We present our new measurement of the cross-section for charm dimuon production in neutrino iron interactions based upon the full statistics collected by the NOMAD experiment. After background subtraction we observe 15 344 charm dimuon events, providing the largest sample currently available. The analysis exploits the large inclusive charged current sample - about 9 x 10(6) events after all analysis cuts - and the high resolution NOMAD detector to constrain the total systematic uncertainty on the ratio of charm dimuon to inclusive Charged Current (CC) cross-sections to similar to 2%. We also perform a fit to the NOMAD data to extract the charm production parameters and the strange quark sea content of the nucleon within the NLO QCD approximation. We obtain a value of m(c)(m(c)) = 1.159 +/- 0.075 GeV/c(2) for the running mass of the charm quark in the (MS) over bar scheme and a strange quark sea suppression factor of kappa(s) = 0.591 +/- 0.019 at Q(2) = 20 GeV2/c(2). (C) 2013 Elsevier B.V. All rights reserved.

The OPERA Collaboration (2011) [1] has reported evidence of superluminal vi, 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 Z(0) mediated processes analogous to Cherenkov radiation. In terms of the parameter delta equivalent to (v(v)(2) - v(c)(2))/v(c)(2), the OPERA result corresponds to delta approximate to 5 . 10(-5). For this value (note that (v(v) - v(c))/v(c) approximate to delta/2 approximate to 2.5 . 10(-5)) of delta, 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 gamma 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 delta < 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 Ice Cube are also pointing to a much stricter limit on delta. (c) 2012 Elsevier B.V. All rights reserved.

We present a search for neutrino induced events containing a single, exclusive photon using data from the NOMAD experiment at the CERN SPS where the average energy of the neutrino flux is ≃25GeV. The search is motivated by an excess of electron-like events in the 200–475 MeV energy region as reported by the MiniBooNE experiment. In NOMAD, photons are identified via their conversion to e+e− in an active target embedded in a magnetic field. The background to the single photon signal is dominated by the asymmetric decay of neutral pions produced either in a coherent neutrino–nucleus interaction, or in a neutrino–nucleon neutral current deep inelastic scattering, or in an interaction occurring outside the fiducial volume. All three backgrounds are determined in situ using control data samples prior to opening the 'signal-box'. In the signal region, we observe 155 events with a predicted background of 129.2±8.5±3.3. We interpret this as null evidence for excess of single photon events, and set a limit. Assuming that the hypothetical single photon has a momentum distribution similar to that of a photon from the coherent π0 decay, the measurement yields an upper limit on single photon events, <4.0×10−4 per νμ charged current event. Narrowing the search to events where the photon is approximately collinear with the incident neutrino, we observe 78 events with a predicted background of 76.6±4.9±1.9 yielding a more stringent upper limit, <1.6×10−4 per νμ charged current event.

Cryogenic noble liquid detectors are presently considered one of the best options for WIMP Dark Matter searches, especially when extensions to multi ton scale sensitive masses are foreseen. The WArP experiment is the first one that exploits the unique characteristics of liquid Argon to make a highly sensitive search for WIMP Dark Matter candidates. In 2008, a double phase detector has been assembled in the Gran Sasso National Laboratory with 140 kg sensitive mass and a discovery potential in the range of 5 × 10-45 cm2 in the spin-independent WIMP-nucleon cross-section. In addition to standard neutrons and gamma-rays passive shields, WArP implements an 8 ton liquid Argon active shield with 4p coverage. The detector was commissioned and put into operation during the first half of 2009 for a first technical run. Detector design, construction and assembly are described, together with the very first results of this technical run.

Important open questions are still present in fundamental Physics and Cosmology, like the nature of Dark Matter, the matter-antimatter asymmetry and the validity of the Standard Model of particle interactions. Addressing these questions requires a new generation of massive particle detectors to explore the subatomic and astrophysical worlds. ICARUS T600 is the first large mass (760 tons) example of a new generation of detectors able to combine the imaging capabilities of the old famous "bubble chamber" with the excellent energy measurement of huge electronic detectors. ICARUS T600 now operates at the Gran Sasso underground laboratory and is used to study cosmic rays, neutrino oscillations and the proton decay. The potential for doing physics of this novel telescope is presented through a few examples of neutrino interactions reconstructed with unprecedented detail. Detector design and early operation are also reported.

