We established Q spectroscopy, a novel method for the study of alpha decay, by combining 4π detection scheme with a low-temperature microcalorimeter. A 4π metal absorber guarantees absolute measurement of radioactivity without energy loss in the source and absorber. As a clear demonstration of Q spectroscopy, the 241Am alpha source enclosed by a thin gold foil was measured below 100 mK. Its resulting energy spectrum has two dominant peaks with 10 keV FWHM. The more dominant one corresponds to the complete absorption of the Q value, the total decay energy, and the less dominant one to γ-ray escapes. Consequential one-to-one correspondence with high-energy resolution appears between mixed radioisotopes and peaks in Q spectroscopy, which will simplify procedures of nuclear material analysis.
METHODS:A modified susceptible-exposed-infectious-hospitalized-removed (SEIHR) compartment model with a discrete feedback-controlled transmission rate was proposed to incorporate individuals' behavioral changes into the model. To figure out relative uncertainties in the infection peak time and the fraction of the infected population at the peak, a deterministic method and 2 stochastic methods were applied.
RESULTS:A relatively small behavioral change of individuals with a feedback constant of 0.02 in the modified SEIHR model resulted in a peak time delay of up to 50% using the deterministic method. Incorporating stochastic methods into the modified model with a feedback constant of 0.04 suggested that the relative random uncertainty of the maximum fraction of infections and that of the peak time for a population of 1 million reached 29% and 9%, respectively. Even without feedback, the relative uncertainty of the peak time increased by up to 20% for a population of 100,000.
CONCLUSIONS:It is shown that uncertainty originates from stochastic properties of infections. Without a proper selection of the evolution scenario, active behavioral changes of individuals could serve as an additional source of uncertainty.
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