Search results for " oscillation"
showing 10 items of 845 documents
Neutrino physics from cosmological observables and oscillation experiments
2018
Aquesta tesi se centra en la física dels neutrins. En particular, se centra en l'estudi de les oscil·lacions de sabor, el paper dels neutrins relíquia en alguns escenaris cosmològics i la interacció entre aquests dos temes. Els neutrins es troben entre les partícules elementals més conegudes. Presenten comportaments interessants, com les seves oscil·lacions, i constitueixen un dels vincles entre les diferents àrees de la física. A través d'aquest document explotem la seva relació amb la cosmologia, amb especial èmfasi en l'Univers primerenc, encara que també parlem de projectes relacionats amb les últimes etapes de la història de l'Univers. En la primera part de la tesi presentem un ajustam…
Interplay between collective effects and non-standard interactions of supernova neutrinos
2009
We consider the effect of nonstandard neutrino interactions (NSI, for short) on the propagation of neutrinos through the supernova (SN) envelope within a three-neutrino framework and taking into account the presence of a neutrino background. We find that for given NSI parameters, with strength generically denoted by epsilon(ij), neutrino evolution exhibits a significant time dependence. For vertical bar epsilon(tau tau)vertical bar greater than or similar to 10(-3) the neutrino survival probability may become sensitive to the V-23 octant and the sign of epsilon(tau tau). In particular, if epsilon(tau tau) greater than or similar to 10(-2) an internal I-resonance may arise independently of t…
The Cumulative Effect of Transient Synchrony States on Motor Performance in Parkinson's Disease.
2020
Bursts of beta frequency band activity in the basal ganglia of patients with Parkinson's disease (PD) are associated with impaired motor performance. Here we test in human adults whether small variations in the timing of movement relative to beta bursts have a critical effect on movement velocity and whether the cumulative effects of multiple beta bursts, both locally and across networks, matter.
Measuring the leptonic CP phase in neutrino oscillations with nonunitary mixing
2017
Non-unitary neutrino mixing implies an extra CP violating phase that can fake the leptonic Dirac CP phase $\delta_{CP}$ of the simplest three-neutrino mixing benchmark scheme. This would hinder the possibility of probing for CP violation in accelerator-type experiments. We take T2K and T2HK as examples to demonstrate the degeneracy between the "standard" (or "unitary") and "non-unitary" CP phases. We find, under the assumption of non-unitary mixing, that their CP sensitivities severely deteriorate. Fortunately, the TNT2K proposal of supplementing T2(H)K with a $\mu$DAR source for better measurement of $\delta_{CP}$ can partially break the CP degeneracy by probing both $\cos \delta_{CP}$ and…
The effect of alertness and attention on the modulation of the beta rhythm to tactile stimulation
2021
Abstract Beta rhythm modulation has been used as a biomarker to reflect the functional state of the sensorimotor cortex in both healthy subjects and patients. Here, the effect of reduced alertness and active attention to the stimulus on beta rhythm modulation was investigated. Beta rhythm modulation to tactile stimulation of the index finger was recorded simultaneously with MEG and EEG in 23 healthy subjects (mean 23, range 19–35 years). The temporal spectral evolution method was used to obtain the peak amplitudes of beta suppression and rebound in three different conditions (neutral, snooze, and attention). Neither snooze nor attention to the stimulus affected significantly the strength of…
Typology of pentad circulation anomalies over the Eastern Africa - Western Indian Ocean region, and their relationship with rainfall
2005
International audience; The aim of this study was to classify the most frequently observed atmospheric circula- tion anomaly patterns in eastern Africa and the adjacent Indian Ocean. As an example of the useful- ness of such a classification, the second objective was to test whether these patterns account for intraseasonal rainfall anomalies in the region. A partitioning algorithm, known as dynamical cluster analysis, was therefore applied to the zonal (U)and meridional (V)components of the wind anom- alies, obtained from the NCEP-NCAR Reanalysis R-2 at the pentad (5 d) timescale. The 3 geopoten- tial levels 850, 700 and 200 hPa were combined. Focus is on the transition seasons (March to Ma…
Hunt for θ13with LENA
2012
In a hunt for by far missing neutrino mixing angle ?13 the accelerator experiments have recently indicated non-zero value and the dedicated reactor neutrino experiments are moving towards the data-taking phase to confirm that. The small effect of ?13 to the neutrino oscillation probabilities can be also complementarily probed using artificially made source of mono-chromatic neutrinos with low energies originated from electron capture processes. Due to the small energy of neutrino and tiny interaction cross section, and the expected scale of ?13 support the use of large liquid scintillation detector. In this work, the estimated sensitivities for measurement of mixing angle ?13 is presented i…
Impact of CP-violation on neutrino lepton number asymmetries revisited
2017
We revisit the effect of the (Dirac) CP-violating phase on neutrino lepton number asymmetries in both mass- and flavor-basis. We found that, even if there are sizable effects on muon- and tau-neutrino asymmetries, the effect on the asymmetry of electron-neutrinos is at most similar to the upper bound set by BBN for initial neutrino degeneracy parameters smaller than order unity. We also found that, for the asymmetries in mass-basis, the changes caused by CP-violation is of sub-\% level which is unlikely to be accesible neither in the current nor in the forthcoming experiments.
Neutrino oscillations and new physics
2005
I discuss the theoretical background and the status of neutrino oscillation parameters from the current worlds' global data sample and latest flux calculations. I give their allowed ranges, best fit values and discuss the small parameters and sin2theta13, which characterize CP violation in neutrino oscillations. I mention the significance of neutrinoless double beta decay and current expectations in view of oscillation results.
Transverse distribution of beam current oscillations of a 14 GHz electron cyclotron resonance ion source
2014
The temporal stability of oxygen ion beams has been studied with the 14 GHz A-ECR at JYFL (University of Jyvaskyla, Department of Physics). A sector Faraday cup was employed to measure the distribution of the beam current oscillations across the beam profile. The spatial and temporal characteristics of two different oscillation “modes” often observed with the JYFL 14 GHz ECRIS are discussed. It was observed that the low frequency oscillations below 200 Hz are distributed almost uniformly. In the high frequency oscillation “mode,” with frequencies >300 Hz at the core of the beam, carrying most of the current, oscillates with smaller amplitude than the peripheral parts of the beam. The result…