ICRM Beta Particle Spectrometry Working Group

The Beta Particle Spectrometry Working Group is devoted to the development of the metrological aspects of beta spectrometry and its applications. This includes, but is not restricted to:

  • Theory
    • Beta (β±) and electron capture (ε) transitions
    • Theoretical shape factors and influence of the nuclear current
    • Atomic effects
  • Experiments
    • Instrumentations used for beta spectrometry
    • Techniques that need beta information
    • Confidence on experimental shape factors
    • Data analysis and unfolding methods
  • Simulations
    • Confidence on the physical processes: low energies, radioactive decays, atomic rearrangements
    • Comparison of the results of different codes: Geant4, Penelope, etc.
  • Evaluations and dissemination
    • Confidence and uncertainties on experimental shape factors
    • Evaluation procedure for establishing recommended experimental shape factors
    • Mean energies, log ft values, database

Interested communities in radionuclide metrology are: nuclear decay data, liquid scintillation counting, ionizing chambers, 4π β-γ counting.

Any experimental shape factor found in the literature can be sent to the coordinator who will keep up-to-date a dedicated database.

Any other suggested topic is welcome. If you want to participate to this working group, please E-mail your contribution to the coordinator: xavier.mougeot@cea.fr

Projects

French ANR Project bSTILED “b: Search for Tensor Interactions in nuclear beta decays” (2020 – 2026)

This proposal aims at performing the most sensitive search for exotic tensor type interactions contributing to the weak interaction involving the lightest quarks. The observation of such contributions would provide a signature for new physics beyond the standard electroweak model whereas their non-observation will provide the tightest constraints on the couplings associated with those interactions. The search will be performed through high precision measurements of the full beta-energy spectrum in the decay of 6He nuclei. The main instrumental effect which has precluded these measurements to be performed so far, associated with the back-scattering of beta particles on detectors, is eliminated by improving and implementing calorimetric techniques in which the active volume of particle detectors fully encloses the decay source.

Coordinator: Oscar Naviliat-Cuncic (naviliat@lpccaen.in2p3.fr)

EMPIR Project PrimA-LTD “Towards new primary activity standardisation methods based on low-temperature detectors” (2021 – 2024)

Radionuclide metrology and specifically activity standardisation are based on well-established measurement techniques, which have been used and improved for decades. However depending on the decay mode, for some nuclides, the achievable uncertainty on the activity is up to an order of magnitude larger than usual. The aim of this project is to achieve new primary activity standardisation methods based on low-temperature detectors, in particular by measuring with high statistics the 55Fe and 129I decays. A high-precision theoretical description of these two decays, including both nuclear and atomic structure, will also be conducted.

Coordinator: Ole Nähle (ole.j.naehle@ptb.de)

Website: https://prima-ltd.net/

EMPIR Project MetroMMC “Measurement of fundamental nuclear decay data using metallic magnetic calorimeters” (2018 – 2021)

The main objective of the MetroMMC project is to improve the knowledge of electron capture decay and subsequent atomic relaxation processes. New theoretical calculation techniques and extensive experiments using MMCs will be developed to determine important decay data which are relevant for primary activity standardisations in radionuclide metrology, in cancer therapy on the DNA level, and when studying the early history of the solar system. The experimental parts will be complemented with a new approach based on microwave coupled resonators.

Coordinator: Dirk Arnold (dirk.arnold@ptb.de)

Website: http://empir.npl.co.uk/metrommc/

EMPIR Project MetroBeta “Radionuclide beta spectra metrology” (2016 – 2019)

This project proposes both theoretical and experimental approaches to improve the knowledge of beta spectra. On the theoretical side, the existing knowledge of the calculation of nuclear wave functions will be used to account for the nuclear structure effect on these spectra. On the experimental side, the development of beta spectrometry with metallic magnetic calorimeters, a class of cryogenic detectors operating at very low temperature, and solid scintillators containing the beta emitters in the structure of the scintillator crystal are addressed. These detectors have the potential to measure the shapes of beta spectra with unprecedented precision and, in particular in the case of metallic magnetic calorimeters, low systematic errors. Comparison of the newly calculated and measured spectra, as well as the application of several complementary detection techniques, will validate the quality of the spectra.

