Operation of a Modular 3D-Pixelated Liquid Argon Time-Projection Chamber in a Neutrino Beam

There is a significant R\&D effort ongoing in the liquid argon (LAr) time projection chamber (TPC) community. Due to the scintillation and ionisation properties of LAr, coupled with its low cost, it is possible to construct detectors with immense fiducial volume at a modest cost. It is for this reason that LAr TPCs are fast becoming the detector of choice for long baseline neutrino physics experiments. Using LAr TPCs it is possible to provide the large targets required to make direct observation of neutrino interactions a statistically reasonable prospect. Experiments such as the deep underground neutrino experiment (DUNE) are proposing the use of 68,000 tons of liquid argon as the target material of choice shared between four colossal LAr TPCs. In a two-phase TPC the charge amplification process is performed in the gas phase. By performing charge amplification in the gas phase it is possible to achieve much higher gains and hence improved signal-to-noise ratios. ARIADNE is a novel and innovative two-phase LAr TPC pioneering the direct imaging of secondary scintillation light produced during the charge amplification process using a THGEM in the gas phase. Optical readout presents many advantages over current readout technologies such as massive reductions in the number of readout channels, ease of scalability, upgrade, installation and maintenance as well as cost effectiveness.

The Deep Underground Neutrino Experiment (DUNE) is a long-baseline (1300 km) neutrino experiment hosted at the Fermi National Accelerator Laboratory (FNAL). It aims to measure neutrino mass ordering and CP violation through neutrino oscillations from a characterized muon neutrino beam. DUNE will deploy four Liquid-Argon Time-Projection-Chamber (LArTPC) detectors with a total mass of approximately 70 kt. The reconstruction of particle interactions, both from the beam and external neutrino sources is achieved by collecting two distinct interaction signals: ionization electrons with the Time Projection Chamber (TPC) and scintillation photons (127 nm) with the Photon Detection System (PDS). Regarding the latter, to fulfil the physics requirements of the experiment, a uniform and efficient collection of the argon scintillation light across the 62 m × 15 m × 14 m detector volume is required to achieve an average detected light yield of at least 20 PE MeV-1. For the case of DUNE's far detector module with vertical drift direction (FD-VD), the system relies on 672 X-ARAPUCA (XA) tiles, which trap photons inside their highly reflective box by shifting VUV light to visible wavelengths. An intensive R&D campaign, involving multiple international institutions, has optimized the design and component selection for the next-generation PDS modules, which have been tested in liquid argon using a dedicated cryogenic setup developed at CIEMAT to evaluate their photon detection efficiency (PDE). Several configurations have been chosen to evaluate the possible design improvements in terms of different light-trapping strategies and reflectiveness.

The Deep Underground Neutrino Experiment (DUNE) is a long-baseline neutrino oscillation experiment that aims to measure whether CP is violated in the leptonic sector (if violated, how much) and unambiguously determine the neutrino mass ordering. DUNE consists of near and far detectors that rely on liquid argon time projection chamber (LArTPC) technology to observe neutrino interactions. The near detector (ND) will be placed in Fermilab, near the neutrino source, while the far detector (FD) will be deployed in Sanford Lab, 1.5 km deep underground, which is 1300 km away from the source. LArTPCs provide excellent particle identification and calorimetry; however, detecting neutrons is challenging, as they do not leave direct ionization signals in LArTPCs. Neutrons can carry away up to 25% of the neutrino energy, introducing a significant uncertainty in DUNE measurements. The DUNE near detector (ND) features a novel modular LArTPC with pixelated charge readout, which enhances event recons truction. The modular design enables precise correlation between ionization signals and light signals in a high-rate environment, improving the identification of delayed energy depositions from neutrons in neutrino interactions. We introduce a neutron tagging technique using the 2x2 Demonstrator, a small-scale prototype of the DUNE ND LArTPC. The analysis utilizes Monte Carlo simulations and deep-learning techniques to identify neutron-induced energy depositions and reconstruct low-energy activity.

