Radionuclide Measurement Techniques in Nuclear Metrology

High-precision determination of radionuclide activity underpins applications from environmental monitoring to nuclear medicine and waste management. Nuclear metrology relies on primary techniques such as liquid scintillation counting, coincidence counting, and high-resolution spectrometry to establish and disseminate standards of activity. Advances in detection systems have focused on reducing measurement uncertainties through improvements in photon-yield characterisation, timing resolution and digital acquisition. Radiochemical separation procedures enable the preparation of pure sources for both half-life measurements and standardisation. Analytical codes and models support the interpretation of complex decay schemes and the propagation of uncertainties. Combined, these methodologies ensure traceability to international reference systems and facilitate consistent measurement across institutes worldwide.

Research from Nature Portfolio

A novel compact detector system has been introduced that uses a Compton spectrometer approach to decouple scintillator light-yield non-linearity from timing properties. The portable assembly, integrating three photomultiplier tubes and digital acquisition, enables simultaneous determination of photoelectron yield and time-domain characteristics across diverse scintillator types. This reduces measurement duration and supports development of new organic and inorganic scintillators for gamma and electron detection. Another study has revisited efficiency estimation in liquid scintillation counting by analysing the cross-correlation distribution of PMT signal intervals. A theoretical model validated by Monte Carlo simulation and experiments with low-energy beta emitters provides new estimators for detection efficiency and quenching indicators. First direct determination of a long-lived radionuclide’s half-life has been achieved by combining high-resolution mass spectrometry and liquid scintillation counting after chemical separation. The result not only refines decay data for nuclear waste modelling but also demonstrates the critical role of advanced separation and counting techniques in reducing uncertainty by an order of magnitude.

Radionuclide Measurement Techniques in Nuclear Metrology publication trend

The graph below shows the total number of articles in radionuclide measurement techniques in nuclear metrology across all publications each year (not limited to Nature Index journals).

Technical terms

Liquid scintillation counting (LSC): A technique that measures radioactive decay by detecting light pulses from a scintillant when beta or electron-capture emissions interact with the cocktail.

Compton spectrometer: A detection system that uses Compton scattering kinematics to characterise energy and non-linearity of scintillator responses.

Triple-to-double coincidence ratio (TDCR): A method in LSC that compares triple and double PMT signal coincidences to determine detection efficiency without external standards.

Photomultiplier tube (PMT): A vacuum tube that amplifies light signals via the photoelectric effect and electron multiplication, used in scintillation detectors.

Quenching: The reduction in light output or detection efficiency due to chemical or colour interference in a scintillation sample.

Log ft value: A parameter combining transition probability and phase-space factor in beta decay, indicative of nuclear structure and decay rate.

References

1. A compact detector system for simultaneous measurements of the light yield non-linearity and timing properties of scintillators. Scientific Reports (2024).
2. BetaShape: A new code for improved analytical calculations of beta spectra. EPJ Web of Conferences (2017).
3. Radiochemical separation and purification of non-carrier-added silicon-32. Radiochimica Acta (2021).
4. Time-domain based evaluation of detection efficiency in liquid scintillation counting. Scientific Reports (2021).
5. Development of FPGA-based standalone, portable TDCR system. Journal of Instrumentation (2023).
6. First direct determination of the 93Mo half-life. Scientific Reports (2021).