Predicted optical performance of the GM/CA@APS micro-focus beamline

Area of Science:

• Structural Biology
• Crystallography
• Materials Science

Background:

• Microcrystallography is crucial for determining the structure of biological molecules from small crystals.
• Recent global successes highlight the growing demand for high-intensity micro-focus X-ray beams.
• GM/CA at APS has existing microcrystallography capabilities with mini-beam collimators and automated software.

Purpose of the Study:

• To develop a new micro-focus endstation at GM/CA to significantly increase beam intensity.
• To meet the increasing demand for high-intensity micro-focus beams for structural biology applications.
• To enhance the capabilities for analyzing microcrystals (2-10 microns).

Main Methods:

• Designed a new micro-focus endstation utilizing a two-stage demagnification optical design.
• Employed Kirkpatrick-Baez geometry with bimorph mirrors for beam focusing.
• Incorporated a secondary source defined by slits, reimaged by a second set of mirrors.
• Implemented two focal modes (mini-beam and micro-beam) with adjustable aperture sizes.

Main Results:

• The new endstation increases mini- and micro-beam intensity by one to two orders of magnitude.
• The design allows rapid adjustment of beam size at the sample position (seconds).
• Quick interchange between mini-beam (20-micron) and micro-beam (5-micron) modes is achievable (minutes).

Conclusions:

• The developed micro-focus endstation significantly enhances GM/CA's microcrystallography capabilities.
• This advancement will accelerate structural biology research by enabling analysis of smaller crystals with greater efficiency.
• The system's flexibility and increased intensity address the growing demand in the field.