Liquid argon (LAr) time projection chambers (TPC) have rapidly increased in importance as particle detectors throughout the past four decades. While much research has been completed, there are still many areas which require further development to build and operate the next generation LAr TPC experiment, such as the Deep Underground Neutrino Experiment (DUNE). These include high voltage breakdown, argon purification and purity monitoring, and vacuum ultraviolet (VUV) scintillation light measurement. Visual monitoring of high voltage breakdown is helpful in allowing assessment of the performance of high voltage component design. Thus, a system of cryogenic cameras, the first of its kind, was developed for use in a large LAr cryostat, without the need for additional electronics heating. The system functioned without problem for 50 days at cryogenic temperature, with some degradation of image quality, and provided a useful monitor for the DUNE 35-ton cryogenics systems. The system did not observe any high voltage breakdowns during the run. Further development of the concept is ongoing for future installation in other experiments. The monitoring of LAr purity using TPC data is a fundamental study for LAr TPC experiments. However, the study has not been performed for a large LAr TPC in the presence of high electronic noise. Custom software was developed and validated for the accurate reconstruction of signals in noisy TPC data. The results of the reconstruction were used to successfully measure the LAr electron lifetime with an uncertainty comparable to alternate methods of measurement. The electron lifetime of the 35-ton Phase II run is determined to be 4.12 ± 0.17 (stat.) ±0.40 (syst.) ms. For general purpose research and development of high purity LAr as a particle detection medium, a dedicated test stand was designed, constructed, and commissioned. The system is used to test the gaseous photomultiplier (GPM) performance at cryogenic temperatures. The GPM functions with photoelectron multiplication at 77 K, at a reduced gain. Further study is required to show the detector’s direct sensitivity to LAr VUV scintillation light.

Neutrinos are tiny mysterious fundamental particles with small cross sections. Through neutrino physics, scientists across the world are trying to answer many intriguing questions about nature such as the dominance of matter over antimatter, CP violation in the lepton sector, number of supernovas in the early universe, etc. Detection of neutrinos requires massive particle detectors and intense neutrino beam owing to their small cross section. Deep Underground Neutrino Experiment (DUNE) is a next-generation neutrino experiment that is planned to start taking data beginning in 2026. DUNE will consist of 4 massive detectors, the first of which will be using single-phase liquid argon time projection chamber (LArTPC) technology. The ProtoDUNE-SP experiment is a prototype of the DUNE built at the CERN neutrino platform and uses the same detector technology that will be used in DUNE first module. The ProtoDUNE-SP experiment collected months of test beam and cosmic ray data beginning in September 2018. It was built to provide a testbed for the installation of detector parts for DUNE, showing long-term stability of the detector, understanding detector response for different test beam particles (including protons, pions, electrons, kaons, muons), and measurement of hadron-argon cross sections. When a particle passes through LArTPC electron-ion pairs are produced. To reconstruct the position and energy of a particle passing through the medium knowledge of ionization electron drift velocity is essential. The electron drift velocity is distorted by an excess positive charge built up in the detector, known as space charge. This study discusses a novel technique for measuring the ionization electron drift velocity using cosmic-ray muons. The technique uses tracks that travel the entire drift distance of the TPC for drift velocity determination. Secondly, the study discusses a method for converting the charge deposited into energy. The method is carried out in two step s. In th e first step detector response for energetic cosmic ray muons crossing the entire the TPC is used to make the charge deposition uniform throughout the TPC, and in the second step stopping cosmic-ray muons are used for determining the energy scale. Finally, the study discusses a pion-argon cross section measurement based on reweighting of Monte Carlo simulations using J. Calcutt's Geant4Reweight framework. Neutrinos cannot be directly detected; they are identified based on the interaction products. Pions are a common interaction product in a neutrino interaction. For precise modeling of neutrino event generators, it is essential to understand the pion-argon interaction. Pion-argon cross section measurement serves as an important input for neutrino interaction models. The results of the pion-argon total reaction cross section using the Geant4 reweighting technique are found to be in good agreement with Geant4 predictions. The many studies carried out in the ProtoDUNE-SP experi ment wil l be useful for current and future neutrino experiments using LArTPC technology including ICARUS, MicroBooNE, DUNE

