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Subject: Radiation Dosimetry measurement
Date: Sat, 18 Nov 2000 17:13:04 +0000
From: Bassam Shakhreet <bshakhreet@HOTMAIL.COM>
Dear all
My subject is in the field of mass energy absorption coefficient measurement
of selected Biological Equivalent Materials.
I will measure this coefficient for two shapes: one is Sphere (diameter is
30 cm) and the other is Cylinder (diameter is 25 cm and high is 14 cm). Both
shaps is made from different materials. I will take readings with variable
thicknesses and distances between detector and source where I put Aluminum
filter in front of detector. I faced many problems and questions, These
questions are:
1) Is the size (diameter & dimensions) of Sphere or cylinder affects with
the readings?
2) Is the size or the type of filter affects with the readings? What is the
main work of this filter?
3) Which is better, to make relation graph between (separation distance
between detector and source”d”) versus count rate or inverse square of that
distance versus count rate? Why?
Thank you very much for each person who will help me and I will appreciate
that for him.
Yours faithfully,
Bassam Shakhreet
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Subject: Re: Radiation Dosimetry measurement
Date: Sat, 18 Nov 2000 15:01:49 -0500
From: Ludwik Kowalski <KowalskiL@MAIL.MONTCLAIR.EDU>
Bassam Shakhreet wrote:
My subject is in the field of mass energy absorption coefficient
measurement of selected Biological Equivalent Materials.
I assume you are measuring doses in rads, I. To determine
the mu coefficient (cm/gram) I would make study the rate
at which I changes with the depth x. [I=Io*exp(-mu*x)]
I will measure this coefficient for two shapes: one is Sphere
(diameter is 30 cm) and the other is Cylinder (diameter is 25 cm
and high is 14 cm). Both shaps is made from different materials.
The coefficient does not depend on the shape, only on material.
I will take readings with variable
thicknesses and distances between detector and source
That seems to be correct. [I=Io*exp(-mu*x)]
where I put Aluminum filter in front of detector.
I suppose you are using Al filter to absorb very soft radiation
which is of no interest to you. In that case the Io should also be
measured with the same filter. There are many traps in such
measurements. One of them is to record scattered radiation.
Absolute measurements of mu are not trivial. I was involved
in doing this about 40 years ago.
Ludwik Kowalski
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Subject: Re: Radiation Dosimetry measurement
Date: Sat, 18 Nov 2000 15:04:20 -0500
From: Ludwik Kowalski <KowalskiL@MAIL.MONTCLAIR.EDU>
Opps, the unit of mu should have been 1/cm. [I=Io*exp(-mu*x)]