Performance study of a 3 x 1 x 1 m(3) dual phase liquid Argon Time Projection Chamber exposed to cosmic rays

This work would not have been possible without the support of the Swiss National Science Foundation, Switzerland; CEA and CNRS/IN2P3, France; KEK and the JSPS program, Japan; Ministerio de Ciencia e Innovacion in Spain under grants FPA2016-77347-C2, SEV-2016-0588 and MdM-2015-0509, Comunidad de Madrid, the CERCA program of the Generalitat de Catalunya and the fellowship (LCF/BQ/DI18/11660043) from "La Caixa" Foundation (ID 100010434); the Programme PNCDI III, CERN-RO, under Contract 2/2020, Romania; the U.S. Department of Energy under Grant No. DE-SC0011686. This project has received funding from the European Union's Horizon 2020 Research and Innovation program under Grant Agreement no. 654168. The authors are also grateful to the French government operated by the National Research Agency (ANR) for the LABEX Enigmass, LABEX Lyon Institute of Origins (ANR-10-LABX-0066) of the Universite de Lyon for its financial support within the program "Investissements d'Avenir" (ANR-11-IDEX-0007).We report the results of the analyses of the cosmic ray data collected with a 4 tonne (3x1x1 m(3)) active mass (volume) Liquid Argon Time-Projection Chamber (TPC) operated in a dual-phase mode. We present a detailed study of the TPC's response, its main detector parameters and performance. The results are important for the understanding and further developments of the dual-phase technology, thanks to the verification of key aspects, such as the extraction of electrons from liquid to gas and their amplification through the entire one square metre readout plain, gain stability, purity and charge sharing between readout views.Swiss National Science Foundation (SNSF)French Atomic Energy CommissionCentre National de la Recherche Scientifique (CNRS)High Energy Accelerator Research Organization (KEK)Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT)Japan Society for the Promotion of ScienceSpanish Government FPA2016-77347-C2 SEV-2016-0588MdM-2015-0509Comunidad de MadridCERCA program of the Generalitat de CatalunyaLa Caixa Foundation LCF/BQ/DI18/11660043 100010434Programme PNCDI III, RomaniaCERN-RO, Romania 2/2020United States Department of Energy (DOE) SC0011686European Commission 654168Universite de Lyon ANR-10-LABX-0066 ANR-11-IDEX-000

Search for electron antineutrino appearance in a long-baseline muon antineutrino beam

Electron antineutrino appearance is measured by the T2K experiment in an accelerator-produced antineutrino beam, using additional neutrino beam operation to constrain parameters of the Pontecorvo-Maki-Nakagawa-Sakata (PMNS) mixing matrix. T2K observes 15 candidate electron antineutrino events with a background expectation of 9.3 events. Including information from the kinematic distribution of observed events, the hypothesis of no electron antineutrino appearance is disfavored with a significance of 2.40σ and no discrepancy between data and PMNS predictions is found. A complementary analysis that introduces an additional free parameter which allows non-PMNS values of electron neutrino and antineutrino appearance also finds no discrepancy between data and PMNS predictions

Scintillator ageing of the T2K near detectors from 2010 to 2021

The T2K experiment widely uses plastic scintillator as a target for neutrino interactions and an active medium for the measurement of charged particles produced in neutrino interactions at its near detector complex. Over 10 years of operation the measured light yield recorded by the scintillator based subsystems has been observed to degrade by 0.9–2.2% per year. Extrapolation of the degradation rate through to 2040 indicates the recorded light yield should remain above the lower threshold used by the current reconstruction algorithms for all subsystems. This will allow the near detectors to continue contributing to important physics measurements during the T2K-II and Hyper-Kamiokande eras. Additionally, work to disentangle the degradation of the plastic scintillator and wavelength shifting fibres shows that the reduction in light yield can be attributed to the ageing of the plastic scintillator. The long component of the attenuation length of the wavelength shifting fibres was observed to degrade by 1.3–5.4% per year, while the short component of the attenuation length did not show any conclusive degradation

Constraint on the matter–antimatter symmetry-violating phase in neutrino oscillations

