nucl-parquet 0.16.0

Nuclear data as Parquet — queryable with DuckDB

nucl-parquet

Nuclear data as Parquet files — cross-sections, stopping powers, decay data, and isotopic abundances from all major evaluated libraries. Queryable with DuckDB, Polars, Pandas, or any Arrow-compatible tool.

Installation

pip install nucl-parquet

The pip package is a thin loader (~50 KB). Data files are either cloned from the git repo or downloaded from GitHub Releases:

import nucl_parquet

# Download the latest data tarball to ~/.nucl-parquet/ (first time only)
nucl_parquet.download()

# Or pin a specific CalVer release
nucl_parquet.download(data_version="2026.05.11")

# Inspect which data version a checkout pins
nucl_parquet.data_version()  # → "2026.05.11"

Or clone the repo directly for the full dataset:

git clone https://github.com/exoma-ch/nucl-parquet.git
export NUCL_PARQUET_DATA=/path/to/nucl-parquet/data

Release scheme — data on CalVer, code on semver

Data tarballs and code packages release on independent cadences. Data refreshes when upstream sources (NIST/Geant4/strata) update — tracked as data-YYYY.MM.DD tags on GitHub. Code releases follow conventional-commit semver via release-please as vX.Y.Z tags. The active data version a checkout pins lives at data/catalog.json::data_version.

Release	Tag form	Trigger	Cadence
Data tarball	data-2026.05.11	manual push of CalVer tag matching catalog.json::data_version	upstream refreshes
Code (PyPI, crates, npm, Go)	v0.14.0	release-please PR merge	conventional-commit semver

Per-package code semver (split MCP from core, etc.) is tracked in #150.

Usage

import nucl_parquet

db = nucl_parquet.connect()

# Cross-section query
db.sql("SELECT * FROM tendl_2023_iso WHERE target_A=63 AND residual_Z=30")

# Compare all libraries
db.sql("SELECT library, energy_MeV, xs_mb FROM xs WHERE target_A=63 AND residual_Z=30")

# Decay chain
db.sql(nucl_parquet.DECAY_CHAIN_SQL, params={"parent_z": 92, "parent_a": 238})

# Stopping power — light ions (NIST PSTAR/ASTAR/ESTAR; catima for ³He)
nucl_parquet.elemental_dedx(db, "p", 29, 10.0)     # protons in Cu at 10 MeV
nucl_parquet.elemental_dedx(db, "a", 29, 5.0)      # α in Cu at 5 MeV (NIST ASTAR)
nucl_parquet.elemental_dedx(db, "e", 29, 1.0)      # electrons in Cu at 1 MeV
nucl_parquet.compound_dedx(db, "p", [(29, 0.5), (30, 0.5)], 10.0)

# Stopping power — heavy ions (CatIMA, any isotope of Z=1-92)
nucl_parquet.elemental_dedx(db, "c12",  6, 12 * 100.0)   # C-12 in C at 100 MeV/u
nucl_parquet.elemental_dedx(db, "pb208", 82, 208 * 50.0)  # Pb-208 in Pb at 50 MeV/u
nucl_parquet.elemental_dedx(db, "xe132", 14, 132 * 50.0)  # Xe-132 in Si at 50 MeV/u

# Heavy-ion total reaction cross-sections (Tripathi 1997)
db.sql("SELECT * FROM hi_xs WHERE target_Z=29 ORDER BY energy_MeV")  # c12 on Cu
db.sql("""
    SELECT energy_MeV, energy_MeV/12 AS energy_MeV_u, xs_mb
    FROM hi_xs WHERE target_Z=6
""")  # c12 on C — typical carbon therapy channel

# Heavy-ion production cross-sections (Geant4 INCL++/ABLA07)
# σ(Zf, Af, E) per residual isotope — 6 projectiles × 92 targets × ~60 energies
db.sql("""
    SELECT residual_Z, residual_A, energy_MeV, xs_mb
    FROM hi_xs_prod
    WHERE target_Z=29 AND library='hi-xs-prod'
    ORDER BY residual_Z, residual_A, energy_MeV
""")  # all C-12 fragmentation products on Cu

