National Physical Laboratory


Absolute Counting
NPL's primary standards of radioactivity are underpinned by absolute counting techniques such as the 4πβ-γ coincidence method. NPL maintains and develops a suite of absolute counting equipment and is extending its capability in this area by developing the technique of Digital Coincidence Counting (DCC).

Liquid Scintillation Counting
LSC is used as the basis of primary standardisation techniques. 4πLS-γ and CIEMAT/NIST are well established, and the Triple-to-Double Coincidence Ratio (TDCR) technique is under development. LSC is also used as a comparitive counting method to verify the dilutions necessary for producing low-level radioactivity standards.

Ionisation Chambers
NPL's secondary standard re-entrant ionisation chambers have been calibrated for some 60 beta/gamma-emitting radionuclides (in formats such as British Standard glass ampoules and P6 vials). They are applied to many projects and customer services.

Gamma Spectrometry
NPL maintains a suite of gamma spectrometers calibrated using standardised solutions. They are used in standardisations, dilution checking and impurity checking.

Alpha Spectrometry
Alpha spectrometry facilities are maintained and are used in radionuclide standardisation and impurity checking.

Large-Area Source Counting Equipment (LASCE)
The LASCE is used to measure the absolute alpha- or beta-particle emission rate from large-area sources of the type used to calibrate surface contamination monitors.

Gas Counting and Gas Monitor Calibration Services
NPL maintains proportional counters for the absolute measurement of gases such as Tritium and 85Kr. Gases standardised in this way can then be used to calibrate customers’ portable monitors. NPL's capability in this area is being extended to the measurement of positron-emitting radionuclides in gas.

Radiochemistry Suite
NPL maintains a suite of state-of-the-art radionuclide source handling and radiochemistry laboratories.

Last Updated: 25 Mar 2010
Created: 14 Jun 2007


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