Results 1 - 10 of 50088
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[en] The authors have measured the differential cross section for two-body deuteron photodisintegration at θcm = 90 degrees, 114 degrees and 143 degrees, and for photon energies between 0.8 and 1.8 GeV. At energies above ≅1.2 GeV, the data at θcm = 90 degrees, and 114 degrees appear to obey a simple scaling law predicted by constituent-counting rules assuming parton degrees of freedom for the deuteron and nucleons. The shape of the angular distribution shows an abrupt change at Eγ ≥ 1.4 GeV, in that at 1.4 and 1.6 GeV cross sections peak at θcm = 143 degrees, but this is not the case for Eγ < 1.2 GeV. Agreement with model calculations based on meson exchange and on open-quotes reduced nuclear amplitudesclose quotes is discussed
[en] Electron interaction cross sections for species found in low-temperature industrial plasma environments are a crucial component to allow for accurate modeling of those plasmas. However, such data are still rarely reported in the literature, due to the complexities of working with such highly reactive species in a laboratory. Here, absolute differential cross section measurements for a 'plasma-like' gas mixture, containing CF3I, CF3, I2, I and C2F6, are reported.
[en] We use the general formalism established in the companion paper 1 to analyse recent measurements of the triple differential cross sections for double photoionization of He and Ne, for equal energy sharing and for 1Se symmetry of the residual ion. A dynamical factor, which depends on the energy and on the mutual angle between the two electrons, is extracted from the experiments without relying on nay dynamical approximation. This factor is expanded with respect to the one-electron angular momentum l, up to a maximum value lmax, which measures the degree of angular correlation attained by the electron pair. We discuss the physical meaning of lmax, and the dependence of the dynamical factor on the target, which is observed when comparing helium and neon results. (author)
[en] Here, we report the electron impact integrated and differential cross sections for excitation to the b "3Σ(+/u), a "3Σ(+/g), c "3Π_u, B "1Σ(+/u), E, F "1Σ(+/g), C "1Π_u, e "3Σ(+/u), h "3Σ (+/g), d "3Π_u, B'' "1Σ(+/u) , D "1Π_u, B'' "1Σ(+/u), and D' "1Π_u states of molecular hydrogen in the energy range from 10 to 300 eV. Total scattering and total ionization cross sections are also presented. The calculations have been performed by using the convergent close-coupling method within the fixed-nuclei approximation. Detailed convergence studies have been performed with respect to the size of the close-coupling expansion and a set of recommended cross sections has been produced. Significant differences with previous calculations are found. Agreement with experiment is mixed, ranging from excellent to poor depending on the transition and incident energies.
[en] Scattering from screened Coulomb potentials in nonrelativistic quantum theory is discussed. The screening functions are used to bypass the difficulties associated with the long-range character of the Coulomb potential. It is shown that for an appropriate class of smooth, spherically symmetric screening functions the screened differential cross section goes over to the Coulomb differential cross section as the screening radius R becomes large. This is done by showing that the screened scattering amplitude goes over to the Coulomb scattering amplitude times an R-dependent phase factor as R becomes large. It is also shown that for an appropriate class of repulsive screened Coulomb potentials the limit is approached at least as fast as R/sup -1/2/. These results allow one to treat Coulomb scattering through conventional short-range scattering theory
[en] Excitation of the autoionizing states of helium by electron impact is shown in calculations in the s-wave limit to leave a clear signature in the singly differential cross section for the (e,2e) process. It is suggested that such behavior should be seen generally in (e,2e) experiments on atoms that measure the single differential cross section
[en] PHENIX at RHIC measured invariant differential cross section and double helicity asymmetry A LL of high p T charged pions production in polarized p + p collision at √s = 200 GeV. Interpretations of preliminary results regarding constraining gluon helicity distribution are discussed.
[en] The well-known relationship between ionization of atoms by fast charged particles and by photons, the Bethe-Born theory, is applied to the ratio of double ionization to single ionization of He, a process that has been under intense recent scrutiny. It is found that for sufficiently fast charged particles, this ratio for the single differential cross sections, differential in the energy transferred to the atom, ΔE, is equal to the photoionization ratio at a photon energy hv = ΔE, and this result is unmodified even for ionization by relativistic charged particles. In addition, a relation for the ratio of total charged particle impact ionization cross sections to the photoionization ratio is derived. The results are compared with recent experimental data and various discrepancies are uncovered. Possible sources of these discrepancies are discussed
[en] This paper describes the importance of microcosmic section measurement technique. The contents are differential cross section double-differential cross section and neutron emission cross section. It describes outline, set-up, method and system of cross section measurement. It can used for correlative work in future. (authors)