# Nuclear structure & decay (v0.11+ — Geant4-derived from strata HF dataset)
db.sql("SELECT * FROM nuclides WHERE Z=43 AND A=99")            # Tc-99g + Tc-99m
db.sql("SELECT * FROM radiation WHERE Z=63 AND A=152 AND state=''")  # Eu-152 lines
db.sql("SELECT * FROM coincidences WHERE Z=27 AND A=60")        # Co-60 cascade pairs
db.sql("SELECT * FROM decay_detailed WHERE Z=43 AND A=99")      # per-shell EC fractions

# Photon-matter interaction (v0.12+ — Geant4 G4EMLOW8.8)
db.sql("SELECT * FROM photon_pe WHERE Z=82 AND shell=0")        # Pb K-shell σ_PE(E)
db.sql("SELECT * FROM photon_compton WHERE Z=29")               # Cu Compton σ(E)
db.sql("SELECT * FROM photon_pair WHERE Z=82 AND channel='total'")  # Pb pair σ(E)
db.sql("SELECT * FROM photon_rayleigh_cdf WHERE Z=82")          # angular sampling CDF
db.sql("SELECT * FROM atomic_relaxation WHERE Z=53 AND vacancy_shell='K'")  # I K-vacancy
db.sql("SELECT * FROM fluorescence WHERE Z=82")                 # Pb fluorescence yields

# Electron-matter interaction (v0.13+ — Geant4 G4EMLOW8.8)
db.sql("SELECT * FROM electron_brem WHERE Z=82")                # Pb bremsstrahlung σ_brem(E)

# NUDEX detailed nuclear data (v0.14+ — Geant4 G4NUDEXLIB1.0)
db.sql("SELECT * FROM nudex_levels WHERE Z=27 AND A=60")        # Co-60 full level scheme
db.sql("SELECT * FROM nudex_level_gammas WHERE Z=82 AND A=208") # Pb-208 transitions
db.sql("SELECT * FROM capture_gammas WHERE Z=27 AND A=60")      # 59Co(n,γ)60Co primaries
db.sql("SELECT * FROM icc_factors WHERE Z=82 AND shell='K'")    # Pb K-shell BrIcc
db.sql("SELECT * FROM psf_e1 WHERE Z=82 AND A=208")             # Pb-208 SMLO E1 GDR
db.sql("SELECT * FROM level_density_bfm WHERE Z=82 AND A=208")  # Pb-208 BFM params

Data resolution

connect() finds data in this order:

1. Explicit data_dir argument
2. $NUCL_PARQUET_DATA environment variable
3. Sibling repo checkout (when running from source)
4. ~/.nucl-parquet/ (downloaded via nucl_parquet.download())

Why Parquet instead of ENDF-6?

The ENDF-6 format dates from the 1960s. It was designed for Fortran on punch cards: 80-character fixed-width records, implicit column positions, and a cryptic MF/MT numbering system.

	ENDF-6	Parquet
Format	Fixed-width Fortran text, 80-char cards	Columnar binary, self-describing schema
Parsers needed	Specialized (NJOY, PREPRO, FUDGE, endf pkg)	Any language — Python, R, Julia, Rust, JS, SQL
Random access	Sequential parse from start	Predicate pushdown, skip irrelevant row groups
Compression	None (or gzip'd text)	zstd columnar compression (5-10x smaller)
Cross-library comparison	Convert each library separately first	SELECT * FROM '*/xs/p_Cu.parquet'
Browser/WASM	Not feasible	Works natively (DuckDB-WASM, Pyodide)

Size comparison for the same data:

Library	ENDF-6 (zipped)	Parquet (zstd)	Reduction
TENDL-2025 neutron	~800 MB (2850 zip files)	25 MB	32x
ENDF/B-VIII.1 (all)	~120 MB	4.3 MB	28x
JENDL-5 (all)	~200 MB	8.6 MB	23x

Libraries included

Library	Projectiles	Source
BROND-3.1	n	IPPE
CENDL-3.2	n	CIAE
ENDF/B-VIII.1	n, p, d, t, ³He, α	NNDC/BNL
EXFOR	n, p, d, t, ³He, α	IAEA NDS
FENDL-3.2	n	IAEA
HI-XS (Tripathi 1997)	ar40, c12, ca40, fe56, he4, ne20, ni58, o16, p, pb208, si28, xe132
HI-XS Production (Geant4 INCL++/ABLA07)	c12, o16, ne20, si28, ar40, fe56
IAEA-Medical	p, d, ³He, α	IAEA
IAEA-PD-2019	γ	IAEA
IRDFF-II	n	IAEA
JEFF-4.0	n, p	NEA
JENDL-5	n, p, d, α	JAEA
JENDL-DEU-2020	d	JAEA
JENDL/AD-2017	n, p	JAEA
TENDL-2023 + Aug 2024 isomeric correction	p, d, t, ³He, α
TENDL-2025	n, p, d, t, ³He, α	PSI

