The measurement sensitivity of the RAD7 to the 220Rn concentration in its internal cell is 30% less than the sensitivity to 222Rn. This reduction in 220Rn sensitivity relative to 222Rn sensitivity has been attributed to the decay of 216Po before it reaches the collection electrode. Analyzing the airflow patterns in the internal cell of RAD7, we propose that this may also be due to a ''short-circuit stream- highly concentrated 220Rn injected into the internal cell and discharged from another port quickly. Since in the ''short-circuit stream'', the 220Rn concentration of outflow is high, the 220...
