标题： 核光吸收 显示英文标题

标题： Photoabsorption on nuclei

摘要： 我们在半经典相空间模型的框架内计算了300 MeV到1 GeV能量范围内原子核上的总光吸收截面。除了介质修正（如费米运动和泡利阻塞）外，我们还关注了相关共振的碰撞展宽。共振对基本截面的贡献通过拟合π介子光产生的部分波振幅来确定。为了计算碰撞展宽，所需的$N \, R \to N \, N$截面通过拟合$N \, N \to N \, N \, \pi$截面的细致平衡获得。我们表明，合理的碰撞展宽无法解释在原子核光吸收截面中实验上观察到的$D_{13}(1520)$共振消失现象。 显示英文摘要

摘要： We calculate the total photoabsorption cross section on nuclei in the energy range from 300 MeV to 1 GeV within the framework of a semi-classical phase space model. Besides medium modifications like Fermi motion and Pauli blocking we focus on the collision broadening of the involved resonances. The resonance contributions to the elementary cross section are fixed by fits to partial wave amplitudes of pion photoproduction. The cross sections for $N \, R \to N \, N$, needed for the calculation of collision broadening, are obtained by detailed balance from a fit to $N \, N \to N \, N \, \pi$ cross sections. We show that a reasonable collision broadening is not able to explain the experimentally observed disappearance of the $D_{13}(1520)$-resonance in the photoabsorption cross section on nuclei.