Decay Data Research Articles

A new evaluation of the decay data for 166Ho

The β−-emitter 166Ho is of interest as a potential radiolabel for therapeutic medical applications. A new decay data evaluation for 166Ho has been performed using the Decay Data Evaluation Project (DDEP) methodology. New recommended values for the half-life, γ-ray emission probabilities, β−- branching ratios, and other relevant nuclear and atomic data are provided. This paper provides a summary of the evaluation; the complete set of recommended data tables and detailed evaluator comments are available at the DDEP website.

Toward Optimal Fitting Parameters for Multi-Exponential DWI Image Analysis of the Human Kidney: A Simulation Study Comparing Different Fitting Algorithms

In DWI, multi-exponential signal analysis can be used to determine signal underlying diffusion components. However, the approach is very complex due to the inherent low SNR, the limited number of signal decay data points, and the absence of appropriate acquisition parameters and standardized analysis methods. Within the scope of this work, different methods for multi-exponential analysis of the diffusion signal in the kidney were compared. To assess the impact of fitting parameters, a simulation was conducted comparing the free non-negative (NNLS) and rigid non-linear least square (NLLS) fitting methods. The simulation demonstrated improved accuracy for NNLS in combination with area-under-curve estimation. Furthermore, the accuracy and stability of the results were further enhanced utilizing optimized parameters, namely 350 logarithmically spaced diffusion coefficients within [0.7, 300] × 10−3 mm2/s and a minimal SNR of 100. The NNLS approach shows an improvement over the rigid NLLS method. This becomes apparent not only in terms of accuracy and omitting prior knowledge, but also in better representation of renal tissue physiology. By employing the determined fitting parameters, it is expected that more stable and reliable results for diffusion imaging in the kidney can be achieved. This might enable more accurate DWI results for clinical utilization.

Magnetic Microcalorimeters for Primary Activity Standardization Within the EMPIR Project PrimA-LTD

The precision of existing decay data of radionuclides for activity determination is often a limitation for actual applications in science, society and industry. For this reason, the EMPIR project PrimA-LTD aims to introduce an advanced primary activity standardization technique that is based on magnetic microcalorimeters (MMCs) and that will offer very low energy threshold of few eV and a decay scheme-independent detection efficiency close to 100%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$100\\,\\%$$\\end{document}. As a proof of concept, we developed two MMC-based detector types in order to standardize an α\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\alpha$$\\end{document}-decaying, a β\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\beta$$\\end{document}-decaying and an electron capture decaying isotope. One detector type aims to introduce a reusable detector setup, while the other aims to provide highly accurate decay spectra by high-resolution measurements with high statistics. We present the designs, fabrication status and first characterization measurements of both detectors types and outline next steps.

DDEP re-evaluation of the radioactive decay scheme of 137Cs

A complete re-evaluation of the 137Cs β‒ decay scheme has been performed within the scope of the Decay Data Evaluation Project (DDEP), taking full advantage of the most recent measurements. An evaluated half-life of 30.018 (22) years is recommended, along with a full revision of the β‒ decay branching ratios that also results in a re-evaluation of the absolute emission probability of the 662-keV gamma ray to give a value of 85.01 (20)%. Recommendations for new measurements are also suggested.

Relaxation enhancement by microwave irradiation may limit dynamic nuclear polarization.

Dynamic nuclear polarization enables the hyperpolarization of nuclear spins beyond the thermal-equilibrium Boltzmann distribution. However, it is often unclear why the experimentally measured hyperpolarization is below the theoretically achievable maximum polarization. We report a (near-) resonant relaxation enhancement by microwave (MW) irradiation, leading to a significant increase in the nuclear polarization decay compared to measurements without MW irradiation. For example, the increased nuclear relaxation limits the achievable polarization levels to around 35% instead of hypothetical 60%, measured in the DNP material TEMPO in 1H glassy matrices at 3.3 K and 7 T. Applying rate-equation models to published build-up and decay data indicates that such relaxation enhancement is a common issue in many samples when using different radicals at low sample temperatures and high Boltzmann polarizations of the electrons. Accordingly, quantification and a better understanding of the relaxation processes under MW irradiation might help to design samples and processes towards achieving higher nuclear hyperpolarization levels.

