Run 18 Regular Proposals

Latest Proposal Schedule

Mode of Access Run Cycle Proposal Call Status Deadline Cycle Begins Cycle Ends
Regular User Proposal LCLS 22  Proposals under review. 28 Mar 2023 Jan 2024 Jun 2024
Data Set Collection (DSC) LCLS 22  Proposals under review. 28 Mar 2023 Jan 2024 Jun 2024
Protein Crystal Screening (PCS) LCLS 22  Proposals under review. 28 Apr 2023 Jan 2024 Jun 2024
MeV-UED Regular User Proposal UED 4 Experiments scheduled   Oct 2022 Jun 2023
Scientific Campaign Ongoing Experiments scheduled   Jan 2022 Jun 2022
Rapid Access LCLS 21   Contact for details

Proposals are submitted through the User Portal.

  Calls For Proposals are posted on the LCLS Annoucements, and e-mailed to the LCLS User Organization e-mail list (subscribe to lclsuo).

LCLS call for Regular Proposals for period: March 2020 – December 2020 (Run 18)

Submission Deadline: 17 September 2019 (4pm PDT)

We are pleased to announce a return to operations of the LCLS facility after an extended shutdown required for the LCLS-II project and associated instrument development and upgrades. For this run, the previously existing copper accelerator (capable of up to 120 Hz) will be available with two new undulator systems and an initial set of upgraded instruments. The new hard X-ray undulator will provide vertical polarization for the first time, and up to 25 keV X-rays in the fundamental, as well as some tuning capability using the new variable gap system. This undulator will provide beam to the same suite of hard X-ray instruments previously available at LCLS.

The second undulator source will deliver soft X-rays to an early configuration of two instruments being developed for LCLS-II. In Run 18, these instruments will be commissioned and an “Early Science” access period will bridge the gap between commissioning and general user access. User proposals should target experiments using up to 120 Hz beam delivery.

Standard Configurations: For Run 18, LCLS will put greater emphasis on the use of Standard Configurations for the hard X-ray instruments, where 50% or more of the beamtime is expected to be awarded to experiments utilizing the many Standard Configurations available at LCLS. These provide a fixed platform for running many similar experiments efficiently, and allow resources to be balanced with LCLS-II commissioning. The reduced amount of setup and test time results in significantly more users and experiments being allocated beam time. Users are strongly encouraged to contact the relevant instrument scientists to discuss and plan their proposals of any kind, but especially those that use (or could be adapted to use) Standard Configurations. LCLS is also encouraging "data collection" proposals, where a single shift should be sufficient to produce a full data set suitable for publication, using a suitable pre-aligned Standard Configurations.

Standard Configurations »

Experimental stations available to users:

Virtual LCLS "Town Hall" User Meeting

A Virtual LCLS “Town Hall” User Meeting was held at 8:30am Pacific Daylight Time on August 16, 2019. Further information and a recording of this meeting can be found on the LCLS website.

Modes of Beam Operation:

For up-to-date information on LCLS performance, please contact the respective instrument e-mail address listed above, and see the Machine FAQ and the Machine Parameters Table, which includes a Multi-Color Pulse Mode Table.

New Capabilities Offered for Run 18

Run 18 marks the return to operations for LCLS after an extended shutdown to allow for LCLS-II installation. Thus, a host of new capabilities is expected upon the restart of operations. However, this will also be an intense period of commissioning new capabilities which will impact how experiments can be scheduled and performed, with periods of operation below 120 Hz.

New Undulators

LCLS is expected to produce X-rays in the energy range from 270 eV to 25 keV in the fundamental using two new undulators, as detailed below:

Soft X-ray Undulator (SXU): A newly installed variable gap undulator system will be used, providing horizontal polarization (same as the previous fixed-gap LCLS undulator) for photon energies from 270 eV to 2000 eV, dependent on instrument choice. A guideline for the expected pulse energy is shown here for soft X-rays, with details dependent on pulse duration and other factors. For more information, please contact Mike Minitti (

Hard X-ray Undulator (HXU): A newly installed variable gap undulator system will be used, providing photon energies up to 25 keV in the fundamental, an increase from the previously achievable maximum of ~13 keV. This new undulator will have vertical polarization, as opposed to the horizontal polarization of the previous system. This is expected to increase the throughput of most monochromatic experiments but some experimental geometries may need some reconsideration. A guideline for the expected pulse energy is shown here for hard X-rays, with details dependent on pulse duration and other factors. For more information, please contact Sebastien Boutet ( or Gilliss Dyer (

New Soft X-ray Instruments: Two new soft X-Ray instruments are expected to be commissioned early in Run 18, and available for experiments during the latter part of Run 18. Detailed information on each instrument can be found via the links below:

Time-resolved AMO (TMO) »

ChemRIXS »

