A
bstract
During May 2012, the CERN-CNGS neutrino beam has been operated for two weeks for a total of ~1.8 × 10
17
p.o.t., with the proton beam made of bunches, few ns wide and separated by 100 ns. ...This beam structure allows a very accurate time of flight measurement of neutrinos from CERN to LNGS on an event-by-event basis. Both the ICARUS-T600 PMT-DAQ and the CERN-LNGS timing synchronization have been substantially improved for this campaign, taking advantage of additional independent GPS receivers, both at CERN and LNGS as well as of the deployment of the “White Rabbit” protocol both at CERN and LNGS. The ICARUS-T600 detector has collected 25 beam-associated events; the corresponding time of flight has been accurately evaluated, using all different time synchronization paths. The measured neutrino time of flight is compatible with the arrival of all events with speed equivalent to the one of light: the difference between the expected value based on the speed of light and the measured value is
δt = tof
c
−tof
ν
= 0.10 ± 0.67
stat.
± 2.39
syst.
ns. This result is in agreement with the value previously reported by the ICARUS Collaboration,
δt
= 0.3 ± 4.9
stat.
± 9.0
syst.
ns, but with improved statistical and systematic accuracy.
Abstract
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 $\sigma^{\rm{H_{2}O}}_{\rm{CC}} = (0.840\pm 0.010(\mathrm{stat.})^{+0.10}_{-0.08}(\mathrm{syst.}))\times10^{-38}\,\mathrm{cm}^2$/nucleon, $\sigma^{\rm{CH}}_{\rm{CC}} = (0.817\pm 0.007(\mathrm{stat.})^{+0.11}_{-0.08}(\mathrm{syst.}))\times10^{-38}\,\mathrm{cm}^2$/nucleon, and $\sigma^{\rm{Fe}}_{\rm{CC}} = (0.859\pm 0.003(\mathrm{stat.})^{+0.12}_{-0.10}(\mathrm{syst.}))\times10^{-38}\,\mathrm{cm}^2$/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 ${\sigma^{\rm{H_{2}O}}_{\rm{CC}}}/{\sigma^{\rm{CH}}_{\rm{CC}}} = 1.028\pm 0.016(\mathrm{stat.})\pm 0.053(\mathrm{syst.})$, ${\sigma^{\rm{Fe}}_{\rm{CC}}}/{\sigma^{\rm{H_{2}O}}_{\rm{CC}}} = 1.023\pm 0.012(\mathrm{stat.})\pm 0.058(\mathrm{syst.})$, and ${\sigma^{\rm{Fe}}_{\rm{CC}}}/{\sigma^{\rm{CH}}_{\rm{CC}}} = 1.049\pm 0.010(\mathrm{stat.})\pm 0.043(\mathrm{syst.})$. 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 OPERA Collaboration (2011) 1 has reported evidence of superluminal νμ propagation between CERN and the LNGS. Cohen and Glashow (2011) 2 argued that such neutrinos should lose energy by producing ...photons and e+e− pairs, through Z0 mediated processes analogous to Cherenkov radiation. In terms of the parameter δ≡(vν2−vc2)/vc2, the OPERA result corresponds to δ≈5⋅10−5. For this value (note that (vν−vc)/vc≈δ2≈2.5⋅10−5) of δ, a very significant deformation of the neutrino energy spectrum and an abundant production of photons and e+e− pairs should be observed at LNGS. We present an analysis based on the 2010 and part of the 2011 data sets from the ICARUS experiment, located at Gran Sasso National Laboratory and using the same neutrino beam from CERN. We find that the rates and deposited energy distributions of neutrino events in ICARUS agree with the expectations for an unperturbed spectrum of the CERN neutrino beam, as also reported by OPERA. Our results therefore refute a superluminal interpretation of the OPERA result according to the Cohen and Glashow (2011) prediction 2 for a weak current analog to Cherenkov radiation. In a dedicated search, no superluminal Cherenkov-like e+e− pair or γ emission event has been directly observed inside the fiducial volume of the “bubble chamber-like” ICARUS TPC-LAr detector, setting the much stricter limit of δ<2.5⋅10−8 at the 90% confidence level, comparable with the one due to the observations from the SN1987a (M.J. Longo, 1987 4). The observations of high energy neutrino events by Super-Kamiokande and IceCube are also pointing to a much stricter limit on δ.
We report on first measurements of low-mass electron-positron pairs in Pb-Au collisions at the CERN SPS beam energy of 40 AGeV. The observed pair yield integrated over the range of invariant masses ...0.2<m</=1 GeV/c(2) is enhanced over the expectation from neutral meson decays by a factor of 5.9+/-1.5(stat)+/-1.2(syst data)+/-1.8(syst meson decays), somewhat larger than previously observed at the higher energy of 158 AGeV. The results are discussed with reference to model calculations based on pi(+)pi(-)-->e(+)e(-) annihilation with a modified rho propagator. They may be linked to chiral symmetry restoration and support the notion that the in-medium modifications of the rho are more driven by baryon density than by temperature.
Liquid Argon Time Projection Chamber (LAr TPC) detectors offer charged particle imaging capability with remarkable spatial resolution. Precise event reconstruction procedures are critical in order to ...fully exploit the potential of this technology. In this paper we present a new, general approach to 3D reconstruction for the LAr TPC with a practical application to the track reconstruction. The efficiency of the method is evaluated on a sample of simulated tracks. We present also the application of the method to the analysis of stopping particle tracks collected during the ICARUS T600 detector operation with the CNGS neutrino beam.
Study of electron recombination in liquid argon with the ICARUS TPC Amoruso, S.; Antonello, M.; Aprili, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2004, Letnik:
523, Številka:
3
Journal Article
Recenzirano
Electron recombination in liquid argon (LAr) is studied by means of charged particle tracks collected in various ICARUS liquid argon TPC prototypes. The dependence of the recombination on the ...particle stopping power has been fitted with a Birks functional dependence. The simulation of the process of electron recombination in Monte Carlo calculations is discussed. A quantitative comparison with previously published data is carried out.
An extension of the new standard model, by introducing a mixing of the low mass “active” neutrinos with heavy ones, or by any model with lepton flavor violation, is considered. This leads to ...non-orthogonal neutrino production and detection states and to modifications of neutrino oscillations in both vacuum and matter. The possibility of the discovery of such effects in current and future neutrino oscillation experiments is discussed. First order approximation formulas for the flavor transition probabilities in constant density matter, for all experimentally available channels, are given. Numerical calculations of flavor transition probabilities for two sets of new physics parameters describing a single “effective” heavy neutrino state, both satisfying present experimental constraints, have been performed. Two energy ranges and several baselines, assuming both the current (±2σ) and the expected future errors (±3%) of the neutrino oscillation parameters are considered, keeping their present central values. It appears that the biggest potential of the discovery of the possible presence of any new physics is pronounced in oscillation channels in which νe and νē are not involved at all, especially for two baselines, L=3000 km and L=7500 km, which for other reasons are also called “magic” for future Neutrino Factory experiments.
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