P. Grabmayr

First measurement of the Gerasimov-Drell-Hearn integral for Hydrogen from 200 to 800 MeV

A direct measurement of the helicity dependence of the total photoabsorption cross section on the proton was carried out at MAMI (Mainz) in the energy range 200<E_gamma<800 MeV. The experiment used a 4

Measurement of the πmeson polarizabilities via the γp → γπ + n reaction

\pi

The neutron skin of 208Pb from coherent pion photoproduction

detection system, a circularly polarized tagged photon beam and a frozen spin target. The contributions to the Gerasimov-Drell-Hearn sum rule and to the forward spin polarizability

Helicity amplitudes A1/2 and A3/2 for the D13(1520) resonance obtained from the gamma-->p-->-->ppi(0) Reaction.

\gamma_0

Quasi-free Compton scattering and the polarizabilities of the neutron

determined from the data are 226 \pm 5 (stat)\pm 12(sys) \mu b and -187 \pm 8 (stat)\pm 10(sys)10^{-6} fm^4, respectively, for 200<E_\gamma<800 MeV.

Compton scattering by the proton using a large-acceptance arrangement

Abstract.An experiment on the radiative π{+}-meson photoproduction from the proton ( γp → γπ{+}n) was carried out at the Mainz Microtron MAMI in the kinematic region 537MeV < Eγ < 817MeV, 140°≤

Proton photoproduction from 12C

\theta_{{\gamma \gamma ^{\prime }}}^{{{{\rm cm}}}}

Backward spin polarizability gamma(pi) of the proton

≤180°. The π{+}-meson polarizabilities have been determined from a comparison of the data with the predictions of two different theoretical models, the first one being based on an effective pole model with pseudoscalar coupling while the second one is based on diagrams describing both resonant and nonresonant contributions. The validity of the models has been verified by comparing the predictions with the present experimental data in the kinematic region where the pion polarizability contribution is negligible ( s1 < 5mπ2) and where the difference between the predictions of the two models does not exceed 3%. In the region, where the pion polarizability contribution is substantial ( 5 < s1/mπ2 < 15, -12 < t/mπ2 < - 2), the difference

12C(γ,π+n) and 12C(γ,π+p) reactions across the Δ resonance region

\ensuremath{(\alpha -\beta )_{\pi^{+}}}

Spectroscopic factors and occupation numbers of 3s protons in lead isotopes

of the electric (α) and the magnetic (β) polarizabilities has been determined. As a result we find