C. Nieuwenhuis
CERN
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Featured researches published by C. Nieuwenhuis.
Physics Letters B | 1983
F. Bergsma; J. Dorenbosch; M. Jonker; C. Nieuwenhuis; J. Allaby; U. Amaldi; G. Barbiellini; L. Barone; C. Berger; A. Capone; W. Flegel; L. Lanceri; M. Metcalf; J. Panman; K. Winter; I. Abt; J. Aspiazu; F.W. Büsser; H. Daumann; P. D. Gall; F. Niebergall; K. H. Ranitzsch; P. Schütt; P. Stähelin; P. Gorbunov; E. Grigoriev; V. Kaftanov; V. Khovansky; A. Rosanov; A. Baroncelli
Abstract A search for heavy neutrinos was conducted in the neutrino beam produced by the 400 GeV proton beam-dump and in the 400 GeV wide-band neutrino beam at CERN. A heavy neutrino associated with the τ lepton was searched for in the beam-dump experiment. No assumption on the nature of heavy neutrinos was made in the wide-band beam experiment. A search was made for neutrinos decaying into two electrons and a light neutrino. Since no events were observed, an upper limit on the neutrino mixing angles as a function of the neutrino mass is derived. The beam-dump experiment is sensitive to a neutrino mass range of 10–250 MeV and an upper limit at 90% confidende level on the square of the neutrino mixing angle of θ10 −10 was obtained for neutrino masses greater than 180 MeV. The wide-band neutrino experiment is sensitive to neutrinos with a mass in a larger range (10–490 MeV), and for masses greater than 250 MeV yields an upper limit on the square of the neutrino mixing angle of θ10 −6 .
Physics Letters B | 1983
F. Bergsma; J. Dorenbosch; M. Jonker; C. Nieuwenhuis; F. Udo; J. Allaby; U. Amaldi; G. Barbiellini; L. Barone; A. Capone; W. Flegel; M. Metcalf; J. Panman; K. Winter; I. Abt; J. Aspiazu; F.W. Büsser; H. Daumann; P. D. Gall; E. Metz; F. Niebergall; K. H. Ranitzsch; P. Stähelin; P. Gorbunov; E. Grigoriev; V. Kaftanov; V. Khovansky; A. Rosanov; A. Baroncelli; B. Borgia
Abstract Inclusive neutrino and antineutrino charged current interactions were studied in the CHARM detector exposed to neutrino and antineutrino Wide Band Beams of the CERN 400 GeV SPS. The x and Q2 dependence of the structure functions F2 and xF3 and of the antiquark momentum distribution q were determined. The data have been interpreted in terms of QCD theory using the Furmanski-Petronzio method. In this way we have determined ΛLO = [190−40+70 (stat) ± 70 (syst.)] MeV and the structure functions of quarks and gluons without specific assumptions on their analytic dependence. The results agree with previous experiments which relied on model assumptions in the analysis. We conclude that the model independent simultaneous analysis of the xF3, F2, q structure functions gives a more reliable determination of the gluon distribution in the nucleon.
Physics Letters B | 1984
F. Bergsma; J. Dorenbosch; M. Jonker; C. Nieuwenhuis; J. Allaby; U. Amaldi; G. Barbiellini; L. Barone; A. Capone; Y. Eisenberg; W. Flegel; L. Lanceri; M. Metcalf; J. Panman; D. Perret-Gallix; R. Plunkett; C. Santoni; F. Vannucci; K. Winter; I. Abt; J. Aspiazu; F.W. Buesser; H. Daumann; P. D. Gall; T. Hebbeker; F. Niebergall; P. Schuett; P. Staehelin; V. Gemanov; P. Gorbunov
Abstract A low-energy muon neutrino beam was used to illuminate two similar fine-grained neutrino detectors placed at 123 m and 903 m from the beginning of the neutrino source. The fiducial masses of the “close” and the “far” detector were about 36 tons and 120 tons respectively. The average energy of the selected neutrino events was 1.5 GeV. Data were recorded for an integrated flux of about 1019 protons. Quasielastic charged current events initiated by νes have been searched for and an upper limit of 2.7%, at 90% confidence level, is obtained for the fraction of νμs transformed into νes. For complete mixing this correspnds to a limit Δm2 ⩽ 0.20 eV2 for the transition νμ → νe and to a minimum value of the mixing parameter sin22θ = 0.04. In the same data sample we compared the rates in the two detectors of νμ-initiated charged current events, mainly of quasielastic type: we conclude that oscillations of νμs to ντs, and possibly heavier neutrinos, do not appear. For complete mixing the limit in this case is Δm2 ⩽ 0.29 eV2.
