# Attenuator plate correction

## Summary
Apply angle-dependent attenuator plate transmission.

## Metadata
- **Module ID:** AttenuatorPlateCorrection
- **Module path:** /home/runner/work/MoDaCor/MoDaCor/src/modacor/modules/technique_modules/scattering/attenuator_plate_correction.py
- **Module version:** 20260902.1
- **Keywords:** attenuator, plate, attenuation, absorption, transmission

## Required data keys
- signal
- CosAlpha

## Modifies
- **signal**: signal, uncertainties

## Required arguments
- with_processing_keys

## Default configuration
```json
{
  "apply_as": "divide",
  "beam_energy": null,
  "beam_energy_source": null,
  "beam_energy_units": "keV",
  "beam_energy_units_source": null,
  "chemical_composition": null,
  "chemical_composition_source": null,
  "correction_key": "attenuator_transmission",
  "cos_alpha_key": "CosAlpha",
  "density": null,
  "density_source": null,
  "density_units": "g/cm^3",
  "density_units_source": null,
  "linear_attenuation_coefficient": null,
  "linear_attenuation_coefficient_source": null,
  "linear_attenuation_coefficient_units": "1/m",
  "linear_attenuation_coefficient_units_source": null,
  "material": null,
  "material_source": null,
  "minimum_cos_alpha": 1e-12,
  "normalize_to_normal_incidence": false,
  "thickness": null,
  "thickness_source": null,
  "thickness_units": "m",
  "thickness_units_source": null,
  "wavelength": null,
  "wavelength_source": null,
  "wavelength_units": "angstrom",
  "wavelength_units_source": null,
  "with_processing_keys": [
    "sample"
  ]
}
```

## Argument specification
| Argument | Type | Required | Default | Dependency role | Description |
|---|---|---|---|---|---|
| `apply_as` | str | No | divide | - | Apply the transmission map by 'divide' for correction or 'multiply' for DAWN-style attenuation. |
| `beam_energy` | int or float or NoneType | No | - | - | Incident beam energy. |
| `beam_energy_source` | str or NoneType | No | - | - | Optional IoSources key for incident beam energy. |
| `beam_energy_units` | str | No | keV | - | Units for beam_energy. |
| `beam_energy_units_source` | str or NoneType | No | - | - | Optional IoSources key for beam energy units. |
| `chemical_composition` | str or NoneType | No | - | - | Alias for material. |
| `chemical_composition_source` | str or NoneType | No | - | - | Optional IoSources key for chemical_composition. |
| `correction_key` | str | No | attenuator_transmission | - | BaseData key used to store the applied transmission map. |
| `cos_alpha_key` | str | No | CosAlpha | - | BaseData key containing the incidence cosine n dot rhat. |
| `density` | int or float or NoneType | No | - | - | Attenuator material density. |
| `density_source` | str or NoneType | No | - | - | Optional IoSources key for attenuator density. |
| `density_units` | str | No | g/cm^3 | - | Units for density. |
| `density_units_source` | str or NoneType | No | - | - | Optional IoSources key for density units. |
| `linear_attenuation_coefficient` | int or float or NoneType | No | - | - | Optional direct linear attenuation coefficient. |
| `linear_attenuation_coefficient_source` | str or NoneType | No | - | - | Optional IoSources key for a direct linear attenuation coefficient. |
| `linear_attenuation_coefficient_units` | str | No | 1/m | - | Units for linear_attenuation_coefficient. |
| `linear_attenuation_coefficient_units_source` | str or NoneType | No | - | - | Optional IoSources key for linear attenuation coefficient units. |
| `material` | str or NoneType | No | - | - | Attenuator material formula or element symbol, used with xraylib lookup. |
| `material_source` | str or NoneType | No | - | - | Optional IoSources key for attenuator material formula or element symbol. |
| `minimum_cos_alpha` | int or float | No | 1e-12 | - | Lower numerical clip for positive cos_alpha values. |
| `normalize_to_normal_incidence` | bool | No | False | - | If true, divide by transmission(cos_alpha) / transmission(cos_alpha=1). |
| `thickness` | int or float or NoneType | No | - | - | Attenuator thickness. |
| `thickness_source` | str or NoneType | No | - | - | Optional IoSources key for attenuator thickness. |
| `thickness_units` | str | No | m | - | Units for thickness. |
| `thickness_units_source` | str or NoneType | No | - | - | Optional IoSources key for thickness units. |
| `wavelength` | int or float or NoneType | No | - | - | Incident wavelength, used to derive beam energy if beam_energy is not configured. |
| `wavelength_source` | str or NoneType | No | - | - | Optional IoSources key for incident wavelength. |
| `wavelength_units` | str | No | angstrom | - | Units for wavelength. |
| `wavelength_units_source` | str or NoneType | No | - | - | Optional IoSources key for wavelength units. |
| `with_processing_keys` | list | Yes | ["sample"] | - | ProcessingData keys whose signal should be corrected. |

## Notes
Material parameters can be provided as direct values or *_source paths. xraylib is used for material lookup unless linear_attenuation_coefficient is configured directly. The default applies a physical correction by dividing by transmission; apply_as='multiply' is provided for DAWN cross-validation where the recorded operation applies the attenuation factor itself.