Data assimilation of decay heat experiments for feedback on nuclear data

Integral decay heat experiments can provide interesting feedback on particular nuclear data (decay data and fission yields mainly). After ensuring that the C/E discrepancies were mostly due to nuclear data discrepancies, a Bayesian inference approach can be applied. Nevertheless, the results strongly depend on the quality of the experiment and on our capability to estimate realistic experimental correlation matrices when considering several integral experiments in the assimilation process. A former study performed in 2019 was dedicated to the data assimilation of a large C/E dataset from the experimental validation database of fuel inventory calculations with the DARWIN2.3 package in order to provide feedback to the nuclear data evaluators. This paper is an attempt to exploit the General Electric decay heat experiments performed in the USA in the 1980s in order to confirm or not the trends on four particular cumulated fission yields: 235U(nth,f)133Cs, 235U(nth,f)137Cs, 239Pu(nth,f)106Ru and 239Pu(nth,f)144Ce.

Need for precise nuclear structure data for reactor studies

This paper highlights the strong need for precise nuclear structure and decay data measurements in order to perform high-quality modelling on nuclear reactors and other applications. The context of nuclear data evaluation, as well as the importance of low uncertainty evaluations, will be first presented. The importance of such data for interpreting nuclear data experimental measurements is stressed throughout. To demonstrate this, we will explain how mass and charge-dependent fission yields, decay data (in particular for the purpose of residual heat calculations), and inelastic neutrons scattering cross section rely on nuclear structure and decay information and how new and higher quality in such data can lead to improved accuracy in the precision of evaluated nuclear data.

Recent improvements in X-ray spectrometry measurements performed at the MADERE facility dedicated to reactor dosimetry requirements

CEA/Cadarache operates the MADERE facility dedicated to measuring the activity of radionuclides generated during the irradiation of specific dosimeters made of hyper-pure materials. This facility is equipped with seven spectrometers, two of which are dedicated to the detection of radionuclides that emit X-rays. The laboratory that operates the MADERE facility processes solid-state rhodium and niobium dosimeters, which emit X-rays of 20 keV and 16 keV respectively. In recent years, there have been significant improvements in nuclear decay data, leading to better measurement of these two X-ray emitters. A joint LDCI and LNHB thesis, defended in 2018, produced major advances (for example self-attenuation corrections for 93mNb and 103mRh). The most significant achievements and outlooks are presented in this paper for the both niobium and rhodium dosimeters.

Assessing hydrophobic deep eutectic solvents for intramolecular excimer formation.

Intramolecular excimer formation by a dipyrenyl probe, 6-(1-pyrenyl)hexyl-11(1-pyrenyl)-undecanoate [1-Py(CH2)10COO(CH2)61-Py], is used to assess hydrophobic deep eutectic solvents (HDESs) for the purpose. n-Decanoic acid (DA), L(-)-menthol (Men) and thymol (Thy) have been utilized to form HDESs with different pairs of constituents in different molar ratios, namely Men : DA (2 : 1, 1 : 1, and 1 : 2), Thy : DA (2 : 1, 1 : 1, and 1 : 2), and Thy : Men (5 : 1, 2 : 1, 1 : 1, 1 : 2, and 1 : 5). The maximum of the excimer-to-monomer emission intensity ratio, (IE/IM)max, is observed at 343.15-353.15 K for all DESs irrespective of the constitution, and it varies in a narrow range exhibiting no correlation with the dynamic viscosity (η) of the DES which varies between 2.05 and 3.56 mPa s. Excited-state intensity decay data reveal excimer dissociation back to the excited monomer to be negligible in all DESs at lower temperatures (T ≤ 323.15 K); the simplistic Birks scheme is followed at higher temperatures (T > 323.15 K). The rate constant for excimer formation/association, ka, ranges from (3.00 ± 0.50) × 106 s-1 to (103 ± 10) × 106 s-1, which is similar to that reported in other media. The temperature-dependence of the equilibrium constant for excimer formation follows the van't Hoff equation with recovered standard enthalpy (ΔaH*⊖) and standard entropy (ΔaS*⊖) changes, indicating the reversible intramolecular excimer formation to be exothermic and energetically-favorable but entropically unfavorable. A plot of kavs. T/η for all the DES systems investigated exhibits a fairly good linear correlation, indicating the adherence to the Stokes-Einstein formulation within the HDESs further emphasizing the homogeneous nature of the solubilizing media. The work helps to highlight the potential of HDESs for intramolecular excimer formation involving non-polar reactants.

