{
  "ran": "2026-10-15T00:24:12.685Z",
  "how": "kit/photochamber.mjs. Light reaching the receiver from a mass M of particles whose diameters follow a log-normal spread around the median d (geometric deviation sigma): number of particles from the mean cube of the diameter, times the mean differential scattering cross-section i(theta)/k² over the receiver window. Mie amplitudes from kit/mie.mjs (BHMIE, checked against Wiscombe 1979 to 4e-7). The ionization response at the same mass: 1 − 1/(1 + tau·N·<beta>) with kit/ionchamber.mjs.",
  "sources": {
    "nist": "NIST, How Do Smoke Detectors Work? (updated 20 Feb 2026): photoelectric alarms are more sensitive to larger, light-colored particles from smoldering fires; ionization alarms detect small soot from flaming fires more quickly."
  },
  "assumptions": {
    "wavelength_m": 8.8e-7,
    "receiverAngle_deg": 90,
    "receiverWindow_deg": 10,
    "sizeSpread_sigma_g": 1.6,
    "density_kg_m3": 1000,
    "refractive": {
      "soot": {
        "n": 1.57,
        "k": 0.56
      },
      "smoke": {
        "n": 1.5,
        "k": 0
      }
    },
    "sizeSpreadSource": "Urban et al., AIAA 2012-3536 (NASA Glenn and NIST): \"geometric standard deviations of 1.6 – 1.9\"; the lower bound is the default, the reader can also pick 1.9 or my first guess 1.4",
    "spreadsOffered": [
      1.4,
      1.6,
      1.9
    ],
    "medians_m": {
      "soot": 1e-7,
      "smoke": 0.000001
    }
  },
  "derived": {
    "mass_kg_m3": 0.000001,
    "ratioSmokeToSoot": 0.8466,
    "ratioPale1To01": 1.657,
    "minTinyRatioAnySpreadAngle": 2.225,
    "minIonRatioAnySpread": 90.98,
    "ionDrop": {
      "soot": 0.06407,
      "smoke": 0.0006841
    }
  },
  "ok": true
}