Cs-137 Point Source Simulation
Status: RunningDetector Crystal
Custom Volume (CsI(Tl))
15.0 cm³
Log scale, 0.5 – 1000 cm³. Moving the slider switches to a CsI(Tl) cylinder (H = D).
Material
NaI(Tl)
Dimensions
—
Volume
—
Projected Area
—
Mean Path / Intrinsic ε
—
Sensitivity
—
Preset crystals use their real published sensitivities (16 / 56 / 390 cps per µrem/hr).
The custom slider crystal is calculated from its size and shape, including self-shielding:
the outer part of a big crystal soaks up gammas before they reach the middle, so doubling
the volume does not double the count rate. The curve chart on the right shows this.
Source & Geometry
Source Activity
10 µCi
µCi
= 370,000 Bq
Distance to Source
1.0 ft
Dose rate = 3 · µCi / d² (µrem/hr, d in ft)
Background Dose Rate
10 µrem/hr
µrem/hr
≈ 160 cps background (same crystal sensitivity)
Live Readout
CPS (3 s avg)
--
counts/sec
Dose Rate (5 s avg)
--
mR/hr
Mean CPS (expected)
--
counts/sec
True Dose Rate
--
mR/hr
Total Counts
0
counts
Elapsed
0
sec
3D View — Radiation Field
Drag to spin the view, scroll to zoom. Green pulse = Cs-137 source | grey dots = gammas flying in every direction
(the ones headed to the detector get absorbed there) | cyan specks = background counts.
The dot spray is thinned out so your screen can keep up — the count numbers use the real rates. The distance axis is squeezed so far-away detectors stay on screen, and tiny crystals are drawn bigger so you can see them.
The dot spray is thinned out so your screen can keep up — the count numbers use the real rates. The distance axis is squeezed so far-away detectors stay on screen, and tiny crystals are drawn bigger so you can see them.
Count Rate (CPS — 3 s avg)
Dose Rate (mR/hr — 5 s avg)
Sensitivity vs Volume (log-log)
Teal curve = CsI(Tl) model | grey dashed = what linear scaling would give | blue dots = NaI presets | white ring = current crystal