NOMAD Collaboration(Samoylov, O. et al), Cervera-Villanueva, A., Gomez-Cadenas, J. J., & Hernando, J. (2013). A precision measurement of charm dimuon production in neutrino interactions from the NOMAD experiment. Nucl. Phys. B, 876(2), 339–375.
Abstract: 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).
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ANTARES Collaboration(Aguilar, J. A. et al), Bigongiari, C., Dornic, D., Emanuele, U., Gomez-Gonzalez, J. P., Hernandez-Rey, J. J., et al. (2010). Performance of the front-end electronics of the ANTARES neutrino telescope. Nucl. Instrum. Methods Phys. Res. A, 622(1), 59–73.
Abstract: ANTARES is a high-energy neutrino telescope installed in the Mediterranean Sea at a depth of 2475 m. It consists of a three-dimensional array of optical modules, each containing a large photomultiplier tube. A total of 2700 front-end ASICs named analogue ring samplers (ARS) process the phototube signals, measure their arrival time, amplitude and shape as well as perform monitoring and calibration tasks. The ARS chip processes the analogue signals from the optical modules and converts information into digital data. All the information is transmitted to shore through further multiplexing electronics and an optical link. This paper describes the performance of the ARS chip: results from the functionality and characterization tests in the laboratory are summarized and the long-term performance in the apparatus is illustrated.
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SuperNEMO Collaboration(Argyriades, J. et al), Carcel, S., Diaz, J., Monrabal, F., Serra, L., & Yahlali, N. (2010). Results of the BiPo-1 prototype for radiopurity measurements for the SuperNEMO double beta decay source foils. Nucl. Instrum. Methods Phys. Res. A, 622(1), 120–128.
Abstract: The development of BiPo detectors is dedicated to the measurement of extremely high radiopurity in (TI)-T-208 and Bi-214 for the SuperNEMO double beta decay source foils. A modular prototype, called BiPo-1, with 0.8 m(2) of sensitive surface area, has been running in the Modane Underground Laboratory since February, 2008. The goal of BiPo-1 is to measure the different components of the background and in particular the surface radiopurity of the plastic scintillators that make up the detector. The first phase of data collection has been dedicated to the measurement of the radiopurity in (TI)-T-208. After more than one year of background measurement, a surface activity of the scintillators of A((TI)-T-208) = 1.5 μBq/m(2) is reported here. Given this level of background, a larger BiPo detector having 12 m(2) of active surface area, is able to qualify the radiopurity of the SuperNEMO selenium double beta decay foils with the required sensitivity of A((TI)-T-208) <2 μBq/kg (90% CL.) with a six month measurement.
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Abgrall, N. et al, Cervera-Villanueva, A., Escudero, L., Monfregola, L., & Stamoulis, P. (2011). Time projection chambers for the T2K near detectors. Nucl. Instrum. Methods Phys. Res. A, 637(1), 25–46.
Abstract: The T2K experiment is designed to study neutrino oscillation properties by directing a high intensity neutrino beam produced at J-PARC in Tokai, Japan, towards the large Super-Kamiokande detector located 295 km away, in Kamioka, Japan. The experiment includes a sophisticated near detector complex, 280 m downstream of the neutrino production target in order to measure the properties of the neutrino beam and to better understand neutrino interactions at the energy scale below a few GeV. A key element of the near detectors is the ND280 tracker, consisting of two active scintillator-bar target systems surrounded by three large time projection chambers (TPCs) for charged particle tracking. The data collected with the tracker are used to study charged current neutrino interaction rates and kinematics prior to oscillation, in order to reduce uncertainties in the oscillation measurements by the far detector. The tracker is surrounded by the former UA1/NOMAD dipole magnet and the TPCs measure the charges, momenta, and particle types of charged particles passing through them. Novel features of the TPC design include its rectangular box layout constructed from composite panels, the use of bulk micromegas detectors for gas amplification, electronics readout based on a new ASIC, and a photoelectron calibration system. This paper describes the design and construction of the TPCs, the micromegas modules, the readout electronics, the gas handling system, and shows the performance of the TPCs as deduced from measurements with particle beams, cosmic rays, and the calibration system.
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Cervera-Villanueva, A., Laing, A., Martin-Albo, J., & Soler, F. J. P. (2010). Performance of the MIND detector at a Neutrino Factory using realistic muon reconstruction. Nucl. Instrum. Methods Phys. Res. A, 624(3), 601–614.
Abstract: A Neutrino Factory producing an intense beam composed of v(e)((v) over bar (e)) and (v) over bar (mu)(v(mu)) from muon decays has been shown to have the greatest sensitivity to the two currently unmeasured neutrino mixing parameters theta(13) and delta(CP) Using the wrong-sign muon signal to measure v(e)-> v(mu)((v) over bar (e) ->(v) over bar (mu)) oscillations in a 50kt Magnetised Iron Neutrino Detector (MIND) sensitivity to delta(CP) could be maintained down to small values of theta(13) However the detector efficiencies used in these previous studies were calculated assuming perfect pattern recognition In this paper MIND is reassessed taking into account for the first time a realistic pattern recognition for the muon candidate Reoptimisation of the analysis utilises a combination of methods including a multivariate analysis similar to the one used in MINOS to maintain high efficiency while suppressing backgrounds ensuring that the signal selection efficiency and the background levels are comparable or better than the ones in previous analyses As a result MIND remains the most sensitive future facility for the discovery of CP violation from neutrino oscillations.
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