About

The Advanced Light Source (ALS) is going through a major upgrade (ALS_U) in the next few years into a diffraction-limited storage ring, which will provide 50-100 times higher brightness than the current ALS and will enable many new capabilities. This DOE-funded upgrade project includes - among others - the construction of a new coherent x-ray scattering beamline in the tender x-ray range (1-5 keV), to be designed to utilize novel contrast mechanisms such as chemical specificity and bond orientation sensitivity at elemental edges and access non-systematic fluctuations in a broad class of materials, with a temporal resolution, down to micro-seconds. This new tool will play a critical role in addressing scientific challenges in many areas, including soft matter, energy materials, biomaterials, and geo-environmental materials.

As we move forward to finalize a preliminary endstation design fall 2021, we seek inputs from our user community and experts in the field. Towards this goal, we are holding a virtual workshop on August 16 and 17 that will bring together leading experts in the areas of material science and coherent x-ray scattering from universities, national labs, and other research institutions.

Key characteristics of this tender scattering beamline include

• high coherent flux, ideal for dynamic studies using x-ray photon correlation spectroscopy (XPCS), with time resolution reaching sub-microsecond;

• tunable energy between 1-5 keV, covering elemental K-edges of Na, Mg, Al, Si, P, S, Cl, K, Ca, Sc and Ti, and L-edges of many other elements that exist in natural and industrially important materials; novel contrast mechanisms may be exploited, such as chemical specificity, bond orientation, charger/orbital order;

• microfocus beam (~ 5 μm), enabling spatially mapping material heterogeneities;

• two-detector setup planned for simultaneous small- and wide-angle XPCS, covering broad length scales from angstroms to hundreds of nanometers

Coming out of this workshop, we hope to have the information needed to answer the following charge questions:

• Given the limited detector availability and limited funds, which scenario should we choose now?

• What auxiliary facilities are necessary and desired?

• What sample preparation facilities are necessary to have at the beamline or nearby at the ALS?

• What are the computing and data analysis needs for this endstation?

• Besides chemical specificity, bond orientation sensitivity, are there other ways to take advantage of the energy tunability (1-5 kev) that require R&D in the next few years?

• We are thinking about a two-detector system, one in a long flight tube to cover the SAXS range and the other in a WAXS chamber to cover the WAXS range.

  1. Should the WAXS chamber be designed for both helium gas environments and vacuum environments, or be designed to focus on one environment?

  2. Which design will provide more flexibility in supporting in situ sample environments?

  3. What would be a good strategy in developing modular sample environments, i.e., sample environments that can be easily and quickly switched?

Chenhui Zhu, Advanced Light Source, LBNL

Cheng Wang, Advanced Light Source, LBNL

Gregory Su, Advanced Light Source, LBNL

Sophie Morley, Advanced Light Source, LBNL

David Kilcoyne, Advanced Light Source, LBNL

Eric Schaible, Advanced Light Source, LBNL

Roland Koch, Advanced Light Source, LBNL

Sujoy Roy, Advanced Light Source, LBNL

Andrea Taylor, Advanced Light Source, LBNL