Kumpanat Punnary, Thawat Chittrakarn, and Tripob Bhongsuwan

pp. 849 - 859

Abstract

Compton scattering of gamma radiation was applied for nondestructive testing of the shogun
mandarin fruits with good quality defined as no dry sack or dry fibrous structures inside. In principle, the
scattering deviated angles to the left and right of a gamma ray that penetrates through a homogeneous
fibrous structure meat of any orange fruit should be equal. The source Cs-137, with an initial gamma ray
activity of 9.25 mCi, placed in a 7 cm thick lead shielding, was radiated through a 10 mm diameter collimator
onto any single fruit to be tested. A NaI(Tl)-detector, oriented perpendicular to both left and right of the
incoming beam, was placed 5 cm from the fruit. Results showed that the net count rate of the scattering beam
between the left and right counting for good-quality shogun mandarin with proper tissue for consumption
was less than 85 counts per minute (average 83 cpm), whereas shogun mandarin with dry sack, which were
unfit for consumption, had twice that rate or more (average 175 cpm).