The science needs for the capabilities of LCLS-II-HE have been developed by the international science community over many years. Following are some of the key workshops organized by SLAC that have driven the development of the science case. Since the original proposal for LCLS-II-HE, we have continued to advance and refine the science opportunities, most recently through a series of “First Experiments” Meetings hosted at SLAC in 2017, followed by a workshop on advanced methods and instrumentation for LCLS-II-HE science hosted at SLAC in 2018.

Advanced X-ray Methods & Instrumentation for LCLS-II-HE Science
October 16-17, 2018      SLAC National Accelerator Laboratory
LCLS-II-HE Advanced Methods and Instrumentation Workshop, Oct. 16-17, 2018

The objective of this workshop is to further engage the science community in helping to identify the most compelling X-ray methods and instrumentation that will exploit the unique capabilities of LCLS-II-HE for the greatest scientific impact. The results of this workshop will help guide the design, performance capabilities, and priorities for new future scientific instrumentation for LCLS-II-HE.

LCLS-II-HE “First Experiments” Meetings:  AMO, Biology, and Quantum Materials
October 30-31, 2017      SLAC National Accelerator Laboratory
LCLS-II-HE “First Experiments” Meeting, Oct 30-31, 2017

The objective of these three parallel workshops is to convene working groups to further develop the science case for the proposed energy upgrade of LCLS-II (LCLS-II-HE) in the following areas:

AMO and Gas-Phase Chemistry:

• Fundamental molecular dynamics
• Strong-field physics
• Chemical-dynamics (imaging/scattering)

Biological Function and Structural Dynamics:

• Spontaneous (stochastic) dynamics and conformational heterogeneity
• Triggered dynamics - pump/probe, rapid mixing
• Advanced algorithms to provide new insight to biological function

Quantum Materials:

• Correlated Materials
• Low-dimensional Materials and Heterostructures
• Exotic magnetism and spin phenomena

LCLS-II-HE will provide X-ray energies extending beyond 12 keV to enable high repetition-rate studies of atomic, electronic, and chemical dynamics at the atomic scale. The near-term goal of these workshops is to define a series of “first experiments” that illustrate the most important science challenges that can be uniquely addressed by LCLS-II-HE. These will further guide the development of instrumentation and related plans for the upgraded facility.

LCLS-II-HE “First Experiments” Meetings:  Chemistry & Materials Physics
July 20-21, 2017      SLAC National Accelerator Laboratory
LCLS-II-HE First Experiments Meeting July 2017

The objective of these two parallel workshops is to convene working groups to further develop the science case for the proposed energy upgrade of LCLS-II (LCLS-II-HE) in the following areas:

Chemistry:

• Chemical dynamics, coordination- and photo-chemistry
• Photo-catalysis, natural and artificial photosynthesis
• Catalysis and environmental chemistry

Material Physics:

• Photo-induced phase transitions, nonequilibrium dynamics, low-dimensional materials
• Stochastic phenomena, fluctuations, heterogeneity
• High energy density science

LCLS-II-HE will provide X-ray energies extending beyond 12 keV to enable high repetition-rate studies of atomic, electronic, and chemical dynamics at the atomic scale. The near-term goal of these workshops is to define a series of “first experiments” that illustrate the most important science challenges that can be uniquely addressed by LCLS-II-HE. These will further guide the development of instrumentation and related plans for the upgraded facility.

Scientific Opportunities for Ultrafast Hard X-rays at High Repetition Rate:
An Energy Upgrade of LCLS-II
September 26-27, 2016      SLAC National Accelerator Laboratory
Scientific Opportunities for Ultrafast Hard X-rays at High Repetition Rate: An Energy Upgrade of LCLS-II, 26-27 September 2016

The proposed energy upgrade of LCLS-II to 8 GeV (LCLS-II-HE) promises to open entirely new areas of science by providing X-ray energies extending beyond 12 keV to enable high repetition-rate studies of atomic, electronic, and chemical dynamics at the atomic scale.

