25A　Coherent X-ray Scattering

Frequently asked questions

Q: What is the q-range of SAXS detector for once acquistion?
A: About two order-of-magnitude (e.g. 0.005~0.5).

Q: Why is the energy of TPS 25A1 not an integer (e.g. 10 keV)?
A: The undulator is the X-ray source for TPS 25A1. Generally, we change the gap of undulator and select the suitable harmonics. The energy value with the highest flux and near the desired energy value will be selected. Therefore, the real energy values usually are not the integer (e.g. 10.005 keV).

Q: Why are the scattering patterns from the same sample different between TPS 25A1 and others?
A: The beamsize in FWHM at sample position of TPS 25A1 is 4μm by 5μm. Other SAXS beamlines provide the beamsize more than 200μm by 200μm. This means that the local micro-scale structure and sample homogeneity of the sample strongly affect the scattering patterns collected at TPS 25A1.

Q: How many exposure time should I set for the sample? Can I set 300 seconds for one acquisition?
A: Depends on your sample system. We suggest to use time-resolved data acquisition. For example, 1 second exposure time per frame and collecting multiple frames. This procedure can help you to identify the radiation damage on sample, and get better statistics after frame-combination if there is no radiation damage effect. Our data reduction program can output every single frame from the mutliple-frame datasets, and also perform frame combinations to get better statistics.

Q: Can I change the q-range or sample appartus during beamtime?
A: Yes, it takes time to change the q-range or sample appartus. If you want to change the condition, please inform us as soon as possible. It would be better to do this during our bussiness time.

Q: Can I do the data reduction at my own computer?
A: Yes, the (GI)-SAXS/(GI)-WAXS data reduction is Python-based program. Please see the 'Resource' for more information.