Early Science: Immediately following technical commissioning of TMO and ChemRIXS, a period of early science on each of these instruments will be organized and led by LCLS staff and will include a limited number of expert users by invitation. These Early Science programs are intended to be pilot experiments that bridge between technical commissioning of the instruments and regular user operations (through the PRP Regular Proposal process). If you are interested to participate and contribute to the Early Science programs on one of these instruments (or for further information) please contact the relevant instrument scientist:


Hard X-Ray Capabilities and Areas of Emphasis for Run 18

The previously existing suite of Hard X-Ray instruments of LCLS will be on offer for Run 18, with a set of new detectors to better support the scientific needs of the users. Please contact the relevant instrument scientists for details on the expected capabilities for each instrument. In addition to Standard Configurations, LCLS expects to give special attention to hard X-ray proposals making use of the following capabilities.

  • >15 keV Operation: With the new hard X-Ray undulator, beam delivery up to 25 keV in the fundamental with pulse energy on the order of 1 mJ is expected. Proposals making using of photon energies above 15 keV are encouraged and will be prioritized where possible. For more information, please contact Sebastien Boutet (
  • Split-and-Delay for XCS: A crystal-based split-and-delay system has been commissioned is available for user experiments. It consists of two four-bounce monochromator branches delayed relative to each other. It is available exclusively on the XCS instrument. It operates in a range of 7-12 keV with a delay range from roughly -5 to 350 ps at 8 keV, with varying ranges as a function of energy. Operations above 13 keV is possible using a higher order reflection of the crystals with a factor of 5 reduction in bandwidth and throughput. Up to 1 ns delay is possible if one branch is bypassed. LCLS is particularly interested in experiments exploiting the methods of X-Ray Photon Correlation Spectroscopy and X-ray Speckle Visibility Spectroscopy to study materials dynamics using the split-and-delay system. For more information, please contact Diling Zhu (


MEC Instrument: Primary MEC laser parameters are unchanged from Run 17. New continuous phase plates have been added for the long pulse laser shock drive configurations, covering 150, 300, and 600 µm focal spots. New spectrometers are in development to cover photon energies above 12 keV, as is an updated imaging platform for Phase Contrast Imaging (PCI), darkfield and direct imaging. Minor updates have been made to the shock drive standard configuration, and a new standard beam delivery for short pulse experiments has been described. For more information, please contact Gilliss Dyer (

Submitting LCLS Proposals

The Linac Coherent Light Source (LCLS) encourages scientists from diverse fields to propose experiments utilizing LCLS's unique capabilities. Access to LCLS is open to the international community. There is no cost to submit proposals or conduct experiments at LCLS. However, users are responsible for their own travel expenses and (in rare cases) for any extraordinary consumables required by the experiment.

Register as a user and submit LCLS proposals through the User Portal

Read the proposal preparation guidelines, along with information on the new Standard Configurations, and the proposal review process prior to writing your proposal. Users are encouraged to review the LCLS instrument descriptions and contact LCLS instrument scientists to discuss technical capabilities and proposed experiments.

Other Access Modes to LCLS

Science Campaigns: LCLS has introduced a new access channel “Scientific Campaign Proposals” that represents an augmentation of the Regular Proposal process. Science campaigns are a mechanism to support more extensive research “programs” or campaigns, requiring a series of beamtimes, and targeting specific areas of science where there is great potential scientific impact from some unique capabilities of LCLS. The scientific scope and impact of the proposed research should be well above a Regular User Proposal as described above. A specific call for hard X-ray Campaign Proposals for Run 18 was issued on June 28 (LOI submission deadline July 22), and is separate from this call for Regular User Proposals for Run 18. Scientific Campaign proposals that are not awarded beamtime as a “campaign” will be automatically considered by the Proposal Review Panel for allocation of a single beamtime in Run 18. For further details regarding Campaign Proposals, please see the updated proposal preparation guidelines and proposal review process.

Protein Crystal Screening (PCS) Proposals: Protein Crystal Screening (PCS) proposals will be entertained by LCLS in Run 18. A separate call for PCS proposals will be issued with a planned submission deadline of October 1, 2019. For more information, please contact Mark Hunter (

SSRL Beam Time: For some LCLS proposals, the science case can be significantly enhanced by having access to SSRL beamtime in addition to proposed LCLS time. For this Run 18 Regular Proposal call, LCLS will consider a limited number of proposals that make a strong scientific case for beamtime access to SSRL. These proposals should indicate how much time is requested, when the time would be needed relative to the LCLS time, as well as which SSRL beamline would be needed. If Users have questions about which SSRL beamlines would be appropriate for the proposed scientific goals, please contact Piero Pianetta ( Scheduling of time across facilities is complicated and availability depends strongly on which of the SSRL beamlines is requested.