The charge-conjugation and parity-reversal (CP) symmetry of fundamental particles is a symmetry between matter and antimatter. Violation of this CP symmetry was first observed in 19641, and CP violation in the weak interactions of quarks was soon established2. Sakharov proposed3 that CP violation is necessary to explain the observed imbalance of matter and antimatter abundance in the Universe. However, CP violation in quarks is too small to support this explanation. So far, CP violation has not been observed in non-quark elementary particle systems. It has been shown that CP violation in leptons could generate the matter–antimatter disparity through a process called leptogenesis4. Leptonic mixing, which appears in the standard model’s charged current interactions5,6, provides a potential source of CP violation through a complex phase δCP, which is required by some theoretical models of leptogenesis7,8,9. This CP violation can be measured in muon neutrino to electron neutrino oscillations and the corresponding antineutrino oscillations, which are experimentally accessible using accelerator-produced beams as established by the Tokai-to-Kamioka (T2K) and NOvA experiments10,11. Until now, the value of δCP has not been substantially constrained by neutrino oscillation experiments. Here we report a measurement using long-baseline neutrino and antineutrino oscillations observed by the T2K experiment that shows a large increase in the neutrino oscillation probability, excluding values of δCP that result in a large increase in the observed antineutrino oscillation probability at three standard deviations (3σ). The 3σ confidence interval for δCP, which is cyclic and repeats every 2π, is [−3.41, −0.03] for the so-called normal mass ordering and [−2.54, −0.32] for the inverted mass ordering. Our results indicate CP violation in leptons and our method enables sensitive searches for matter–antimatter asymmetry in neutrino oscillations using accelerator-produced neutrino beams. Future measurements with larger datasets will test whether leptonic CP violation is larger than the CP violation in quarks

Measurements of neutrino oscillation parameters from the T2K experiment using 3.6 × 10²¹ protons on target

The T2K experiment presents new measurements of neutrino oscillation parameters using 19.7(16.3)×10²⁰ protons on target (POT) in (anti-)neutrino mode at the far detector (FD). Compared to the previous analysis, an additional 4.7×10²⁰ POT neutrino data was collected at the FD. Significant improvements were made to the analysis methodology, with the near-detector analysis introducing new selections and using more than double the data. Additionally, this is the first T2K oscillation analysis to use NA61/SHINE data on a replica of the T2K target to tune the neutrino flux model, and the neutrino interaction model was improved to include new nuclear effects and calculations. Frequentist and Bayesian analyses are presented, including results on sin² θ₁₃ and the impact of priors on the δ_CP measurement. Both analyses prefer the normal mass ordering and upper octant of sin² θ₂₃ with a nearly maximally CP-violating phase. Assuming the normal ordering and using the constraint on sin² θ₁₃ from reactors, sin² θ₂₃ = 0.561⁺⁰.⁰²¹₋₀.₀₃₂ using Feldman–Cousins corrected intervals, and Δm²₃₂ = 2.494⁺⁰.⁰⁴¹₋₀.₀₅₈×10−3 eV² using constant Δχ² intervals. The CP-violating phase is constrained to δCP=−1.97⁺⁰.⁹⁷₋₀.₇₀ using Feldman–Cousins corrected intervals, and δ_CP = 0,π is excluded at more than 90% confidence level. A Jarlskog invariant of zero is excluded at more than 2σ credible level using a flat prior in δCP, and just below 2σ using a flat prior in sin δ_CP. When the external constraint on sin² θ₁₃ is removed, sin² θ₁₃ = 28.0+2.8−6.5×10−3, in agreement with measurements from reactor experiments. These results are consistent with previous T2K analyses.ISSN:1434-6044ISSN:1434-605

Endocrine Characterization of the Designer Steroid Methyl-1-Testosterone: Investigations on Tissue-Specific Anabolic-Androgenic Potency, Side Effects, and Metabolism

Various products containing rarely characterized anabolic steroids are nowadays marketed as dietary supplements. Herein, the designer steroid methyl-1-testosterone (M1T) (17 beta-hydroxy-17 alpha-methyl-5 alpha-androst-1-en-3-one) was identified, and its biological activity, potential adverse effects, and metabolism were investigated. The affinity of M1T toward the androgen receptor (AR) was tested in vitro using a yeast AR transactivation assay. Its tissue-specific androgenic and anabolic potency and potential adverse effects were studied in a Hershberger assay (sc or oral), and tissue weights and selected molecular markers were investigated. Determination of M1T and its metabolites was performed by gas chromatography mass spectrometry. In the yeast AR transactivation assay, M1T was characterized as potent androgen. In rats, M1T dose-dependently stimulated prostate and levator ani muscle weight after sc administration. Oral administration had no effect but stimulated proliferation in the prostate and modulated IGF-I and AR expression in the gastrocnemius muscle in a dose-dependent manner. Analysis of tyrosine aminotransferase expression provided evidence for a strong activity of M1T in the liver (much higher after oral administration). In rat urine, 17 alpha-methyl-5 alpha-androstane-3 alpha, 17 beta-diol, M1T, and a hydroxylated metabolite were identified. In humans, M1T was confirmed in urine in addition to its main metabolites 17 alpha-methyl-5 alpha-androst-1-ene-3 alpha, 17 beta-diol and 17 alpha-methyl-5 alpha-androstane-3 alpha, 17 beta-diol. Additionally, the corresponding 17-epimers as well as 17 beta-hydroxymethyl-17 alpha-methyl-18-nor-5 alpha-androsta-1,13-dien-3-one and its 17-epimer were detected, and their elimination kinetics was monitored. It was demonstrated that M1T is a potent androgenic and anabolic steroid after oral and sc administration. Obviously, this substance shows no selective AR modulator characteristics and might exhibit liver toxicity, especially after oral administration. (Endocrinology 152: 4718-4728, 2011

