Shielding (narrow-beam)
Exponential narrow-beam layer: T = exp(−μx). Tabulated μ values in bundled data are illustrative unless you replace them with sourced coefficients (for example NIST XCOM).
Not modeled here
Buildup factors, scatter, broad-beam geometry, workload, occupancy factor, use factor, skyshine, leakage paths, and full structural shielding design are not modeled in this release.
Shielding data audit
Transparency for the μ value driving this page (narrow-beam model only).
- Material
- Lead
- μ source
- tabulated
- Coefficient match method
- Nearest within tolerance (tabulated)
- Requested energy
- 662 keV
- Match tolerance
- ±40 keV
- Matched coefficient energy
- 662 keV
- Energy delta (matched − requested)
- 0.0 keV
- Reference id
- nist-xcom
- Coefficient notes
- For facility work, replace with spectrum-integrated or measured μ from qualified data.
- Provenance note
- Illustrative value near common Cs-137 gamma energies; does not include buildup, scatter, or broad-beam factors. Cross-check with NIST XCOM (nist-xcom) for the lead thickness and energy grid you use.
- Confidence
- Illustrative
Bundled μ is illustrative or placeholder relative to authoritative databases—verify coefficients before any safety-significant use.
Coefficient selection (no interpolation)
- The nearest tabulated coefficient within your selected energy tolerance is used when not using custom μ.
- No energy interpolation is currently performed between tabulated points.
- If you need a precise energy-specific μ, enter μ manually with custom μ enabled and document the basis in the override fields.
Optional: nuclide photon-energy hints (documentation)
Selecting a catalog nuclide does not change μ or material tables. Use the buttons to copy tabulated photon energies into the nominal energy field above when convenient.
Brachytherapy (historical)
Catalog id: cs-137
- Half-life (bundled row)
- 30.17 y
- Decay modes
- β⁻ (Ba-137m), γ
- Photon energies (keV)
- 662
- Gamma constant (µSv·m²/MBq·h)
- 0.08
- Gamma constant confidence / provenance
- IllustrativeScreening air-kerma-rate style constant (µSv·m²/MBq·h) bundled for training; verify against your approved reference table or measurement certificate.
Used to pick nearest tabulated μ when not using custom μ.
Coefficient row must be within ± this value of nominal energy.
Lead
Match method: Nearest tabulated row within tolerance
μ source: tabulated row at 662 keV (nearest within ±40 keV).
- HVL
- 0.602737 cm
- TVL
- 2.00225 cm
- μ used
- 1.15000 1/cm
- Nominal energy
- 662 keV
μ confidence:Illustrative
Illustrative value near common Cs-137 gamma energies; does not include buildup, scatter, or broad-beam factors. Cross-check with NIST XCOM (nist-xcom) for the lead thickness and energy grid you use.
Coefficient reference id: nist-xcom
Row notes: For facility work, replace with spectrum-integrated or measured μ from qualified data.
Energy match delta: 0.0 keV (tabulated row vs nominal)
Illustrative or placeholder confidence: bundled μ is not a substitute for spectrum-specific values from NIST XCOM or qualified measurements.
Density: 11.34 g/cm³
Typical uses
- Gamma shielding
- collimators
- storage containers
Coefficients are not validated for your beam quality; buildup and scatter are not modeled.
Follows material + energy selection unless you enable custom μ.
Material coefficient rows (read-only)
All bundled rows for Lead. The active row for calculations depends on nominal energy, tolerance, and whether custom μ is enabled.
