Corrections for exchange and screening effects in low-energy beta decays

Xavier Mougeot (1) , Marie-Martine Bé (1) , Charlène Bisch (1) , Martin Loidl (1)

1 LNHB (CEA, LIST) - Laboratoire National Henri Becquerel (CEA, LIST)

The beta spectra of $^{241}$Pu and $^{63}$Ni have been recently measured using metallic magnetic calorimeters. This powerful experimental technique allows theoretical beta spectra calculations to be tested at low energy with an accuracy never before achievable. Their comparison with classical beta calculations exhibits a significant deviation below 4 keV for $^{241}$Pu and 8 keV for $^{63}$Ni. The atomic exchange effect explains the main part of this deviation in the $^{63}$Ni beta spectrum. This effect has a significant contribution, equivalent to the magnitude of the screening, in the $^{241}$Pu beta spectrum.

Mots clés: $^{63}$Ni; Metallic magnetic calorimeters; metrology; ionizing radiation; radioactivity; instrumentation; nuclear instrumentation; beta-rays; spectrum analysis; Primary activity measurement; Decay data measurement; Calorimeter; Beta spectrum; $^{241}$Pu

Domaines: Physique Nucléaire Expérimentale [nucl-ex]

Xavier Mougeot, Marie-Martine Bé, Charlène Bisch, Martin Loidl. Corrections for exchange and screening effects in low-energy beta decays. Nuclear Data Sheets, 2014, 120, pp.129 - 132. ⟨10.1016/j.nds.2014.07.026⟩. ⟨cea-01848991⟩