Run 17 Regular Proposals
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 (minitti@slac.stanford.edu).
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 bandwidthExpected 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 (sboutet@slac.stanford.edu).
- 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 on the 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 (dlzhu@slac.stanford.edu) 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 isdelivered 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 (gilliss@slac.stanford.edu). - 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:
- Atomic, molecular and optical science (AMO) - contact srd-sxd@slac.stanford.edu
- Soft X-ray Material Science (SXR) - contact srd-sxd@slac.stanford.edu
- X-ray Pump Probe (XPP) - contact srd-hxd@slac.stanford.edu
- Coherent X-ray Imaging (CXI) - contact srd-cxi@slac.stanford.edu
- Macromolecular Femtosecond Crystallography (MFX) - contact srd-cxi@slac.stanford.edu
- X-ray Correlation Spectroscopy (XCS) - contact srd-hxd@slac.stanford.edu
- Matter in Extreme Conditions (MEC) - contact srd-mec@slac.stanford.edu
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 srd-sxd@slac.stanford.edu.
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.
