Speaker
Description
Reactor antineutrino energy spectra are the subject of active experimental researches nowadays, either through large reactor neutrino experiments, short baseline neutrino experiments at research reactors or through dedicated nuclear physics measurements of the properties of the fission products. The summation method relies on the use of nuclear data to build the reactor antineutrino energy spectrum emitted by a reactor, or after the fission of each actinide at the origin of the thermal power in-core[1,2]. It is a unique alternative to converted spectra[3], which rely on measurements of integral beta spectra and a subsequent conversion approach. The summation method presents in addition the advantage of being predictive ; it can be used for the computation of reactor antineutrino spectra associated to innovative fuels, of interest for non-proliferation purposes, or to predict the antineutrino spectrum in wider energy ranges (lower/larger energies) than accessible with the conversion method, of interest for the fundamental study of neutrino properties.
During the last decade, the precision achieved by the summation method to predict reactor antineutrino spectra has been greatly improved by nuclear data measurements using the Total Absorption Gamma-ray Spectroscopy technique (TAGS)[4], reaching a level comparable to the conversion method[1,3]. The main drawback of the summation predictions is the difficulty to propagate the uncertainties of nuclear data on the antineutrino observable, which require covariance matrices for fission yields and for beta decay data. Covariance matrices for fission yields could be obtained consistently with predictions for fission yields from a model such as the GEF model[5].
Recently, we have used the reactor antineutrino observable to improve the GEF model [6], making it a useful tool to predict fission yields for antineutrino spectra calculations, along with their uncertainties. The level of prediction achieved by the antineutrino flux obtained with the GEF fission yields is now close to the one obtained in[4], it is thus possible to use GEF to compute the associated uncertainties.
At this conference, we will present new summation method antineutrino predictions based on fission yields computed with the new version of the GEF code, updated with the latest Total Absorption Gamma-ray Spectroscopy (TAGS) results [6] and, for the first time, with their associated computed uncertainties. Spectra will be displayed for the main uranium and plutonium isotopes contributing to the fissions in a Pressurized Water Reactor, but also for various fuels to be used in innovative reactor designs. The results will be compared with recent measurements of reactor antineutrino flux and energy spectra.
[1] Th. A. Mueller et al., Phys.Rev. C 83 , 054615 (2011)
[2] M. Fallot et al., Phys. Rev. Lett. 109 , 202504 (2012)
[3] P. Huber, Phys. Rev. C 84, 024617 (2011). Also presented in ND2013.
[4] M. Estienne et al., Phys. Rev. Lett. 123, 022502 (2019).
[5] K.-H. Schmidt, B. Jurado, C. Amouroux, C. Schmitt, Nucl. Data Sheets 131 (2016) 107
[6] K.-H. Schmidt, M. Estienne, M. Fallot et al., Nuclear Data Sheets Volume 173, (2021)