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Time-Resolved EIS Data Processing

Tools to correlate EIS (Electrochemical Impedance Spectroscopy) timing with neutron scattering event data.

Overview

The workflow is designed to be run in two stages:

  1. Extract EIS intervals (can run on any machine)
  2. Filter/reduce neutron events (must run on Mantid cluster)

Data Format

EIS files (.mpt) are EC-Lab ASCII format with:

  • Header containing Acquisition started on : MM/DD/YYYY HH:MM:SS.fff
  • Tab-separated data with time/s column for elapsed time

Step 1: Extract EIS Intervals

Use eis-intervals to extract timing from EIS files into JSON:

eis-intervals --data-dir /path/to/eis/data --output intervals.json

This produces:

{
  "source_directory": "/path/to/eis/data",
  "n_intervals": 9,
  "intervals": [
    {
      "filename": "sequence_1_..._PEIS_C02_1.mpt",
      "start": "2025-04-20T10:55:16.521000",
      "end": "2025-04-20T11:05:06.361862",
      "duration_seconds": 589.84
    },
    ...
  ]
}

Options

Option Description
--data-dir Directory containing EIS .mpt files (required)
--pattern Glob pattern to match files (default: *C02_?.mpt)
--exclude Exclude files containing this string (default: fit)
--output Output JSON file path (prints to stdout if not specified)
--quiet Suppress progress messages

Step 2: Process on Mantid Cluster

Copy intervals.json and the scripts from scripts/mantid/ to the cluster.

Option A: Filter Events Only

python eis_filter_events.py \
    --intervals intervals.json \
    --event-file /SNS/REF_L/IPTS-XXXXX/nexus/REF_L_12345.nxs.h5 \
    --output-dir ./filtered_events

Outputs:

  • One NeXus file per EIS interval

Option B: Filter + Reduce

python eis_reduce_events.py \
    --intervals intervals.json \
    --event-file /SNS/REF_L/IPTS-XXXXX/nexus/REF_L_12345.nxs.h5 \
    --template /SNS/REF_L/IPTS-XXXXX/shared/templates/template.xml \
    --output-dir ./reduced_data

Outputs:

  • Reflectivity text files (Q, R, dR, dQ) per interval
  • Summary plot (*_eis_summary.png)
  • Reduction metadata JSON

Complete Example

# On your local machine (with EIS data access)
eis-intervals \
    --data-dir /Users/m2d/data/expt11/ec-data \
    --output intervals.json

# Copy to Mantid cluster, then run:
python eis_reduce_events.py \
    --intervals intervals.json \
    --event-file /SNS/REF_L/IPTS-34347/nexus/REF_L_218281.nxs.h5 \
    --template /SNS/REF_L/IPTS-34347/shared/templates/expt11.xml \
    --output-dir ./expt11_reduced

Files

File Location Description
eis_interval_extractor.py analyzer_tools/ Extracts intervals → JSON
eis_filter_events.py scripts/mantid/ Mantid script for filtering
eis_reduce_events.py scripts/mantid/ Mantid script for reduction

Resolution Modes

The eis-intervals tool supports two resolution modes:

Per-File (Default)

One interval per EIS file - good for reduction workflows:

eis-intervals --data-dir /path/to/eis/data --resolution per-file

Per-Frequency

One interval per frequency measurement - for detailed analysis:

eis-intervals --data-dir /path/to/eis/data --resolution per-frequency