The gamma ray spectrum resolution from a 241Am-Be source-based prompt gamma
ray activation analysis set-up has been observed to increase in the energy
region of interest with enclosing the NaI detector in a proper neutron and
gamma ray shield. We have investigated the tact that the peak resolution of
prompt gamma rays in the region of interest from the set-up depends on the
source activity to the great extent, size and kind of the detector and the
geometry of the detector shield. In order to see the role of a detector
shield, five kinds of the detector shield were used and finally the proper
kind was introduced. Since the detector shield has an important contribution
in the reduction of the undesirable and high rate gamma rays coming to the
gamma ray detector, a good design of a proper shield enables the elimination
of the unwanted events, such as a pulse pile-up. By improving the shielding
design, discrete and distinguishable photoelectric peaks in the energy region
of interest have been observed in the spectrum of prompt gamma rays.