Study of neutron beta decay with the Nab experiment

The current three sigma tension in the unitarity test of the Cabbibo-Kobayashi-Maskawa (CKM) matrix is a notable problem with the Standard Model of elementary particle physics. A long-standing goal of the study of free neutron beta decay is to better determine the CKM element Vud through measurements of the neutron lifetime and a decay correlation parameter. The Nab collaboration intends to measure a, the neutrino-electron correlation, with accuracy sufficient for a competitive evaluation of Vud based on neutron decay data alone. This paper gives a status report and an outlook.

Nano-second life time decay and Z-scan measurement: A tool to investigate the relevance of excited state dynamics with non-linear optical parameters in cis substituted Wells-Dawson POM-Porphyrin hybrids

Materials possessing non-linear optical NLO responses have gained considerable attention in the field of photonics because they have the potential to produce new frequencies when they interact with intense light by means of non-linear interactions. Synthesizing NLO materials based on porphyrin covalently bonded with polyoxometalates (POMs) is complicated and rigorous, requiring special techniques in order to get pure compounds with a higher yield. Here, we study the third-order NLO parameters along with the fluorescence lifetime decay values in a nanosecond(ns) time span for WDPOMCis2PyP and WDPOMCis2PhP (bearing the Wells-Dawson POM at the cis position) and their porphyrin precursors Cis2PyPTris and Cis2PhPTris, respectively. A comparison of third-order NLO characteristics with fluorescence lifetime decay data indicates that an increase in NLO properties has been observed with shorter lifetime decay values and vice versa. From the results, it is clear that WDPOMCis2PhP showed better third-order NLO (χ3 = 2.60 × 10−10 esu and β = 8.26 × 10−11 cm/W) than WDPOMCis2PyP (χ3 = 2.25 × 10−10 esu and β = 5.60 × 10−11 cm/W), which is supported by lifetime decay values. The lifetime decay value for WDPOMCis2PhP (τ1 = 2.77 ns) is shorter than WDPOMCis2PyP (τ1 = 6.02 ns). In addition to the factors mentioned based on substituent impact and molecular geometry, the WDPOMCis2PyP has a larger dipole moment than other POM-based porphyrin hybrids, which accounts for the improved third-order NLO response. Minor energy variance among singlet, triplet excited states, and charge-separated states favors quicker intersystem crossing of the WDPOMCis2PyP and WDPOMCis2PhP, which boosts NLO responses, and this actually makes WDPOMCis2PyP and WDPOMCis2PhP better than their corresponding POMs free porphyrins Cis2PyPTris and Cis2PhPTris, leading to their uses in optical devices.

