LEA Cerca - gamma sources

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Sectors of activity

gamma sources

LEA produces two categories of gamma standard sources :

• sources for activity calibration

These sources enable direct activity calibration of all gamma detectors and spectrometers, for radionuclides for which standards are available.
In the field of nuclear medicine, gamma point sources (barium 133 and cobalt 57) are designed for use in checking the orientation of gamma cameras.

• sources for efficiency calibration

These standard sources are characterized in terms of photon flux within 4 pi sr, expressed in s^-1, for each specified gamma line.
The source activity is given as an indicative value.
Where radioactivity standards are used to determine the efficiency of a gamma spectrometer as a function of photon energy, certain decay scheme parameters are required (number of gamma photons per transition, internal conversion coefficient, etc.).
The calibration uncertainty is the combination of the uncertainty with respect to the activity of the standard, and the uncertainties pertaining to the decay scheme parameters.
These sources were designed to allow direct efficiency/energy calibration without knowledge of decay schemes.
They therefore enable high-precision calibration.
The quasi-point sources (diameter 3 mm) are hot-sealed between two thin plastic foils (total mass per unit area : 28 mg.cm^-2).
They are mounted in a plastic ring to ensure rigidity and ease of handling.

Four types of sources are available :

• gamma quasi-point sources
• Distributed gamma sources
• Plastic gamma sources
• gamma sources with cylindrical holders

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