8,849 research outputs found
Single/Double-Spin Asymmetry Measurements of Semi-Inclusive Pion Electroproduction on a Transversely Polarized 3He Target through Deep Inelastic Scattering
Parton distribution functions, which represent the flavor and spin structure
of the nucleon, provide invaluable information in illuminating quantum
chromodynamics in the confinement region. Among various processes that measure
such parton distribution functions, semi-inclusive deep inelastic scattering is
regarded as one of the golden channels to access transverse momentum dependent
parton distribution functions, which provide a 3-D view of the nucleon
structure in momentum space. The Jefferson Lab experiment E06-010 focuses on
measuring the target single and double spin asymmetries in the 3He(e, e'pi+,-)X
reaction with a transversely polarized 3He target in Hall A with a 5.89 GeV
electron beam. A leading pion and the scattered electron are detected in
coincidence by the left High-Resolution Spectrometer at 16\circ and the BigBite
spectrometer at 30\circ beam right, respectively. The kinematic coverage
concentrates in the valence quark region, x \sim0.1-0.4, at Q2 \sim 1-3 GeV2.
The Collins and Sivers asymmetries of 3He and neutron are extracted. In this
review, an overview of the experiment and the final results are presented.
Furthermore, an upcoming 12-GeV program with a large acceptance solenoidal
device and the future possibilities at an electron-ion collider are discussed.Comment: 14 pages, 6 figures, to be published in Modern Physics Letters
Mode dispersion and delay characteristics of optical waveguides using equivalent TL circuits
A new analysis leading to an exact and efficient algorithm is presented for calculating directly and without numerical differentiation the mode dispersion characteristics of cylindrical dielectric waveguides of arbitrary refractive-index profile. The new algorithm is based on the equivalent transmission-line (T-L) technique. From Maxwell's equations, we derive an equivalent T-L circuit for a cylindrical dielectric waveguide. Based on the TL-circuit model we derive exact analytic formulas for a recursive algorithm which allows direct calculation of mode delay and dispersion. We demonstrate this technique by calculating the fundamental mode dispersion for step, triangular, and linear chirp optical fiber refractive index profiles. The accuracy of the numerical results is also examined. The proposed algorithm computes dispersion directly from the propagation constant without the need for curve fitting and subsequent successive numerical differentiation. It is exact, rapidly convergent, and it results in savings for both storage memory and computing time
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