DAN Two-Layer Retrieval Data Release (Sols 3501–4100)

This repository contains processed Dynamic Albedo of Neutrons (DAN) two-layer retrieval products and supporting summary products for Curiosity observations spanning sols 3501–4100. The release is organized into region-level summary products and per-location retrieval products. File names use a consistent `site / drive / start_sol / stop_sol` convention so that products from different subdirectories can be matched directly. Retrievals are performed on coadds of all observations at a given site/drive, producing one retrieval per location.

Repository structure

2_layer_DAN_sols_3501_4100/
└── retrieval_products/

retrieval_products/

This directory contains the observation-level retrieval products and diagnostics.

retrieval_products/
├── background_subtracted_coadd/
├── coadd_observations/
├── coadd_product/
├── corner_plots/
├── GMMs/
│   ├── unmix_2/
│    │  └── gmm_mix/
│   └── unmix_variable/
│       ├── gmm_mix/
│       └── gmm_selection/
├── MCMC_backend/
├── SNR/
├── times/
└── walker_plots/

Naming convention

Most files share a common stem:

site_<SITE>_drive_<DRIVE>_start_sol_<START>_stop_sol_<STOP>

For example:

site_026_drive_1274_start_sol_542_stop_sol_542
This stem is followed by a product-specific suffix, for example:

- _bg_dat.npy
- _label_matched.txt
- _coadded.npy
- _corner_plot.png
- _gmm_mix.png
- _gmm_selection.png
- _MCMC.h5.zip
- _CETN_SNR.npy
- _CTN_SNR.npy
- _times.npy
- _walker_plot.png

This convention allows all products associated with a given coadded retrieval to be aligned by filename.

Retrieval content

The products in this release correspond to a two-layer retrieval framework. The primary retrieved physical parameters are:

- Bottom Layer WEH: bottom-layer water-equivalent hydrogen, in wt%
- Top Layer WEH: top-layer water-equivalent hydrogen, in wt%
- Bottom Layer Σ_abs: bottom-layer bulk macroscopic neutron absorption cross section (BNACS), in cm^2/g
- Top Layer Σ_abs: top-layer bulk macroscopic neutron absorption cross section (BNACS), in cm^2/g
- Depth: modeled interface depth between the two layers, in cm

Posterior diagnostics may also include an additional logf[counts] fit parameter in the MCMC products.

Observation-level products

Each retrieval generally includes one file in each of the subdirectories below.

background_subtracted_coadd/

Files ending in _bg_dat.npy contain the background-subtracted count data used in retrieval processing.

coadd_observations/

Files ending in _label_matched.txt list the DAN observation label or labels contributing to the coadded retrieval product. These files provide the traceability link between the retrieval and the original contributing observation set.

coadd_product/

Files ending in _coadded.npy contain the coadded observation-space product used as the retrieval input.

corner_plots/

Files ending in _corner_plot.png are posterior diagnostic figures showing parameter distributions and pairwise covariances.

GMMs/

This directory contains Gaussian mixture model post-processing products.

- unmix_2/ contains fixed two-component mixture summaries.
- unmix_variable/ contains variable-component mixture exploration products.

Within these directories:

- gmm_mix/ contains posterior unmixing summary plots.
- gmm_selection/ contains model-selection plots used to compare mixture counts.

These products support interpretation of multimodal posterior structure.

MCMC_backend/

Files ending in _MCMC.h5.zip are compressed HDF5 backends containing the archived MCMC chains. These are the primary reproducibility products for users who want to regenerate posterior summaries, diagnostics, or alternate post-processing results.

SNR/

This directory contains per-observation signal-to-noise products:

- *_CETN_SNR.npy
- *_CTN_SNR.npy

These arrays store time-bin-level SNR values associated with the retrieval input data.

times/

Files ending in _times.npy contain the time-bin definitions associated with the DAN die-away measurement.

walker_plots/

Files ending in _walker_plot.png show the evolution of the MCMC walkers as a function of iteration number and are intended for quality control and convergence assessment.

Recommended use

A typical use pattern is:

1. Start with regional_summaries/ to review region-scale behavior and identify observations of interest.
2. Use coadd_observations/ to trace a retrieval back to the contributing DAN observation labels.
3. Use coadd_product/, background_subtracted_coadd/, SNR/, and times/ for observation-space analysis.
4. Use corner_plots/, walker_plots/, and GMMs/ for posterior interpretation and quality control.
5. Use MCMC_backend/ when full reproducibility or custom post-processing is required.

Acknowledgment

If you use these products in published work, please cite the associated data release and the relevant scientific publications describing the DAN retrieval methodology.