Latest Proposal Schedule

Run Cycle Proposal Type Proposal Deadline Cycle Begins Cycle Ends
1 MeV-UED Regular - Solid State (Materials) and Warm Dense Matter (Single Shot) Mar 12, 2019
4 pm PST
Jun 2019 Dec 2019

  LCLS and MeV-UED proposals are submitted through the User Portal.

We are pleased to announce an additional period of experimental time (“Run 17”) prior to the 1 year shutdown for LCLS-II installation. This will be the final Run for the Soft-X-Ray instruments in their current arrangement. This is a relatively short Run that will be conducted alongside substantial preparation work for LCLS-II, and so we ask for proposals that can utilize this limited amount of beamtime in the most impactful and effective way.

A Virtual LCLS User Meeting was held on January 18, 2018

A webcast meeting will be held to better inform the users about the developments at LCLS before the upcoming LCLS proposal deadline on February 8th. LCLS staff will inform the community about the latest capabilities and be available for Q&A. Information on how to connect will be sent separately.

Submitting LCLS Proposals

The Linac Coherent Light Source (LCLS) encourages scientists from diverse fields to propose experiments utilizing the 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.

Important Information & Updates

Standard Configuration Beam Time

Since Run 13, LCLS has been running in a new mode of operation, called Standard Configuration Beam Time. Selected areas will operate for some part of the Run in a contiguous block of time during which the instrument will be in a Standard Configuration. The intent is to reduce the amount of time that is taken each run tearing down, setting up, and testing the same configurations at different times throughout the run. The reduced amount of setup and test time has resulted in significantly more users and experiments being allocated beam time. If you feel your experiment is able to operate in a Standard Configuration for one of the instruments, please indicate this in your proposal and follow the directions provided. See the Standard Configuration page for more details.

In addition, LCLS is encouraging "Data Collection" proposals which are intended to be short (typically one to two 12-hour shift), where it is assumed that a suitable standard configuration is ready to go and requires no alignment time, and a single shift is expected to be sufficient to produce a full data set suitable for publication. These "Data Collection" proposals are expected to be particularly suitable, but not limited, to protein crystallography. "Data Collection" proposals should be highlighted as such in the proposal title and are limited to using existing standard configurations.

SSRL Beam Time

User feedback has suggested that for some LCLS proposals, the science case can be significantly enhanced by having access to SSRL beam time in addition to proposed LCLS time. For this run 17 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.

New Capabilities Offered for Run 17

  • Sub-Femtosecond Operation: During Run 17 we expect to deliver sub-fs soft-X-ray pulses with a new recently tested configuration known as XLEAP. This will use a high-power infrared laser to compress a short fraction of the electron bunch to very high current. The setup is anticipated to be able to deliver ~0.5 fs pulses with a large coherent bandwidth, which is controllable using the space-charge boost given by the long LCLS undulator. XLEAP is predicted to be able to deliver a single sub-fs pulse or a train of pulses separated by ~ 6.8 fs

    The expected XLEAP performance is as follows. Please note however, that actual performance has not yet been quantified. The system is thus being offered “at risk” in Run 17. Please review the LCLS Machine Parameters table for period updates.

    • ~ 30-50 μJ per pulse
    • ~ 0.5 fs FWHM pulse duration
    • 4 to 8 eV FWHM bandwidth

Expected setup times are on the order of 3-4 hours. Submitted proposals shouldn't rely solely on XLEAP’s performance & robust operation, but preparing experiments/proposals that would work without XLEAP, but could benefit from it when it becomes available is strongly advised. For more information, please contact Mike Minitti (

  • Sub-Femtosecond, single spike Hard X-ray Operation: Sub-femtosecond hard x-ray pulses made of a single FEL spike have been demonstrated by LCLS and this mode of operation will be available to users in Run 17.

    The expected hard x-ray sub-fs performance is as follows. While the capabilities have been demonstrated, they have not been regularly used and are therefore being offered “at risk” in Run 17.  Periodic performance updates will be available via the Machine Parameters table.

    o ~ 10 μJ per pulse
    o ~ 0.2 to 0.5 fs FWHM pulse duration
    o ~8 to 14 eV FWHM coherent bandwidth

    Expected setup times are on the order of 3-4 hours. Submitted proposals should not rely solely on sub-fs performance & robust operation, but preparing experiments/proposals that would work without sub-fs pulses, but could benefit from them is strongly advised. For more information, please contact Sebastien Boutet (

  • Split-and-Delay for XCS: A crystal-based split-and-delay system has been commissioned during Run 15 and is available for user experiments in Run 17. It consists of two four-bounce monochromator branches delayed relative to each other. It is available exclusively onthe XCS instrument. It operates in a range of 7-12 keV with a delay range from roughly -5 to 350 ps at 8keV, with varying ranges as a function of energy. Up to 1 ns delay is possible if one branch is bypassed. Contact Diling Zhu ( for more detail.

