Accelerated Event-by-Event Neutrino Oscillation Reweighting with Matter Effects on a GPU

Oscillation probability calculations are becoming increasingly CPU intensive in modern neutrino oscillation analyses. The independency of reweighting individual events in a Monte Carlo sample lends itself to parallel implementation on a Graphics Processing Unit. The library "Prob3++" was ported to the GPU using the CUDA C API, allowing for large scale parallelized calculations of neutrino oscillation probabilities through matter of constant density, decreasing the execution time by a factor of 75, when compared to performance on a single CPU.Comment: Final Update: Post submission update Updated version: quantified the difference in event rates for binned and event-by-event reweighting with a typical binning scheme. Improved formatting of reference

Argon Purification Studies and a Novel Liquid Argon Re-circulation System

Future giant liquid argon (LAr) time projection chambers (TPCs) require a purity of better than 0.1 parts per billion (ppb) to allow the ionised electrons to drift without significant capture by any electronegative impurities. We present a comprehensive study of the effects of electronegative impurity on gaseous and liquid argon scintillation light, an analysis of the efficacy of various purification chemicals, as well as the Liverpool LAr setup, which utilises a novel re-circulation purification system. Of the impurities tested - Air, O_2, H_2O, N_2 and CO_2 in the range of between 0.01 ppm to 1000 ppm - H_2O was found to have the most profound effect on gaseous argon scintillation light, and N_2 was found to have the least. Additionally, a correlation between the slow component decay time and the total energy deposited with 0.01 ppm - 100 ppm O_2 contamination levels in liquid argon has been established. The superiority of molecular sieves over anhydrous complexes at absorbing Ar gas, N_2 gas and H_2O vapour has been quantified using BET isotherm analysis. The efficiency of Cu and P_2O5 at removing O_2 and H_2O impurities from 1 bar N6 argon gas at both room temperature and -130 ^oC was investigated and found to be high. A novel, highly scalable LAr re-circulation system has been developed. The complete system, consisting of a motorised bellows pump operating in liquid and a purification cartridge, were designed and built in-house. The system was operated successfully over many days and achieved a re-circulation rate of 27 litres/hour and high purity

Measurement of double-differential muon neutrino charged-current interactions on C8 H8 without pions in the final state using the T2K off-axis beam

We report the measurement of muon neutrino charged-current interactions on carbon without pions in the final state at the T2K beam energy using 5.734×1020 protons on target. For the first time the measurement is reported as a flux-integrated, double-differential cross section in muon kinematic variables (cosθμ, pμ), without correcting for events where a pion is produced and then absorbed by final state interactions. Two analyses are performed with different selections, background evaluations and cross-section extraction methods to demonstrate the robustness of the results against biases due to model-dependent assumptions. The measurements compare favorably with recent models which include nucleon-nucleon correlations but, given the present precision, the measurement does not distinguish among the available models. The data also agree with Monte Carlo simulations which use effective parameters that are tuned to external data to describe the nuclear effects. The total cross section in the full phase space is σ=(0.417±0.047(syst)±0.005(stat))×10-38 cm2 nucleon-1 and the cross section integrated in the region of phase space with largest efficiency and best signal-over-background ratio (cosθμ\u3e0.6 and pμ\u3e200 MeV) is σ=(0.202±0.036(syst)±0.003(stat))×10-38 cm2 nucleon-1

Measurement of the muon neutrino inclusive charged-current cross section in the energy range of 1-3

We report a measurement of the νμ-nucleus inclusive charged-current cross section (=σcc) on iron using data from the INGRID detector exposed to the J-PARC neutrino beam. The detector consists of 14 modules in total, which are spread over a range of off-axis angles from 0° to 1.1°. The variation in the neutrino energy spectrum as a function of the off-axis angle, combined with event topology information, is used to calculate this cross section as a function of neutrino energy. The cross section is measured to be σcc(1.1 GeV)=1.10±0.15 (10-38 cm2/nucleon), σcc(2.0 GeV)=2.07±0.27 (10-38 cm2/nucleon), and σcc(3.3 GeV)=2.29±0.45 (10-38 cm2/nucleon), at energies of 1.1, 2.0, and 3.3 GeV, respectively. These results are consistent with the cross section calculated by the neutrino interaction generators currently used by T2K. More importantly, the method described here opens up a new way to determine the energy dependence of neutrino-nucleus cross sections