Physics Letters B | 1983
F. Bergsma; J. Dorenbosch; M. Jonker; C. Nieuwenhuis; J. Allaby; U. Amaldi; G. Barbiellini; L. Barone; A. Capone; W. Flegel; M. Metcalf; J. Panman; K. Winter; J. Aspiazu; F.W. Büsser; H. Daumann; P. D. Gall; E. Metz; F. Niebergall; K. H. Ranitzsch; P. Stähelin; P. Gorbunov; E. Grigoriev; V. Kaftanov; V. Khovansky; A. Rosanov; M. B. Voloshin; M. I. Vysotsky; A. Baroncelli; B. Borgia
Abstract We estimate the magnitude of effects induced by gluino hadroproduction and subsequent gluino decay into a photino and hadrons in a proton beam-dump experiment. By comparing our estimates with results obtained by us in an experiment performed at the CERN SPS we set a lower bound on the gluino mass which is a function of the scalar quark mass. The results do not favour the existence of low mass gluinos (
Physics Letters B | 1987
James V Allaby; U. Amaldi; G. Barbiellini; A. Capone; C. Nieuwenhuis; F. De Notaristefani; V D Khovanskii; B. Borgia; P. Monacelli; E. Longo; M. Diemoz; P. Gorbunov; A. Rosanov; F. Bergsma; K. Winter; F.W. Büsser; P. Stähelin; E. Grigoriev; U. Dore; P. D. Gall; F. Niebergall; F. Ferroni; L. Luminari; G. Martinelli; I. Abt; T. Hebbeker; L. Lanceri; S. Morganti; M. Metcalf; V. Blobel
Abstract We present a parametrization of the parton densities as derived from the data collected by the CHARM Collaboration in the wide band beam neutrino and antineutrino weak charged-current interactions. They are rescaled to the proton and calculated at a reference Q 2 value of 10 GeV 2 including the next-to-leading order corrections and imposing the Gross-Llewellyn Smith and the momentum sum rules.
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment | 1986
J.P. DeWulf; F. Bergsma; C. Busi; A. Capone; T. Delbar; D. De Pedis; A. Ereditato; Wilfried Flegel; B. Friend; W. Glessing; H. Grote; A. King; G. Lebée; C. Nieuwenhuis; Jaap Panman; A. Seiden; K. Winter; V. Zacek; T. Bauche; F.W. Büsser; L. Gerland; F. Niebergall; H. Riege; J. Schütt; P. Stähelin; A. Tadsen; J.L. Doumont; G. Grégoire; T. Mouthuy; P. Gorbunov
Abstract The CHARM II Collaboration is building a massive, fine-grained and low-density detector for the study of neutrino-electron scattering. Its target calorimeter consists of 441 detector planes with 155 232 plastic streamer tubes with digital readout of the wires and analog readout of external pickup strips. At the time of this report, about 25% of the calorimeter planes were equipped with electronics. Results on the performance of these tubes are presented as obtained with cosmic-rays and with electron and pion beams. We have also investigated the use of water vapour as an additive to the gas to suppress coating of the anode wires. The use of water would be of particular importance when using the tubes in a high-rate environment.
