{
  "source": "NIST PSTAR online calculator, Polyethylene preset (material 221), default energy grid",
  "source_url": "https://physics.nist.gov/PhysRefData/Star/Text/PSTAR.html",
  "query_date": "2026-09-29",
  "source_text_file": "nist-pstar-polyethylene-source.txt",
  "source_text_sha256": "eb32beabac16946666202fcb6c65a974b0a79e1255bfd4babf97f04b5d3d9d21",
  "n_rows": 133,
  "plotted_column": "RANGE(p), projected range in g/cm\u00b2",
  "density_g_cm3": 0.94,
  "conversion": "equivalent depth in cm = projected areal range (g/cm\u00b2) / 0.94 g/cm\u00b3",
  "NASA_comparison": "NASA/TP-2020-220514, printed p.4, footnote 7; report figure 4 separately attributes its curve to SRIM/Nikezic et al. (2016). The four printed footnote values are preserved separately from NIST values.",
  "limits": [
    "A mean projected range is not a sharp stopping boundary or shield thickness recommendation.",
    "No particle fluence, mixed space spectrum, secondary-particle transport, dose, dose equivalent, biological effect, spacecraft geometry, or shielding performance is calculated.",
    "NIST and NASA report are model/text comparisons, not a new measurement."
  ]
}