ORTEC radEAGLE, User Manual

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B Glossary
The glossary contains key technical terms used throughout this manual.
Background The term background refers to the ambient radiation present around the in-
strument. The background includes
Þ
Natural background and mixtures of pertur-
bation sources surrounding the measurement site. Situations may arise, where the
reduction of perturbation sources cannot be optimal, e.g. in laboratories operating
with radiation sources.
Centroid Center of a peak. The centroid is used to measure peak position. Its numerical
value is often generated by a peak fit routine. In the radEAGLE , a peak fit is performed
in the calibration screens, presenting you the centroid and resolution of the peak.
Full-width-at-half-maximum (FWHM) There are two points of the peak which have a height
that equals half the height of the centroid position. One point on the left, another
one right of the centroid. The distance between the energies of these two points is
called the full-width-at-half-maximum abbreviated as FWHM. The FWHM divided by
the centroid energy leads to the resolution.
Geiger-Müller Detector (GM) Secondary detector onboard the radEAGLE . The GM detec-
tor consists of a pressurized tube filled with a radiation sensitive gas. Various gases
can be used here, typically inert gases such as helium, argon, neon or xenon. Often
these are mixed with an organic vapor or a halogen gas. GM tubes detect radiation
utilizing an anode-cathode pair inside this gas. The cathode is the tube housing while
the anode is a small wire in the center of the chamber. Radiation ionizes the atoms
of the gas initiating a charge avalanche which drives a current towards the anode
which generates a count. The number of counts is proportional to the strength of the
radiation. GM detectors are non-spectroscopic.
Natural Background Natural background is the radiation around the instrument caused
by natural processes. First, there are particles and photons coming from space,
including the radiation of sun and cosmic rays. This type of natural background is
called the cosmic background. There are certain materials in the earth land masses
that are radioactive, such as uranium, thorium or potassium. This material is called
naturally occurring radioactive material or NORM).
Naturally Occurring Material (NORM) Naturally occurring materials are, e.g., potassium
40
K, thorium
232
Th and uranium ore, which by now has arrived in its radium ground
state and consequently is reflected by a radium
226
Ra spectrum. NORM constitutes
the terrestrial background radiation.
© innoRIID GmbH • 2019-04-11 Software 3.2.12 • Document 3.3.0o 125/147