Time-Tool

The time-tool (TT) compensates for the 200-300 fs temporal jitter of the x-rays. Nominal time resolution of the TT is below 50 fs. This means if you make a 100 or 200 fs steps scan, the jitter of the x-rays will automatically fill in the middle of the steps, which will be later sorted out but the TT.

The two main components of the TT system are a laser beam (dispersed white line) and a thin target (Si2N3, yag.... up to 6) placed in the x-ray path and coincidentally irradiated by the laser and the x-rays.

The x-ray pulse changes the reflection index of the target. By making the white line arriving at the target before the X-ray pulse (the laser is longer than the X-ray pulse ~ps) and analyzing the white line after the target (with an spectrometer), we can see effect of the X-ray pulse on the white line when compared (substracted) to the white line before the target and get information about the arrival time of the X-ray pulse with tens of fs precission.

The targets holder includes a mirror to steer a new reference laser beam into the lines. (not installed reference laser)

For basic alignment of the time tool go here

To check for power on time tool

TTfactor('Si3N4',2e-6,1e-3,E=9,FWHM=200e-6) TTfactor ('material',thickness,FEL pulse in J, x-ray energy, beam size)

TTfactor = 1 means 10% jump, it has to be close to 1 (at least 5% so at least 0.5)