LCLS Call for Proposals for Run 20

By pjones
May 20, 2021

Call for Proposals - Run 20
Linac Coherent Light Source - SLAC National Accelerator Laboratory

Deadline: 4:00 p.m. Pacific Daylight Time (PDT) 19 July 2021
This call is for experiments to run from January 2022 through June 2022

We are pleased to announce the next call for LCLS Proposals as the facility continues its instrument deployment in conjunction with the LCLS-II upgrade. For this run, the copper accelerator (capable of up to 120 Hz) will be available with two separate undulator systems and an increasing set of upgraded instruments.

The hard X-ray undulator will provide vertical polarization and up to 25 keV X-rays in the fundamental, as well as rapid tuning/scanning capability using the new variable gap system. This undulator will provide beam to the existing suite of hard X-ray instruments.

The second undulator source will deliver soft X-rays to an early configuration of three instruments being developed for LCLS-II (TMO, ChemRIXS and qRIXS). User proposals should target experiments using up to 120 Hz beam delivery.

For full details of the call, please visit:

Please note the following important information:

(1) A Virtual LCLS “Town Hall” User Meeting will be held on June 22, 2021
On Tuesday June 22, 2021 LCLS will host a virtual “Town Hall” meeting to inform the user community about the latest technical developments at LCLS. This interactive webinar will include a series of short talks by LCLS staff, with interactive Q&A throughout and open questions at the end of the session. The whole community is invited to participate, with members of the Users Executive Committee (UEC) and LCLS moderating questions. To register for this webinar please visit

(2) New Proposal Template
A proposal template has been created to provide guidance on the format and structure of proposal submissions. As always, please talk to the LCLS staff as you prepare your proposal.

(3) Capabilities offered for Run 20

  • Soft X-ray Undulator (SXU): A 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.
  • Hard X-ray Undulator (HXU): A variable gap undulator system will be used, providing photon energies up to 25 keV in the fundamental. This undulator will have vertical polarization. This is expected to increase the throughput of most monochromatic experiments but some experimental geometries may need some reconsideration.

(4) Early Science
Immediately following technical commissioning of the qRIXS sample chamber and goniometer, a period of early science will be organized and led by LCLS staff and will include a limited number of expert users. This Early Science program will focus on elastic scattering (i.e. without the emission spectrometer) and is intended to be pilot experiments that bridge between technical commissioning of the instrument and regular user operations.

(5) Experimental stations available to users:

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

(6) Protein Crystal Screening (PCS) Proposals
Protein Crystal Screening (PCS) proposals will be included in Run 20. A separate call for PCS proposals will be issued with a planned submission deadline of October 1, 2021. For more information, please contact Mark Hunter.

For more general information about LCLS, please visit:

I look forward to seeing your proposals!
Many thanks,
Mike Dunne
Director, LCLS