The objective of this workshop is to further develop the science case for this proposed upgrade, and refine the technical requirements to ensure maximum scientific impact. The results of this workshop will help guide the design and performance capabilities of the upgraded facility; and will inform the planning for new future scientific instrumentation. More than 160 participants from around the world attended this workshop and contributed to the science drivers that were captured in the LCLS-II-HE CD-0 proposal.

Previous SLAC workshops informing LCLS-II-HE science

XFELO Science Workshop
June 29-July 1, 2016      SLAC National Accelerator Laboratory
XFELO Science Workshop, June 29-July 1, 2016

This workshop comprised two and half days of in-depth discussion from international participants of various scientific opportunities that might be enabled by an XFEL oscillator (XFELO). The scientific discussion also provided valuable input for developing the science case for extending the performance of LCLS-II into the hard X-ray range (LCLS-II-HE) as there is significant overlap in capabilities with XFELO.

High-gain free electron lasers at the LCLS at SLAC and other laboratories around the world have demonstrated the power of FELs for X-rays. An oscillator-type FEL is also feasible for the hard X-ray spectral region producing fully coherent, intense X-ray pulses of high spectral purity with MHz repetition rate. It appears that an XFELO is within the reach of current technology and, furthermore, the 4 GeV CW-SCRF linac under construction for the LCLS-II is a suitable driver a practical XFELO.

Research Opportunities in Photochemistry, Solar Energy
& Advanced X-ray Methods
June 16-17, 2016      SLAC National Accelerator Laboratory
Research Opportunities in Photochemistry, Solar Energy & Advanced X-ray Methods, 16-17 June 2016

This workshop was jointly organized by LCLS and SSRL and focused on fundamental questions in solar energy conversion and opportunities where advanced X-ray methods will have a significant impact. The workshop goals were to: (i) facilitate the exchange of ideas and foster collaborations between scientists focused on solar energy conversion and researchers with expertise in time-resolved X-ray science, (ii) identify challenges and opportunities for time-resolved X-ray methods for addressing problems in basic energy science, and (iii) propose development paths for the most compelling science areas. More than 140 participants attended, and there were three breakout sessions on:

1. Nano- and solid state materials for solar energy conversion
2. Molecular materials for solar energy conversion
3. Fundamental chemistry and physics of light driven phenomena

These discussions identified a number of important scientific opportunities in the areas of photochemistry and molecular energy capture requiring the unique capabilities of both LCLS-II and LCLS-II-HE.

LCLS-II Scientific Opportunities Workshops
February 9-13, 2015      SLAC National Accelerator Laboratory
LCLS-II Scientific Opportunities Workshops, 9-13 February 2015

The LCLS-II Scientific Opportunities Workshop series was organized to advance the scientific opportunities of this new facility, and refine the technical requirements to ensure maximum impact during early operations and into the future. The series comprised four sequential meetings focused on: Materials Physics, Life Sciences, Chemistry, and Materials in Extreme Conditions. More than 400 participants from around the world attended these workshops and contributed to the workshop report. The results of these workshops feed directly in to the science strategy for LCLS-II; to help guide the design, commissioning and ultimate operation of the upgraded facility; and further inform the R&D roadmap for instrumentation and machine performance.

While the focus of the meeting was on science drivers for the soft and tender X-ray range of LCLS-II, there was also significant discussion of science needs for extending the high-repetition-rate performance in to the hard X-ray range.

LCLS-II New Instruments Workshop
March 19-22, 2012      SLAC National Accelerator Laboratory

The goal of the original LCLS-II workshops was to identify the most exciting science and corresponding parameters which to help define the LCLS-II instrumentation. Scientists from around the world provided short descriptions of the scientific opportunities they envision at LCLS-II. The workshops focused on four broadly defined science areas: biology, materials sciences, chemistry and atomic, molecular and optical physics (AMO).