Coordinator: Mark A. Kellett (mark.kellett@cea.fr)

Website: http://metrobeta-empir.eu/

Meetings

  • MetroMRT Workshop – Paris, France (May 21-22, 2014). Website: http://projects.npl.co.uk/metromrt/

  • ICRM 2015, 20th International Conference on Radionuclide Metrology and its Applications – Vienna, Austria (June 8-11, 2015). First meeting of the Beta Particle Spectrometry Working Group.

  • Kick-off meeting of MetroBeta – Saclay, France (July 5-6, 2016).

  • 6th Decay Data Evaluation Project Workshop and ICRM Working Group meetings – National Physical Laboratory, Teddington, UK (September 19-22, 2016).

  • A Working Group meeting took place in Buenos Aires during the last ICRM conference (May 15-19, 2017).

  • Joint radionuclide metrology meetings took place at NIST (September 10-14, 2018):
    1. Decay Data Evaluation Project (September 10-11, 2018)
    2. Nuclear Decay Data Working Group (September 11, 2018)
    3. Beta-Particle Spectrometry Working Group (September 11, 2018)
    4. Radionuclide Metrology Technique Working Group (September 12, 2018)
    5. NIST – BIPM Workshop on low electrical current measurement for radioactivity metrology (September 13, 2018)
    6. MetroBeta Workshop (September 14, 2018)
    7. MetroMMC workshop (October 24, 2019)

  • A Working Group meeting took place in Salamanca during the ICRM 2019 conference (May 27-31, 2019). Three presentations were given:
    1. M. A. Kellett (LNHB), Overview of the MetroBeta Project.
    2. K. Kossert (PTB), Comparison and validation of beta spectra measurements.
    3. D. Arnold (PTB), Overview of the MetroMMC project.

  • The MetroMMC Workshop took place at LNHB (October 24, 2019).

  • Joint radionuclide metrology meetings took virtually place at LNHB (October 26-30, 2020):
    1. Decay Data Evaluation Project (October 26, 2020).
    2. Nuclear Decay Data Working Group (October 27, 2020).
    3. Beta-Particle Spectrometry Working Group (October 27, 2020).
    4. Radionuclide Metrology Technique Working Group (October 28, 2020).
    5. Gamma Spectrometry Working Group (October 29-30, 2020).

    The virtual character of the Working Group meeting (October 27, 2020) noticeably increased the audience, with 26 attendees. This possibility should be kept for future meetings, even without any travel restriction. Four presentations were given:
    1. M. Loidl (LNHB), Measurement of nuclear decay data by means of metallic magnetic calorimeters within European metrology research (EMPIR) projects.
    2. P. Ranitzsch (PTB), MMC measurements at PTB-BS.
    3. A. Singh (LNHB), Measurements of beta spectra with silicon detectors.
    4. X. Mougeot (LNHB), New version of the BetaShape code.

    B. Zimmerman (NIST) announced that the Radioactivity Group successfully defended a project dedicated to the development of a cryogenic facility for radiation measurements. This project will last 5 years, starting in 2021.

  • The 2nd MetroMMC stakeholders meeting took place at NPL (December 17, 2021).

  • The PrimA-LTD Workshop took place at CIEMAT (November 24, 2022).

  • A Working Group meeting took place in Bucharest during the ICRM 2023 conference (March 27-31, 2023). The meeting was in hybrid format, with attendees of the ICRM conference and 24 additional attendees online. Four presentations were given, with one online:
    1. K. Kossert (PTB) – Overview of the European project PrimA-LTD.
    2. D. Bergeron (NIST) – Progresses and plans on Decay Energy Spectrometry with Transition Edge Sensors.
    3. G. Cavoto (Sapienza Uni. Roma & INFN Roma) – Development of detectors for ultra-low energy neutrinos. (online)
    4. X. Mougeot (LNHB) – Recent collaborative studies on beta decays.

