Reference Sources

Single or mixed radionuclide sources are available which have been developed to check the correct functioning of radiation measurement equipment such as surface contamination monitors, survey dosimeters and personal dosimeters. Stainless steel encapsulated sources are also available for instrument checking and oil well logging devices.

These sources emit alpha, beta and gamma radiation for checking the operation of surface contamination monitors and survey dosimeters. The advantages are:

• Cost effective -one source type can be used for all monitors on site
• Convenient -saves specifying 3 or more sources
• Compact -saves carrying sets of sources

Alpha spectrometry sources are intended for calibrating and checking solid state alpha
spectrometers, for applications in environmental monitoring and research.

The advantages of these sources are:

• Narrow line widths (normally less than 20keV) - easy, accurate, calibration of spectrometer
• Wipe test results comparable to sealed sources - low risk of contaminating equipment

These gamma reference sources are designed for calibrating and checking gamma-ray spectrometers, gamma counters and electron spectrometers.Typical applications in research, environmental measurements and nuclear medicine include:

1. Calibrating high resolution gamma-ray spectrometers
2. Calibrating NaI spectrometers
3. Calibrating NaI counters

The advantages of the sources described are:

• Sealed sources - robot design for cost effective, long, useful life
• Easy to mount in jigs for reproducible measurement conditions
• Choice of capsule dimensions and source activities
• minimal self-absorption and small active volume - accurate calibrations
• Traceable to national standard laboratories including NIST, NPL, PTB, LPRI

Tube type sources are used in the quality control of well-type NaI detectors used in biomedical research and nuclear medicine.

For the quality control of multi-well detectors, matched sets of tube sources and multi-finger sources are available. The advantages of using a multi-finger source are:

• Saves time - 1 source for 12 measurements simultaneously
• No half life correction needed (I-129 sources)
• Sealed sources - safer to handle than liquid standards

These sources have been designed to minimize self-absorption of low energy photons, so they are suitable for calibrating X-ray spectrometers such as Si(Li) detectors. For energy calibration only, a more robust source design is used. 

A thin deposit of active material 5mm in diameter is heat sealed between plastic foils. The foils are mounted in an aluminium frame 25mm in diameter, 3mm thick (drawing VZ-1562). The 20 - 37 kBq sources are sealed between foils 0.1mm and 0.015mm thick, with the thinner foil on the engraved side. The 370 kBq sources are sealed between foils 150 pCi thick (drawing VZ-2402).

The Cs-137 is fixed in a glass matrix and sealed by welding the glass between two stainless steel discs. This inner capsule is welded into an outer stainless steel capsule. The overall dimensions are 12.7mm diameter x 3.2mm. The active diameter is 5.8mm.

These sources meet the requirements for oil well logging sources and each source is pressure tested to 25,000psi.