Search results for "MAGNETIC FIELD"
showing 10 items of 1488 documents
Solar antineutrinos from fluctuating magnetic fields at Kamiokande
1998
We consider the effect of a strongly chaotic magnetic field at the narrow bottom of the convective zone of the Sun together with resonant matter oscillations on the production of electron Majorana antineutrinos. Even for moderate levels of noise, we show that it is possible to obtain a small but significant probability for $\nu_e\to \bar{\nu}_e$ conversions (1-3%) at the energy range 2-10 MeV for large regions of the mixing parameter space while still satisfying present (Super)-Kamiokande antineutrino bounds and observed total rates. In the other hand it would be possible to obtain information about the solar magnetic internal field if antineutrino bounds reach the 1% level and a particle p…
Pulsar Velocities without Neutrino Mass
1998
We show that pulsar velocities may arise from anisotropic neutrino emission induced by resonant conversions of massless neutrinos in the presence of a strong magnetic field. The main ingredient is a small violation of weak universality and neither neutrino masses nor magnetic moments are required.
Solar neutrino problem accounting for self-consistent magnetohydrodynamics solution for solar magnetic fields
2001
The analysis of the resonant spin-flavour (RSF) solutions to the solar neutrino problem in the framework of simplest analytic solutions to the solar magneto-hydrodynamics (MHD) equations is presented. We performed the global fit of the recent solar neutrino data, including event rates as well as day and night recoil electron spectra induced by solar neutrino interactions in SuperKamiokande. We compare quantitatively our simplest MHD-RSF fit with vacuum oscillation (VAC) and MSW--type (SMA, LMA and LOW) solutions to the solar neutrino problem using a common well-calibrated theoretical calculation and fit procedure and find MHD-RSF fit to be somewhat better than those obtained for the favored…
A potential test of the CP properties and Majorana nature of neutrinos
1999
The scattering of solar neutrinos on electrons may reveal their CP properties, which are particularly sensitive to their Majorana nature. The cross section is sensitive to the neutrino dipole moments through an interference of electro-magnetic and weak amplitudes. We show how future solar neutrino experiments with good angular resolution and low energy threshold, such as Hellaz, can be sensitive to the resulting azimuthal asymmetries in event number, and could therefore provide valuable information on the CP properties and the nature of the neutrinos, provided the solar magnetic field direction is fixed.
A trigger system for measurements of proton-induced rare hadronic reactions around Tp=400MeV
2008
Abstract We developed a trigger system for the measurement of proton-induced rare hadronic reactions around the beam kinetic energy T p = 400 MeV based on highly segmented trigger scintillation detectors and programmable logic modules. The trigger system was designed to enhance events with the negative-pion production by the difference of the curvatures of the particle tracks in a magnetic field. Since the production cross-section of the negative-pion by the proton-induced reactions was smaller by about 3 orders of magnitude than the total cross-section around the beam energy, we expected large reduction of the trigger rate by the negative-pion selection. The construction of the trigger sys…
Lepton asymmetries and the growth of cosmological seed magnetic fields
2007
Primordial cosmological hypermagnetic fields polarize the early Universe plasma prior to the electroweak phase transition (EWPT). As a result of the long range parity violating gauge interaction present in the Standard Model their magnitude gets amplified, opening a new, perturbative way, of accounting for the observed intergalactic magnetic fields.
Bounds on Neutrino Transition Magnetic Moments in Random Magnetic Fields
1995
We consider the conversions of active to sterile Majorana neutrinos $\nu_{a}$ and $\nu_{s}$, due to neutrino transition magnetic moments in the presence of random magnetic fields (r.m.f.) generated at the electroweak phase transition. From a simple Schr\"{o}dinger-type evolution equation, we derive a stringent constraint on the corresponding transition magnetic moments and display it as a function of the domain size and field geometry. For typical parameter choices one gets limits much stronger than usually derived from stellar energy loss considerations. These bounds are consistent with the hypothesis of seeding of galactic magnetic fields by primordial fields surviving past the re-combina…
The Crystal Barrel spectrometer at LEAR
1992
The crystal Barrel spectrometer used at LEAR, CERN to study the products of pd annihilations is described. A 1380 element array of Csl crystals measures photons from the decay of π0, η, η′ and ω mesons. A segmented drift chamber in a 1.5T magnetic field is used to identify and measure charged particles. A fast on-line trigger on charged and neutral multiplicities and on the invariant mass of secondary particles is available. The performance of the detector is discussed.
Performance of the cost-effective Planacon ® MCP-PMTs in strong magnetic fields
2020
Abstract We present the behavior of the cost-effective Planacon MCP-PMTs with 25 μ m pore diameter in the presence of axial magnetic fields up to 0.5 T. Having a batch of 62 devices of the same type, two MCP-PMTs were selected and their gain variation measured in different magnetic fields. These two otherwise identical devices satisfied the selection criteria by requiring the lowest (1.15 kV) and one of the highest (1.4 kV) bias voltage values to achieve a given gain. Both MCP-PMTs have a nearly identical tolerance of the strong magnetic field despite the significant difference in the bias voltage. This clarifies the mechanism of the B-field influence on the MCP-PMT gain, emphasizing the im…
Direct URCA process in neutron stars with strong magnetic fields
1997
We calculate the emissivity for the direct URCA process in strongly magnetized, degenerate matter in neutron stars, under $\beta $-equilibrium. We show that, if the magnetic field is large enough for protons and electrons to be confined to the ground Landau levels, the field-free threshold condition on proton concentration no longer holds, and direct URCA reactions are open for an arbitrary proton concentration. Direct URCA process leads to an early phase of fast neutron star cooling. This circumstance allows us to constrain the initial magnetic field inside observed pulsars.