We report measurements by the T2K experiment of the parameters \(\theta_{23}\) and \(\Delta m^2_{32}\) which govern the disappearance of muon neutrinos and antineutrinos in the three-flavor PMNS ...neutrino oscillation model at T2K's neutrino energy and propagation distance. Utilizing the ability of the experiment to run with either a mainly neutrino or a mainly antineutrino beam, muon-like events from each beam mode are used to measure these parameters separately for neutrino and antineutrino oscillations. Data taken from \(1.49 \times 10^{21}\) protons on target (POT) in neutrino mode and \(1.64 \times 10^{21}\) POT in antineutrino mode are used. The best-fit values obtained by T2K were \(\sin^2\left(\theta_{23}\right)=0.51^{+0.06}_{-0.07} \left(0.43^{+0.21}_{-0.05}\right)\) and \(\Delta m^2_{32}=2.47^{+0.08}_{-0.09} \left(2.50^{+0.18}_{-0.13}\right)\)\evmass for neutrinos (antineutrinos). No significant differences between the values of the parameters describing the disappearance of muon neutrinos and antineutrinos were observed. An analysis using an effective two-flavor neutrino oscillation model where the sine of the mixing angle is allowed to take non-physical values larger than 1 is also performed to check the consistency of our data with the three-flavor model. Our data were found to be consistent with a physical value for the mixing angle.
We report measurements of the flux-integrated \(\bar{\nu}_\mu\) and \(\bar{\nu}_\mu+\nu_\mu\) charged-current cross-sections on water and hydrocarbon targets using the T2K anti-neutrino beam, with a ...mean neutrino energy of 0.86 GeV. The signal is defined as the (anti-)neutrino charged-current interaction with one induced \(\mu^\pm\) and no detected charged pion nor 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, \(p_{\mu}>400~{\rm MeV}/c\) and \(\theta_{\mu}<30^{\circ}\), in the laboratory frame. Absence of pions and protons in the detectable phase space of "\(p_{\pi}>200~{\rm MeV}/c\) and \(\theta_{\pi}<70^{\circ}\)", and "\(p_{\rm p}>600~{\rm MeV}/c\) and \(\theta_{\rm p}<70^{\circ}\)" is required. In this paper, both of the \(\bar{\nu}_\mu\) cross-sections and \(\bar{\nu}_\mu+\nu_\mu\) cross-sections on water and hydrocarbon targets, and their ratios are provided by using D'Agostini unfolding method. The results of the integrated \(\bar{\nu}_\mu\) cross-section measurements over this phase space are \(\sigma_{\rm H_{2}O}\,=\,(1.082\pm0.068(\rm stat.)^{+0.145}_{-0.128}(\rm syst.)) \times 10^{-39}~{\rm cm^{2}/nucleon}\), \(\sigma_{\rm CH}\,=\,(1.096\pm0.054(\rm stat.)^{+0.132}_{-0.117}(\rm syst.)) \times 10^{-39}~{\rm cm^{2}/nucleon}\), and \(\sigma_{\rm H_{2}O}/\sigma_{\rm CH} = 0.987\pm0.078(\rm stat.)^{+0.093}_{-0.090}(\rm syst.)\). The \(\bar{\nu}_\mu+\nu_\mu\) cross-section is \(\sigma_{\rm H_{2}O} = (1.155\pm0.064(\rm stat.)^{+0.148}_{-0.129}(\rm syst.)) \times 10^{-39}~{\rm cm^{2}/nucleon}\), \(\sigma_{\rm CH}\,=\,(1.159\pm0.049(\rm stat.)^{+0.129}_{-0.115}(\rm syst.)) \times 10^{-39}~{\rm cm^{2}/nucleon}\), and \(\sigma_{\rm H_{2}O}/\sigma_{\rm CH}\,=\,0.996\pm0.069(\rm stat.)^{+0.083}_{-0.078}(\rm syst.)\).
The Muon Ionization Cooling Experiment (MICE) will perform a detailed study of ionization cooling to evaluate the feasibility of the technique. To carry out this program, MICE requires an efficient ...particle-identification (PID) system to identify muons. The Electron-Muon Ranger (EMR) is a fully-active tracking-calorimeter that forms part of the PID system and tags muons that traverse the cooling channel without decaying. The detector is capable of identifying electrons with an efficiency of 98.6%, providing a purity for the MICE beam that exceeds 99.8%. The EMR also proved to be a powerful tool for the reconstruction of muon momenta in the range 100-280 MeV/\(c\).
The international Muon Ionization Cooling Experiment (MICE) will perform a systematic investigation of ionization cooling with muon beams of momentum between 140 and 240\,MeV/c at the Rutherford ...Appleton Laboratory ISIS facility. The measurement of ionization cooling in MICE relies on the selection of a pure sample of muons that traverse the experiment. To make this selection, the MICE Muon Beam is designed to deliver a beam of muons with less than \(\sim\)1\% contamination. To make the final muon selection, MICE employs a particle-identification (PID) system upstream and downstream of the cooling cell. The PID system includes time-of-flight hodoscopes, threshold-Cherenkov counters and calorimetry. The upper limit for the pion contamination measured in this paper is \(f_\pi < 1.4\%\) at 90\% C.L., including systematic uncertainties. Therefore, the MICE Muon Beam is able to meet the stringent pion-contamination requirements of the study of ionization cooling.
