4 research outputs found
Search for eV (pseudo)scalar penetrating particles in the SPS neutrino beam
We carried out a model-independent search for light scalar or pseudoscalar particles 's (an example of which is the axion) that couple to two photons by using a photon-regeneration method at high energies allowing a substantial increase in the sensitivity to masses.\ The experimental set-up is based on elements of the CERN West Area Neutrino Facility (WANF) beam line and theNOMAD neutrino detector.\ The new particles, if they exist, could be produced through the Primakoff effect in interactions of high energy photons, generated by the 450 protons in the CERN SPS neutrino target, with virtual photons from the WANF horn magnetic field.\ The particles would penetrate the downstream shieldingand would be observed in the NOMAD neutrino detector through their re-conversion into real high energy photons byinteracting with the virtual photons from the magnetic field of the NOMAD dipole magnet.\ From the analysis of the data collected during the 1996 run with protons on target, 312 candidate events with energy between 5 and 140 were found.\ This number is in general agreement with the expectation of 27218 background events from standard neutrino processes.\ A 90 upper limit on the -coupling 1.5 for masses up to 40 is obtained.
A more sensitive search for oscillations in NOMAD
With additional data and improved algorithms, we have enhanced the sensitivity of our appearance search for \numunutau oscillations in the NOMAD detector in the CERN-SPS wide-band neutrino beam. The search uses kinematic criteria to identify \nutau charged current interactions followed by decay of the to one of several decay modes. Our ``blind'' analyses of deep-inelastic scattering data taken in 1996 and 1997, combined with consistent reanalyses of previously reported 1995 data, yield no oscillation signal. For the two-family oscillation scenario, we present the contour outlining a 90\% C.L. confidence region in the plane. At large , the confidence region includes (a limit 3.5 times more stringent than in our previous publication), while at , the confidence region includes eV/
Precision measurement of scaled momentum, charge multiplicity and thrust in and Interactions
By focusing on the notion of electronic document, we differentiate two evolutions which are useful to distinct titles: on the one hand are the documents, which have value of reference. Its administrator will take care to preserve its integrity and its context of production which is strongly significant. On the other hand are resources, evolutionary elements by nature, which the user must be able to appropriate and who must thus be placed at the disposal so that the production is erased, to focus on a logic of exploitation and service