Quick guide
How to use this calculator
- Choose the physical radiation quantity and solve direction before entering measurements. Keep activity, count rate, absorbed dose, equivalent dose, time, distance, material attenuation, and detector efficiency separate.
- Enter isotope, detector, geometry, material, or field data only from an applicable measurement or authoritative record; these pages do not supply generic safety values or hidden presets.
- Use companion outputs to reconcile the arithmetic, then retain every stated boundary. A screening result is not authorization for exposure, handling, shielding, release, transport, treatment, or disposal.
Calculation method
How the radiation count rate, background and efficiency calculator works
Automate background normalization and Poisson count-rate uncertainty without hiding non-positive net signals or detector assumptions.
Net rate = gross counts/gross time − background counts/background time. Standard count-rate uncertainty = √(gross counts/tg² + background counts/tb²). For a positive net rate, estimated activity = net rate/(efficiency × emission probability).
Worked example
Radiation Count Rate, Background and Efficiency example
1,200 gross counts and 120 background counts over equal 60-second intervals give 18 net counts/s; at 25% efficiency and 100% yield the estimated activity is 72 Bq.
Net rate = gross counts/gross time − background counts/background time. Standard count-rate uncertainty = √(gross counts/tg² + background counts/tb²). For a positive net rate, estimated activity = net rate/(efficiency × emission probability).
Supported inputs
Precision and limits
Radiation boundary
This simple independent-Poisson model excludes dead time, coincidence, geometry, attenuation, energy-window effects, calibration uncertainty, blank variability, minimum detectable activity, decay during counting, and instrument-specific corrections. A non-positive net rate is not converted into negative activity.
Units and precision
Calculations normalize compatible units once, retain working precision, and round only for display. Very small and large nonzero values use scientific notation; displayed precision cannot exceed the entered measurements or source data.
Decision boundary
This calculator does not provide a dose limit, regulatory threshold, medical interpretation, personal-risk estimate, radiation-protection program, or professional approval. Use applicable instruments, current authoritative data, and qualified radiation-protection expertise for consequential decisions.
Privacy
Entered values and results stay in this browser and are not sent to analytics or third parties.
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