neutrino facilities. We present here the main physics objectives and outline the conceptual design of such a detector.

Decoupling supernova and neutrino oscillation physics with LAr TPC detectors

Core collapse supernovae are a huge source of all flavour neutrinos. The flavourcomposition, energy spectrum and time structure of the neutrino burst from a galacticsupernova can provide information about the explosion mechanism and the mechanisms ofproto neutron star cooling. Such data can also give information about the intrinsicproperties of the neutrino such as flavour oscillations. One important question isto understand to what extent the supernova and the neutrino physics can bedecoupled in the observation of a single supernova. On one hand, the understandingof the supernova explosion mechanism is still plagued by uncertainties whichhave an impact on the precision with which one can predict time-, energy- andflavour-dependent neutrino fluxes. On the other hand, the neutrino mixing propertiesare not fully known, since the type of mass hierarchy and the value of theθ13 angle are unknown, and in fact large uncertainty still exists on the prediction ofthe actual effect of neutrino oscillations in the event of a supernova explosion.In this paper we discuss the possibility of probing the neutrino mixing angleθ13 and the type of mass hierarchy from the detection of supernova neutrinos with a liquidargon TPC detector. Moreover, describing the supernova neutrino emission by a set of fiveparameters (average energy of the different neutrino flavours, their relative luminosity andthe total supernova binding energy), we quantitatively study how it is possible to constrainthese parameters. A characteristic feature of the liquid argon TPC is the accessibility tofour independent detection channels ((1) elastic scattering off electrons, (2) chargedneutrino and (3) antineutrino and (4) neutral currents on argon nuclei) which have differentsensitivities to electron neutrino, anti-electron neutrino and other neutrino flavours (muonand tau (anti)neutrinos). This allows us to over-constrain the five supernova andthe flavour mixing parameters and to some extent disentangle neutrino fromsupernova physics. Numerically, we find that a very massive liquid argon detector(O(100 kton)) is needed to perform accurate measurements of these parameters, speciallyin supernova scenarios where the average energies of electron and non-electronneutrinos are similar (almost degenerate neutrinos) or if no information about theθ13 mixing angle and type of mass hierarchy is available.