Save results into nexus format.

[YooSunYoung]

The result of first data reduction step should be saved into nexus format to be fed to the next process.

It can be implemented once #15 is finished.

Required Fields

• Sample name
• Distance from source to sample
• Other source information
• Detector origen(?)
• Fast axes (in beamline frame(?))
• Slow axes (in beamline frame(?))
• Proton charge (?)
• Detector counts (grouped weights/counts, gzip compressed)
• Time bins (in [ms])
• Pixel IDs
• Crystal Rotation

Questions

• Is there anything can be already done in the first reduction step instead...?
• Many fields used to be hard-coded and not straightforward where to retrieve them from the McStas file.
  Should users be able to update them manually some how...?

[YooSunYoung]

Here are more detailed explanations of each field.

• Other source information
  Mostly hardcoded/manually input except for the number of detectors.
  All other information related to each detector should be in a combined list, sorted by the detector ID.)
• Detector origen(?)
  3d vector position of the first pixel from the sample
• Fast axes
  The axis along which pixel IDs grows by the number of pixels in one row (1280)
• Slow axes
  The axis along which pixel IDs grows by 1
• Proton charge
  Number of protons hitting the target within the measurement time frames
  It is proportional to the normalization factor. Normalization is done on the integrated events.
  For simulation data, it doesn't have to be precise, and can be arbitrarily derived by the number of events.
  (Since McStas simulation starts from neutron, not proton.)
• Time bins (in [ms])
  Edges of time binned data.

[YooSunYoung]

The exporting method should work regardless of the data. (whether simulation or measurement.)