NXcanSAS has I_partial for XPCS applications?

[ambarb]

Open questions:

The words is this is "I(Q) for stability". This is added as per specific request by XPCS scientists that want to understand the stability.

• [x] is this for dynamic or static or both q-bins
• [x] is this also as a function of time (So broadly I(t) for each row

[ambarb]

Asking Suresh about this:

• static q bins ONLY

• roughly a function of time (for every N/10 frames, N frames are used to compute)

• the look at this series of time binned frames with static q binning to determine if the structure of the sample changes with time (i.e., diffraction ring diameters change )

Quoting Suresh's explanation is below. To clarify, Suresh is using ROI to indicate the entire qmap area (historically, they set the AreaDetector ROI to read out a small portion of their older detectors).

Let us say a time series has N frames.
We have a user defined parameter /xpcs/static_mean_window_size which has a default of N/10. 
So for every N/10 segment in time, we compute I(q,phi) and this has the structure of a 3D array
 I(q,phi,10 if window size is N/10)

We use this to check if structure is stable over time. User can define this window =1 if they want 
per frame I(q,phi).

Before this, we have the totalIntensity vs time which is per frame and is the average intensity over 
the entire ROI (inside mask region) and we use this as a q-agnostic overall degradation probe.

We have a /xpcs/dynamic_mean_window_size which is supposed to do the same but for g2 but in 
this case, g2 is computed for say the N/10 segments in a cumulative manner. In our original MPI 
version (<2010), we had the real time g2 feature, like your lazy one time. Then we moved to non-real 
time tools due to resource issues and we lost this real time capability.

Miaoqi is bringing the real time back again and we will re-enable this lost feature.

[ambarb]

Asking more about /xpcs/dynamic_mean_window_size. We may need to add it to NXxpcs data after frame_sum and frame_ average.

See #44. @JulReinhardt @AbbyGi @prjemian should I go ahead and create a new issue for this?

[prjemian]

Yes, seems right to create new issue for this.

[ambarb]

will take care of this.