Showing papers by "C. Wilkinson published in 2018"

Search for CP Violation in Neutrino and Antineutrino Oscillations by the T2K Experiment with 2.2×1021 Protons on Target

Abstract: The T2K experiment measures muon neutrino disappearance and electron neutrino appearance in accelerator-produced neutrino and antineutrino beams. With an exposure of $14.7(7.6)\times 10^{20}$ protons on target in neutrino (antineutrino) mode, 89 $ u_e$ candidates and 7 anti-$ u_e$ candidates were observed while 67.5 and 9.0 are expected for $\delta_{CP}=0$ and normal mass ordering. The obtained $2\sigma$ confidence interval for the $CP$ violating phase, $\delta_{CP}$, does not include the $CP$-conserving cases ($\delta_{CP}=0,\pi$). The best-fit values of other parameters are $\sin^2\theta_{23} = 0.526^{+0.032}_{-0.036}$ and $\Delta m^2_{32}=2.463\pm0.065\times10^{-3} \mathrm{eV}^2/c^4$.

The DUNE Far Detector Interim Design Report Volume 1:Physics, Technology and Strategies

Abstract: The DUNE IDR describes the proposed physics program and technical designs of the DUNE Far Detector modules in preparation for the full TDR to be published in 2019. It is intended as an intermediate milestone on the path to a full TDR, justifying the technical choices that flow down from the high-level physics goals through requirements at all levels of the Project. These design choices will enable the DUNE experiment to make the ground-breaking discoveries that will help to answer fundamental physics questions. Volume 1 contains an executive summary that describes the general aims of this document. The remainder of this first volume provides a more detailed description of the DUNE physics program that drives the choice of detector technologies. It also includes concise outlines of two overarching systems that have not yet evolved to consortium structures: computing and calibration. Volumes 2 and 3 of this IDR describe, for the single-phase and dual-phase technologies, respectively, each detector module's subsystems, the technical coordination required for its design, construction, installation, and integration, and its organizational structure.

Characterization of nuclear effects in muon-neutrino scattering on hydrocarbon with a measurement of final-state kinematics and correlations in charged-current pionless interactions at T2K

Abstract: This paper reports measurements of final-state proton multiplicity, muon and proton kinematics, and their correlations in charged-current pionless neutrino interactions, measured by the T2K ND280 near detector in its plastic scintillator (C8H8) target. The data were taken between years 2010 and 2013, corresponding to approximately 6×1020 protons on target. Thanks to their exploration of the proton kinematics and of imbalances between the proton and muon kinematics, the results offer a novel probe of the nuclear-medium effects most pertinent to the (sub-)GeV neutrino-nucleus interactions that are used in accelerator-based long-baseline neutrino oscillation measurements. These results are compared to many neutrino-nucleus interaction models which all fail to describe at least part of the observed phase space. In case of events without a proton above a detection threshold in the final state, a fully consistent implementation of the local Fermi gas model with multinucleon interactions gives the best description of the data. In the case of at least one proton in the final state, the spectral function model agrees well with the data, most notably when measuring the kinematic imbalance between the muon and the proton in the plane transverse to the incoming neutrino. Within the models considered, only the existence of multinucleon interactions are able to describe the extracted cross section within regions of high transverse kinematic imbalance. The effect of final-state interactions is also discussed.

The DUNE Far Detector Interim Design Report, Volume 2: Single-Phase Module

Abstract: The DUNE IDR describes the proposed physics program and technical designs of the DUNE far detector modules in preparation for the full TDR to be published in 2019 It is intended as an intermediate milestone on the path to a full TDR, justifying the technical choices that flow down from the high-level physics goals through requirements at all levels of the Project These design choices will enable the DUNE experiment to make the ground-breaking discoveries that will help to answer fundamental physics questions Volume 2 describes the single-phase module's subsystems, the technical coordination required for its design, construction, installation, and integration, and its organizational structure

First measurement of the νμ charged-current cross section on a water target without pions in the final state

Abstract: This paper reports the first differential measurement of the charged-current interaction cross section of νμ on water with no pions in the final state. This flux-averaged measurement has been made using the T2K experiment’s off-axis near detector, and is reported in doubly differential bins of muon momentum and angle. The flux-averaged total cross section in a restricted region of phase space was found to be σ=(0.95±0.08(stat)±0.06(det syst)±0.04(model syst)±0.08(flux))×10−38 cm2/n.

