The RAD7 has the unusual ability to distinguish between the
“new” radon daughters and the “old” radon daughters left from
previous tests.Even so,a very high radon sample can cause
daughter activity that can affect the next measurement(RAD7 RAD
H2O). In order to determinate the background level,a distilled
water sample is used as a radon-free water sample.The background sample was measured using the same protocol.The
minimum detectable activity (MDA) was estimated to be
0.073 Bql1