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Sep 24 – 29, 2023
US/Eastern timezone

Systematic studies of beam-normal single spin asymmetries at MAMI

Sep 25, 2023, 2:30 PM
30m
Junior D3 (Durham Convention Center)

Junior D3

Durham Convention Center

Talk Low Energy Spin Physics with Lepton, Photon and Hadron Probes Low Energy Spin Physics with Lepton, Photon and Hadron Probes

Speaker

Michaela Thiel

Description

Pushing the precision frontiers further 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 the 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 determined. The follow-up experiments on $^{28}$Si and $^{90}$Zr investigated the charge dependence of the transverse asymmetry and have paved the way for a future experiment on $^{208}$Pb, thus benchmarking the theoretical calculations in the heavier mass regime.

Primary author

Presentation materials