Hints for proposals

  • If you want to use the mini-TIMER setup, you have to ask for the DiPROI beamline (not TIMER!) and to state in the proopsal field "other requirements" that you need mini-TIMER.
  • During the allocation phase we may evaluate the possibility to schedule the experiments on TIMER in place of mini-TIMER or vice-versa. If you need to use a specific instrument please stress the motivations in ypur proposal.
  • The "standard duration" of an experiment is 11 shifts (1 shift = 8 hours), we recommend to try fitting your experimental plan in 11 shifts. The facility usually adds one shift for beamline preparation before each user experiment (in some cases we may add more preparation shifts). Please consider that the time needed to align mini-TIMER or TIMER is roughly one shift and any changes in the experimental geometry (FEL crossing angle, angle of incidence of the probing laser, etc.) require a couple of hours time.
  • It is not possible to operate the FEL1 and FEL2 sources in the same beamtime. If you need wavelengths within the range of both sources please write two proposals. Keep in mind that, in this case the two experiments cannot be scheduled one after the other (most likely there will be some to several weeks in between). Moreover, the whole range of FEL2 cannot be covered within the same beamtime, since it requires different electron bunch energies. Please refer to the FEL2 beam parameters and contact the beamline scientist for more details.
  • Typical pulse energies at the source in order to observe a reasonable TG signal are on the order of ~10-20 uJ.
  • The ML of the TIMER delay line reflect only vertically polarized light. However, we typically request circular polarized light to maximize pulse energy at the source.
  • If you need two-color FEL emission (e.g. for CRS) state that clearly in the proposal and consider that the total energy radiated in the two pulses (I1+12) is lower than in single pulse mode. Also keep in mind that using our split-delay-recombination system (see the Research page for some more details) half of total emitted energy (I1+12) goes into the pre- and post-pulses. The time separation between the two-color pulses is typically in the 0.3-0.5 ps range while the maximum relative separation in the photon energy, Δω/ω=(ωFEL1-ωFEL2)/ωFEL1, is typically 0.5% of the central wavelength, e.g. 500 meV for ωFEL1=100 eV. Larger values of Δω/ω, e.g. up to 1%, are possible in some cases. Please ask the beamline scientist before submitting the proposal.
  • Always ask for the user laser, even when using the EUV probe, since it is needed to adjust the timing between the FEL pulses (for this activity we prefer the fundamental harmonic: wavelength 785 nm).
  • Typical spot sizes are in the range 100-200 x 50-100 μm (Hor x Vert). Using mini-TIMER it is possible to tune the focal spot size, at EIS-TIMER not.
  • In general we noticed sample damage for pulse energies larger than 40 uJ at the source, in these condtions you burn very nice permanent gratings on the sample. We typically collected TG data with pulse energies at the source in the 2-10 uJ range, roughly twice in the case of CRS (remember that in our CRS scheme half of the total pulse energy goes into the pre- and post-pulses). To have TG data with a signal-to-noise of about 1000 we need to integrate ~1 minute per time-delay point. In CRS the signal-to-noise is of about 100 in similar conditions (same integration time and twice the total pulse energy).

If you have any questions do not hesitate to contact us

Last Updated on Friday, 18 October 2019 17:40