Investigating methods to quantifying uncertainty in PM2.5 emission rates from cooking by toasting bread

Exposure to airborne fine particulate matter (PM2.5) is linked to multiple negative health effects and indoor sources are important contributors to personal exposure. Cooking is a common indoor source, but reported emission rates have high variability. Methods to quantify uncertainty in PM2.5 cooking emission rates are investigated so that they can be used in probabilistic exposure models to evaluate interventions. Controlled tests were conducted to measure emission rates from the toasting of bread because it is simple and repeatable. Two methods were compared: residential kitchen field tests and large chamber tests. The theoretical peak calculation method was used to determine emission rates from time-resolved PM2.5 concentration measurements. The large chamber tests produced more consistent results than the residential field tests, with a coefficient of variance almost an order of magnitude lower due to the improved control of variables. Then, the emission rates were normally distributed with mean 0.23mg/min and standard deviation 0.067mg/min. However, this distribution may be less representative of normal behaviour. The resulting dataset can be combined with other sources to represent housing stock exposures in probabilistic models, enabling the exploration of exposure uncertainties and interventions. More generally, key recommendations when measuring PM2.5 emission rates include: high temporal resolution measurements; custom calibration factors; identifying periods for emissions, mixing, and decay; constant ventilation rates; quantifying mixing conditions; and ensuring high quality decay data.

A Review of Organ Dose Calculation Methods and Tools for Patients Undergoing Diagnostic Nuclear Medicine Procedures

Exponential growth has been observed in nuclear medicine procedures worldwide in the past decades. The considerable increase is attributed to the advance of positron emission tomography and single photon emission computed tomography, as well as the introduction of new radiopharmaceuticals. Although nuclear medicine procedures provide undisputable diagnostic and therapeutic benefits to patients, the substantial increase in radiation exposure to nuclear medicine patients raises concerns about potential adverse health effects and calls for the urgent need to monitor exposure levels. In the current article, model-based internal dosimetry methods were reviewed, focusing on Medical Internal Radiation Dose (MIRD) formalism, biokinetic data, human anatomy models (stylized, voxel, and hybrid computational human phantoms), and energy spectrum data of radionuclides. Key results from many articles on nuclear medicine dosimetry and comparisons of dosimetry quantities based on different types of human anatomy models were summarized. Key characteristics of seven model-based dose calculation tools were tabulated and discussed, including dose quantities, computational human phantoms used for dose calculations, decay data for radionuclides, biokinetic data, and user interface. Lastly, future research needs in nuclear medicine dosimetry were discussed. Model-based internal dosimetry methods were reviewed focusing on MIRD formalism, biokinetic data, human anatomy models, and energy spectrum data of radionuclides. Future research should focus on updating biokinetic data, revising energy transfer quantities for alimentary and gastrointestinal tracts, accounting for body size in nuclear medicine dosimetry, and recalculating dose coefficients based on the latest biokinetic and energy transfer data.

Fractional derivative method for anomalous aquitard flow in a leaky aquifer system with depth-decaying aquitard hydraulic conductivity

Aquitards significantly affect groundwater flow in multi-aquifer systems through adjacent aquifer leakage. Despite this, studies focusing on their heterogeneity and the non-conventional diffusion patterns of their flow are still limited. In this study, a factional derivative approach was first extended to explore the time-dependent behavior of flow transport in the aquitard. Two analytical solutions were derived for specific discharges in independent aquitards under different boundary conditions. The findings revealed that aquitard flow exhibits obvious anomalous diffusion behaviors, characterized by slower decay and heavy-tailed specific discharge data. The fractional derivative model provided a more accurate representation of this behavior than traditional models, as evidenced by its superior agreement with experimental data. Moreover, a transient model for pumping tests in a leaky aquifer system was developed, incorporating the memory effect of anomalous flow and vertical heterogeneity in aquitards. Relevant semi-analytical solutions were derived to explore the impacts of memory factor β and decay exponent of aquitard hydraulic conductivity (K) on the leakage aquifer system. Theoretical results demonstrated that stronger memory effect reduces drawdowns in the aquitard and confined aquifer during mid-to-late times. A larger dimensionless decay exponent (Ad) decreases aquitard drawdown and increases aquifer drawdown at late times. Sensitivity analysis showed aquitard drawdown experiences two peaks in sensitivity to β and Ad at early- or mid-times, affected by memory effect and decay exponent of aquitard K, signifying maximal impact at these specific intervals. This study provides a practical model to effectively manage groundwater resources by accurately reflecting aquitard memory and heterogeneity effects.

