Specifications
20
Built in Isotope Eciencies
The Inspector EXP has a number of built in eciencies for specic isotopes. If you know the isotope being
surveyed, then you can select one of the pre-programmed isotope eciencies to calculate the acvity of your
known source. The acvity (DPM and Bq) is dierent from the rates of exposure (mR/hr, µSv/hr, CPM, and CPS).
Acvity is the number of disintegraons of a radioacve substance in a given unit of me, which is specic
to the isotope being detected. The eciencies programmed into the Inspector EXP USB are based on the
geometry of a 1 cm distance from the end window of the detector. Cauon: Do not use the built in eciencies
unless you are surveying a known isotope, as doing so will give you inaccurate results.
Decay
When an atom emits an alpha or beta parcle or a gamma ray, it becomes a dierent type of atom. Radioacve
substances may go through several stages of decay before they change into a stable, or non-ionizing, form. For
example; U-238 has 14 dierent stages of decay before it stabilizes.
An element may have several forms or isotopes. A radioacve isotope of an element may be called a
radioisotope. However, the more correct term is radionuclide.
Selecng a Built-In Isotope Eciency
Enter the Ulity Menu and scroll to the USE menu item and press SET on the end panel of the unit to select
the isotope eciency you want to use for your survey. For example, if you know you are surveying Iodine-131,
then you would select I131 from the menu. Once you have selected the cooresponding isotope, press the SET
buon to select it. Press SET again to begin normal operaon of the Inspector EXP.
You can select from any of the following isotope eciencies built into the Inspector EXP:
35
Sulfur (S-35),
90
Stronum (Sr/y-90),
137
Cesium (Cs-137),
32
Phosphorus (P-32),
14
Carbon (C-14),
131
Iodine (I-131),
60
Cobalt (Co-
60), and Alpha.
Selecng Between DPM and Bq
Enter the Ulity Menu and scroll to the UNIT menu item and press SET on the end panel of the unit to change
the units of measurement between DPM (when mR/hr and CPM are selected) and Bq (when µSv/hr and CPS
are selected).
Chapter 9: Built in Isotope Eciencies