Measurement of the charged-current electron (anti-)neutrino inclusive cross-sections at the T2K off-axis near detector ND280

The electron (anti-)neutrino component of the T2K neutrino beam constitutes the largest background in the measurement of electron (anti-)neutrino appearance at the far detector. The electron neutrino scattering is measured directly with the T2K off-axis near detector, ND280. The selection of the electron (anti-)neutrino events in the plastic scintillator target from both neutrino and anti-neutrino mode beams is discussed in this paper. The flux integrated single differential charged-current inclusive electron (anti-)neutrino cross-sections, dσ/dp and dσ/d cos(θ), and the total cross-sections in a limited phase-space in momentum and scattering angle (p > 300 MeV/c and θ ≤ 45°) are measured using a binned maximum likelihood fit and compared to the neutrino Monte Carlo generator predictions, resulting in good agreement.ISSN:1126-6708ISSN:1029-847

First combined measurement of the muon neutrino and antineutrino charged-current cross section without pions in the final state at T2K

This paper presents the first combined measurement of the double-differential muon neutrino and antineutrino charged-current cross sections with no pions in the final state on hydrocarbon at the off-axis near detector of the T2K experiment. The data analyzed in this work comprise 5.8×1020 and 6.3×1020 protons on target in neutrino and antineutrino mode respectively, at a beam energy peak of 0.6 GeV. Using the two measured cross sections, the sum, difference, and asymmetry were calculated with the aim of better understanding the nuclear effects involved in such interactions. The extracted measurements have been compared with the prediction from different Monte Carlo generators and theoretical models showing that the difference between the two cross sections have interesting sensitivity to nuclear effects.ISSN:1550-7998ISSN:0556-2821ISSN:1550-236

Measurements of ν̅μ and ν̅μ + νμ charged-current cross-sections without detected pions or protons on water and hydrocarbon at a mean anti-neutrino energy of 0.86 GeV

We report measurements of the flux-integrated (nu) over bar (mu) and (nu) over bar (mu) + nu(mu) charged-current cross -sections on water and hydrocarbon targets using the T2K anti-neutrino beam with a mean beam energy of 0.86 GeV. The signal is defined as the (anti -)neutrino charged-current interaction with one induced mu(+/-) and no detected charged pion or proton. These measurements are performed using a new WAGASCI module recently added to the T2K setup in combination with the INGRID Proton Module. The phase space of muons is restricted to the high-detection efficiency region, p(mu) > 400 MeV/c and theta(mu) 200 MeV/c, theta(pi) 600 MeV/c, theta(p) (mu), cross-sections and (nu) over bar (mu) + nu(mu), cross-sections on water and hydrocarbon targets and their ratios are provided by using the D'Agostini unfolding method. The results of the integrated (nu) over bar (mu), cross-section measurements over this phase space are sigma(H2O) = (1.082 +/- 0.068(stat.)(+0.145)(-0.128)(syst.)) x 10(-39) cm(2)/nucleon, sigma(CH) = (1.096 +/- 0.054 (stat.)(+0.132)(-0.117)(syst.)) x 10(-39) cm(2) /nucleon, and sigma(H2O)/sigma(CH) = 0.987 +/- 0.078 (stat.)(+0.093)(-0.090)(syst.). The (nu) over bar (mu), + nu(mu), cross-section is sigma(H2O) = (1.155 +/- 0.064(stat.)(+0.148)(-0.129)(syst.)) x 10(-39) cm(2)/nucleon, sigma(CH) = (1.159 +/- 0.049(stat.)(+0.129)(-0.115)(syst.)) x 10(-39) cm(2)/nucleon, and sigma(H2O)/sigma(CH) = 0.996 +/- 0.069(stat.)(+0.083)(-0.078)(syst.)