Search results for "electric [charge]"
showing 10 items of 729 documents
AN EXPERIMENTAL PROOF OF THE BACK-SCATTERING MODEL FOR DICHROIC EFFECTS IN VUV PHOTOEMISSION
2002
The energy dependence of the circular dichroism in the angular distribution of photoelectrons (CDAD) was investigated from the shallow Cs 5p core levels. Cesium was prepared in a hexagonal ordered monolayer on W(110). The results are mainly influenced by scattering of the photoelectrons within the adlayer. At low energies, the behavior observed is described by means of a model that treats only the back-scattering of photoelectrons at the potential step between the adlayer and the substrate. It leads to a simple method determining the position of the monolayer with respect to the substrate. In this approach, the back-scattering model is matched with the measured energy dependence of the CDA…
Thermoelectric radiation detector based on a superconductor-ferromagnet junction : Calorimetric regime
2018
We study the use of a thermoelectric junction as a thermal radiation detector in the calorimetric regime, where single radiation bursts can be separated in time domain. We focus especially on the case of a large thermoelectric figure of merit $ZT$ affecting significantly for example the relevant thermal time scales. This work is motivated by the use of hybrid superconductor/ferromagnet systems in creating an unprecedentedly high low-temperature $ZT$ even exceeding unity. Besides constructing a very general noise model which takes into account cross correlations between charge and heat noise, we show how the detector signal can be efficiently multiplexed by the use of resonant LC circuits gi…
First transmission of electrons and ions through the KATRIN beamline
2018
The Karlsruhe Tritium Neutrino (KATRIN) experiment is a large-scale effort to probe the absolute neutrino mass scale with a sensitivity of 0.2 eV (90% confidence level), via a precise measurement of the endpoint spectrum of tritium β-decay. This work documents several KATRIN commissioning milestones: the complete assembly of the experimental beamline, the successful transmission of electrons from three sources through the beamline to the primary detector, and tests of ion transport and retention. In the First Light commissioning campaign of autumn 2016, photoelectrons were generated at the rear wall and ions were created by a dedicated ion source attached to the rear section; in July 2017, …
Manufacturing and testing a thin glass mirror shell with piezoelectric active control
2015
Optics for future X-ray telescopes will be characterized by very large aperture and focal length, and will be made of lightweight materials like glass or silicon in order to keep the total mass within acceptable limits. Optical modules based on thin slumped glass foils are being developed at various institutes, aiming at improving the angular resolution to a few arcsec HEW. Thin mirrors are prone to deform, so they require a careful integration to avoid deformations and even correct forming errors. On the other hand, this offers the opportunity to actively correct the residual deformation: a viable possibility to improve the mirror figure is the application of piezoelectric actuators onto t…
In-process tool force and rotation variation to control sheet thickness change in friction stir welding of magnesium alloys
2016
Two different in-process control strategies, developed in order to produce sound joints in AZ31 magnesium alloy by Friction Stir Welding on sheet blanks with a non-uniform thickness, are presented and compared. To this purpose, sheets with dip or hump were machined and welded by either changing the rotational speed or the tool plunging in order to keep constant the vertical force occurring during welding. The mechanical strength of the joints was measured in the zones where the sheets before welding were characterised by different thicknesses. The sheets welded by the two different strategies are characterized by very similar ultimate tensile strength values. Finally, the results showed tha…
Search for supersymmetric particles in events with lepton pairs and large missing transverse momentum in sqrt{s} = 7 TeV proton-proton collisions wit…
2011
Results are presented of searches for the production of supersymmetric particles decaying into final states with missing transverse momentum and exactly two isolated leptons in √ s = 7 TeV proton–proton collisions at the Large Hadron Collider. Search strategies requiring lepton pairs with identical-sign or opposite-sign electric charges are described. In a data sample corresponding to an integrated luminosity of 35 pb−1 collected with the ATLAS detector, no significant excesses are observed. Based on specific benchmark models, limits are placed on the squark mass between 450 and 690 GeV for squarks approximately degenerate in mass with gluinos, depending on the supersymmetric mass hierarchy…
Electron spin polarization in the photoemission of NEA GaAs1?x P x
1982
Negative electron affinity GaAs1−xPx-photocathodes emit spin-polarized electrons if irradiated with circularly polarized light. The spectra of spin polarization of photoelectrons emitted from crystals with different phosphorus contentx resemble each other in shape but shift to shorter wavelengths with increasingx. Polarization values up to 40% are observed for electrons from crystals withx=0 andx=0.38. Cathodes with higher phosphorus contents increasing fromx=0.65 tox=0.87 and tox = 1.0 deliver photoelectrons with decreasing degrees of spin polarization of 17%, 15%, and 9%, respectively, at maximum.
Influence of dissipative tunneling on the photodielectric effect associated with the excitation of impurity complexes A+ + e in a quasi-zero-dimensio…
2022
Effect of tunneling decay for the quasi-stationary A+-state, in an impurity complex A+ + e (a hole, localized on a neutral acceptor, interacting with an electron, localized in the ground state of a quantum dot) on the photodielectric effect, associated with the excitation of impurity complexes A+ + e in a quasi-zero-dimensional structure, has been studied in the zero-radius potential model in the one-instanton approximation. Calculation of the binding energy of a hole in an impurity complex A+ + e was performed in the zero radius potential model in the adiabatic approximation. It is shown that as the probability of dissipative tunneling increases, the binding energy of a hole in a complex A…
Search for anomalous production of prompt like-sign muon pairs and constraints on physics beyond the Standard Model with the ATLAS detector
2012
An inclusive search for anomalous production of two prompt, isolated muons with the same electric charge is presented. The search is performed in a data sample corresponding to 1.6 fb−1 of integrated luminosity collected in 2011 at √s=7 TeV with the ATLAS detector at the LHC. Muon pairs are selected by requiring two isolated muons of the same electric charge with pT>20 GeV and |η|<2.5. Minimal requirements are placed on the rest of the event activity. The distribution of the invariant mass of the muon pair m(μμ) is found to agree well with the background expectation. Upper limits on the cross section for anomalous production of two muons with the same electric charge are placed as a func…
Spin caloric effects in antiferromagnets assisted by an external spin current
2018
Searching for novel spin caloric effects in antiferromagnets we study the properties of thermally activated magnons in the presence of an external spin current and temperature gradient. We predict the spin Peltier effect -- generation of a heat flux by spin accumulation -- in an antiferromagnetic insulator with cubic or uniaxial magnetic symmetry. This effect is related with spin-current induced splitting of the relaxation times of the magnons with opposite spin direction. We show that the Peltier effect can trigger antiferromagnetic domain wall motion with a force whose value grows with the temperature of a sample. At a temperature, larger than the energy of the low-frequency magnons, this…