• Dr. Monalisha Dhibar

: In cascade gamma-ray decays, coincident gamma photons may deposit their energies simultaneously within the active volume of a detector, resulting in the formation of a composite gamma spectrum. Such coincidence events give rise to sum peaks that appear in addition to the individual photo-peaks. These sum peaks provide a quantitative basis for absolute activity determination of radioactive sources. The modified sum-peak method offers a precise and reliable approach for performing these measurements. In the present study, this method has been employed to conduct both experimental measurements and Monte Carlo simulations of the total count rate under the full energy spectrum, as well as the peak count rates corresponding to individual gamma lines, using a 2"×2" NaI(Tl) scintillation detector. Double gamma-emitting radionuclides such as Co-60, Nb-94, Sc-46, and Na-24 were investigated. The formalism was validated using a 60Co source, where the modified sum-peak method proved highly effective in determining the source activity. The measured activity was in good agreement with the results obtained from GEANT4 simulations.

Modified sum-peak method, Activity, GEANT4

"Simulation based study on activity of gamma sources for different source to detector separation in scintillation detector ", International Journal of Emerging Technologies and Innovative Research (www.jetir.org), ISSN:2349-5162, Vol.9, Issue 9, page no.f620-f626, September 2022, Available :http://www.jetir.org/papers/JETIR2209605.pdf

"Simulation based study on activity of gamma sources for different source to detector separation in scintillation detector ", International Journal of Emerging Technologies and Innovative Research (www.jetir.org | UGC and issn Approved), ISSN:2349-5162, Vol.9, Issue 9, page no. ppf620-f626, September 2022, Available at : http://www.jetir.org/papers/JETIR2209605.pdf