Parquet schemas

Evaluated cross-sections ({library}/xs/*.parquet):

Column	Type	Description
target_A	Int32	Target mass number
residual_Z	Int32	Product atomic number
residual_A	Int32	Product mass number
state	Utf8	Isomer state: "", "g", "m"
energy_MeV	Float64	Projectile energy in MeV
xs_mb	Float64	Cross-section in millibarn

EXFOR experimental (exfor/*.parquet):

Column	Type	Description
exfor_entry	Utf8	EXFOR accession number
target_Z	Int32	Target atomic number
target_A	Int32	Target mass number (0 = natural)
residual_Z	Int32	Product atomic number
residual_A	Int32	Product mass number
state	Utf8	Isomer state
energy_MeV	Float64	Projectile energy in MeV
energy_err_MeV	Float64	Energy uncertainty (nullable)
xs_mb	Float64	Cross-section in millibarn
xs_err_mb	Float64	Cross-section uncertainty (nullable)
author	Utf8	First author
year	Int32	Publication year

Stopping powers (stopping/{source}.parquet — one file per source):

Column	Type	Description
source	Utf8	PSTAR, ASTAR, ESTAR, dSTAR, tSTAR, catima_C12, …
target_Z	Int32	Target element Z (1–92)
energy_MeV	Float64	Projectile kinetic energy (MeV, total)
dedx	Float64	Mass stopping power (MeV cm²/g)

Files: PSTAR.parquet, ASTAR.parquet, ESTAR.parquet, dSTAR.parquet, tSTAR.parquet, and the federated CaTiMA heavy-ion shards catima_<Sym><A>.parquet — one per beam isotope (≈399 files spanning every Z=1–99 isotope in the inventory, each covering all 92 targets), build-generated by build_heavy_ions.py. Each shard carries both energy_MeV_u (per-nucleon) and energy_MeV (total) so it is queryable as an isotope table or as a NIST-style source. The former single 92×92 monolith was removed in favour of the shards (#252).

PSTAR and ASTAR are reproducible from NIST CGI via uv run python -m nucl_parquet.build_stopping. ESTAR is rebuilt from the strata-data em/estar_long.parquet upstream via uv run python -m nucl_parquet.build_em_stopping (which also emits the richer stopping/em/electron_stopping.parquet and stopping/em/density_effect_params.parquet; see "Electron-matter tables" below). dSTAR and tSTAR are velocity-scaled from PSTAR (exact, same Z=1, just relabel energy axis) by build_light_ions.py. ³He has no published NIST table; α and ³He earlier shipped via wrong-by-4× files that have been removed (#137) — α now uses NIST ASTAR (ICRU-49 reference), ³He uses CaTiMA. NIST PSTAR/ASTAR only publish 25 elemental targets; for elements outside that list (e.g. Tc, Pm, Po, Rn), elemental_dedx() falls back to CaTiMA (Bethe-Bloch), which covers all Z=1–92.

Heavy-ion total reaction cross-sections (hi-xs/xs/{proj}_{target}.parquet):

Tripathi (1997) semi-empirical parameterization — total reaction cross-sections for all 12 projectiles against all 92 target elements. Energy stored as total MeV for the projectile; 1–1000 MeV/u range, 60 log-spaced points.

Column	Type	Description
target_Z	Int32	Target atomic number (1–92)
target_A	Int32	Target mass number (most-abundant stable isotope)
energy_MeV	Float64	Total projectile kinetic energy (MeV)
xs_mb	Float64	Total reaction cross-section (mb)

Heavy-ion production cross-sections (hi-xs-prod/xs/{proj}_{target}.parquet):

Geant4 11.3.2 FTFP_INCLXX physics list (INCL++ cascade + ABLA07 de-excitation) — per-isotope fragment production cross-sections σ(Zf,Af,E) in mb, normalized to Tripathi (1997) σ_R. Covers C-12, O-16, Ne-20, Si-28, Ar-40, Fe-56 projectiles against all 92 target elements, ~60 log-spaced energy points from 1–1000 MeV/u.

