The quasifree \(\overrightarrow{\gamma } d\rightarrow \pi ^0n(p)\) photon beam asymmetry, \(\varSigma \), has been measured at photon energies, \(E_\gamma \), from 390 to 610 MeV, corresponding to center of mass energy from 1.271 to 1.424 GeV, for the first time. The data were collected in the A2 hall of the MAMI electron beam facility with the Crystal Ball and TAPS calorimeters covering pion center-of-mass angles from 49\(^\circ \) to 148\(^\circ \). In this kinematic region, polarization observables are sensitive to contributions from the \(\varDelta (1232)\) and N(1440) resonances. The extracted values of \(\varSigma \) have been compared to predictions based on partial-wave analyses (PWAs) of the existing pion photoproduction database. Our comparison includes the SAID, MAID and Bonn–Gatchina analyses; while a revised SAID fit, including the new \(\varSigma \) measurements, has also been performed. In addition, isospin symmetry is examined as a way to predict \(\pi ^0n\) photoproduction observables, based on fits to published data in the channels \(\pi ^0p\), \(\pi ^+n\) and \(\pi ^-p\).

准自由\(\overrightarrow{\gamma } d\rightarrow \pi ^0n(p)\)光子束不对称性\(\varSigma \)已在光子能量\(E_\gamma \)下测量，从 390首次达到 610 MeV，对应的质心能量从 1.271 到 1.424 GeV。数据是在 MAMI 电子束设施的 A2 大厅中收集的，其中水晶球和 TAPS 量热仪覆盖从 49 \(^\circ \)到 148 \(^\circ \)的π介子质心角。在这个运动学区域中，偏振观测值对来自\(\varDelta (1232)\)和N (1440) 共振的贡献很敏感。\(\varSigma \)的提取值已与基于现有π介子光电生产数据库的部分波分析（PWA）的预测进行了比较。我们的比较包括 SAID、MAID 和 Bonn-Gatchina 分析；同时还进行了修订的 SAID 拟合，包括新的\(\varSigma \)测量。此外，基于对通道\(\pi ^0p\) 、 \ (\pi ^+n\)和\(\pi ^-p\)。