Clientelism as civil society? Unpacking the relationship between clientelism and democracy at the local level in South Africa

This article, building on analyses from the global south, attempts to reframe democratic expectations by considering where previously maligned practices such as clientelism may hold moments of democracy. It does so by comparing the theory of civil society with that of clientelism, and its African counterpart neo-patrimonialism. It argues that clientelism as civil society may fulfil democratic tasks such as holding the (local) state accountable, strengthening civil and political liberties and providing channels of access for previously marginalised groups. Clientelism is not necessarily a reflection of imposed power relations but, at times, can demonstrate a conscious political strategy, to generate development, on the part of its protagonists.IS

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

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\u27s 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 Muon Antineutrino Oscillations with an Accelerator-Produced Off-Axis Beam

T2K reports its first measurements of the parameters governing the disappearance of ν-μ in an off-axis beam due to flavor change induced by neutrino oscillations. The quasimonochromatic ν-μ beam, produced with a peak energy of 0.6 GeV at J-PARC, is observed at the far detector Super-Kamiokande, 295 km away, where the ν-μ survival probability is expected to be minimal. Using a data set corresponding to 4.01×1020 protons on target, 34 fully contained μ-like events were observed. The best-fit oscillation parameters are sin2(θ-23)=0.45 and |Δm-322|=2.51×10-3 eV2 with 68% confidence intervals of 0.38-0.64 and 2.26-2.80×10-3 eV2, respectively. These results are in agreement with existing antineutrino parameter measurements and also with the νμ disappearance parameters measured by T2K

Updated T2K measurements of muon neutrino and antineutrino disappearance using 1.5×1021 protons on target

We report measurements by the T2K experiment of the parameters θ23 and Δm322 governing the disappearance of muon neutrinos and antineutrinos in the three-flavor neutrino oscillation model. Utilizing the ability of the experiment to run with either a mainly neutrino or a mainly antineutrino beam, the parameters are measured separately for neutrinos and antineutrinos. Using 7.482×1020 POT in neutrino running mode and 7.471×1020 POT in antineutrino mode, T2K obtained sin2(θ23)=0.51-0.07+0.08 and Δm322=2.53-0.13+0.15×10-3 eV2/c4 for neutrinos, and sin2(θ-23)=0.42-0.07+0.25 and Δm-232=2.55-0.27+0.33×10-3 eV2/c4 for antineutrinos (assuming normal mass ordering). No significant differences between the values of the parameters describing the disappearance of muon neutrinos and antineutrinos were observed

Combined Analysis of Neutrino and Antineutrino Oscillations at T2K

T2K reports its first results in the search for CP violation in neutrino oscillations using appearance and disappearance channels for neutrino- and antineutrino-mode beams. The data include all runs from January 2010 to May 2016 and comprise 7.482×1020 protons on target in neutrino mode, which yielded in the far detector 32 e-like and 135 μ-like events, and 7.471×1020 protons on target in antineutrino mode, which yielded 4 e-like and 66 μ-like events. Reactor measurements of sin22θ13 have been used as an additional constraint. The one-dimensional confidence interval at 90% for the phase δCP spans the range (-3.13, -0.39) for normal mass ordering. The CP conservation hypothesis (δCP=0, π) is excluded at 90% C.L

First measurement of the muon neutrino charged current single pion production cross section on water with the T2K near detector

The T2K off-axis near detector, ND280, is used to make the first differential cross section measurements of muon neutrino charged current single positive pion production on a water target at energies ∼0.8 GeV. The differential measurements are presented as a function of the muon and pion kinematics, in the restricted phase space defined by pπ+\u3e200 MeV/c, pμ\u3e200 MeV/c, cos(θπ+)\u3e0.3 and cos(θμ)\u3e0.3. The total flux integrated νμ charged current single positive pion production cross section on water in the restricted phase space is measured to be