Physics Letters B | 1983
F. Bergsma; J. Dorenbosch; M. Jonker; C. Nieuwenhuis; F. Udo; J. Allaby; U. Amaldi; G. Barbiellini; L. Barone; A. Capone; W. Flegel; M. Metcalf; J. Panman; K. Winter; I. Abt; J. Aspiazu; F.W. Büsser; H. Daumann; P. D. Gall; E. Metz; F. Niebergall; K. H. Ranitzsch; P. Stähelin; P. Gorbunov; E. Grigoriev; V. Kaftanov; V. Khovansky; A. Rosanov; A. Baroncelli; B. Borgia
Abstract We present data of the reaction νμe−→μ−νe, the inverse of muon decay, collected in a long exposure of the CH ARM neutrino detector to the CERN SPS hornfocussed wide band neutrino beam. After corrections for efficiencies, a sample of 594 ± 56(syst.) ± 22(syst.) events has been found. The ratio of the measured and expected cross sections is 0.98 ± 0.12 assuming pure V - A interaction. In an SU (2)L × SU (2)R × U (1) model containing two charged intermediate vector bosons, one can relate this ratio to the ratio of the masses of the two vector bosons and to their mixing angle ω. From the result of this experiment, the limits M(W2)/M(W1) ⩾ 1.9 and ω ⩽ 15° at 90% cl can be derived. A search for the reaction ν μ e − →μ − ν e , allowed by multiplicative lepton number conservation, gave a limit of σ ( ν μ e − →μ − ν e /σ(ν μ e − →μ − ν e ) , at 90% confidence level.
Physics Letters B | 1984
F. Bergsma; J. Dorenbosch; M. Jonker; C. Nieuwenhuis; J. Allaby; U. Amaldi; G. Barbiellini; L. Barone; A. Capone; W. Flegel; M. Metcalf; J. Panman; K. Winter; I. Abt; J. Aspiazu; F.W. Büsser; H. Daumann; P. D. Gall; E. Metz; F. Niebergall; K. H. Ranitzsch; P. Stähelin; P. Gorbunov; E. Grigoriev; V. Kaftanov; V. Khovansky; A. Rosanov; A. Baroncelli; B. Borgia; C. Bosio
Abstract The x dependence of the longitudinal structure function F L was determined with the CHARM neutrino detector exposed to neutrino and antineutrino wide-band beams of the CERN 400 GeV SPS. The results show a clear deviation from the Callan-Gross relation. The amount and the x dependence of this deviation are in agreement with the contribution coming from a finite transverse momentum of the partons in the nucleon if both the intrinsc and perturbative QCD terms are taken into account.
European Physical Journal C | 1988
J. Allaby; U. Amaldi; G. Barbiellini; M. Baubillier; F. Bergsma; A. Capone; W. Flegel; F. Grancagnolo; L. Lanceri; M. Metcalf; C. Nieuwenhuis; R. Pain; J. Panman; R. Plunkett; K. Winter; I. Abt; J. Aspiazu; A. Bungener; F.W. Büsser; P. D. Gall; T. Hebbeker; F. Niebergall; P. Schütt; P. Stähelin; P. Gorbunov; E. Grigoriev; V. Khovansky; A. Rosanov; B. Borgia; M. Diemoz
AbstractNew measurements of the total crosssections of charged-current interactions of muonneutrinos and antineutrinos on isoscalar nuclei have been performed. Data were recorded in an exposure of the CHARM detector in an 160 GeV narrow-band beam. The antineutrino flux was determined from the measurements of the pion and kaon flux, and independently from the muon flux measured in the shield; the two methods are found to agree. The neutrino flux was determined from the muon flux ratio forvμ and
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment | 1987
J. Dorenbosch; F. Udo; J. Allaby; U. Amaldi; G. Barbiellini; F. Bergsma; A. Capone; W. Flegel; L. Lanceri; M. Metcalf; C. Nieuwenhuis; J. Panman; C. Santoni; K. Winter; I. Abt; J. Aspiazu; A. Bungener; F.W. Büsser; H. Daumann; P. D. Gall; T. Hebbeker; F. Niebergall; P. Schütt; P. Stähelin; P. Gorbunov; E. Grigoriev; V. Khovansky; A. Rosanov; A. Baroncelli; Luciano Barone