Alireza Mahdavipour - Technical and vocational University Shiraz, Fars
Tahereh eskandari - Department of Education of Fars Shiraz, Fars

Coincidence counting are the most precise method to recognize radioactive materials and to measure the activity of them. Absolute activity is measured by coincidence counting of two or several especial and certain radiation like Beta and Gamma (γ). There is usually a Gamma disintegration after a Beta decay.A real coincidence happens when two signals are created exactly at the same time, but this happens rarely. A coincidence unit should be designed to register the signals that enters at a short period ( ) as a coincidence. The signals enter the central process or (ARM- LPC1769) through A & B entrance channels. Each of the channels is checked individually by another processor before entering the central processor. Central processor processes the input data of A& B channels by a program called C.

Beta and Gamma coincidence- Absolute Activity - Beta counting- Gamma counting