We report measurements of ${\pi }^{+}$ and ${\pi }^0$ meson photoproduction from longitudinally spin-polarised protons by an energy tagged (0.73-2.3 GeV) and linearly polarised photon beam. A close to complete solid angle coverage for the reaction products was provided by the CEBAF Large Acceptance Spectrometer at Jefferson Laboratory. The double-polarisation observable $\mathbb{G}$ is extracted from Maximum Likelihood fits to the data, enabling the first accurate determination for the reaction $\overrightarrow{\gamma }\overrightarrow{p}\to {\pi }^{+}n$, while also significantly extending the kinematic coverage for $\overrightarrow{\gamma }\overrightarrow{p}\to {\pi }^{0}p$. This large data set provides an important constraint on the properties and spectrum of excited nucleon states decaying to Nπ in the mass range from 1.4 to 2.2 GeV, as well as for background (non-resonant) photoproduction processes. The considerable improvement achieved in the description of the observable $\mathbb{G}$ within the SAID and Bonn-Gatchina approaches after implementation of our data, illustrates that the partial-wave analyses now significantly extend the knowledge on Nπ photoproduction amplitudes at $W>1.8$ GeV. A partial-wave analysis using the new high-precision data set has a large impact on the extracted properties of high-spin nucleon excited states.

我们报告的测量 ${\pi }^{+}$ 和 ${\pi }^0$介子通过能量标记的（0.73-2.3 GeV）和线性极化的光子束从纵向自旋极化的质子产生光子。杰斐逊实验室的CEBAF大验光光谱仪提供了接近完全的立体角覆盖反应产物。可观察到双极化$\mathbb{G}$ 从最大似然拟合中提取出来，以拟合该数据，从而能够对反应进行第一个准确的确定 $\overrightarrow{\gamma }\overrightarrow{p}\to {\pi }^{+}ñ$，同时还大大扩展了运动学范围 $\overrightarrow{\gamma }\overrightarrow{p}\to {\pi }^{0}p$。这个庞大的数据集对从1.4到2.2 GeV的质量范围内衰减到Nπ的激发核子态的性质和光谱以及背景（非共振）光生过程提供了重要的约束。在可观察对象的描述中取得了相当大的进步$\mathbb{G}$数据实施后，在SAID和Bonn-Gatchina方法中的应用表明，分波分析现在大大扩展了关于Nπ光产生振幅的知识。$\mathrm{w\; ^}>1.8$GeV。使用新的高精度数据集进行的分波分析对高自旋核子激发态的提取特性有很大影响。