Run 20 PCS Proposals

LCLS Call for Protein Crystal Screening (PCS) Proposals, Closing Date: October 15, 2021

  Submit Proposals through the User Portal by 4:00 pm Pacific Time (PDT), October 15, 2021.

We are pleased to announce the next call for LCLS Protein Crystal Screening (PCS) Proposals. This PCS beamtime is to be awarded during LCLS Run 20, expected to be between January 2022 and June 2022.

The LCLS Protein Crystal Screening (PCS) program aims to enable increased access to LCLS beamtime for biological structure determination by making use of short, 6-12 hour runs to screen the quality of different sample preparations or potentially collect a full data set under good running conditions. To enable measurements within such a short time frame and maximize efficiency and the chances of success, these studies must be carried out with limited instrumentation flexibility to minimize the time impact of setup changes.

PCS experiments at CXI are expected to be available using the standard CXI configuration, using the refocused X-ray beam from the 1 µm focus as a parasitic measurement to a primary experiment. PCS experiments at atmospheric pressure are expected to be available at the MFX instrument with multiple options likely to be available, including a goniometer system, allowing scanning of fixed-mounted crystals, and a liquid jet system compatible with various types of jets.

The following sample delivery configurations are expected to be supported at CXI (in vacuum) and MFX (in atmosphere) for PCS in this current call for proposals:

  • Gas Dynamic Virtual Nozzle (GDVN)
  • Dual Flow Focusing Nozzles (DFFN)
  • Lipidic Cubic Phase (LCP) jets
  • Microfluidic Electrokinetic Sample Holder (MESH)
  • Droplet-on-Demand (DoD) – Currently in commissioning at MFX
  • Sheet Jets

Other sample delivery techniques supplied by user groups (ie. liquid jet, fixed target, goniometer, tape drive, etc) that are compatible with the basic CXI or MFX system could also be considered if the schedule allows it and at the discretion of LCLS. Schedule constraints are unpredictable, and no guarantees can be made that any of the mentioned experimental setups will be available for PCS in any given run.

Other Experimental Geometries or Capabilities

Time-resolved studies and spectroscopy are currently not within the scope of PCS beam time.

Proposal Review and Beamtime Award

These PCS proposals will be reviewed by the PRP BIO-C panel separately from the regular proposals. It is desirable to shorten the period between PCS proposal submission and beam time allocation to maximize flexibility and the ability to be reactive to novel samples or ideas. LCLS will aim to pre-allocate blocks of beamtime on CXI and/or MFX based on the overall demand. The expected amount of beamtime is approximately 10-12 shifts in every LCLS run. Proposals will be awarded beam time by LCLS based on the scientific recommendation of the Proposal Review Panel and other technical considerations by LCLS, including sample readiness, technical feasibility and scheduling constraints. A minimum two months’ notice will be given to the selected user groups to allow for appropriate preparation.

Overlap with Regular LCLS Proposals

There is no restriction with regards to possible overlap or redundancy with regular LCLS proposals. Submission of PCS proposals similar or related to regular LCLS proposals are encouraged and will not adversely impact the rankings of either types of proposals. Regular LCLS proposals that do not receive beamtime may be considered for PCS if deemed suitable.

Proposal Format

PCS proposals follow a similar format as regular proposals. They must be submitted separately. PCS proposals are evaluated by the PRP on the scientific impact and risk, need for LCLS, and by LCLS staff on technical feasibility. LCLS PCS proposals should be submitted through the User Portal. Provide a descriptive title of your proposed experiment that you would be willing to be made public if awarded beam time.

The proposal text is limited to 2 pages in PDF format. Pages should have at least 1 inch margins and not less than 10 pt font. It should include the following information:

Which elements of the proposed instrument do you require for the proposal?
What additional equipment is needed, including detector, sample delivery/environment, temperature, pressure, etc.?
How do you plan to provide/organize the additional equipment?

  • Experimental Team: In a table, list the names, institution, email address of PIs and collaborators who would participate in the proposed experiment (e.g., sample prep, theory, data collection, data analysis). The team can be shortened to only containing the list of team leaders for the main aspects of the experiment, e.g. the data analysis team lead. However, proposals that seek to use the in-house resources of the LCLS facility for sample delivery and data analysis are welcome but should clearly state this in the proposal.
  • Scientific Case: Briefly explain the background and significance of your experiment. In particular, why is LCLS required for this experiment? Itemize the specific aims and particular questions you want to answer. Focus on the specific experiment and avoid broad discussions in general terms.
  • Experimental Procedure: If the PCS proposal is related to one or more regular LCLS proposals that have been submitted or already received beam time, state this in the proposal. Tell us if you plan or have carried out supporting experiments at other facilities. Describe any additional equipment you plan to bring to LCLS for the experiment. We strongly recommend that you contact LCLS Scientist Mark Hunter (mhunter2@slac.stanford.edu) before proposal submission to discuss capabilities, to identify possible problems in integrating external equipment with LCLS instrumentation and to determine possible solutions.
  • Technical Feasibility: Proposals must contain sufficient information for LCLS to review the proposal for technical feasibility. This information should include:
    • Equipment
      • Which elements of the proposed instrument do you require for the proposal?
      • What additional equipment is needed, including detector, sample delivery/environment, temperature, pressure, etc.?
      • How do you plan to provide/organize the additional equipment
    • Experimental protocol
      • Describe the experimental geometry.
      • Describe samples and concentrations, sample preparation and storage if this is well understood.
      • Describe local facilities that may be required.

* Safety related documents must be submitted during the safety management portion of the LCLS proposal submission process in the user portal. List and describe any safety concerns that may arise with samples you will examine, equipment you will use, or techniques you will perform (including any physical, chemical or biological hazards) and how these issues will be addressed in the experiment design.

LCLS is seeking proposals for PCS beamtime to be awarded during LCLS Run 20 expected to be scheduled between Jan 2022 and June 2022. View the latest LCLS long-range operating plans here.

Questions about the LCLS PCS program should be directed to Mark Hunter (mhunter2@slac.stanford.edu). For more general information about LCLS, please visit: http://lcls.slac.stanford.edu