Column	Type	Description
proj_Z	Int32	Projectile atomic number
proj_A	Int32	Projectile mass number
target_Z	Int32	Target atomic number (1–92)
target_A	Int32	Target mass number (most-abundant stable isotope)
residual_Z	Int32	Fragment atomic number
residual_A	Int32	Fragment mass number
energy_MeV	Float64	Mean actual reaction vertex energy (MeV total)
xs_mb	Float64	Production cross-section (mb)

Heavy-ion stopping powers (stopping/catima.parquet):

Full 92×92 matrix — all projectile elements Z=1–92 against all target elements Z=1–92, computed with CatIMA. Energy stored in MeV/u; isotope-independent (divide total MeV by A to look up).

Column	Type	Description
proj_Z	Int32	Projectile atomic number (1–92)
target_Z	Int32	Target atomic number (1–92)
energy_MeV_u	Float64	Kinetic energy per nucleon (MeV/u)
dedx	Float64	Mass stopping power (MeV cm²/g)

Nuclear structure & decay (v0.11+, Geant4-derived)

Sourced from the strata project's HuggingFace dataset, which republishes G4ENSDFSTATE3.0 + PhotonEvaporation6.1.2 + RadioactiveDecay6.1.2 as Parquet. Replaces the v0.10.x IAEA-LiveChart pipeline; six bug classes eliminated by construction (see ADR-0002). Stable isotopes ship half_life_s = +inf (use is_finite(half_life_s) to test).

View	Source	What's in it
nuclides	meta/ensdf/nuclides.parquet	All known states (ground + isomers) with half-life, J^π, decay modes, AME2020 mass excess, IUPAC composition
ground_states	nuclides WHERE state = ''	Compatibility view
decay / decay_detailed	meta/decay{,_detailed}.parquet	Decay branches per (Z, A, state). decay_detailed adds parent_ex_kev, daughter_ex_kev, q_value_kev, forbiddenness, and per-shell EC fractions (KshellEC/LshellEC/MshellEC/NshellEC)
radiation	meta/ensdf/radiation/{Symbol}.parquet	Per-element gamma + X-ray + Auger lines, unioned by rad_type discriminator
coincidences	meta/ensdf/coincidences/{Symbol}.parquet	Gamma cascade pairs (~600k pairs, 104 element files)
summing_partners	meta/ensdf/summing_partners/{Symbol}.parquet	ICC-corrected summing partners for HPGe TCS corrections
emissions	meta/ensdf/emissions/{Symbol}.parquet	Absolute per-decay emission intensities (NuDat-equivalent, parent-keyed)
beta_spectra	meta/ensdf/beta_spectra/{Symbol}.parquet	Continuous beta-decay kinetic-energy spectra (dN/dE, 200 bins)
levels	meta/ensdf/levels/{Symbol}.parquet	Excited-state level schemes
dose_constants	meta/dose_constants.parquet	Dose rate constants (Sv/h per Bq at 1 m)

Photon-matter interaction (v0.12+, G4EMLOW8.8)

Per-process cross-sections + sampling kernels for "photon hits material" queries. Lets users break down xcom's integrated µ/ρ into the dominant processes (PE / Compton / Rayleigh / pair / atomic relaxation). All views live under data/em/; epic #95.

View	Process	Use case
photon_pe	Photoelectric per-shell σ	"After K-shell ionization in iodine at 33 keV…"
photon_pe_high_z_params	Analytic fit coefficients	High-Z extrapolation near edges
photon_pe_angular	Photoelectron emission angle kernel	Monte Carlo angular sampling
photon_compton	Compton σ_C(E, Z)	Bound-electron Klein-Nishina total
compton_scattering_function	S(x, Z)	Differential dσ/dΩ via S(x,Z) × Klein-Nishina
compton_doppler_profiles	Per-shell f(p)	Doppler broadening of scattered energy
photon_rayleigh_cdf	Coherent-scattering CDF	Inverse-CDF angular sampling
xray_form_factor	Anomalous f1, f2 (Henke/CXRO)	Low-energy Rayleigh corrections
photon_pair	Pair + triplet σ	Per-channel breakdown above 1.022 MeV (channel ∈ {nuclear, triplet, total})
atomic_relaxation	Full vacancy cascade	Radiative + Auger transitions per shell
fluorescence	Radiative subset	K_α / K_β / L_α yields per Z

Worked example — "what fraction of 511 keV photons in lead Compton-scatter vs photoelectric-absorb?"

