N1: Accomplishments of the second funding period

  • Elastic charge form factor of the Deuteron
    The analysis is still ongoing. Preliminary results of form factor analysis will be available before end of the year. Final results are foreseen for mid of next year.
  • Inclusive electron scattering on \(\mathbf{^4}\)He at low momentum transfer
    The data analysis of the old 2009 data has been completed but the error bars prevent drawing definite conclusions from the comparison with theory. A new experiment has been performed in 2016 and the corresponding data analysis is being finalized. First results expected for mid next year.
  • Neutron Skin Studies via coherent \(\mathbf{\pi^0}\) photoproduction
    The coherent (\(\gamma ,\pi^0\)) reaction has been used to obtain information on the matter form fac- tor of four spin zero nuclei (\(^{116,120,124}\)Sn, \(^{58}\)Ni) over the photon energy range from threshold to 350 MeV during the first funding period. The analysis has been delayed substantially due to maternity leave.
    Meanwhile new theory calculations are being developed with special emphasis on the determination of the corresponding systematic error on the neutron skin extraction from this method. The theoretical efforts focus on two aspects. First the development of a proper DWIA code to describe the reaction in order to properly include the distortion and absorption of the pion-nucleus interaction within the outgoing channel. To reach this goal a precise pion-nucleus optical potential is currently under development. In the second aspect we study theoretically the influence of the neutron skin thickness in the reaction calculations. This effort is performed in close collaboration with J. Piekarewicz (FSU), who has provided us with accurate mean-field calculations of the tin isotopes considered in this study. First results on the neutron skin development along the Sn isotopic chain are expected within the end of next year.
    The experimental program on beam-normal single-spin asymmetries for \(^{12}\)C has been completed  and paper submission is expected within a couple of weeks. For the first time the \(Q^2\) dependence of the beam-normal single-spin asymmetry \(A_n\) has been measured in the elastic scattering of 570 MeV vertically polarized electrons on \(^{12}\)C. The experimental results have been compared to a theoretical calculation relating \(A_n\) to the imaginary part of the two-photon exchange amplitude.
    A first paper describing the determination of beam polarization has been already published.
  • MITP Workshop on neutron skins
    The two-week program has taken place in spring 2016. Currently a review on Journal of Physics G is being drafted. Publication is foreseen around spring next year.