  • A virtual MMC Workshop was organized within the PrimA-LTD project (May 2-3, 2024).

  • The 2nd stakeholders Workshop of the PrimA-LTD project took place at PTB Braunschweig (May 23, 2024).

  • The latest Working Group meeting took place in Paris during the ICRM 2025 conference (May 19-22, 2025). Three presentations were given:
    1. K. Kossert (PTB) – Outcomes of the PrimA-LTD partners.
    2. D. Bergeron (NIST) – Towards beta spectroscopy with transition edge sensors at NIST: Experience with 239Np.
    3. X. Mougeot (LNHB) – Theoretical calculation of the 99Tc forbidden non-unique transition.

  • A workshop took place at CEA Saclay (France) in the framework of the “Espace of Structure and Nuclear reaction Theory” (ESNT) from 7 to 11 July 2025. It was co-organized by B. Charles Rasco (Physics Division, Oak Ridge National Laboratory) and X. Mougeot (LNHB) on the topic “Probing nuclear structure with β-decay energy spectra, present and near future state”. The workshop convened approximately twenty participants from North America, Europe and the United Kingdom, with a mixture of half theorists and half experimentalists. The discussions were very fruitful, and it is anticipated that a similar meeting will be convened in the near future.
    Website: https://esnt.cea.fr/Phocea/Page/index.php?id=129

Software

BetaShape

The BetaShape program has been developed for improving the nuclear data related to beta emission properties. The theoretical model was implemented with analytical calculations, except for the relativistic electron wave functions which are numerical solutions of the Dirac radial equations. Mean energies, log ft values as well as beta and neutrino spectra for single and multiple transitions are provided. A database of experimental shape factors is also included and the uncertainties from the input parameters are propagated.

Link: http://www.lnhb.fr/rd-activities/spectrum-processing-software/

Working Group reports

Annual reports of the Working Group are available here:

Scientific publications

Relevant articles, books and reports for beta spectrometry and its applications will be listed here after agreement of the members of the Working Group.

