44 research outputs found
On the formfactor of the imaginary part and its coupling to the real optical potential for the -nucleus scattering
The model-independent formfactor of the absorptive cc-nucleus potential was calculated and compared with model dependent ones. The coupling between the shapes of the real and imaginary potential is discussed
Chemistry-dependent magnetic properties at the FeNi oxide–metal interface
Fe and Ni compounds and their oxides offer stoichiometry dependent magnetic properties, exploitable for the design of magnetic heterojunctions
Growth and electronic and magnetic structure of iron oxide films on Pt(111)
Ultrathin (111)-oriented polar iron oxide films were grown on a Pt(111)
single crystal either by the reactive deposition of iron or oxidation of
metallic iron monolayers. These films were characterized using low energy
electron diffraction, scanning tunneling microscopy and conversion electron
Mossbauer spectroscopy. The reactive deposition of Fe led to the island growth
of Fe3O4, in which the electronic and magnetic properties of the bulk material
were modulated by superparamagnetic size effects for thicknesses below 2 nm,
revealing specific surface and interface features. In contrast, the oxide films
with FeO stoichiometry, which could be stabilized as thick as 4 nm under
special preparation conditions, had electronic and magnetic properties that
were very different from their bulk counterpart, w\"ustite. Unusual long range
magnetic order appeared at room temperature for thicknesses between three and
ten monolayers, the appearance of which requires severe structural modification
from the rock-salt structure.Comment: 17 pages, 6 figures, 50 reference
Meson Production in p+d Reactions
The production of neutral and charged pions as well as eta mesons is studied
in the Delta and N* resonance region, respectively. Heavy A=3 recoils were
measured with the GEM detector. The differential cross sections covering the
full angular range are compared with model calculations.Comment: 4 pages, latex, 4 figures, talk presented at the XVIIth European
Conference on Few-Body Problems in Physics, Evora, Portugal, September 2000;
to be published in Nucl. Phys.
Measurement of p + d -> 3He + eta in S(11) Resonance
We have measured the reaction p + d -> 3He + eta at a proton beam energy of
980 MeV, which is 88.5 MeV above threshold using the new ``germanium wall''
detector system. A missing--mass resolution of the detector system of 2.6% was
achieved. The angular distribution of the meson is forward peaked. We found a
total cross section of (573 +- 83(stat.) +- 69(syst.))nb. The excitation
function for the present reaction is described by a Breit Wigner form with
parameters from photoproduction.Comment: 8 pages, 2 figures, corrected typos in heade
Also at National Accelerator Centre, Faure, South Africa On leave from ICUF
Abstract A stack of annular detectors made of high-purity germanium was developed. The detectors are position sensitive with radial structures. The first one ("Quirl") is double-sided position sensitive defining 40 000 pixels, the following three (E1, E2 and E3) have 32 wedges each. The Quirl acts as tracker while the other three act as calorimeter. The stack was successfully operated in meson production reactions close to threshold