Deuteron Compton scattering below pion photoproduction threshold is considered in the framework of the nonrelativistic diagrammatic approach with the Bonn OBE potential. A complete gauge-invariant set of diagrams is taken into account which includes resonance diagrams without and with NN-rescattering and diagrams with one- and two-body seagulls. The seagull operators are analyzed in detail, and their relations with free- and bound-nucleon polarizabilities is discussed. It is found that both dipole and higher-order polarizabilities of the nucleon are needed for a quantitative description of recent experimental data. An estimate of the isospin-averaged dipole electromagnetic polarizabilities of the nucleon and the polarizabilities of the neutron is obtained from the data.Comment: 48 pages, 16 figures, final version; discussion is slightly extended, a few references added, a figure for asymmetry is replace

High energy photon colliders (γγ,γe) are based on e-e-linear colliders where high energy photons are produced using Compton scattering of laser light on high energy electrons just before the interaction point. This paper is a part of the Technical Design Report of the linear collider TESLA.1Physics program, possible parameters and some technical aspects of the photon collider at TESLA are discussed.

Differential cross-sections for quasi-free Compton scattering from the proton and neutron bound in the deuteron have been measured using the Glasgow/Mainz photon tagging spectrometer at the Mainz MAMI accelerator together with the Mainz 48 cm Ø × 64 cm NaI(Tl) photon detector and the Göttingen SENECA recoil detector. The data cover photon energies ranging from 200 MeV to 400 MeV at θ LAB γ = 136.2 • . Liquid deuterium and hydrogen targets allowed direct comparison of free and quasi-free scattering from the proton. The neutron detection efficiency of the SENECA detector was measured via the reaction p(γ, π + n). The "free" proton Compton scattering cross sections extracted from the bound proton data are in reasonable agreement with those for the free proton which gives confidence in the method to extract the differential cross section for free scattering from quasi-free data. Differential cross-sections on the free neutron have been extracted and the difference of the electromagnetic polarizabilities of the neutron has been determined to be αn − βn = 9.8 ± 3.6(stat) +2.1 −1.1 (syst) ± 2.2(model) in units of 10 −4 fm 3 . In combination with the polarizability sum αn + βn = 15.2 ± 0.5 deduced from photoabsorption data, the neutron electric and magnetic polarizabilities, αn = 12.5 ± 1.8(stat) +1.1 −0.6 (syst) ± 1.1(model) and βn = 2.7 ∓ 1.8(stat) +0.6 −1.1 (syst) ∓ 1.1(model) are obtained. The backward spin polarizability of the neutron was determined to be γ (n) π = (58.6 ± 4.0) × 10 −4 fm 4 . PACS. 13.60.Fz Compton scattering -14.20.Dh Protons and neutrons -25.20.Dc Photon absorption and scattering ⋆ Supported by Deutsche Forschungsgemeinschaft (SFB 201, SFB 443, Schwerpunktprogramm 1034 through contracts DFG-Wi1198 and DFG-Schu222), and by the German Russian exchange program 436 RUS 113/510.) a Part of the Doctoral Thesis b Present address: Physikalisch-Technische Bundesanstalt, Bundesallee 100, D-38116 Braunschweig c Part of the Doctoral Thesis d Part of the Habilitation Thesistomary to consider special properties of these amplitudes which have a transparent physical interpretation. These properties are given in terms of electromagnetic structure constants of which the E2/M1 ratio of the p → ∆ transition, the electric and magnetic polarizabilities α and β, respectively, and the spin polarizabilities γ 0 and γ π , for the forward and backward direction, respectively, are the most prominent.These electromagnetic structure constants have been studied for the proton for a long time, whereas the corresponding investigations for the neutron are only beginning. This contrasts with the fact that for their interpretation it is of great interest to know whether or not the proton and the neutron have the same or different electromagnetic structure constants. This is one reason to study the electromagnetic polarizabilities of the neutron in addition to those for the proton. Since Compton scattering

Incoherent pion photoproduction on the deuteron is studied in the first resonance region. The unpolarized cross section, the beam asymmetry, and the vector and tensor target asymmetries are calculated in the framework of a diagrammatic approach. Pole diagrams and one-loop diagrams with N N scattering in the final state are taken into account. An elementary operator for pion photoproduction on the nucleon is taken in various on-shell forms and calculated using the SAID and MAID multipole analyses. Model dependence of the obtained results is discussed in some detail. A comparison with predictions of other works is given. Although a reasonable description of many available experimental data on the unpolarized total and differential cross sections and photon asymmetry has been achieved, in some cases a significant disagreement between the theory and experiment has been found. Invoking known information on the reactions γd → π 0 d and γd → np we predict the total photoabsorption cross section for deuterium. We find that our values strongly overestimate experimental data in the vicinity of the ∆ peak.