Spectra, utility & cross-run reductions

Steps that finish a binned spectrum (normalize, background-subtract), a utility step to drop keys, and the one reduction that runs across all completed runs. See the step reference overview for the shape vocabulary.

Spectra

normalize_xes

Area-normalize each spectrum so it sums to 1 over a pixel range.

• Reads: spectrum on — 1D (pixels,) or 2D (bins, pixels).
• Writes: <on>_normalized; also <on>_normalized_std when a matching _std key exists.
• Parameters:

name	default	description
on	required	spectrum key (usually _time_binned)
pixel_range	full range	[start, end] pixels the sum is taken over

For 2D input each row (bin) is divided by its own sum; zero-sum rows are left unchanged. If <on> carries a companion _std array, it is scaled by the same factor and written as <on>_normalized_std.

- step: normalize_xes
  on: epix_ROI_1_time_binned
  pixel_range: [100, 400]

subtract_polynomial_background

Fit a polynomial baseline along the spatial axis and subtract it. Non-destructive.

• Reads: spectrum on — 1D (pixels,) or 2D (bins, pixels).
• Writes: <on>_bkgsub; same shape.
• Parameters:

name	default	description
on	required	spectrum key
axis	last	spatial axis to fit along
order	2	polynomial degree
background	None	list of [start, end] signal-free ranges to fit
peak_mask	None	range(s) to EXCLUDE; single [start, end] or a list of ranges

Give either background (the regions to fit) or peak_mask (the regions to skip). peak_mask takes a list of ranges so multiple dispersed lines, e.g. Kalpha and Kbeta on one detector, are masked together. background wins if both are set.

- step: subtract_polynomial_background
  on: epix_ROI_1_time_binned
  order: 2
  peak_mask: [[120, 180], [300, 360]]   # two emission lines

Utility

purge_keys

Set the listed run attributes to None to free memory mid-pipeline.

• Reads: nothing.
• Writes: sets each named attribute to None.
• Parameters:

name	default	description
keys	[]	list of attribute names to drop

- step: purge_keys
  keys: [epix, epix_ROI_1]

Cross-run reduction

combine_runs

A reduction, not a step: runs once after all per-run pipelines finish, summing laser-on and laser-off binned data across runs and returning a results dict.

• Signature: reduction(runs) -> dict (operates on the list of completed runs, not a single run).
• Reads (per run): <detector_key><laser_on_suffix>, <detector_key><laser_off_suffix>, and their _bincount arrays.
• Returns: a dict with laser_on_summed, laser_off_summed, laser_on_count, laser_off_count, and, when all four are present, laser_on_average, laser_off_average, and difference ((on - off) / off).
• Parameters:

name	default	description
detector_key	"epix_ROI_1"	base detector key
laser_on_suffix	"_simultaneous_laser_time_binned"	laser-on data suffix
laser_off_suffix	"_xray_not_laser_time_binned"	laser-off data suffix

Results land in pipe.results under the reduction name.

reduction:
  - step: combine_runs
    detector_key: epix_ROI_1