A dedicated test of the effects of Oxygen contamination in liquid Argon has been performed at the INFN-Gran Sasso Laboratory (LNGS, Italy) within the WArP R&D program. Two detectors have been used: the WArP 2.3 lt prototype and a small (0.7 lt) dedicated detector, coupled with a system for the injection of controlled amounts of gaseous Oxygen. Purpose of the test with the 0.7 lt detector is to detect the reduction of the long-lived component lifetime of the Argon scintillation light emission at increasing O2 concentration. Data from the WArP prototype are used for determining the behavior of both the ionization electron lifetime and the scintillation long-lived component lifetime during the O2-purification process activated in closed loop during the acquisition run. The electron lifetime measurements allow to infer the O2 content of the Argon and correlate it with the long-lived scintillation lifetime data. The effect of Oxygen contamination on the scintillation light has been thus measured over a wide range of O2 concentration, spanning from about 10^-3 ppm up to about 10 ppm. The rate constant of the light quenching process induced by Oxygen in LAr has been found to be k'(O2)=0.54+-0.03 micros^-1 ppm^-1.

An unprecedentedly high value of electron lifetime in a liquid argon TPC, about 21ms, has been measured in a test facility at INFN-LNL. This results opens the way to the future development of TPCs with very long drift distances.

A special dedicated double-rebinning algorithm has been successfully developed in order to extract the physical hit signal from the TPC wires. This solution has been implemented on digital boards, allowing to realize a local trigger able to identify even localized low-energy small events.

A key feature for the success of the liquid Argon imaging TPC (LAr-TPC) technology is the industrial purification against electro-negative impurities, especially Oxygen and Nitrogen remnants, which have to be continuously kept at an exceptionally low level by filtering and recirculating liquid Argon. Improved purification techniques have been applied to a 120 liters LAr-TPC test facility in the INFN-LNL laboratory. Through-going muon tracks have been used to determine the free electron lifetime in liquid Argon against electro-negative impurities. The short path length here observed (30 cm) is compensated by the high accuracy in the observation of the specific ionization of cosmic ray muons at sea level as a function of the drift distance. A free electron lifetime of iota similar to (21.4(-4.3)(+7.3)) ms, namely > 15.8 ms at 90% C.L. has been observed over several weeks under stable conditions, corresponding to a residual Oxygen equivalent of approximate to 15 ppt (part per trillion). At 500 V/cm, the free electron speed is 1.5 mm/mu s. In a LAr-TPC a free electron lifetime in excess of 15 ms corresponds for instance to an attenuation of less than 20% after a drift path of 5 m, opening the way to the operation of the LAr-TPC with exceptionally long drift distances.

The MODULAr project foresees the exploitation of a new liquid Argon imaging detector, of at least 20 kt fiducial mass, to be operated in a shallow depth location under the Gran Sasso Mountain. It will be devoted to study neutrino oscillations with an optimized off-axis CNGS neutrino beam. Cosmic neutrinos as well as proton decay will also be addressed. The MODULAr detector will vastly inherit from the technology developed for ICARUS-T600. However, such an increase in the volume over the current ICARUS-T600 needs to be carefully considered. It is concluded that a single, huge volume is an inoperable and uneconomical solution for many reasons. A very large mass is best realized with a modular set of many identical, independent units, each of about 5 kt, ``cloning'' the basic technology of the ICARUS-T600. Several of such modular units will be assembled to reach at least 20 kt as initial sensitive volume. The increase of the active volume of about one order of magnitude with respect to the ICARUS-T600 detector requires some specific R&D activity, which will be implemented in a ∼ 360 ton prototype unit (SLICE) of reduced length.

