Test on goodness of fit of the model, used for 
estimation of radionuclide activities on scintillation spectrum

S.A. Tolstov, V.A. Muravsky

     In applied scintillation spectrometry of ionizing radiation,  the
estimates  of  nuclides  activities  are  obtained  by  fitting of the
experimental scintillation spectrum with its theoretical model.  As  a
rule,  such  approximation is done by the least squares or the maximum
likelihood method.
     In scintillation spectrometry the model of scintillation spectrum
is  presented  as  linear  combination  of  scintillation  spectra  of
individual radionuclides.  Such spectra of radionuclides are  obtained
experimentally, as a rule. Therefore these spectra inescapably contain
statistical noise and deviations of spectrometric scale.
     The chi-square  functional  has  been  developed  for  testing of
goodness of fit of  the  processed  scintillation  spectrum  with  its
theoretical model.  That functional takes into account the statistical
noise and deviations  of  spectrometric  scale  in  the  scintillation
spectra of individual radionuclides being used in theoretical model of
the processed scintillation spectra.