  • Enhanced energy and beam delivery of the MEC shock driver: The Matter in Extreme Conditions long pulse laser was substantially upgraded in 2017. The energy has been more than doubled, to achieve 60 J in a 10 ns square pulse at 527nm. This energy is delivered in four laser arms, which are polarization multiplexed into two beamlines for delivery on to target in the standard configurations. Note that the maximum pulse energy will be different for pulse shapes other than the square 10 ns pulse. This capability was demonstrated in Run 16 to deliver planar shocks exceeding 2 Mbar in user targets.
    One continuous phase plate (for a ~350 µm spot) will be made available for shock driving experiments. Continuous phase plates have the advantage of coupling more laser energy into the central spot.
    The process of delivering new pulse shapes has been streamlined. A custom pulse shape can be delivered with 30 minutes to an hour of dedicated time with the long pulse laser. It is still strongly advised that pulse shapes still be declared at least two months in advance.  For more information, please contact Gilliss Dyer (

  • New Modes of Beam Operation: For up-to-date information on LCLS performance, please contact the respective instrument e-mail address listed below, and see the Machine FAQ and the Machine Parameters table.
    A number of 2-pulse modes of operation are under constant development. See LCLS for up-to-date information. For a summary of some key options, see summary of some key options.

Experimental stations available to users:

LCLS has demonstrated routine FEL operations over the energy range 250 eV to 11.2 keV using the fundamental, with pulse energies of at least 1-3 mJ depending on the pulse duration and photon energy.  For some configurations, the pulse energy can now be extended up to 5 mJ. In addition, the photon energy may be extendable up to 12.8 keV. If high pulse energy or high photon energy is required, please contact the appropriate station at the emails above.

Third harmonic radiation is available up to 25 keV at about 1% of the fundamental pulse energy. The pulse length can be varied from 40 fs to 300 fs for hard X-rays, while for soft X-rays the range is extended to 500 fs. Shorter pulses, ranging down to <10 fs, with a reduced number of photons per pulse can also be provided.

Self-seeding systems are available for both hard X-ray and soft-X-ray regions. Seeded beams can provide up to 50-fold higher brightness. For hard X-rays (5.5 keV to 9.5 keV), the narrow seeded line, 0.4 to 1.1 eV FWHM, for 50 fs pulse duration typically contains an average pulse energy of 0.3 mJ, with occasional shots up to 1 mJ. Set up time from a SASE beam is about 30 minutes. Soft X-ray self-seeding has been successfully demonstrated across the range of 400-1000 eV with a resolving power of 2000-5000. Recent work has shortened the set up time, which is now typically 2 hours. Note that a SASE pedestal of comparable total energy may be present. The machine energy stability has improved during the past few years, resulting in a ~80% energy acceptance of the seeding systems, meaning ~80% of the beam pulses fall within the energy range of the seeding crystal or grating.

Contact LCLS for further details of performance.

The Delta Undulator has demonstrated variable polarization output including left/right circular on the order of 100 microjoules per pulse across an X-ray energy range of 530 to 1200 eV. The degree of circularly polarization can reach 95-99%. Users are expected to provide experimentally necessary polarization diagnostics and include details in their proposal. For more information please contact

LCLS is currently offering a wide range of two-pulse and two-color operating modes, where pairs of FEL pulses are produced with variable temporal separation, and/or up to 1% photon energy separation, in both the hard and soft X-ray regimes.

See Machine FAQ for further details » See Multi-color Pulse Mode Summary Table »

Data Set Collection (DSC) Proposals

Submit new Data Set Collection (DSC) Proposals for Run 17 by 4 PM PACIFIC March 2, 2018.

This DSC beamtime is to be awarded during LCLS Run 17, expected to be between September 2018 and December 2018.

See details on DSC Proposals »

Protein Crystal Screening (PCS) Proposals

Submit new Protein Crystal Screening (PCS) Proposals for Run 16 by 4 PM PACIFIC June 26, 2017.

This PCS beamtime is to be awarded during LCLS Run 16, expected to be between November 2017 and June 2018.

See details on PCS Proposals »