Gamma Exposure Rate
Compute the exposure (or dose) rate of a point gamma source, X = Γ·A/d², from the exposure-rate constant (Γ, specific to the radionuclide), the source activity (A) and the distance (d). It combines the source strength with the inverse square law, allowing you to estimate the dose received at a given distance — fundamental in planning tasks with radioactive sources. Enter the gamma constant, the activity and the distance.
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Taxa de exposição gama
Quanto de dose por hora uma pessoa recebe perto de uma fonte gama? A taxa de exposição (ou de dose) de uma fonte pontual é X = Γ·A/d², combinando dois fatores: a intensidade da fonte (sua atividade A) e a lei do inverso do quadrado (a queda com a distância d). A constante Γ (gamma) é específica de cada radionuclídeo e embute a energia e o número de fótons gama emitidos por desintegração — o cobalto-60, por exemplo, é um emissor 'duro' com Γ alto, enquanto outros são mais brandos. O resultado permite ao físico médico ou ao supervisor de radioproteção estimar a dose de uma tarefa antes de executá-la: se a taxa é tal a 1 metro, qual será a 3 metros? quanto tempo posso ficar sem ultrapassar o limite? É a ferramenta de planejamento que materializa o princípio ALARA (As Low As Reasonably Achievable). Informe a constante gama, a atividade e a distância.
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Decay Constant
Compute the radioactive decay constant, λ = ln(2)/T½, from the half-life (T½). The constant λ is the probability of a nucleus decaying per unit time — the larger it is, the more unstable the isotope and the shorter its half-life. It links the half-life (time for half the nuclei to decay) to the activity and to the exponential decay law. Enter the isotope's half-life.
Radioactive Activity
Compute the activity of a radioactive sample, A = λ·N, the product of the decay constant (λ) and the number of radioactive nuclei present (N). Activity, measured in becquerel (Bq = 1 disintegration/s) or curie, expresses how many nuclei decay per second. It is the fundamental quantity quantifying a radioactive source, and it decreases over time as nuclei decay. Enter the decay constant and the number of nuclei.
Maximum Noise Exposure Time
Calculate the maximum daily allowed noise exposure time, T = 8 ÷ 2^((SPL − 85) ÷ 5), from the sound pressure level SPL (dB(A)). The result, in hours, is the maximum exposure duration before reaching a 100% dose under the Brazilian NR-15 (85 dB(A) limit for 8 h, with a 5 dB dose-doubling rate). Every 5 dB above 85 halves the allowed time: 90 dB(A) allows 4 h, 95 dB(A) only 2 h. It is the basis for dose calculation and the planning of rotation and breaks. Enter the sound pressure level.
The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.