WITH pe_total AS (
    SELECT Z, energy_MeV, SUM(sigma_b) AS sigma_pe
      FROM photon_pe
     WHERE Z = 82 AND ABS(energy_MeV - 0.511) < 1e-3
     GROUP BY Z, energy_MeV
)
SELECT 'PE' AS process, sigma_pe AS sigma_b FROM pe_total
UNION ALL
SELECT 'Compton', sigma_b FROM photon_compton
 WHERE Z = 82 AND ABS(energy_MeV - 0.511) < 1e-3;

Electron-matter interaction (v0.13+, G4EMLOW8.8)

Per-process electron transport cross-sections — companion to the v0.12 photon-matter views. Epic #114 tracks the full electron-matter rollout (bremsstrahlung shipped; Seltzer-Berger DCS, MSC, DPWA, ESTAR migration in progress).

View	Process	Use case
electron_brem	Bremsstrahlung total σ_brem(Z, T)	Photon-emission rate from electron transport

Detailed nuclear data — NUDEX (v0.14+, G4NUDEXLIB1.0)

Where nuclides / radiation / coincidences ship the summary G4 PhotonEvaporation tables, the NUDEX views below import the fully-detailed ENSDF source — every known nuclear level, every measured gamma transition, full BrIcc internal-conversion tables, neutron-capture primary spectra, photon strength functions, and statistical-model level density parameters. Epic #115 (5/5 sub-issues complete).

View	Rows	What's in it
nudex_levels	158,900	Per-level: energy, J^π, half-life, decay modes (3,331 isotopes)
nudex_level_gammas	245,975	Per-transition: source/dest level, γ energy, intensity, uncertainty
nudex_isotopes	3,331	Per-isotope summary: level/gamma counts, mass excess, S_n
capture_gammas	39,157	Neutron-capture primary γ spectra (PGAA / activation analysis)
capture_gammas_summary	982	Per (target, daughter): reaction, S_n, multiplicity
icc_factors	579,380	Per-shell BrIcc factors (35 shells × 10 multipolarities × 117 Z)
psf_e1	8,980	IAEA SMLO E1 (recommended modern default)
psf_gdr_lor / mlo / slo	145 / 178 / 180	Experimental GDR Lorentzian / Modified-Lorentzian / Standard-Lorentzian
psf_gdr_theor	5,986	Goriely theoretical PSF systematics
psf_photonuclear	1,912	Photonuclear (γ,abs)/(γ,sn)/(γ,xn) experimental peaks
level_density_bfm	289	Back-shifted Fermi-gas effective parameters
level_density_ctm	289	Constant-temperature effective parameters
level_density_params	3,353	Per-nuclide T, U_cutoff, N_levels

Schema overlap with v0.11: nudex_levels and ensdf_levels coexist by design. Use ensdf_levels for transport-aligned queries (matches G4's bundled level set); use nudex_levels for high-fidelity gamma spectroscopy and statistical decay calculations.

Worked example — "predict the prompt-gamma signature of a neutron-irradiated Co-59 sample"

SELECT energy_keV, intensity_pct
  FROM capture_gammas
 WHERE Z = 27 AND A = 60 AND variant = 'default'
 ORDER BY intensity_pct DESC
 LIMIT 10;

All registered views

The complete inventory of DuckDB views registered by nucl_parquet.connect(). All views are declared in catalog.json::views — adding a new data table to the catalog makes it queryable with zero code changes across all clients (Python, TypeScript, Rust).

