Splitting and delaying fully coherent FELs pulses for advancing ultrafast x-ray science: the AC/DC optical device at the FERMI FEL
Bibliographic record
Abstract
Free-electron lasers (FELs) are currently the most advanced light sources operating worldwide, thanks to their capability to lase coherent ultrashort pulses, marked by photon energies bridging the gap between the Extreme-Ultraviolet (EUV) and the Soft (SXR) and Hard (HXR) X-Rays, alongside with unique high-brightness and temporal duration lying in the femtosecond (fs) timescale. FELs can exploit, in a time-resolved approach, spectroscopies daily employed at synchrotron light sources, mostly combining EUV, SXR and HXR pulses with optical ones. Nonetheless, the next advances in ultrafast x-Ray science are strongly linked to the extension of these time-resolved schemes to perform experiments engaging exclusively EUV, SXR and HXR pulses, so triggering (and probing) matter at its (or nearby) electronic resonance(s), to reveal the microscopic mechanisms hiding behind matter phases of primary interest for broadband applications. Indeed, designing the next generation of quantum devices, as well as tailoring a new classes of biomolecules for pharmacological applications, are just two examples that can be strongly boosted by means of this optical approach. To do this, is mandatory to split and delay (in time) FELs pulses, without impacting on both the radiation coherence properties and on the photon transport. At the seeded FERMI FEL (Trieste, Italy) this goal is committed by the optical device known as AC/DC, which stands for the Auto Correlator/Delay Creator, designed to split the incoming EUV and/or SXR pulse, introducing a tunable delay between these two pulses, marked by an intrinsic resolution in the sub-fs, and aided by an opto-numerical pointing feedback system.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".