Neutrino- and antineutrino-oxygen neutral-current quasielastic-like interactions are measured at Super-Kamiokande using nuclear de-excitation \(\gamma\)-rays to identify signal-like interactions in ...data from a \(14.94 \ (16.35)\times 10^{20}\) protons-on-target exposure of the T2K neutrino (antineutrino) beam. The measured flux-averaged cross sections on oxygen nuclei are \(\langle \sigma_{\nu {\rm -NCQE}} \rangle = 1.70 \pm 0.17 ({\rm stat.}) ^{+ {\rm 0.51}}_{- {\rm 0.38}} ({\rm syst.}) \times 10^{-38} \ {\rm cm^2/oxygen}\) with a flux-averaged energy of 0.82 GeV and \(\langle \sigma_{\bar{\nu} {\rm -NCQE}} \rangle = 0.98 \pm 0.16 ({\rm stat.}) ^{+ {\rm 0.26}}_{- {\rm 0.19}} ({\rm syst.}) \times 10^{-38} \ {\rm cm^2/oxygen}\) with a flux-averaged energy of 0.68 GeV, for neutrinos and antineutrinos, respectively. These results are the most precise to date, and the antineutrino result is the first cross section measurement of this channel. They are compared with various theoretical predictions. The impact on evaluation of backgrounds to searches for supernova relic neutrinos at present and future water Cherenkov detectors is also discussed.
This paper reports the first differential measurement of the charged-current \(\overline{\nu}_{\mu}\) interaction cross section on water with no pions in the final state. The unfolded flux-averaged ...measurement using the T2K off-axis near detector is given in double differential bins of \(\mu^+\) momentum and angle. The integrated cross section in a restricted phase space is \(\sigma=\left(1.11\pm0.18\right)\times10^{-38}\) cm\(^{2}\) per water molecule. Comparisons with several nuclear models are also presented.
We report the measurements of 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 \(5.56\times10^{20}\) 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 \(\sigma = (11.76 \pm 0.44 \text{(stat)} \pm 2.39 \text{(syst)}) \times 10^{-40} \text{cm}^2\)~\(\text{nucleon}^{-1}\). 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.
We report a measurement of the flux-integrated \(\nu_{\mu}\) charged-current cross sections on water, hydrocarbon, and iron in the T2K on-axis neutrino beam with a mean neutrino energy of 1.5 GeV. ...The measured cross sections on water, hydrocarbon, and iron are \(\sigma^{\rm{H_{2}O}}_{\rm{CC}}\) = (0.840\(\pm 0.010\)(stat.)\(^{+0.10}_{-0.08}\)(syst.))\(\times\)10\(^{-38}\)cm\(^2\)/nucleon, \(\sigma^{\rm{CH}}_{\rm{CC}}\) = (0.817\(\pm 0.007\)(stat.)\(^{+0.11}_{-0.08}\)(syst.))\(\times\)10\(^{-38}\)cm\(^2\)/nucleon, and \(\sigma^{\rm{Fe}}_{\rm{CC}}\) = (0.859\(\pm 0.003\)(stat.) \(^{+0.12}_{-0.10}\)(syst.))\(\times\)10\(^{-38}\)cm\(^2\)/nucleon respectively, for a restricted phase space of induced muons: \(\theta_{\mu}<45^{\circ}\) and \(p_{\mu}>\)0.4 GeV/\(c\) in the laboratory frame. The measured cross section ratios are \({\sigma^{\rm{H_{2}O}}_{\rm{CC}}}/{\sigma^{\rm{CH}}_{\rm{CC}}}\) = 1.028\(\pm 0.016\)(stat.)\(\pm 0.053\)(syst.), \({\sigma^{\rm{Fe}}_{\rm{CC}}}/{\sigma^{\rm{H_{2}O}}_{\rm{CC}}}\) = 1.023\(\pm 0.012\)(stat.)\(\pm 0.058\)(syst.), and \({\sigma^{\rm{Fe}}_{\rm{CC}}}/{\sigma^{\rm{CH}}_{\rm{CC}}}\) = 1.049\(\pm 0.010\)(stat.)\(\pm 0.043\)(syst.). These results, with an unprecedented precision for the measurements of neutrino cross sections on water in the studied energy region, show good agreement with the current neutrino interaction models used in the T2K oscillation analyses.
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 \(\nu_e\) candidates and 7 anti-\(\nu_e\) 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 \(\Delta m^2_{32}=2.463^{+0.071}_{-0.070}\times10^{-3} \mathrm{eV}^2/c^4\).
A novel single-particle technique to measure emittance has been developed and used to characterise seventeen different muon beams for the Muon Ionisation Cooling Experiment (MICE). The muon beams, ...whose mean momenta vary from 171 to 281 MeV/c, have emittances of approximately 1.5--2.3 \pi mm-rad horizontally and 0.6--1.0 \pi mm-rad vertically, a horizontal dispersion of 90--190 mm and momentum spreads of about 25 MeV/c. There is reasonable agreement between the measured parameters of the beams and the results of simulations. The beams are found to meet the requirements of MICE.