The Role of Air in Laser-Induced Thermal Emission of Surface Layers of Porous Carbon Materials

The influence of the surrounding air on the amplitude and shape of thermal radiation pulses (at a wavelength of 430 nm) during the heating of the surface layer of a porous carbon material (to temperatures of the order of 2000–3000 K) by the radiation of a Q-switched neodymium laser is studied. When the pressure of the surrounding air is reduced to forevacuum conditions, the experiments showed a one-and-a-half-fold increase in the amplitude of pulsed signals of thermal radiation and an increase in the decay time of the glow by about a third. Numerical calculations of the dynamics of the temperature field in the surface layer of the material during the irradiation by nanosecond laser pulses are carried out. An improved model is used in the calculations, which accounts for (i) the porosity of the material and (ii) the temperature dependence of the coefficients of thermal conductivity and the heat capacities of carbon and air. To calculate the thermal conductivity of the porous material, a model of a cubic array of intersecting square rods is used. The satisfactory consistency of calculation results with experimental data is obtained. The above-mentioned improvements of the calculation model made it possible to reconcile the estimates of the thermal characteristics of surface layers of carbon, obtained from the emission decay data, with the reference data published in the literature.

Nuclear Structure and Decay Data for A = 222 Isobars

Evaluated data are presented for 11 known A=222 nuclides (Bi, Po, At, Rn, Fr, Ra, Ac, Th, Pa, U, and Np), and relevant Jπ and T1/2 data for A=226 nuclei decaying by α-decay to A=222 nuclei. For 222Bi, only the isotopic identification is established with no measurement of its half-life. For 222Po, 222At, 222Fr, 222U, and 222Np, data are available only for the ground states, with static magnetic dipole and electric quadrupole moments, and charge radius measurements for the 222Fr ground state. For 222Ac and 222Pa, two low-lying levels are known from 226Pa α decay, and 226Np decay, respectively, but with no information about Jπ assignments and γ decays of these levels. For 222Pa, a long-lived isomeric state is known, decaying dominantly by α decay. 222Rn, 222Ra, and 222Th have been investigated in detail, the low-spin states by α decay and the high-spin studies of ground-state and octupole bands by in-beam γ-ray studies for all the three nuclei, as well as by Coulomb excitation for 222Rn and 222Ra. Low-spin levels in 222Ra have been investigated also through the β− decay of 222Fr. Half-lives of the excited states are known for 7 levels in 222Rn, 12 levels in 222Ra, and 3 levels in 222Th. Octupole deformations, with the presence of alternating-parity bands up to (16+) and (21−) in 222Rn, (20+) and (19−) in 222Ra, and (26+) and (25−) in 222Th, and with interband E1 transitions, have been established in these three nuclei. The present evaluation supersedes the previous A=222 ENSDF evaluations: (2011Si24), (1996El01), (1987El06) and (1977To14).

Recommended Nuclear Structure and Decay Data for A = 200 Isobars

Evaluated nuclear structure and decay data for all nuclei with mass number A=200 (200Os, 200Ir, 200Pt, 200Au, 200Hg, 200Tl, 200Pb, 200Bi, 200Po, 200At, 200Rn, and 200Fr), are presented. All available experimental data are compiled and evaluated, and best values for level and γ-ray energies, quantum numbers, lifetimes, γ-ray intensities and transition probabilities, as well as other nuclear properties, are recommended. Inconsistencies and discrepancies that exist in the literature are discussed. A number of computer codes (https://www-nds.iaea.org/public/ensdf_pgm/) developed by members of the NSDD network were used during the evaluation process. This work supersedes the earlier evaluation by F.G. Kondev and S. Lalkovski (2007Ko42), published in Nuclear Data Sheets108, 1471 (2007).

