Atomic beam devices are frequently equipped with sextupole magnets to focus the beam or to act as spin filters in combination with RF-transitions for manipulating the hyperfine population within the ...atomic beam. A useful tool for the analysis of sextupole systems, the application of time-of-flight (TOF) measurements is presented. TOF measurements are enabled without mechanical beam chopper by utilizing adiabatic radio frequency transitions to select atoms within a certain time interval. This method is especially interesting for the use in atomic beam devices that are already equipped with RF-transitions and sextupole magnets and where space limitations or the required quality of the vacuum do not allow the installation of a mechanical chopper. The measurements presented here were performed with the atomic beam polarimeter of the HERMES polarized deuterium target and the results have been used to optimize the sextupole system of the polarimeter.
To evaluate the influence of composition and high‐temperature heat treatment on the occurrence of stacking faults and intergrowths in the layered superconducting compound YNi2B2C a series of ...polycrystalline samples and a single crystal were investigated by TEM. Stacking faults were found in the most inhomogeneous sample only, which was annealed at 1100°C. Homogenisation at temperatures of 1450°C and higher results in a recovery of stacking faults. The observed faults should develop during crystallisation by formation of extra planes of YC or Ni2B, resulting in a local deviation from the stoichiometric composition. In highly faulted areas the distance of stacking faults was about 50nm. These faults have apparently no influence on the superconduction transition temperature Tc.
A measurement of the proton spin structure function g1p(x,Q{sup 2}) in deep-inelastic scattering is presented. The data were taken with the 27.6 GeV longitudinally polarised positron beam at HERA ...incident on a longitudinally polarised pure hydrogen gas target internal to the storage ring. The kinematic range is 0.021<x<0.85 and 0.8 GeV{sup 2}<Q{sup 2}<20 GeV{sup 2}.
The Hermes experiment has investigated the tensor spin structure of the deuteron using the 27.6 GeV/c positron beam of DESY HERA. The use of a tensor-polarized deuteron gas target with only a ...negligible residual vector polarization enabled the first measurement of the tensor asymmetry A{sub zz}{sup d} and the tensor structure function b{sub 1}{sup d} for average values of the Bjorken variable 0.01< <0.45 and of the negative of the squared four-momentum transfer 0.5 GeV{sup 2}<<Q{sup 2}><5 GeV{sup 2}. The quantities A{sub zz}{sup d} and b{sub 1}{sup d} are found to be nonzero. The rise of b{sub 1}{sup d} for decreasing values of x can be interpreted to originate from the same mechanism that leads to nuclear shadowing in unpolarized scattering.
The influence of the nuclear medium on the production of charged hadrons in semi-inclusive deep-inelastic scattering has been studied by the HERMES experiment at DESY using a 27.5 GeV positron beam. ...The differential multiplicity of charged hadrons and identified charged pions from nitrogen relative to that from deuterium has been measured as a function of the virtual photon energy \(\nu\) and the fraction z of this energy transferred to the hadron. There are observed substantial reductions of the multiplicity ratio \(R_M^{h}\) at low \(\nu\) and at high z, both of which are well described by a gluon-bremsstrahlung model of hadronization. A significant difference of the \(\nu\)-dependence of \(R_M^{h}\) is found between positive and negative hadrons. This is interpreted in terms of a difference between the formation times of protons and pions, using a phenomenological model to describe the \(\nu\)- and z-dependence of \(R_M^{h}\).
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