Das integrale Reflexionsvermögen von gebogenen Quarzkristallen für Röntgenstrahlen im Transmissionsfall

A calculation procedure is described which permits evaluation of the material functions (electrical conductivityσ and radiation densityu as a function of the heat flux potentialS)from the measured arc characteristicsE(I) andU(I) (field strength and radiated power per unit arc length as a function of current strength). Hereto must be employed the additional relationship of energy balance and the current transport equation. The procedure is applied to N₂ and Ar. If furthermore the radial temperature distribution is known the temperature dependence ofσ, u.S andκ (thermal conductivity) may also be determined. In this way the material functions of the N₂-plasma are evaluated from available measurements.     

On the coupling of the giant multipole resonances to the surface quadrupole oscillations of nuclei

Within the framework of the hydrodynamic model the exact coupling constants of the coupling of the giant multipole resonances to the surface quadrupole oscillations of nuclei are derived. The differences to former variational calculations are discussed. It is found that the coupling constants for the terms linear in the surface variables are almost the same whereas the coupling constants for the quadratic terms differ appreciably. The influence on the photon absorption and scattering cross sections of spherical nuclei is discussed.     

Isobar configurations in nuclei

A comprehensive review of the role of nucleon resonances in nuclear structure is given with emphasis on the two-, three-, and four-nucleon systems and nuclear matter.     

A surprising method for polarising antiprotons

We propose a method for polarising antiprotons in a storage ring by means of a polarised positron beam moving parallel to the antiprotons. If the relative velocity is adjusted to v/c ≈ 0.002 the cross-section for spin-flip is as large as about 2 ^. 10¹³ barn as shown by new QED calculations of the triple spin cross-sections. Two possibilities for providing a positron source with sufficient flux density are presented. A polarised positron beam with a polarisation of 0.70 and a flux density of approximately 1.5 ^. 10¹⁰ /(mm² s) appears to be feasible by means of a radioactive ¹¹C dc-source. A more involved proposal is the production of polarised positrons by pair production with circularly polarised photons. It yields a polarisation of 0.76 and requires the injection into a small storage ring. Such polariser sources can be used at low (100MeV) as well as at high (1GeV) energy storage rings providing a time of about one hour for polarisation build-up of about 10¹⁰ antiprotons to a polarisation of about 0.18. A comparison with other proposals show a gain in the figure of merit by a factor of about ten.     

Deuteron electrodisintegration near threshold with the Bonn potential

Deuteron electrodisintegration near threshold is calculated for the Bonn potential including consistent meson exchange currents. Experimental data can fairly well be described over the whole q-range if G_E is used as electromagnetic form factor for the exchange current, whereas F₁ leads to a large overestimation at high q.     

General formulae for polarization observables in two-body break-up of deuteron photodisintegration

The formal expressions of all possible polarization observables ind(,N)N with polarized photons and oriented deuterons are derived in terms of thet-matrix elements. Furthermore, using the multipole expansion of thet-matrix, all observables are expanded in terms of Legendre polynomials or associated functions, the coefficients of which are given as bilinear forms of the multipole moments and allow a model independent analysis of experimental data.Supported by the Deutsche Forschungsgemeinschaft (SFB 201)     

Survey on polarization observables in deuteron photodisintegration below pion-production threshold

Polarization observables of deuteron photodisintegration with polarized photons and oriented deuterons are systematically investigated below -production threshold with respect to their sensitivity to subnuclear degrees of freedom and relativistic effects, to the different electric and magnetic multipole contributions, and to various realistic potential models. In particular, a complete survey on all single- and double-polarization observables like beam and target asymmetries of the differential cross section, nucleon polarization and proton-neutron spin correlation is given.Partially supported by the Deutsche Forschungsgemeinschaft (SFB 201)