in its explanation of experimental observations. An exception is the intriguing nature of neutrinos. Particularly, neutrino flavour eigenstates do not coincide with their mass eigenstates. The flavour eigenstates are a mixture of the mass eigenstates, resulting in oscillations for non-zero neutrino masses. Neutrino mixing and oscillations have been extensively studied during the last few decades probing the parameters of the three flavour model. Nevertheless, unanswered questions remain: the possible existence of a Charge conjugation Parity symmetry (CP) violating phase in the mixing matrix and the ordering of the neutrino mass eigenstates. The Deep Underground Neutrino Experiment (DUNE) is being built to answer these questions via a detailed study of long-baseline neutrino oscillations. Like any beam experiment, DUNE requires two detectors: one near the source to characterise the unoscillated beam, and one far away to measure the oscillations. Achieving sensitivity to CP violation and mass ordering will require a data sample of unprecedented size and precision. A high-intensity beam (2MW) and massive detectors (40 kt at the far site) are required. The detectors need to provide excellent tracking and calorimetry. Liquid Argon Time Projection Chambers (LArTPCs) were chosen as Far Detectors (FDs) because they fulfil these requirements. A LArTPC component is also necessary in the Near Detector (ND) complex to bring systematic uncertainties down to the required level of a few percent. A drawback of LArTPCs is their comparatively low speed due to the finite charge drift velocity (~ 1mmμs−1). Coupled with the high beam intensity this results in event rates of 0.2 piled-up events per tonne in the ND. Such a rate poses significant challenges to traditional LArTPCs: Their 3D tracking capabilities are limited by wire charge readouts providing only 2D projections. To address this problem a pixelated charge readout was developed and successfully tested as part of this thesis. This is the first time pixels were deployed in a single-phase LArTPC, representing the single largest advancement in the sensitivity of LArTPCs—enabling true 3D tracking. A software framework was established to reconstruct cosmic muon tracks recorded with the pixels. Another problem with traditional LArTPCs is the large volume required by their monolithic design resulting in long drift distances. Consequentially, high drift voltages are required. Current LArTPCs are operating at the limit beyond which electric breakdowns readily occur. This prompted world-leading studies of breakdowns in LAr including high-speed footage, current-voltage characteristics, and optical spectrometry. A breakdown-mitigation method was developed which allows LArTPCs to operate at electric fields an order of magnitude higher than previously achieved. It was found however that a safe and prolonged operation can be achieved more effectively by keeping fields below 40 kVcm−1 at all points in the detector. Therefore, high inactive clearance volumes are required for traditional monolithic LArTPCs. Avoiding dead LAr volume intrinsically motivates a segmented TPC design with lower cathode voltages. The comprehensive conclusion of the HV and charge readout studies is the development of a novel fully modular and pixelated LArTPC concept—ArgonCube. Splitting the detector volume into independent self-contained TPCs sharing a common LAr bath reduces the required drift voltages to a manageable level and minimises inactive material. ArgonCube is incompatible with traditional PMT-based light readouts occupying large volumes. A novel cold SiPM-based light collection system utilised in the pixel demonstrator TPC enabled the development of the compact ArgonCube Light readout system (ArCLight). ArgonCube’s pixelated charge readout will exploit true 3D tracking, thereby reducing event pile-up and improving background rejection. Results of the pixel demonstration were used in simulations of the impact of pile-up for ArgonCube in the DUNE ND. The influence piled-up π0-induced EM showers have on neutrino energy reconstruction was investigated. Misidentified neutrino energy in ArgonCube is conservatively below 0.1% for more than 50% of the neutrino events, well within the DUNE error budget. The work described in this thesis has made ArgonCube the top candidate for the LAr component in the DUNE ND complex.

The Deep Underground Neutrino Experiment (DUNE) is an international flagship project in particle physics and one of the most ambitious neutrino beam experiments ever conceived, hosted by the United States Department of Energy national laboratory, Fermilab. This experiment will use the Liquid Argon Time Projection Chamber (LArTPC) technology, proposed by C. Rubbia in 1977. DUNE will consist of a far detector with four modules and a near detector complex exposed to the world's most intense neutrino beam that will be originated at the Long Base Neutrino Facility (LBNF). When the neutrino beam interacts in liquid argon, charged particles are produced, which in turn will ionize and excite the argon atoms. The free electrons, obtained from the ionization, begin to move with the drift velocity towards the anode; while the de-exitation of the argon atoms produces scintillation light that will be detected by the photon detector system (PDS). The PDS is an independent system that will provide valuable time information for the reconstruction of the interaction. The PDS of the first two far detectors modules will be composed of photon detection devices named X-ARAPUCAs. In this talk I will present the PDS with an emphasis on the design, features and status of the X-ARAPUCA technology.

The Deep Underground Neutrino Experiment (DUNE) aims to provide a broad physics program primarily addressed to probing CP violation in the neutrino sector and identifying the neutrino mass hierarchy.The search for proton decay, the observation of supernova neutrino bursts,and the investigation of solar neutrinos represent other additional goals of DUNE experiment, which can be enhanced by theuse and the high performances of the Photon Detection System (PDS).Using the technology based on liquid argon Time Projection Chamber (LArTPC), the experiment plans to observe neutrino interactions inside detectors located 1300 km away from the Long Baseline Neutrino Facility (LBNF) at Fermi National Accelerator Laboratory (FNAL), where the neutrinos are produced.The experiment consists of two main parts, respectively the far and near detectors. The far site will comprise four detector modules. The first module is constituted by a vertical drift single-phase LArTPC, while the second module provides a horizontal drift single-phase LArTPC. The configurations of the other modules are still under definition.Neutrino detection in LArTPCs is achieved by identifying the charge and light generated from its interactions with liquid argon. The wire planes of the instrumented anode and the PDS detect these signals, respectively.The PDS in the first two modules, detailed in the present document, uses a modified version of the so-called ARAPUCA technology, named X-ARAPUCA.This system consisting of a highly reflecting box with an entrance window made by dichroic filters and wavelength shifters, creates a trap to detect the VUV (128 nm) scintillation photons.The X-ARAPUCA of the first module is called Supercell, and it has dimensions of 488×100 mm2, while Megacell is the second module version, with an active area of 60×60 cm2. This latter configuration also represents a significant technological advancement. Since half of the modules are placed on the cathode at high voltage, they are powered and read out using innovative power-over-fiber (PoF) and signal-over-fiber (SoF) technologies. Meanwhile, the other half are installed in a membrane behind the field cage, with a total transparency of around 70%.

