The time tool can be found in the "Beamline" tab of the home screen for most hutches.

The time tool is used to make sure that time is the same between the optical laser and the beam, it is located on the DSB stand. The time tool measures the difference in time between the laser and the FEL using two methods: 

  1. spatial encoding (also called "reflection" mode), where the X-rays change the reflectivity of a material and a laser probes that change by the incident angle of its wavefront; or
  2. spectral encoding (also called "transmission" mode), where the X-rays change the transmission of a material and a chirped laser probes it by a change in the spectral components of the transmitted laser.

Nearly all experiments use option #2. If you are running in option #1, ignore the rest of this page and get help (ask your PoC). I will proceed describing mode 2.

A "timetool" is composed of the following elements:

  • A laser setup that creates a chirped white-light ps-length pulse concurrently with the pump
  • A "target", usually YAG or SiNx, that gets put in the path of both the white light and LCLS x-ray beam
  • A diffraction grating that disperses the white light pulse after it goes through the target
  • A camera that captures the dispersed white light

Above information taken from: TimeTool confluence page.

More information on the time tool can be found here.


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