We present a Study of exclusive neutral pion production in neutrino-nucleus Neutral Current interactions using data from the NOMAD experiment at the CERN SPS. The data correspond to 1.44 x 10(6) muon-neutrino Charged Current interactions in the energy range 2.5 <= E-nu <= 300 GeV. Neutrino events with only one visible pi(0) in the final state are expected to result from two Neutral Current processes: coherent pi(0) production, nu + A -> nu + A + pi(0) and single pi(0) production in neutrino-nucleon scattering. The signature of coherent pi(0) production is an emergent pi(0) almost collinear with the incident neutrino while pi(0)'s produced in neutrino-nucleon deep inelastic scattering have larger transverse momenta. In this analysis all relevant backgrounds to the coherent pi(0) production signal are measured using data themselves. Having determined the backgrounds, and using the Rein-Sehgal model for the coherent pi(0) production to compute the detection efficiency, we obtain 4630 +/- 522(stat) +/- 426(syst) corrected coherent-pi(0) events with E-pi 0 >= 0.5 GeV. We measure sigma(nu A -> nu A pi(0)) = 172.6 +/- 8.1 (stat) +/- 6.9(syst)] x 10(-40) cm(2)/nucleus. This is the most precise measurement of the coherent pi(0) production to date. (C) 2009 Elsevier B.V. All rights reserved.

We have studied the muon neutrino and antineutrino quasi-elastic (QEL) scattering reactions (ν μ n→μ − p and \(\bar{\nu }_{\mu}p\to\mu^{+}n\)) using a set of experimental data collected by the NOMAD Collaboration. We have performed measurements of the cross-section of these processes on a nuclear target (mainly carbon) normalizing it to the total ν μ (\(\bar{\nu}_{\mu}\)) charged-current cross section. The results for the flux-averaged QEL cross sections in the (anti)neutrino energy interval 3–100 GeV are \(\langle \sigma_{\mathrm{qel}}\rangle_{\nu_{\mu}}=(0.92\pm0.02(\mathrm{stat})\pm0.06(\mathrm{syst}))\times10^{-38}~\mathrm{cm}^{2}\) and \(\langle\sigma_{\mathrm{qel}}\rangle_{\bar{\nu}_{\mu}}=(0.81\pm0.05(\mathrm{stat})\pm0.09(\mathrm{syst}))\times10^{-38}~\mathrm{cm}^{2}\) for neutrino and antineutrino, respectively. The axial mass parameter M A was extracted from the measured quasi-elastic neutrino cross section. The corresponding result is M A =1.05±0.02(stat)±0.06(syst) GeV. It is consistent with the axial mass values recalculated from the antineutrino cross section and extracted from the pure Q 2 shape analysis of the high purity sample of ν μ quasi-elastic 2-track events, but has smaller systematic error and should be quoted as the main result of this work. Our measured M A is found to be in good agreement with the world average value obtained in previous deuterium filled bubble chamber experiments. The NOMAD measurement of M A is lower than those recently published by K2K and MiniBooNE Collaborations. However, within the large errors quoted by these experiments on M A , these results are compatible with the more precise NOMAD value.

Two dedicated and distinct tests of the effects of Nitrogen and Oxygen contaminations in liquid Argon (LAr) have been performed within the WArP R&D program. Purpose of the tests is to detect the reduction of the LAr scintillation light emission as a function of the amount of the contaminant injected in the Argon volume. The rate constant of the light quenching process induced by Nitrogen in LAr has been found to be k(N2)=0.11μs-1ppm-1 (part per million), while the rate constant for Oxygen has been found to be k′(O2)=0.54±0.03μs-1ppm-1. Direct PMT signals acquisition allowed to extract with high precision the main characteristics of the scintillation light emission in pure and contaminated LAr. In particular, the decreasing behavior in lifetime and relative amplitude of the slow component is found to be appreciable from O (1 ppm) of Nitrogen concentrations and from O (0.1 ppm) of Oxygen concentrations.

