Here, we collect thoughts and opinions on what the MFX flagship experiment(s) should be in the LCLS-II-HE era. We collect the timeline of discussions that we had at the end of this page and summarize what emerges from them by categorizing between things we all agree on (Consensus) and things we are debating (Sticking points).
What's a flagship experiment?
Consensus
- MFX identity: high-throughput time-resolved multimodal imaging+spectroscopy for Biology and Chemistry.
Sticking points
- "specialization vs flexibility": specialization is key?
- "not-low" background at MFX means:
- SPI belongs at CXI/TXI?
- EXAFS could find a niche at MFX to rival recent developments in synchrotrons?
Potential Collaborators
- Lois Pollack: time-resolved solution scattering
- David Baker: protein-encapsulated nanoparticles
- Nate Hohman: SFX of small molecules
Timeline of discussions
Instrument meeting 6/27/23
During this meeting, Leland asked the MFX team to start brainstorming about identifying LCLS-II-HE flagship experiments starting circa 2026, highlighting the 3 characteristics that these experiments could benefit from, namely 1) High repetition rate (up to 1MHz), 2) High flux (more info?) and 3) High energy (up to 20 keV).
- High repetition rate
- Dan R pointed out that Single Particle Imaging (SPI) could benefit from it, to compensate for ultra-low hit statistics. In terms of samples, gold dumbells or protein-encapsulated nanoparticles (work from the Baker Lab; maybe see this recent preprint?) were mentioned. It was pointed out that the main challenge for SPI remains injection: Mark H mentioned ongoing work in that direction: maybe worth following up? Who is working on this, what is the current plan, etc.
- Fluctuation X-ray Scattering (FXS) would also benefit from high rep rate
- High-throughput SFX for Biology and Chemistry (see Nate Hohman). See ideas submitted to BRaVE3 for automated experiment steering.
- High flux
- Extended X-ray Absorption Fine Structure (EXAFS) would benefit from higher flux and could be used to study PSII with LBNL.
- High energy
- Again for spectroscopy, reaching Mo K-edge would help to study nitrogenases with LBNL (Mo pterin?)
Follow-up emails on 6/28/23
Following up, Fred P wrote:
Either way, I was thinking about this flagship experiment thing, and I guess what this is really about is defining the “identity” of the instrument. And I remember that someone (Mark? Ray?) once introduced MFX to me as “the beamline that produces a lot of SFX data/papers”. Another way that I think of MFX is by opposition to CXI in terms of background levels. So for me it would be natural to think of MFX as the SFX/solution-scattering beamline going forward, going after high-throughput and productivity more than it would go after challenging signals buried in the background or “one-off” experiments.
It could be defined as the beamline that delivers on high-throughput time-resolved multimodal bioimaging+spectroscopy experiments?
Another idea that might be behind defining flagship experiments is to reduce overlap between instruments. For example, would it make sense to push for SPI at MFX if it can be done more successfully at CXI or TXI? And likewise, do we really need to do SFX at CXI or other instruments if MFX does it so well? For solution scattering, the jury is still out: Lois Pollack would love to do it at MFX because it’s much simpler but in her current experience was only able to get good data at CXI, etc.
To which Leland answered:
These are excellent points you make. I struggle with the "specialization vs. flexibility" going into the future. My impression from the LCLS-II HE retreat was that specialization is key going forward and spectroscopy+bioimaging seemed to be accepted as MFX's strong niche - so your point about SPI at MFX vs. CXI/TXI is reasonable. I feel some signal poor experiments could find a niche at MFX, for example bio-EXAFS experiments started a boom in the synchrotron world that we have not yet paralleled.