Gamma Spectroscopy (NORM and TENORM)
N = number of nuclides
D = disintegration rate (Bq, Ci, dimension s-1)
A = activity is disintegration rate D per unit of volume or unit of mass (dimension s-1)
We distinguish between two notions:
As(i) = specific activity is activity per unit of mass of that particular element the actual
radionuclide i belongs to. This notion is also used to express the activity of a
particular radiolabelled molecule in relation to the total mass of the same molecule
(labelled and unlabelled) in the sample (for instance when the inactive molecule is present
as a carrier).
Ac(i) = activity concentration is the activity of a special radionuclide i or all present
radionuclides (AcT = Ac(i) = total aktivity) per unit of volume or unit of weight of a radioactive
sample.
N,D and A may, in addition, have an index t (i.e. Nt, Dt and At). This denotes the parameter values at time t relative to a starting time t = 0.
R = counting rate (cps, cpm or generally cpt where t should be defined, dimention s-1)
S = number of counts
N, D, A, R and S may, in addition, have indexes B = background, T = total or N = net. The relations between them are: RN = RT - RB and SN = ST - SB. Other indexes may also be used, for instance SCr-51 in order to separate from SFe-59.