nucl-parquet 0.8.1

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 data to ~/.nucl-parquet/ (first time only)
nucl_parquet.download()

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

Usage

import nucl_parquet

db = nucl_parquet.connect()

# Cross-section query
db.sql("SELECT * FROM tendl_2024 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)
nucl_parquet.elemental_dedx(db, "p", 29, 10.0)     # protons in Cu at 10 MeV
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

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
TENDL-2024	n, p, d, t, ³He, α	IAEA/PSI
TENDL-2025	n, p, d, t, ³He, α	PSI
ENDF/B-VIII.1	n, p, d, t, ³He, α	NNDC/BNL
JEFF-4.0	n, p	NEA
JENDL-5	n, p, d, α	JAEA
CENDL-3.2	n	CIAE
BROND-3.1	n	IPPE
FENDL-3.2	n	IAEA
EAF-2010	n	CCFE
IRDFF-II	n	IAEA
IAEA-Medical	p, d	IAEA
EXFOR	n, p, d, t, ³He, α	IAEA NDS (experimental)
HI-XS (Tripathi 1997)	p, ⁴He, ¹²C, ¹⁶O, ²⁰Ne, ²⁸Si, ⁴⁰Ar, ⁴⁰Ca, ⁵⁶Fe, ⁵⁸Ni, ¹³²Xe, ²⁰⁸Pb	semi-empirical (Tripathi 1997)
HI-XS Production (Geant4 INCL++/ABLA07)	¹²C, ¹⁶O, ²⁰Ne, ²⁸Si, ⁴⁰Ar, ⁵⁶Fe	Geant4 11.3.2 Monte Carlo

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, He3STAR, 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, He3STAR.parquet, and catima_{beam}.parquet for C12/O16/Ne20/Si28/Ar40/Fe56. The full 92×92 CaTiMA matrix (MeV/u units) lives separately at stopping/catima/catima.parquet.

dSTAR, tSTAR, and He3STAR are velocity-scaled from PSTAR/ASTAR — exact for electronic stopping since Z_proj and velocity fully determine dE/dx. For elements not in the NIST table (e.g. Ra, Rn, Ac, Po, Fr, At, Tc, Pm), elemental_dedx() automatically 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)

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

MIT