Measurement of inclusive double-differential νμ charged-current cross section with improved acceptance in the T2K off-axis near detector

Abstract: We thank the J-PARC staff for superb accelerator performance. We thank the CERN NA61/SHINE Collaboration for providing valuable particle production data. We acknowledge the support of MEXT, Japan; NSERC (Grant No. SAPPJ-2014-00031), NRC and CFI, Canada; CEA and CNRS/IN2P3, France; DFG, Germany; INFN, Italy; National Science Centre (NCN) and Ministry of Science and Higher Education, Poland; RSF, RFBR, and Ministry of Education and Science, Russia; MINECO and European Regional Development Fund, Spain; SNSF and SERI, Switzerland; STFC, UK; and DOE, U.S. We also thank CERN for the UA1/NOMAD magnet, DESY for the HERA-B magnet mover system, NII for SINET4, the WestGrid and SciNet consortia in Compute Canada, and GridPP in the United Kingdom. In addition, participation of individual researchers and institutions has been further supported by funds from ERC (FP7), H2020 Grant No. RISE-GA644294-JENNIFER, European Union; JSPS, Japan; Royal Society, United Kingdom; and the Alfred P. Sloan Foundation and the DOE Early Career program, U.S.

Comparisons and challenges of modern neutrino scattering experiments (TENSIONS2016 report)

Abstract: Over the last decade, there has been enormous effort to measure neutrino interaction cross sections important to oscillation experiments. However, a number of results from modern experiments appear to be in tension with each other, despite purporting to measure the same processes. The TENSIONS2016 workshop was held at University of Pittsburgh July 24-31, 2016 and was sponsored by the Pittsburgh High Energy Physics, Astronomy, and Cosmology Center (PITT-PACC). The focus was on bringing experimentalists from three experiments together to compare results in detail and try to find the source of tension by clarifying and comparing signal definitions and the analysis strategies used for each measurement. A set of comparisons between the measurements using a consistent set of models was also made. This paper summarizes the main conclusions of that work.

Measurement of the single pi(0) production rate in neutral current neutrino interactions on water

Abstract: The single π0 production rate in neutral current neutrino interactions on water in a neutrino beam with a peak neutrino energy of 0.6 GeV has been measured using the POD, one of the subdetectors of the T2K near detector. The production rate was measured for data taking periods when the POD contained water (2.64×1020 protons-on-target) and also periods without water (3.49×1020 protons-on-target). A measurement of the neutral current single π0 production rate on water is made using appropriate subtraction of the production rate with water in from the rate with water out of the target region. The subtraction analysis yields 106±41±69 signal events where the uncertainties are statistical (stat.) and systematic (sys.) respectively. This is consistent with the prediction of 157 events from the nominal simulation. The measured to expected ratio is 0.68±0.26(stat)±0.44(sys)±0.12(flux). The nominal simulation uses a flux integrated cross section of 7.63×10−39 cm2 per nucleon with an average neutrino interaction energy of 1.3 GeV.

PhyStat-$\nu$ 2016 at the IPMU: Summary of Discussions

Abstract: The presentations, discussions and findings from the inaugural `PhyStat-$ u$' workshop held at the Kavli Institute for the Physics and Mathematics of the Universe (IPMU) near Tokyo in 2016 are described. PhyStat-$ u$ was the first workshop to focus solely on statistical issues across the broad range of modern neutrino physics, bringing together physicists who are active in the analysis of neutrino data with experts in statistics to explore statistical issues in the field. It is a goal of PhyStat-$ u$ to help serve the neutrino physics community by providing a forum within which such statistical issues can be discussed and disseminated broadly. This paper is adapted from a summary document that was initially circulated amongst the participants soon after the workshop. Another PhyStat-$ u$ workshop is being held at CERN in January 2019, building on the discussions in 2016. Advances in experimental neutrino physics in recent years have led to much larger datasets and more diversity in the properties of neutrinos that are being investigated. The discussions here raised several areas where improved statistical errors and more complicated interpretations of the data require statistical methods to be revisited, as well as topics where broader discussions between experimentalists, phenomenologists and theorists will required, which are summarised here. It is important to record the state of the field as it stands today, as much is expected to change over the coming years, including the emergence of more inter-collaborational studies and increasing sophistication in global parameter fitting and model selection methods. The document is also intended to serve as a reference for pedagogical material for those who are new to the use of modern statistical techniques to describe experimental data, as well as those who are well-versed in these techniques and wish to apply them to new data.