8BM OPTICS UPGRADE CHARACTERIZATION AND ANALYSIS

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得主要资金，因此可以在其他CRISP条目中表示。所列机构为中心，不一定是研究者所在机构。已经做出的决定是，8BM光学器件的重新调试和表征将导致当前单色仪的升级。这将在束线仍处于8-BM时进行，以减少移动到扇区24偏转磁体源后的调试时间。光学特性已经确定了当前单色器的几个元素，可以从升级中受益。第一种是早期发现的，在直接冷却第一个晶体的过程中出现了问题，导致第一个晶体中可能会出现凸起。这个问题的一个可能的解决方案是将第一个单色晶体替换为一个更新的，微鳍，直接水冷的晶体，可以改装成牛津Danfysik双晶体单色器。这个新的第一个晶体安装在2005年12月与牛津Danfysik。 由矢状第二晶体完成的水平聚焦从未达到全部潜力。由于难以区分第一个晶体和第二个晶体中的问题，第二个晶体弯曲器的重新设计工作进展缓慢。作为改进第二晶体性能的第一步，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。齿轮减速器和LVDT的组合将增加这种运动的再现性。来自齿轮减速电机的增加的扭矩将能够适应在光束线重新定位到扇区24之后可能的较小半径。2005年12月安装了新的矢状弯曲机组件，并安装了第一个晶体。 早期调试和表征的大部分工作仅限于克服安装新的第一晶体和第二晶体的弯曲电机的变化所带来的变化。偏航马达中的限制的反复出现的问题已经被克服，并且已经完成了对新的和重新安装的晶体的高度的轻微变化的补偿，沿着布拉格角的重新校准。显然，垂直聚焦性能并不令人满意。测量的通量与升级前的通量相似。当光束在6月回来时，将进行进一步的表征。 最后，反射镜的4.7 mrad倾斜角和第二晶体行进中的人为限制的组合将单色器的当前能量范围限制为14.5 keV。这将在进一步表征后解决。

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.