Project Summary/Abstract
The goal of this proposal is the purchase and installation of a high-performance DECTRIS EIGER2 S
16M pixel array detector for the new microfocus branchline of GEMINI at the Advanced Light Source
(ALS). The Berkeley Center for Structural Biology (BCSB) operates six macromolecular crystallography
beamlines at the ALS. Its latest undulator-based microfocus beamline, GEMINI, is just starting operation
and available to NIH users. BCSB has received funds for the construction of a second microfocus
beamline from the same source. Building a second branch that provides a high brightness user-focusable
beam down to 15 microns is required to address the national demand for high brightness small-beam
crystallography in the United States where existing microfocus beamlines are oversubscribed and
demand far exceeds capacity. Addressing this lack of national capacity now is particularly critical, as we
prepare for half of the total U.S. synchrotron macromolecular crystallography resources going dark in the
near future with the upcoming major upgrade of the Advanced Photon Source and the enormous impact
that will have on NIH-funded investigators. Guided by the expertise of the BCSB development team, our
beamlines provide state-of-the-art capabilities in automation, software processing, and hardware control;
the addition of a large surface area, fast-readout, high-end detector system at GEMINI will complement
the qualities of the new GEMINI beamline and allow further development of new techniques in multi-
temperature crystallography and synchrotron serial crystallography. Photon counting pixel array
detectors are the gold standard in macromolecular crystallography due to their zero noise, high frame
rate, excellent point-spread function, and high dynamic range; they have become standard at many
national synchrotron facilities throughout the world. These detectors have been critical in the success of
many structural biology projects and the latest design by DECTRIS, the EIGER2, have marked
improvements on the speed and quantum efficiency of detectors that are available at the ALS. The
EIGER2 S 16M has zero deadtime due to its two counters per pixel that enables fine slicing data collection
that can reduce radiation damage—especially in multi-temperature experiments. The high dynamic range
means both strong and weak reflections can be collected simultaneously, and the large surface area
combined with a single pixel point-spread-function allows collection on samples with large unit cells
and/or high resolution. These attributes will maximize the success of NIH researchers at GEMINI and
allow the BCSB to excel in its commitment to provide our users the highest quality data and the cutting-
edge capabilities needed at the modern synchrotron.