2,140 research outputs found
Theory of AC Anomalous Hall Conductivity in d-electron systems
To elucidate the intrinsic nature of anomalous Hall effect (AHE) in
-electron systems, we study the AC anomalous Hall conductivity (AHC) in a
tight-binding model with ()-orbitals. We drive a general
expression for the AC AHC , which is valid for finite
quasiparticle damping rate =, and find that the AC AHC is
strongly dependent on . When , the AC AHC shows a spiky peak
at finite energy that originates from the interband particle-hole
excitation, where represents the minimum band-splitting measured from
the Fermi level. In contrast, we find that this spiky peak is quickly
suppressed when is finite. By using a realistic value of
at in -electron systems, the spiky peak
is considerably suppressed. In the present model, the obtained results also
represents the AC spin Hall conductivity in a paramagnetic state.Comment: 13pages, 9 figure
Correlation of high energy muons with primary composition in extensive air shower
An experimental investigation of high energy muons above 200 GeV in extensive air showers has been made for studying high energy interaction and primary composition of cosmic rays of energies in the range 10 to the 14th power approx. 10 to the 15th power eV. The muon energies are estimated from the burst sizes initiated by the muons in the rock, which are measured by four layers of proportional counters, each of area 5 x 2.6 sq m, placed at 30 m.w.e. deep, Funasaka tunnel vertically below the air shower array. These results are compared with Monte Carlo simulations based on the scaling model and the fireball model for two primary compositions, all proton and mixed
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Influence of pre and post testing on return on investment calculations in training and development.
When expenses become an issue, training is often one of the first budget items to be cut. There have been a number of evaluation studies about rates of return from training interventions. Most results are based on interviewing participants about the value of the intervention and its effect on their productivity. This often results in quadruple digit return on investment indications. Decision makers who control the budget often view these kinds of results with skepticism. This study proposes a methodology to evaluate training interventions without asking participants their opinions. The process involves measuring learning through a series of pre-tests and post-tests and determining if scores on pre-tests can be used as predictors of future return on investment results. The study evaluates a series of return on investment scores using analysis of variance to determine the relationship between pre-tests and final return on investment results for each participant. Data is also collected and evaluated to determine if the financial results of the organization during the period of the training intervention could be correlated to the results of the training intervention. The results of the study suggest that the proposed methodology can be used to predict future return on investment from training interventions based on the use of pre-tests. These rates of return can be used as a method of selecting between competing training intervention proposals. It is a process that is easily understood by the key decision makers who control the allocation of financial resources. More importantly, it is a process that can maximize the value of each dollar spent on training
Proportional drift tubes for large area muon detectors
A proportional drift chamber which consists of eight rectangular drift tubes with cross section of 10 cm x 5 cm, a sense wire of 100 micron phi gold-plated tungsten wire and the length of 6 m, was tested using cosmic ray muons. Spatial resolution (rms) is between 0.5 and 1 mm over drift space of 50 mm, depending on incident angle and distance from sense wire
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Precise measurements of the energy losses of heavy ions
Accurate measurements of the energy loss of all charged particles are needed to determine the reliability of the Bethe theory of stopping power. Few measurements have been made for particles with energies greater than 20 MeV/u. A first step to accurate measurements is to establish the precision of an experimental method. The authors report here about the recent energy loss measurements for 290 MeV/u carbon ions from the HIMAC. They have been made with the method used for 70 MeV protons. The ion beam traverses an absorber of thickness t and the residual range of the ions is measured with a water container of adjustable thickness (``range gauge``)
Inelastic X-Ray Scattering Study of Exciton Properties in an Organic Molecular crystal
Excitons in a complex organic molecular crystal were studied by inelastic
x-ray scattering (IXS) for the first time. The dynamic dielectric response
function is measured over a large momentum transfer region, from which an
exciton dispersion of 130 meV is observed. Semiempirical quantum chemical
calculations reproduce well the momentum dependence of the measured dynamic
dielectric responses, and thus unambiguously indicate that the lowest Frenkel
exciton is confined within a fraction of the complex molecule. Our results
demonstrate that IXS is a powerful tool for studying excitons in complex
organic molecular systems. Besides the energy position, the IXS spectra provide
a stringent test on the validity of the theoretically calculated exciton wave
functions.Comment: 4 pages, 4 figure
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