View	Path	Type
abundances	meta/abundances.parquet	file
astar_compounds	stopping/compounds/ASTAR_compounds.parquet	file
atomic_relaxation	meta/eadl/*.parquet	glob
beta_spectra	meta/ensdf/beta_spectra/*.parquet	glob
capture_gammas	meta/capture_gammas.parquet	file
capture_gammas_summary	meta/capture_gammas_summary.parquet	file
catima_stopping	stopping/catima_*.parquet	glob
coincidences	meta/ensdf/coincidences/*.parquet	glob
compound_compositions	meta/compound_compositions.parquet	file
compton_doppler_profiles	em/compton_doppler_profiles.parquet	file
compton_scattering_function	em/compton_scattering_function.parquet	file
decay	meta/decay.parquet	file
decay_detailed	meta/decay_detailed.parquet	file
density_effect_params	stopping/em/density_effect_params.parquet	file
dose_constants	meta/dose_constants.parquet	file
eedl_electron_xs	meta/eedl/*.parquet	glob
electron_brem	em/electron_brem.parquet	file
electron_brem_sb_dcs	em/electron_brem_sb_dcs.parquet	file
electron_stopping	stopping/em/electron_stopping.parquet	file
elements	meta/elements.parquet	file
emissions	meta/ensdf/emissions/*.parquet	glob
ensdf_gammas	meta/ensdf/gammas/*.parquet	glob
ensdf_levels	meta/ensdf/levels/*.parquet	glob
epdl_anomalous	meta/epdl97/anomalous/*.parquet	glob
epdl_form_factors	meta/epdl97/form_factors/*.parquet	glob
epdl_photon_xs	meta/epdl97/photon_xs/*.parquet	glob
epdl_scattering_fn	meta/epdl97/scattering_fn/*.parquet	glob
epdl_subshell_pe	meta/epdl97/subshell_pe/*.parquet	glob
ground_states	meta/ensdf/ground_states.parquet	file
icc_factors	meta/icc_factors.parquet	file
kerma	meta/kerma/*.parquet	glob
level_density_bfm	meta/level_density_bfm.parquet	file
level_density_ctm	meta/level_density_ctm.parquet	file
level_density_params	meta/level_density_params.parquet	file
neutron_total	meta/neutron_total/*.parquet	glob
nuclides	meta/ensdf/nuclides.parquet	file
nudex_general_stat	meta/nudex_general_stat.parquet	file
nudex_isotopes	meta/nudex_isotopes.parquet	file
nudex_level_gammas	meta/nudex_level_gammas.parquet	file
nudex_levels	meta/nudex_levels.parquet	file
nudex_shellcor	meta/nudex_shellcor.parquet	file
nudex_special_inputs	meta/nudex_special_inputs.parquet	file
photon_compton	em/photon_compton.parquet	file
photon_pair	em/photon_pair.parquet	file
photon_pe	em/photon_pe.parquet	file
photon_pe_angular	em/photon_pe_angular.parquet	file
photon_pe_high_z_params	em/photon_pe_high_z_params.parquet	file
photon_pe_total	em/photon_pe_total.parquet	file
photon_rayleigh_cdf	em/photon_rayleigh_cdf.parquet	file
psf_e1	meta/psf_e1.parquet	file
psf_gdr_lor	meta/psf_gdr_lor.parquet	file
psf_gdr_mlo	meta/psf_gdr_mlo.parquet	file
psf_gdr_slo	meta/psf_gdr_slo.parquet	file
psf_gdr_theor	meta/psf_gdr_theor.parquet	file
psf_photonuclear	meta/psf_photonuclear.parquet	file
pstar_compounds	stopping/compounds/PSTAR_compounds.parquet	file
radiation	meta/ensdf/radiation/*.parquet	glob
spectrum_xs	meta/spectrum_xs.parquet	file
stopping	stopping/*.parquet	glob
summing_partners	meta/ensdf/summing_partners/*.parquet	glob
xcom_compounds	meta/xcom_compounds.parquet	file
xcom_elements	meta/xcom_elements.parquet	file
xray_form_factor	em/xray_form_factor.parquet	file
xs	union of all XS libraries	derived
ground_states	filtered from nuclides	derived
eadl_transitions	alias for atomic_relaxation	derived
fluorescence	filtered from atomic_relaxation	derived

MCP servers

Three MCP servers expose nucl-parquet data to AI assistants:

Client	Language	Registration
clients/py/nucl-parquet-mcp	Python (DuckDB)	catalog-driven
clients/ts/nucl-parquet-mcp	TypeScript (DuckDB)	catalog-driven
clients/rs/nucl-parquet-mcp	Rust (ParquetStore)	catalog-driven

All three read catalog.json::views for view registration and catalog.json::libraries for cross-section libraries. The Rust MCP uses the ParquetStore from the nucl-parquet client crate for zero-dependency Parquet I/O.

Development

# Install dev dependencies
uv sync --dev

# Run unit tests (no data needed)
uv run pytest tests/test_loader.py -v

# Run full test suite (requires data)
uv run pytest tests/ -v

License & data attribution

Code & conversion: MIT (see LICENSE).

Bundled nuclear data: third-party — MIT does not apply to it. Each library keeps its own terms and required citation; see ATTRIBUTION.md (machine-readable in data/licenses.toml) and the NOTICE. The data is provided as-is — see DISCLAIMER.md.