The Deep Underground Neutrino Experiment (DUNE) will be the next generation long-baseline neutrino experiment. The far detector is designed as a complex of four LAr-TPC (Liquid Argon Time Projection Chamber) modules with 17 kt of liquid argon each. The development and validation of the first far detector technology is pursued through ProtoDUNE Single Phase (ProtoDUNE-SP), a 770 t LAr-TPC at CERN Neutrino Platform. Crucial in DUNE is the photon detection system that will ensure the trigger of non-beam events — proton decay, supernova neutrino burst and BSM searches — and will improve the timing and calorimetry for neutrino beam events. Doping liquid argon with xenon is a known technique to shift the light emitted by argon (128 nm) to a longer wavelength (178 nm) to ease its detection. The largest xenon doping test ever performed in a LAr-TPC was carried out in ProtoDUNE-SP. From February to May 2020, a gradually increasing amount of xenon was injected to also compensate for the light loss due to air contamination. The response of such a large TPC has been studied using the ProtoDUNE-SP Photon Detection System (PDS) and a dedicated setup installed before the run. With the first it was possible to study the light collection efficiency with respect to the track position, while with the second it was possible to distinguish the xenon light (178 nm) from the LAr light (128 nm). The light shifting mechanism proved to be highly efficient even at small xenon concentrations (<20 ppm in mass) furthermore it allowed recovering the light quenched by pollutants. The light collection improved far from the detection plane, enhancing the photon detector response uniformity along the drift direction and confirming a longer Rayleigh scattering length for 178 nm photons, with respect to 128 nm ones. The charge collection by the TPC was monitored proving that xenon up to 20 ppm does not impact its performance.

The Deep Underground Neutrino experiment will conduct a broad program of physics research by studying a beam of neutrinos from Fermilab, atmospheric neutrinos, neutrinos from potential supernovae, and potential nucleon decay events. In pursuit of these studies, the experiment will deploy four 10kt fiducial mass liquid argon time projection chambers underground in Lead, South Dakota. Liquid argon time projection chambers allow high-resolution tracking and energy measurements. A precise timing signal is needed to provide the necessary time stamp to localize events in the drift direction. As liquid argon is a natural scintillator, a photon detection system will be deployed to provide such a signal, especially for non-beam events. In the baseline design for the single-phase time projection chamber, the detectors are contained within the anode plane assemblies. The design of two prototypes utilizing wavelength shifters and light guides are presented, and aspects of the research and development program are discussed.

A number of liquid argon time projection chambers (LAr TPCs) are being built or are proposed for neutrino experiments on long- and short baseline beams. For these detectors, a distortion in the drift field due to geometrical or physics reasons can affect the reconstruction of the events. Depending on the TPC geometry and electric drift field intensity, this distortion could be of the same magnitude as the drift field itself. Recently, we presented a method to calibrate the drift field and correct for these possible distortions. While straight cosmic ray muon tracks could be used for calibration, multiple coulomb scattering and momentum uncertainties allow only a limited resolution. A UV laser instead can create straight ionization tracks in liquid argon, and allows one to map the drift field along different paths in the TPC inner volume. Here we present a UV laser feed-through design with a steerable UV mirror immersed in liquid argon that can point the laser beam at many locations through the TPC. The straight ionization paths are sensitive to drift field distortions, a fit of these distortion to the linear optical path allows to extract the drift field, by using these laser tracks along the whole TPC volume one can obtain a 3D drift field map. The UV laser feed-through assembly is a prototype of the system that will be used for the MicroBooNE experiment at the Fermi National Accelerator Laboratory (FNAL).

