Decay data: review of measurements, evaluations and compilations

TDCRPy: A python package for TDCR measurements

The TDCR (Triple-to-Double Coincidence Ratio) measurement technique is a primary standardization method used by metrology laboratories to accurately determine the activity of radioactive solutions, particularly for radionuclides unsuitable for traditional coincidence counting methods, such as pure beta emitters. The TDCR method leverages a liquid scintillation counter equipped with three photomultiplier tubes (PMTs). This paper introduces TDCRPy, a novel Python package developed by the BIPM, designed to calculate detection efficiency of liquid scintillation counters using Monte Carlo simulations and decay data evaluations from the Decay Data Evaluation Project (DDEP). The software simulates particle interactions within the liquid scintillation counter, utilizing pre-calculated probability distributions for energy deposition. Comparisons with the PENNUC/NUR code and tests with measurement from the BIPM.RI(II)-K1.Co-60 key comparison demonstrate the potential of TDCRPy. This open-source package is distributed at https://pypi.org/project/TDCRPy and available for collaborative development on GitHub https://github.com/RomainCoulon/TDCRPy, where detailed user documentation can be found.

Absolute emission intensities of the gamma rays from the decay of 224Ra and 212Pb progenies and the half-life of the 212 Pb decay

Absolute gamma-ray emission intensities for 36 characteristic gamma rays from the decay of 224Ra, 212Pb, and their progeny were determined by measuring sources calibrated for activity by means of primary methods based on well-defined high-purity germanium (HPGe) detectors at both NIST and NPL. Results from the two laboratories agree with recent data evaluations, except for gamma rays with low emission intensities. The decay schemes have been re-balanced based on the new results. In addition, the half-life for 212Pb was measured using several HPGe detectors, ionization chambers, and a well-type NaI(Tl) detector.

IAEA Coordinated Research Project: updated decay data library for actinides

Recommended nuclear decay data for specific actinides are important in fuel-cycle studies for thermal and fast reactors and inventory studies for safeguards. Therefore, a programme of work was initiated in 2005 to improve the actinide decay data library of the International Atomic Energy Agency through the efforts of a Coordinated Research Project (CRP). The proposed contents of the new database are described, including the agreement to include additional actinides and a significant number of natural decay chain radionuclides. This work is on-going, and is estimated for completion in 2009/10.

Nuclear decay data: Observations and reflections

Decay data constitute an important feature of nuclear physics that plays a significant role in the various work programmes of members and associates of the International Committee for Radionuclide Metrology (ICRM). At the invitation of the ICRM, a review has been undertaken with the joint aims of emphasising decay-data achievements over the previous 10 years, and highlighting inadequacies that remain to be addressed in the future.

Determining 234Th and 238U in rocks, soils, and sediments via the doublet gamma at 92.5 keV

Efficient and accurate measurements of uranium (U) and U-series radionuclides in earth's materials are needed to assess its environmental impact, reconstruct geochemical histories, and quantify heat production in the crust. To date, measurements of 234Th and 238U by gamma spectrometry have relied on the quantification of 234Th gamma emissions at approximately 63 keV (absolute intensity = 3.7%) and the (234m)Pa gamma at 1001 keV (absolute intensity = 0.84%). However, use of the 63 keV emissions can be hampered by 232Th interferences and self absorption, and the 1001 keV photon has a very low yield. Here we describe the effective use of the 234Th doublet gamma emission at approximately 92.5 keV (total absolute intensity = 4.8%) for 234Th and 238U measurements. This doublet has been largely ignored because of its proximity to the Th K(alpha1) (93.3 keV) and thus its vulnerability to a Th self-fluorescence interference. We demonstrate that additions of U and 40K to a Th ore sample do not increase the count rate at 92-93 keV above that which would be expected from the associated additions of U and 234Th. We also show that the Th self-fluorescence interference appears to be an anomaly associated only with the analysis of relatively thick (>1 mm) Th minerals, and suggest that fluorescence will not complicate the 92-93 keV region in most environmental samples. A review of decay data reveals that Th K(alpha1) X-rays associated with the decay of 235U and 228Ac can significantly interfere with quantification of the 92.5 keV 234Th doublet. We show that simple experimentally-derived correction factors for these X-rays can be used to accurately determine 234Th using its strongest gammas, resulting in higher count rates and smaller self-absorption corrections relative to the traditional analytical lines. Total 1 sigma analytical error associated with U measurements at 92.5 keV ranged from 1 to 9% and is dominated by the relative size of the 228Ac interference. Detection limits for U in environmental samples using this technique are on the order of 50 ppb.