|
|
T2K Collaboration(Abe, K. et al), Cervera-Villanueva, A., Izmaylov, A., Novella, P., & Sorel, M. (2017). Updated T2K measurements of muon neutrino and antineutrino disappearance using 1.5 x 10(21) protons on target. Phys. Rev. D, 96(1), 011102–9pp.
Abstract: We report measurements by the T2K experiment of the parameters theta(23) and Delta m(32)(2) 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 x 10(20) POT in neutrino running mode and 7.471 x 10(20) POT in antineutrino mode, T2K obtained sin(2) (theta(23)) = 0.51(-0.07)(+0.08) and Delta (m) over bar (2)(32) = (+0.15)(-2.53) -0.13 x 10(-3) eV(2)/c(4) for neutrinos, and sin(2) ((theta) over bar (23)) = 0.42(-0.07)(+0.25) and Delta(m) over bar (2)(32) = 2.55(-0.27)(+0.33) x 10(-3) eV(2)/c(4) 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.
|
|
|
|
T2K Collaboration(Abe, K. et al), Cervera-Villanueva, A., Izmaylov, A., & Novella, P. (2018). First measurement of the nu(mu) charged-current cross section on a water target without pions in the final state. Phys. Rev. D, 97(1), 012001–16pp.
Abstract: This paper reports the first differential measurement of the charged-current interaction cross section of nu(mu) 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 sigma = (0.95 +/- 0.08(stat) +/- 0.06(det syst) +/- 0.04(model syst) +/- 0.08(flux)) x 10(-38) cm(2)/n.
|
|
|
|
T2K Collaboration(Abe, K. et al), Antonova, M., Cervera-Villanueva, A., Izmaylov, A., & Novella, P. (2018). Measurement of inclusive double-differential nu(mu) charged-current cross section with improved acceptance in the T2K off-axis near detector. Phys. Rev. D, 98(1), 012004–18pp.
Abstract: We report a measurement of the flux-integrated cross section for inclusive muon neutrino charged-current interactions on carbon. The double-differential measurements are given as a function of the muon momentum and angle. Relative to our previous publication on this topic, these results have an increased angular acceptance and higher statistics. The data sample presented here corresponds to 5.7 x 10(20) protons on target. The total flux-integrated cross section is measured to be (6.950 +/- 0.662) x 10(-39) cm(2) nucleon(-1) and is consistent with our simulation.
|
|
|
|
NEXT Collaboration(Henriques, C. A. O. et al), Alvarez, V., Benlloch-Rodriguez, J. M., Botas, A., Carcel, S., Carrion, J. V., et al. (2019). Electroluminescence TPCs at the thermal diffusion limit. J. High Energy Phys., 01(1), 027–23pp.
Abstract: The NEXT experiment aims at searching for the hypothetical neutrinoless double-beta decay from the Xe-136 isotope using a high-purity xenon TPC. Efficient discrimination of the events through pattern recognition of the topology of primary ionisation tracks is a major requirement for the experiment. However, it is limited by the diffusion of electrons. It is known that the addition of a small fraction of a molecular gas to xenon reduces electron diffusion. On the other hand, the electroluminescence (EL) yield drops and the achievable energy resolution may be compromised. We have studied the effect of adding several molecular gases to xenon (CO2, CH4 and CF4) on the EL yield and energy resolution obtained in a small prototype of driftless gas proportional scintillation counter. We have compared our results on the scintillation characteristics (EL yield and energy resolution) with a microscopic simulation, obtaining the diffusion coefficients in those conditions as well. Accordingly, electron diffusion may be reduced from about 10 for pure xenon down to 2.5 using additive concentrations of about 0.05%, 0.2% and 0.02% for CO2, CH4 and CF4, respectively. Our results show that CF4 admixtures present the highest EL yield in those conditions, but very poor energy resolution as a result of huge fluctuations observed in the EL formation. CH4 presents the best energy resolution despite the EL yield being the lowest. The results obtained with xenon admixtures are extrapolated to the operational conditions of the NEXT-100 TPC. CO2 and CH4 show potential as molecular additives in a large xenon TPC. While CO2 has some operational constraints, making it difficult to be used in a large TPC, CH4 shows the best performance and stability as molecular additive to be used in the NEXT-100 TPC, with an extrapolated energy resolution of 0.4% at 2.45 MeV for concentrations below 0.4%, which is only slightly worse than the one obtained for pure xenon. We demonstrate the possibility to have an electroluminescence TPC operating very close to the thermal diffusion limit without jeopardizing the TPC performance, if CO2 or CH4 are chosen as additives.
|
|
|
|
T2K Collaboration(Abe, K. et al), Antonova, M., Cervera-Villanueva, A., Fernandez, P., Izmaylov, A., & Novella, P. (2020). Measurement of the muon neutrino charged-current single pi(+) production on hydrocarbon using the T2K off-axis near detector ND280. Phys. Rev. D, 101(1), 012007–19pp.
Abstract: We report the measurements of the single and double differential cross section of muon neutrino charged-current interactions on carbon with a single positively charged pion in the final state at the T2K off-axis near detector using 5.56 x 10(20) protons on target. The analysis uses data control samples for the background subtraction and the cross section signal, defined as a single negatively charged muon and a single positively charged pion exiting from the target nucleus, is extracted using an unfolding method. The model-dependent cross section, integrated over the T2K off-axis neutrino beam spectrum peaking at 0.6 GeV, is measured to be sigma = (11.76 +/- 0.44(stat) +/- 2.39(syst)) x 10(-40) cm(2) nucleon(-1). Various differential cross sections are measured, including the first measurement of the Adler angles for single charged pion production in neutrino interactions with heavy nuclei target.
|
|
