Abstract.

The fundamental parameter method (FPM) is an analytical approach for intrinsic calibration of gamma-ray spectrometer using fundamental nuclear and atomic parameters such as gamma-ray branching intensity, half-life time, isotopic ratio and concentration ratio. The main advantage of this approach is the wide range of its applications in gamma-ray efficiency calibration, nuclear safeguards (nuclear materials measurement and isotopic ratios) and others. In this work, the calculation of relative efficiency (RE; photopeak count rate divided by branching ratio) was modified based on the relative intensity concept of 226Ra in equilibrium with 222Rn decay products (214Bi-214Pb). The modified FPM was applied to reevaluate the absolute intensity (I%) of gamma-ray transition of 234mPa at 1001.03 keV. using certified uranium ore samples, 226Ra point source and gamma-ray spectrometers based on hyper pure germanium detector. The newly confirmed I % of 1001.03 keV is 1.0164±0.0636.

Key words: fundamental parameter method/ 1001.03 keV/ gamma-ray transition/ 238U