Speaker
Description
Reaching new precision frontiers in nuclear physics brings up new experimental challenges as well as the demand for more sophisticated theoretical calculations. Especially in parity-violation electron scattering experiments the contribution from higher order processes, such as two-photon exchange, is comparable in size with the observed asymmetry $A_{PV}$. Hence, a precise knowledge of this contribution is mandatory to determine the systematic uncertainties.
Beam-normal single-spin asymmetries $A_{n}$ (or so-called transverse asymmetries) are a direct probe of the imaginary part of the two-photon exchange amplitude in the elastic scattering of transversely polarized electrons from unpolarized nucleons. Up to now, there is significant disagreement between experiment and theory for $^{208}$Pb, which motivates more measurements to study the $Q^{2}$ and $Z$ dependence. During a successful campaign at the MAinz MIcrotron (MAMI), using the spectrometer setup of the A1 collaboration, the $Q^{2}$ dependence of $A_{n}$ for $^{12}$C was measured. The follow-up experiments on $^{28}$Si and $^{90}$Zr investigate the charge dependence of the transverse asymmetry at one $Q^{2}$ point, thus benchmarking the theoretical calculations in the heavier mass regime
| Topic | Nuclear Structure and Nuclear Astrophysics |
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