The paper is considering an opportunity for the CERN/GranSasso (CNGS) neutrino complex, concurrent time-wise with T2K and NOvA projects, with the aim of improving the sensitivity on v(mu) <-> v(e) theta(13) mixing angle by nearly an order of magnitude with respect to T2K expectations. The experiment is based on approximate to 20 kt fiducial volume LAr-TPC, following very closely the technology developed for the ICARUS-T600.The present preliminary proposal, called MODULAr, is focused on the following three main activities, for which we seek an extended international collaboration:(1) The neutrino beam from the CERN 400 GeV proton beam and an optimized horn focussing, eventually with an increased intensity in the framework of the LHC accelerator improvement programme.(2) A new experimental area LNGS-B, of at least 50,000 m(3) at 10 km off-axis from the main laboratory, eventually upgradable to larger sizes. A location is under consideration at about 1.2 km equivalent water depth. The bubble chamber like imaging and the very fine calorimetry of the LAr-TPC detector will ensure the best background recognition not only from the off-axis neutrinos from the CNGS but also for proton decay and cosmic neutrinos.(3) A new LAr Imaging detector, at least initially with about 20 kt fiducial mass, realised with a modular set of four identical, but independent units, each of about 5 kt, "cloning" the basic technology of the T600. Further phases may foresee extensions of MODULAr to a mass required by the future physics goals.Compared with large water Cherenkov (T2K) and fine grained scintillators (NOvA), the LAr-TPC offers a higher detection efficiency for a given mass and lower backgrounds, since virtually all channels may be unambiguously recognized. In addition to the search for 013 oscillations and CP violation, it would be possible to collect a large number of accurately identified cosmic ray neutrino events and perform search for proton decay in the exotic channels. (C) 2008 Elsevier B.V. All rights reserved.

We present a measurement of the muon neutrino–nucleon inclusive charged current cross section, off an isoscalar target, in the neutrino energy range 2.5⩽Eν⩽40GeV. The significance of this measurement is its precision, ±4% in 2.5⩽Eν⩽10GeV, and ±2.6% in 10⩽Eν⩽40GeV regions, where significant uncertainties in previous experiments still exist, and its importance to the current and proposed long baseline neutrino oscillation experiments.

We report on the first measurement of 39Ar in argon from underground natural gas reservoirs. The gas stored in the US National Helium Reserve was found to contain a low level of 39Ar. The ratio of 39Ar to stable argon was measured to be ⩽4×10-17 (84% C.L.), less than 5% the value in atmospheric argon (39Ar/Ar=8×10-16). The total quantity of argon currently stored in the National Helium Reserve is estimated at 1000tons. 39Ar represents one of the most important backgrounds in argon detectors for WIMP dark matter searches. The findings reported demonstrate the possibility of constructing large multi-ton argon detectors with low radioactivity suitable for WIMP dark matter searches.

A new method of searching for dark matter in the form of weakly interacting massive particles (WIMP) has been developed with the direct detection of the low energy nuclear recoils observed in a massive target (ultimately many tons) of ultra pure liquid argon at 87 K. A high selectivity for argon recoils is achieved by the simultaneous observation of both the VUV scintillation luminescence and of the electron signal surviving columnar recombination, extracted through the liquid-gas boundary by an electric field.First physics results from this method are reported, based on a small 2.31 test chamber filled with natural argon and an accumulated fiducial exposure of about 100 kg day, supporting the future validity of this method with isotopically purified Ar-40 and for a much larger unit presently under construction with correspondingly increased sensitivities. (C) 2007 Elsevier B.V. All rights reserved.

We report on the rst measurement of 39 Ar in argon from underground natural gas reservoirs. The gas stored in the US National Helium Reserve was found to contain a low level of 39 Ar. The ratio of 39 Ar to stable argon was found to be 4 10 17 (84% C.L.), less than 5% the value in atmospheric argon ( 39 Ar=Ar=8 10 16 ). The total quantity of argon currently stored in the National Helium Reserve is estimated at 1000 tons. 39 Ar represents one of the most important backgrounds in argon detectors for WIMP