8BM OPTICS UPGRADE CHARACTERIZATION AND ANALYSIS

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 已经做出决定，8BM光学元件的重新调试和表征将导致当前单色仪的升级。这项工作是在光束线仍处于8-BM状态时进行的，以便在转移到扇区24弯曲磁源后缩短调试时间。 对光学的表征已经确定了当前单色仪的几个元素，这些元素可以从升级中受益。第一个是很早就被发现的。在第一个晶体的直接冷却过程中存在问题，导致第一个晶体可能会鼓起。这个问题的一个可能的解决方案是用一种较新的微鳍直接水冷晶体取代第一个单色器晶体，这种晶体可以改装成牛津Danfysik双晶单色器。这个新的第一个晶体是在2005年12月与牛津丹菲斯克公司一起安装的。 由矢状第二晶体完成的水平聚焦从未达到最大潜力。第一个晶体和第二个晶体中的问题很难分离，这减缓了第二个晶体折弯机的重新设计。作为改善第二块晶体性能的第一步，我们决定减小用于弯曲晶体的电机的步长，并安装线性可变差动变压器(LVDT)来直接测量位移。减速机和LVDT的结合将增加这一运动的重复性。减速电机增加的扭矩将能够适应光束线重新定位到24扇区后可能产生的较小半径。新的矢状折弯机组件于2005年12月与第一个水晶安装一起安装。 大多数早期调试和表征仅限于克服安装新的第一个晶体和改变第二个晶体的弯曲马达所带来的变化。解决了偏航电机中反复出现的限制问题，并完成了对新的和重新安装的晶体高度的微小变化以及布拉格角的重新校准的补偿。很明显，垂直聚焦性能并不令人满意。测得的流量与升级前的流量相似。当光束在6月份返回时，将进行进一步的表征。 最后，4.7mrad的反射镜倾角和对第二晶体行进的人为限制相结合，将单色器的电流能量范围限制在14.5keV。这个问题将在进一步表征后得到解决。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The decision has been made that the re-commissioning and characterization of the 8BM optics would lead to upgrades in the current monochromator. This was to be carried out while the beamline is still at 8-BM so as to reduce the commissioning time after the move to the Sector 24 bending magnet source. Characterization of the optics has identified several elements of the current monochromator that could benefit from upgrades. The first was discovered early on. There were problems in the direct cooling of the first crystal that has led to the possibility of a bulge in the first crystal. A possible solution to this problem is the replacement of the first monochromator crystal by a newer, micro-finned, direct, water-cooled crystal that can be retrofitted into the Oxford Danfysik double crystal monochromator. This new first crystal was installed in December 2005 in conjunction with Oxford Danfysik. The horizontal focusing that is accomplished by the sagittal second crystal has never reached full potential. The difficulty of separating the problems in the first crystal and that of the second has slowed the redesign in the second crystal bender. As a first step in the direction of improving the performance of the second crystal, we have decided to reduce the step size of the motors used to bend the crystal and to install Linear Variable Differential Transformers (LVDT) to measure the displacement directly. The combination of gear reducers and LVDT's will increase the reproducibility of this motion. The added torque from the gear reduced motors will be able to accommodate the smaller radii that are possible after the relocation of the beamline to Sector 24. The new sagittal bender assembly was installed in December 2005 with the first crystal installation. The majority of the early commissioning and characterization has been restricted to overcoming the changes introduced by the installation of a new first crystal and the change in the bending motors of the second crystal. Recurring problems with restrictions in the Yaw motor have been overcome and compensation for the slight changes in the height of the new and re-installed crystals along with a recalibration of the Bragg angle has been accomplished. It is clear that the vertical focusing performance is not satisfactory. The measured flux is similar to the one prior to the upgrade. Further characterization will be performed when the beam comes back in June. Finally, a combination of a 4.7 mrad tilt angle of the mirrors and artificial restrictions in the travel of the second crystal have limited the current energy range of the monochromator to 14.5 keV. This will be resolved after further characterization.