| Energy (keV) | μ (1/cm) | Confidence | Reference id | Notes | Provenance |
|---|---|---|---|---|---|
| 80 | 2.1 | Illustrative | nist-xcom | Not extracted from XCOM line-by-line; confidence remains illustrative. | Illustrative screening μ for lead near low-energy photons; order-of-magnitude only—verify against NIST XCOM (nist-xcom) or measurement for your spectrum and geometry. |
| 662 | 1.15 | Illustrative | nist-xcom | For facility work, replace with spectrum-integrated or measured μ from qualified data. | Illustrative value near common Cs-137 gamma energies; does not include buildup, scatter, or broad-beam factors. Cross-check with NIST XCOM (nist-xcom) for the lead thickness and energy grid you use. |
| 1250 | 0.52 | Illustrative | nist-xcom | Labeled illustrative; numeric μ is not a certified design input. | Illustrative higher-energy screening value; self-filtration and spectral hardening are not modeled. Compare trend only to NIST XCOM (nist-xcom), not an endorsement of this numeric μ. |
Target transmission → thickness
Solve x = −ln(T)/μ for narrow-beam T strictly between 0 and 1.
Required thickness: 2.00225 cm
- Solve x = -ln(T)/μ for narrow-beam transmission T.
Target dose rate → thickness
Solve x = ln(I₀/Iₜarget)/μ after converting both rates to µSv/h. Requires initial dose rate greater than target.
Required thickness: 2.00225 cm
- Convert dose rates to µSv/h.
- Solve x = ln(I0 / Itarget) / μ for narrow-beam attenuation.
Results
0.356346uSv/h
- Transmission
- 17.82%
- Percent reduction
- 82.18%
- HVL
- 0.602737 cm
- TVL
- 2.00225 cm
I = I0 * exp(-mu * x); HVL = ln(2)/mu; TVL = ln(10)/mu
Chart shows shielded dose rate and transmission versus thickness for the current initial dose rate and μ. Vertical dashed lines mark HVL, TVL, and target-thickness solutions when they fall within the plotted range.
Dose rate and transmission vs thickness
No chart data for current inputs.
Vertical markers (when within chart range): HVL/TVL and optional target-thickness solutions.
Material comparison (tabulated μ only)
Rows appear only when a material has a coefficient within ±40 keV of 662 keV. Others are omitted until you widen tolerance, change energy, or add sourced rows to materials.json.
| Material | μ (1/cm) | E req (keV) | E match (keV) | ΔE (keV) | Ref id | HVL (cm) | TVL (cm) | x @ 10% T | x @ 1% T | Conf. | Source / notes |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Lead | 1.1500 | 662 | 662 | 0.0 | nist-xcom | 0.60274 | 2.0022 | 2.0022 | 4.0045 | Illustrative | Illustrative value near common Cs-137 gamma energies; does not include buildup, scatter, or broad-beam factors. Cross-check with NIST XCOM (nist-xcom) for the lead thickness and energy grid you use.Notes: For facility work, replace with spectrum-integrated or measured μ from qualified data.Tabulated row 662 keV vs requested 662 keV (Δ 0.0 keV). |
| Concrete | 0.10000 | 662 | 662 | 0.0 | nist-xcom | 6.9315 | 23.026 | 23.026 | 46.052 | Illustrative | Generic ordinary concrete screening μ near typical diagnostic energies; verify with NIST XCOM (nist-xcom) or project-specific vendor data.Notes: Labeled illustrative; field concrete differs from any single tabulated row.Tabulated row 662 keV vs requested 662 keV (Δ 0.0 keV). |
| Steel | 0.45000 | 662 | 662 | 0.0 | nist-xcom | 1.5403 | 5.1169 | 5.1169 | 10.234 | Illustrative | Illustrative mid-energy μ for generic steel; use NIST XCOM (nist-xcom) or mill certificates when traceability matters.Notes: Labeled illustrative.Tabulated row 662 keV vs requested 662 keV (Δ 0.0 keV). |
| Water | 0.063000 | 662 | 662 | 0.0 | nist-xcom | 11.002 | 36.549 | 36.549 | 73.098 | Illustrative | Illustrative screening μ for photons in liquid water; compare to NIST XCOM (nist-xcom) for H₂O at the energies you care about.Notes: Labeled illustrative.Tabulated row 662 keV vs requested 662 keV (Δ 0.0 keV). |