MeV-UED Proposals

LCLS MeV-UED Run 6 Call for Proposals

For period October 2025 to August 2026

Submission Deadline: 16th May 2025 (4pm PDT)

LCLS is pleased to announce the proposal call for MeV-UED’s sixth external user experimental run, scheduled to begin in October 2025. In “Run 6”, LCLS MeV-UED will offer two specialized chambers for chemical science experiments. The first chamber is designed for gas-phase experiments, while the second chamber allows experiments using liquid-sheet jets. Both chambers offer a broad range of optical pumps at their interaction points.

Since 2014, the SLAC UED instrument has been developing robust methods in the pursuit of time-resolved measurements to control and understand structural dynamics and chemical dynamics in a variety of material and chemical systems.  Run 6 will leverage these successes and continue system-level improvements in machine performance and reliability.

Please note the following important information:

Virtual town hall: April 18th 2025 at 8:30am Pacific Daylight Time

A webcast virtual town hall meeting will be held to inform potential users about the developments at MeV-UED before the proposal deadline on May 16th 2025. MeV-UED staff will inform the community about the latest capabilities and be available for Q&A.

Experimental stations available to users in Run 6:

  • Gas-phase UED chamber

  • Liquid-phase UED chamber 

See Endstations for details.

Detailed information about the experimental capabilities on offer for Run 6 are available at MeV-UED Run 6 Scientific Capabilities. Please note that solid phase samples are not included in this proposal call.  For further information on MeV-UED’s performance, please contact the instrument experimental points of contact listed below and see our instrument specifications, and experimental layout.

Register as a user and submit MeV-UED proposals through the Universal Proposal System

Registration in UPS is required for all members of the proposal team (Principal Investigator(s) and Co-Proposers). For information about the UPS system and to explain the features and functionality of this new tool please visit the link below:

Universal Proposal System Information

MeV-UED Proposal Submission

LCLS encourages scientists from diverse fields to propose experiments utilizing the MeV-UED's unique capabilities. Access to LCLS MeV-UED is open to the international community. New users are particularly welcome: the staff listed above will provide advice on how to translate your scientific ideas into a MeV-UED experiment and can help introduce new users to potential partner user groups if desired. For all users, communication with the instrument team is strongly encouraged to help maximize your chances of success.

Access to LCLS is open to the international community, with selection based on scientific merit (More details about the MeV-UED Proposal Review Process). There is no charge to conduct experiments at LCLS, and the facility is able to help with the costs of performing experiments (e.g. consumables). However, users are responsible for their own travel expenses. Consider applying for Proprietary Research time if you do not plan to publish.

We recommend that scientists describe well-posed experiments that can be accomplished within 96-120 hours of beam time. Proposals must include brief discussions of the expected scientific or technological impact and anticipated feasibility and probability of success of experiments.

Each proposal is for one specific experiment. Proposals can be re-submitted at each call, but this will not happen automatically and a re-submission will not receive preference during the review process. There is no limit to the number of proposals that can be submitted by a scientist or team, but multiple similar proposals from the same team members may not be reviewed favorably by the Proposal Review Panel (PRP).
Proposals may be made in the context of a larger scope than can be covered in a single experiment. All proposals, even these broader proposals that address important problems, must be resubmitted each cycle in order to be peer reviewed and considered for beam time. However, in the absence of sufficient information to evaluate progress (data disseminated from previous beam time, publications, etc.), the PRP may recommend or MeV-UED may decide that some proposal(s) be postponed for consideration until a future review cycle.

Please refer to the MeV-UED Run 6 Scientific Capabilities page for information on the currently offered instruments and the proposal review process prior to writing your proposal.

A proposal template has been created to provide guidance on the format and structure of proposal submissions.

Download the MeV-UED Proposal Template

Required Content for Your Proposal

Provide a descriptive title of your proposed experiment that you would be willing to be made public if awarded beam time.

Provide an abstract that concisely (less than 2,000 characters) summarizes the proposed experiment, quantities to be measured, samples to be studied, expected scientific results and impact. The proposal text is limited to 4 pages in PDF format - this 4 page limit does not include the completed standard parameters table, references or one-page progress reports on previous beamtimes. Proposals should include the following information (include the spokesperson's name in the upper right-hand corner of each page):

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). This section could also briefly mention directly-relevant previous work done by the team members.

Scientific Case: Briefly explain the background and significance of your experiment. In particular, why is MeV-UED 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: Provide specific information so that the feasibility of this experiment at the requested MeV-UED instrument can be evaluated. Tell us if you plan or have carried out supporting experiments at other facilities. Have simulations of the experiment been performed? What are the anticipated data rates? Provide a beam time plan, indicating what could be accomplished shift by shift. Describe any additional equipment you plan to bring to MeV-UED for the experiment.

We strongly recommend that you contact the MeV-UED instrument scientist(s) before proposal submission to discuss capabilities, identify possible problems with integrating external equipment and to determine possible solutions.

Technical Feasibility: Proposals must contain sufficient information for the MeV-UED instrument staff 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 laser, detector, sample delivery/environment, temperature, pressure, etc?
    • How do you plan to provide/organize the additional equipment?
  • Parameters
    • Describe electron beam energy, pulse energy, beam size, repetition rate, and pulse duration
    • If an optical laser is required, describe laser wavelength, pulse energy, bandwidth, beam size, repetition rate, pulse duration, timing, geometry.
  • Experimental protocol
    • Describe the experimental geometry.
    • Calculate the expected signal rate/background.
    • Describe samples and concentrations, sample preparation and storage.
    • Describe local facilities that may be required.

As part of the proposal process, we will contact the Spokesperson for proposals that have the potential of being awarded beamtime. The Spokesperson will be asked to provide specific experimental parameters to help inform the viability and schedule.

Progress Report: When submitting a new proposal, also upload a brief progress report summarizing proposals that have previously received LCLS MeV-UED beam time; include proposal number(s), date(s) of experiment, instrument(s) used, a brief summary of how experiment time was used and results disseminated (list major invited talks, papers published or in press, awards or special recognition). These reports do not count towards the proposal length limits. NOTE: User publications are extremely important in demonstrating the scientific impact of LCLS.

Register as a user and submit MeV-UED proposals through the Universal Proposal System

Acknowledgement: Proposal teams must inform and acknowledge MeV-UED and the DOE Office of Science in presentations and publications using this template:  
"MeV-UED is operated as part of the Linac Coherent Light Source at the SLAC National Accelerator Laboratory, supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515"