A new determination of the 68Ga half-life and evaluation of literature data

Inconsistencies within the 68Ga half-life dataset have been repeatedly identified in nuclear decay data evaluations performed over the past decade. In this paper, a half-life has been determined using ionisation chambers measurements and HPGe gamma-ray spectrometry (T1/2 = 67.783(27) min). The current literature has been reviewed and possible causes of discrepancy have been identified, such as neglected contaminant effects, robustness of analysis, and underestimation of systematic effects. This could lead to a significant improvement of the half-life in future evaluations.

Non-factorisable effects in the decays {overline{B}}_s^0to {D}_s^{+}{pi}^{-} and {overline{B}}^0to {D}^{+}{K}^{-} from LCSR

In light of the current discrepancies between the recent predictions based on QCD factorisation (QCDF) and the experimental data for several non-leptonic colour-allowed two-body B-meson decays, we obtain new determinations of the non-factorisable soft-gluon contribution to the decays {overline{B}}_s^0to {D}_s^{+}{pi}^{-} and {overline{B}}^0to {D}^{+}{K}^{-} , using the framework of light-cone sum rule (LCSR), with a suitable three-point correlation function and B-meson light-cone distribution amplitudes. In particular, we discuss the problem associated with a double light-cone (LC) expansion of the correlator, and motivate future determinations of the three-particle B-meson matrix element with the gluon and the spectator quark aligned along different light-cone directions. Performing a LC-local operator product expansion of the correlation function, we find, for both modes considered, the non-factorisable part of the amplitude to be sizeable and positive, however, with very large systematic uncertainties. Furthermore, we also determine for the first time, using LCSR, the factorisable amplitudes at LO-QCD, and thus the corresponding branching fractions. Our predictions are in agreement with the experimental data and consistent with the results based on QCDF, although again within very large uncertainties. In this respect, we provide a rich outlook for future improvements and investigations.

Luminescence and optical thermometry strategy based on emission spectra of Li2Ba5W3O15:Pr3+ phosphors

In this study, a series of Pr3+ ions doped Lithium Barium Tungstate (Li2Ba5W3O15) was synthesized using the conventional high-temperature solid state method. The structure and phase of the phosphors were analysed using X-ray diffraction (XRD) patterns. Fourier Transform Infrared (FT-IR) spectroscopy was used to examine the different vibrational bands present. The optical band gap values of the optimized LBW phosphor and the undoped LBW sample were measured using diffuse reflectance spectra (DRS). Under 319 nm excitation, the photoluminescence (PL) spectra of the Pr3+-activated LBW phosphor exhibited strong visible blue and reddish emissions at 488 nm and 647 nm respectively corresponding to the 3P0 → 3H4 and 3F2 transitions of the Pr3+ ions. The evaluated CIE color chromaticity coordinates of the as-prepared LBW:Pr3+ phosphors lie within the white region. The temperature-dependent PL (TDPL) measurement demonstrated relatively good thermal stability for the synthesized phosphor. Moreover, the fluorescence intensity ratio (FIR) was used to analyze the optical sensing properties of the LBW:Pr1.0 phosphor. A maximum relative sensitivity (Sr) of 1.03 % K−1indicated the potential of these phosphors for optical thermometry applications. A double exponential trend with decreasing lifetime was observed in the PL decay data at 647 nm emission (λem) under 319 nm excitation (λex), with an increase in the Pr3+ ions concentration in the host matrix. In conclusion, the investigations conducted demonstrate that the Pr3+ ions doped LBW phosphors show great potential for applications in solid-state lighting and optical thermometry. Its emission characteristics, thermal stability, and optical sensing capabilities establish it as a suitable candidate for these applications.