6,017 research outputs found
International Europhysics Conference on HEP PROCEEDINGS
No full textWe present the results of a search for # # e neutrino oscillations in the NOMAD experiment at CERN. The experiment looked for the appearance of # e in a predominantly # wide-band neutrino beam at the CERN SPS. No evidence for oscillations was found. The 90% confidence limits obtained are #m < 0.4 eV for maximal mixing and sin (2#) < 1.210 -3 for large #m , excluding the LSND allowed region of oscillation parameters with #m
First Results From The
No full textIntroduction The NOMAD experiment 1 has been designed to look for ¯ ! ø oscillations, aiming to identify the ø through its charged current interactions and the subsequent detection of the ø \Gamma decay products. In order to exploit the low e contamination (ß 1%) in the CERN-SPS wide band ¯ beam, the apparatus has been optimized to efficiently detect electrons and in particular e charged current interactions ( e CC). Their analysis is relevant for the ¯ ! e search, since an oscillation signal would manifest itself as an excess of events in the total energy spectrum (E ) for that sample. The interest for this kind of study has recently highly increased, following the LSND<F5
Performance- and stimulus-dependent oscillations in monkey prefrontal cortex during short-term memory
No full textShort-term memory requires the coordination of sub-processes like encoding, retention, retrieval and comparison of stored material to subsequent input. Neuronal oscillations have an inherent time structure, can effectively coordinate synaptic integration of large neuron populations and could therefore organize and integrate distributed sub-processes in time and space. We observed field potential oscillations (14–95 Hz) in ventral prefrontal cortex of monkeys performing a visual memory task. Stimulus-selective and performance-dependent oscillations occurred simultaneously at 65–95 Hz and 14–50 Hz, the latter being phase-locked throughout memory maintenance. We propose that prefrontal oscillatory activity may be instrumental for the dynamical integration of local and global neuronal processes underlying short-term memory
NOMAD, a search for
No full textIntroduction NOMAD stands for Neutrino Oscillation MAgnetic Detector [1]. It is installed at CERN in the wide-band neutrino beam and used to search for ¯ ! ø oscillations with a sensitivity about 10 times higher than previous experiments. The aim of the experiment and its principle are first detailed. The detector is then described and its performance reviewed. Finally the status of the analysis is given. 2 Aim and principle There are several reasons for wanting to know more about the neutrino mass and whether it is zero or not. In particle physics the standard model does not say anything about this mass and the simplest assumption is that it is zero, but the experiments should always push down the limit on this mass. In cosmology, massive neutrinos are considered as serious candidates to solve at least partly the dark matter problem in the universe. An indirect way to know about this mass would be to observe
(Oscillating) non-exponential decays of unstable states
No full textWe discuss deviations from the exponential decay law which occur when going beyond the BreitWigner distribution for an unstable state. In particular, we concentrate on an oscillating behavior, remisiscent of the Rabi-oscillations, in the short-time region. We propose that these oscillations can explain the socalled GSI anomaly, which measured superimposed oscillations on top of the exponential law for hydrogen-like nuclides decaying via electron-capture. Moreover, we discuss the possibility that the deviations from the Breit-Wigner in the case of the GSI anomaly are (predominantely) caused by the interaction of the unstable state with the measurement apparatus. The consequences of this scenario, such as the non-observation of oscillations in an analogous experiment perfromed at Berkley, are investigated
A search for neutrino oscillations in a muon neutrino beam
No full textThis is a report on a search for \nu\sb{\mu}\to\nu\sb{e} oscillations using the E776 detector at Brookhaven National Laboratory with Professor T. A. O'Halloran as my advisor. The detector consisted of a large fiducial mass electromagnetic calorimeter followed by a toroidal muon spectrometer and was located 1 km from the target at the AGS. 1.43 10\sp{19} protons on target were collected in the wide band beam with a peak neutrino energy of 1.1 GeV. No evidence for neutrino oscillations was observed. The 90% confidence limits obtained are \Delta\ m\sp2\leq0.107\ eV\sp2 for large mixing angle, and sin\sp2\ 2\theta\leq 7.7 10\sp{-3} in the limit of large \Delta\ m\sp2.Made available in DSpace on 2011-05-07T13:15:58Z (GMT). No. of bitstreams: 2
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Search for neutron-antineutron oscillations at the Sudbury Neutrino Observatory
No full textTests on B-L symmetry breaking models are important probes to search for new physics. One proposed model with Δ(B-L)=2 involves the oscillations of a neutron to an antineutron. In this paper, a new limit on this process is derived for the data acquired from all three operational phases of the Sudbury Neutrino Observatory experiment. The search concentrated on oscillations occurring within the deuteron, and 23 events were observed against a background expectation of 30.5 events. These translated to a lower limit on the nuclear lifetime of 1.48×10³¹ yr at 90% C.L. when no restriction was placed on the signal likelihood space (unbounded). Alternatively, a lower limit on the nuclear lifetime was found to be 1.18×10³¹ yr at 90% C.L. when the signal was forced into a positive likelihood space (bounded). Values for the free oscillation time derived from various models are also provided in this article. This is the first search for neutron-antineutron oscillation with the deuteron as a target
Search for νμ - ντ oscillations in BEBC
No full textWe search for νμ - ντ oscillations, by measuring the neutral to charged current ratio of the PS νμ beam at &lt;Eν&gt;≈1.3 GeV. We exclude at 90% confidence level δm2≤0.25 eV2 for maximum mixing and sin2(2θ)≤0.20 at δm2 = 3 eV2. © 1990
A SEARCH FOR NEUTRON - ANTI-NEUTRON OSCILLATIONS USING FREE NEUTRONS
No full textA search for neutron-antineutron oscillations in a 6-metre long magnetically shielded region has been carried out using the H18 cold neutron beam at the ILL reactor. A limit g > 0.8 x 106 secs at 90% confidence level can be set for the neutron-antineutron mixing time τ N[MATH]
Search for νμ→νe oscillations with the OPERA experiment in the CNGS beam
No full textA first result of the search for nu(mu)->nu(e) oscillations in the OPERA experiment, located at the Gran Sasso Underground Laboratory, is presented. The experiment looked for the appearance of nu(e) in the CNGS neutrino beam using the data collected in 2008 and 2009. Data are compatible with the non-oscillation hypothesis in the three-flavour mixing model. A further analysis of the same data constrains the non-standard oscillation parameters theta(new) and Delta m(new)(2) suggested by the LSND and MiniBooNE experiments. For large Delta m(new)(2) values (>0.1 eV(2)), the OPERA 90% C.L. upper limit on sin(2)(2 theta(new)) based on a Bayesian statistical method reaches the value 7.2 x 10(-3)
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