ACCURATE DETERMINATION OF SOURCE DISINTEGRATION RATES WITH NaI (Tl) GAMMA RAY SPECTROMETER
ACCURATE DETERMINATION OF SOURCE DISINTEGRATION RATES WITH NaI (Tl) GAMMA RAY SPECTROMETER
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Date
2006-08
Authors
NASIRU, SA’ADU
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Abstract
The aim of this project is to measure the absolute activity (disintegration rates) of gamma
sources. The measurement was achieved using a NaI (Tl) spectrometer. The major factors
that contribute to uncertainties in the measurement were taken in to account and relevant
uncertainties were propagated accordingly. The spectrometre is fully setup for
disintegration rates determination.
The spectrometer was calibrated for efficiency at three chosen geometries (10, 14 and 20)
cm, the calibration was performed in such a way that significant factors that affect the
measurements were considered. The fitted efficiency function coefficients at these chosen
levels were obtained and used to write a computer program that calculates the measured
absolute activity of sources and its uncertainty easily. The energy gamma range covered
by the work is (59 to 1836) KeY.
Therefore the work was able to integrate IAEA Quality Assurance (QA)
recommendations, to simplify an accurate methodology for setting up gamma ray
spectrometres, using a NaI(Tl) spectrometre. The setup spectrometre used to determine
the absolute activity of two old standard calibration sources 137Cs and 60Co, the activity of
the 137Cs compared well with that quoted by the manufacturer, while that of 60Co did not
agree, its activity was determined to be (31319 ± 2153) BG, because it leaked prior to this
work, it can henceforth be used when needed.
Description
A Thesis submitted to the Post Graduate School,
Ahmadu Bello University, Zaria, Nigeria.
In partial fulfillment of the requirement for the award of the degree
Master of Science (Physics)
Physics Department,
Ahmadu Bello University, Zaria, Nigeria.
AUGUST 2006.
Keywords
ACCURATE,, DETERMINATION,, DISINTEGRATION,, RATES,, GAMMA RAY,, SPECTROMETER.