Preliminary measurement of the 147Pm beta decay spectrum with a 4π Si(Li) beta spectrometer G. Craveiro et al. Applied Radiation and Isotopes 226, 112193 (2025) DOI Internal bremsstrahlung in beta decays X. Mougeot et al. Applied Radiation and Isotopes 226, 112197 (2025) DOI Direct experimental constraints on the spatial extent of a neutrino wavepacket J. Smolsky et al. Nature 638, 640-644 (2025) DOI Influence of atomic modeling on electron capture and shaking processes A. Andoche, L. Mouawad, P.-A. Hervieux, X. Mougeot, J. Machado, J. P. Santos Physical Review A 109 (2024), 032826 DOI / OpenAccess High precision measurement of the 99Tc β spectrum M. Paulsen et al. Physical Review C 110, 055503 (2024) DOI Unfolding experimental distortions in beta spectrometry G. Craveiro et al. Frontiers in Physics 12, 1435615 (2024) DOI Comprehensive revision of the summation method for the prediction of reactor νe fluxes and spectra L. Périssé et al. Physical Review C 108, 055501 (2023) DOI Search for low-mass dark matter WIMPs with 12 ton-day exposure of DarkSide-50 P. Agnes et al. Physical Review D 107, 063001 (2023) DOI Development of a 4π detection system for the measurement of the shape of β spectra A. Singh et al. Nuclear Instruments and Methods in Physics Research, A 1053, 168354 (2023) DOI Activity standardization of 60Co and 106Ru/106Rh by means of the TDCR method and the importance of the beta spectrum C. Bobin et al. Applied Radiation and Isotopes 201, 110993 (2023) DOI Atomic exchange correction in forbidden unique beta transitions X. Mougeot Applied Radiation and Isotopes 201 (2023) 111018 DOIOpenAccess Updated evaluation of potential ultralow Q-value β-decay candidates D.K. Keblbeck et al. Physical Review C 107, 015504 (2023) DOI Measurements and computational analysis of the natural decay of 176Lu F. G. A. Quarati, G. Bollen, P. Dorenbos, M. Eibach, K. Gulyuz, A. Hamaker, C. Izzo, D. K. Keblbeck, X. Mougeot, D. Puentes, M. Redshaw, R. Ringle, R. Sandler, J. Surbrook, I. Yandow Physical Review C 107, 024313 (2023) DOI / OpenAccess Systematics of log ft values for β-, and EC/β+ transitions Steffen Turkat, Xavier Mougeot, Balraj Singh, Kai Zuber Atomic Data and Nuclear Data Tables 152 (2023) 101584 DOIOpenAccess K- and L-shell theoretical fluorescence yields for the Fe isonuclear sequence Daniel Pinheiro, André Fernandes, César Godinho, Jorge Machado, Gonçalo Baptista, Filipe Grilo, Luís Sustelo, Jorge M. Sampaio, Pedro Amaro, Roberta G. Leitão, José P. Marques, Fernando Parente, Paul Indelicato, Miguel de Avillez, José Paulo Santos, Mauro Guerra Radiation Physics and Chemistry 203 (2023) 110594 DOIOpenAccess High precision measurement of the 151Sm beta decay by means of a metallic magnetic calorimeter Karsten Kossert, Martin Loidl, Xavier Mougeot, Michael Paulsen, Philipp Ranitzsch, Matias Rodrigues Applied Radiation and Isotopes 185 (2022) 110237 DOIOpenAccess High-precision measurement of the 6He half-life M. Kanafani et al. Physical Review C 106, 045502 (2022) DOI Improved activity standardization of 90Sr/90Y by means of liquid scintillation counting K. Kossert, X. Mougeot Applied Radiation and Isotopes 168, 109478 (2021) DOI Improved calculations of beta decay backgrounds to new physics in liquid xenon detectors S. Haselschwardt, J. Kostensalo, X. Mougeot, J. Suhonen Physical Review C 102, 065501 (2020) DOI Excess Electronic Recoil Events in XENON1T E. Aprile et al. Physical Review D 102, 072004 (2020) DOI Direct measurement of the 7Be L/K capture ratio in Ta-based superconducting tunnel junctions S. Fretwell et al. Physical Review Letters 125, 032701 (2020) DOI Toward high-precision calculation of electron capture decays X. Mougeot Applied Radiation and Isotopes 154, 108884 (2019) DOI Activity determination of 60Co and the importance of its beta spectrum K. Kossert, J. Marganiec-Gałązka, X. Mougeot, O.J. Nähle Applied Radiation and Isotopes 134, 212-218 (2018) DOI Improved calculations of electron capture transitions for decay data and radionuclide metrology X. Mougeot Applied Radiation and Isotopes 134, 225-232 (2018) DOI High precision analytical description of the allowed β spectrum shape L. Hayen, N. Severijns, K. Bodek, D. Rozpedzik, X. Mougeot Reviews of Modern Physics 90, 015008 (2018) DOI Experiments and theory of 138La radioactive decay F. G. A. Quarati, P. Dorenbos, X. Mougeot Applied Radiations and Isotopes 109, 172-176 (2016) DOI Reliability of usual assumptions in the calculation of β and ν spectra X. Mougeot Physical Review C 91, 055504 (2015) DOI The importance of the beta spectrum calculation for accurate activity determination of 63Ni by means of liquid scintillation counting K. Kossert, X. Mougeot Applied Radiation and Isotopes 101, 40-43 (2015) DOI Beta spectrometry with metallic magnetic calorimeters M. Loidl et al. Applied Radiation and Isotopes 87, 302-305 (2014) DOI

Disclaimer
This site is non-commercial. Materials and manufacturers are cited only for information purposes and citation does not mean that the site host or the working group recommend or support these materials. Any hyperlinks are only given for convenience and do not imply any support from the working group, the International Committee for Radionuclide Metrology or the French Commissariat à l’Énergie Atomique et aux Énergies Alternatives.
The opinions presented in this site are those of the ICRM working group moderated by the coordinator.