  The use of the Monte Carlo technique in a reliable and inexpensive way
without the need for a standard radioactive source in determining the detector
efficiency is becoming widespread every passing day. It is important to model
the detector with the real dimensions for an accurate and precise results for
the method. Another parameter as important as detector modeling is the number
of histories in the simulation code examined in this study. In this study, the
effect of the number of histories on the efficiency was examined in detail
using different simulation codes. The results obtained in this work, at least
107 particle numbers should be used in all three programs where the uncertainty
is below 1%. If the existing facilities are sufficient, it can be increased to
108s in case of having a more equipped and fast computer. However, going higher
than this value does not make any sense as seen from the study.
