Speakers
Description
Reliable and precise nuclear decay data are essential in many applications. In radionuclide metrology, decay data are input parameters in calculations related to radioactivity measurements, when absolute or relative standardisation methods are used. This is why the metrology community, especially in Europe, has carefully evaluated decay schemes and atomic and nuclear data for the last 50 years.
This paper presents the results obtained recently concerning the update of the nuclear decay data evaluations of a number of radionuclides of interest for nuclear medicine: ${^{52}}Mn$, ${^{52m}}Mn$, ${^{226}}Th$ and ${^{230}}U$. The initial evaluations were produced in the framework of the IAEA CRP F41029 “Nuclear Data for Charged-particle Monitor Reactions and Medical Isotope Production” (2012-2018) $^{1,2,3,4}$. The work was undertaken using the procedures and tools of the Decay Data Evaluation Project (DDEP), an international co-operation officially founded 25 years ago $^{5}$. New developments in this field have recently become available. For example, the new Atomic Mass Evaluation (AME 2020) $^6$ has enabled updated decay energies (Q-values) to be included, which influence the beta endpoint energies in the decay schemes, having a particular importance for these evaluations. Furthermore, a new version (2.2/2021) of the BetaShape code $^{7,8}$ for $\beta$ transitions and electron captures (EC) has been released and provides improved calculations for single transition and total $\beta$ spectra, EC probabilities and their ratios for all subshells, mean energies, log ft values, EC/$\beta_+$ ratios and branch splitting. The new Q values from AME 2020 are included in this new version of the code as an external file, and a simple option allows for an automatic update of this parameter. These developments can lead to important improvements in the recommended data resulting from the evaluation procedure, beyond possible new published measurements. The nuclear decay data update for the two manganese radionuclides ${^{52}}Mn$ and ${^{52m}}Mn$, decaying by EC/$\beta_+$ transitions, is a good example of what improved theoretical predictions can provide. The updates to the two alpha-particle emitters, ${^{226}}Th$ and ${^{230}}U$, will also be discussed. The authors have also considered the question “How often should nuclear decay data evaluations be updated?”. Several criteria to support the decision of undertaking data evaluation updates are proposed and discussed, along with recent examples relevant for radionuclide metrology.
Acknowledgement: This work was funded through the research programme Program Nucleu, carried out with the support of the Romanian Ministry of Research, Innovation and Digitization (MCID), project no. PN 19 06 02 04 /2021.
References:
$^1$ A. Luca, Appl. Radiat. Isot. 155 (2020) 108941
$^2$ A. Luca, M.-R. Ioan, Appl. Radiat. Isot. 134 (2018) 426-428
$^3$ R. Capote et al., EPJ Web of Conferences 146, 08007 (2017)
$^4$ A. Luca, EPJ Web of Conferences 146, 08003 (2017)
$^5$ M.A. Kellett, O. Bersillon, EPJ Web of Conferences 146, 02009 (2017)
$^6$ Meng Wang et al., Chinese Phys. C 45 (2021) 030003
$^7$ X. Mougeot, Physical Review C 91, 055504 (2015); Erratum Phys. Rev. C 92, 059902 (2015)
$^8$ X. Mougeot, Appl. Radiat. Isot. 154 (2019) 108884