The Deep Underground Neutrino Experiment (DUNE) is an international project for neutrino physics and proton-decay searches, currently in the design and construction stages. Once built, DUNE will consist of two detectors exposed to the world's most intense neutrino beam. The near detector will record neutrino interactions near the beginning of the beamline, at Fermilab. The other, much larger, detector, comprising four 17-kton liquid argon time projection chambers (LArTPCs), will be installed at a depth of 1.5 km at the Sanford Underground Research Facility in South Dakota, about 1300 km away from the neutrino source. The unique combination of the high-intensity neutrino beam with DUNE's high-resolution near detector system and massive LArTPC far detector enables a variety of probes of BSM physics, either novel or with unprecedented sensitivity, from the potential discovery of new particles (sterile neutrinos or dark matter), to precision tests of the three-flavour neutrino mixing paradigm, or the detailed study of rare processes.

Precise modeling of neutrino interactions on argon is crucial for the success of future experiments such as the Deep Underground Neutrino Experiment (DUNE) and the Short-Baseline Neutrino (SBN) program, which will use liquid argon time projection chamber (LArTPC) technology. Argon is a large nucleus, and nuclear effects—both on the initial and final-state particles in the interaction—are expected to be large in neutrino–argon interactions. Therefore, measurements of neutrino scattering cross sections on argon will be of particular importance to future DUNE and SBN oscillation measurements. This article presents a review of neutrino–argon interaction measurements from the MicroBooNE and ArgoNeuT collaborations, using two LArTPC detectors that have collected data in the NuMI and Booster Neutrino Beams at Fermilab. Measurements are presented of charged-current muon neutrino scattering in the inclusive channel, the ‘0pi ’ channel (in which no pions but some number of protons may be produced), and single pion production (including production of both charged and neutral pions). Measurements of electron neutrino scattering are presented in the form of nu _e+bar{nu }_e inclusive scattering cross sections.

The Deep Underground Neutrino Experiment (DUNE) is a next-generation long-baseline neutrino oscillation experiment aimed at determining the neutrino mass hierarchy and the CP-violating phase. The DUNE physics program also includes the detection of astrophysical neutrinos and the search for signatures beyond the Standard Model, such as nucleon decays. DUNE consists of a near detector complex located at Fermilab and four 17 kton Liquid Argon Time Projection Chamber (LArTPC) far detector modules to be built 1.5 km underground at SURF, approximately 1300 km away. The detectors are exposed to a wideband neutrino beam generated by a 1.2 MW proton beam with a planned upgrade to $>$ 2 MW. Two 770 ton LArTPCs (ProtoDUNEs) have been operated at CERN for over 2 years as a testbed for DUNE far detectors and have been optimized to take new cosmic and test-beam data in 2024-2025. The DUNE and ProtoDUNE experiments and physics goals, as well as recent progress and results, are presented.

The Deep Underground Neutrino Experiment (DUNE) is a next-generation neutrino experiment which will be built at the Sanford Underground Research Facility (SURF), and will receive a wide-band neutrino beam from Fermilab, 1300~km away. At this baseline DUNE will be able to study many of the properties of neutrino mixing, including the neutrino mass hierarchy and the value of the CP-violating complex phase ($\delta_{CP}$). DUNE will utilise Liquid Argon (LAr) Time Projection Chamber (TPC) (LArTPC) technology, and the Far Detector (FD) will consist of four modules, each containing 17.1~kt of LAr with a fiducial mass of around 10~kt. Each of these FD modules represents around an order of magnitude increase in size, when compared to existing LArTPC experiments. \\ The 35 ton detector is the first DUNE prototype for the single (LAr) phase design of the FD. There were two running periods, one from November 2013 to February 2014, and a second from November 2015 to March 2016. During t he second running period, a system of TPCs was installed, and cosmic-ray data were collected. A method of particle identification was developed using simulations, though this was not applied to the data due to the higher than expected noise level. A new method of determining the interaction time of a track, using the effects of longitudinal diffusion, was developed using the cosmic-ray data. A camera system was also installed in the detector for monitoring purposes, and to look for high voltage breakdowns. \\ Simulations concerning the muon-induced background rate to nucleon decay are performed, following the incorporation of the MUon Simulations UNderground (MUSUN) generator into the DUNE software framework. A series of cuts which are based on Monte Carlo truth information is developed, designed to reject simulated background events, whilst preserving simulated signal events in the $n \rightarrow K^{+} + e^{-}$ decay channel. No background events are seen to survive the app lication of these cuts in a sample of 2~$\times$~10$^9$ muon! s, representing 401.6~years of detector live time. This corresponds to an annual background rate of <~0.44~events$\cdot$Mt$^{-1}\cdot$year$^{-1}$ at 90\% confidence, using a fiducial mass of 13.8~kt.