Heidelberg 2015 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 55: Structure and Dynamics of Nuclei 11

HK 55.5: Vortrag

Donnerstag, 26. März 2015, 15:45–16:00, T/SR19

Neutronskin studies in heavy nuclei with coherent π⁰ photoproduction — •Maria Isabel Ferretti Bondy for the A2 collaboration — Institut für Kernphysik - Johannes Gutenberg Universität Mainz

The charge distribution of nuclei is known with very high accuracy, i.e. in electron scattering experiments, conversely, the mass distribution is experimentally less accessible and therefore less precisely known. An accurate determination of the neutron density distribution is of particular interest. Especially in nuclei with N >> Z, a strong neutron skin is expected, since the excess neutrons are pushed outwards against surface tension by the coulomb forces. With the precise experimental determination of the neutron skin thickness essential constraints for the nuclear equation of state (EOS) can be provided and thus allowing to draw conclusions on the size of neutron stars.

The method of coherent π⁰ photoproduction, A (γ, π⁰) A, provides a powerful tool to determine the mass distribution of various nuclei. In a novel experimental campaign carried out in 2012 within the A2 collaboration at the Mainz Microtron (MAMI), five nuclei have been measured: ⁵⁸Ni, ^{116, 120, 124}Sn, ²⁰⁸Pb. The tin targets are of special interest because most of the systematic errors due to pion-nucleon interaction can be neglected, and they allow a precise investigation along an isotopic chain.

First results of these studies will be presented in this talk.