.. _indra-igor-data-description:
.. _dataDescription:

Igor experiments
================

.. index::
    Indra; USAXS/SAXS/WAXS data description
    Indra; Data naming systems

There are two basic types of measured data — ``USAXS`` and ``QRS`` — which
you need to distinguish when browsing an Igor experiment with reduced data
from this instrument. Irena also recognizes *Irena results* as a data type
produced by its own analysis tools (Size distribution, Unified fit, etc.).

USAXS data type
---------------

.. index::
    Indra; USAXS data type

Regardless of whether Fly scanning or step scanning was used, data will be of
type ``USAXS``. Data are stored in ``root:USAXS``, organized into one folder
per data collection run — for example, ``SampleName_0001``. Inside that folder
you will find many waves, but two groups are of primary importance:

1. ``SMR_Qvec``, ``SMR_Int``, ``SMR_Error`` — Q vector, intensity, and
   uncertainty for **slit-smeared** data. The slit length (typically
   0.025–0.035 Å\ :sup:`−1`) is stored in the wave note. These data are on
   absolute intensity scale when a proper sample thickness was provided during
   data reduction. *Irena* can use these data for modeling, as slit smearing
   is built into the code and is activated automatically when needed.

2. ``DSM_Qvec``, ``DSM_Int``, ``DSM_Error`` — Q vector, intensity, and
   uncertainty for **pinhole (desmeared)** data. These are obtained either by
   desmearing (during or after data reduction using the dedicated tool) or by
   using a 2D-collimated USAXS instrument geometry.

SAXS/WAXS data type
-------------------

.. index::
    Indra; SAXS data type
    Indra; WAXS data type

SAXS and WAXS data are reduced using Nika, which uses the QRS naming
convention. Data are organized in ``root:SAXS`` and ``root:WAXS`` folders,
with one subfolder per data collection run, ideally named to match the
associated USAXS dataset: ``SampleName_0001_xyz``. The ``xyz`` code identifies
the type of data reduction applied:

1. ``270_30`` (SAXS) — Sector average in the 270° direction (vertically down),
   ±30° width. These are pinhole-collimated SAXS data for direct use or for
   merging with ``DSM``-type USAXS data. Generated by default in all data
   reduction runs.

2. ``u`` (SAXS) — Nika-generated pseudo-slit-smeared data using the same slit
   length as the USAXS data. Used exclusively for merging with ``SMR``-type
   USAXS data. Generated only when the "USAXS data not desmeared" checkbox is
   selected on the control panel.

3. ``C`` (WAXS) — Circular average around the beam center over the valid data
   region.

In the :ref:`QRS naming system <QRSdataDescription>`, a folder named
``SampleName_0001_xyz`` contains ``q_SampleName_0001_xyz`` (Q vector),
``r_SampleName_0001_xyz`` (intensity), and ``s_SampleName_0001_xyz``
(uncertainty).

Merged data types
-----------------

.. index::
    Indra; Merged data types

Data merging is performed using the :ref:`Data Merge tool <data_merge>`. After
merging, new folders appear inside the parent folder of the first (left-hand,
low-Q) dataset, using that dataset's type. Naming examples:

* **USAXS + SAXS** → ``root:USAXS:SampleName_0001_mrg`` — USAXS-type data
  (SMR or DSM), extended through the SAXS Q range.
* **USAXS + SAXS + WAXS** → ``root:USAXS:SampleName_0001_mrg_mrg`` — USAXS-type
  data covering approximately 5 decades in Q. Note that such a wide Q range
  typically requires separate analysis approaches for different regions.
* **SAXS + WAXS** → ``root:SAXS:SampleName_0001_270_30_mrg`` — QRS-type data.
  Ensure SAXS is set to "max number of points" before reduction.

Merged USAXS datasets (``_mrg``) are recognized as USAXS-type by Irena and
can be used directly for modeling in either SMR or DSM form.

Export for other tools
----------------------

.. warning::

   Do not export slit-smeared (SMR) data for use in other software tools
   unless you are certain those tools correctly handle the slit-smearing
   geometry used here. Verify compatibility with beamline staff before doing
   so.

Use the :ref:`Export data tool <export_data>` to export ASCII or NeXus/NXcanSAS
for SAS analysis tools, or GSAS xye format for WAXS tools such as GSAS-II.