Scattering and Reactions of Intermediate Energy Projectiles

这笔赠款将支持罗格斯大学中能核物理小组的实验工作。该小组主要在弗吉尼亚州纽波特纽斯的杰斐逊实验室的新型连续电子束加速器CEBAF上进行电子束实验。他们是为这个设施设计和建造大型偏振仪的领导者；它决定了被高能电子击出原子核的质子的自旋方向。用这种旋光仪进行测量，可以获得关于自由质子基本电磁性质的高度准确的信息，并应揭示当质子束缚在原子核内部时，这些性质可能发生的变化。相关实验将在德国美因茨的加速器上以较低的能量进行。其他这样的自旋测量将测试简单的夸克模型描述的反应，在这些反应中，质子通过入射的高能光子从氘目标发射出来。自旋测量比以前的实验对夸克描述反应中可能存在的问题更加敏感。最后，第三个主要程序通过研究当中子在靶中自旋的方向改变时散射电子的概率的变化，直接解决夸克对中子自旋的贡献。

This grant will support the experimental work of the Intermediate Energy Nuclear Physics Group at Rutgers University. This group carries out experiments with electron beams primarily at the new continuous electron beam accelerator, CEBAF, at the Jefferson Laboratory in Newport News, Virginia. They were leaders in designing and constructing a large polarimeter for this facility; it determines the direction of the spin of protons knocked out of the nucleus by the highly energetic electrons. Measurements with this polarimeter yield highly accurate information on the fundamental electromagnetic properties of the free proton, and should reveal possible changes in these properties when the proton is bound inside a nucleus. Related experiments will be carried out at lower energies at an accelerator in Mainz, Germany. Other such spin measurements will test simple quark model descriptions of reactions in which protons are emitted from a deuterium target by incident high-energy photons. The spin measurements are much more sensitive than previous experiments to possible problems in the quark description of the reaction. Finally, a third major program addresses directly the contributions of quarks to the spin of the neutron by examining changes in the probability for scattering electrons when the direction of the neutron's spin in the target is changed.