Speaker
Description
The accurate determination of reactor antineutrino spectra remains a very actual research topic for which new interrogations have emerged in the latest years. Indeed, after the “reactor anomaly”[1] – a deficit of measured antineutrinos at short baseline reactor experiments with respect to spectral predictions – the three international reactor neutrino experiments Double Chooz, Daya Bay and Reno have evidenced spectral distortions in their measurements w.r.t the same spectral predictions[2]. This puzzle is called the “shape anomaly”. The latter predictions were obtained through the conversion of integral beta energy spectra obtained at the ILL research reactor[3]. Several studies have shown that the underlying nuclear physics required for the conversion of these spectra into antineutrino spectra is not totally under control[4]. The unique alternative to converted spectra is a complementary approach consisting in determining the antineutrino spectrum through nuclear data[5,6]. It was shown that beta properties of some key fission products suffer from the pandemonium effect[7] which can be circumvented through the use of the Total Absorption Gamma-ray Spectroscopy technique (TAGS). The main contributors to the PWR (Pressurized Water Reactor) antineutrino spectrum in the region where the spectral distortion has been observed have been measured at the radioactive beam facility of the university of Jyväskylä in two TAGS experiments[8,9,10]. The analysis of these experiments is now complete and new yet unpublished results will be shown at this conference. We will then display an update of the cumulative impact on the predictions of reactor antineutrino spectra of the final results of these TAGS campaigns and compare with the results of reactor antineutrino experiments. Besides, comparisons of measured experimental beta strengths with predictions from theoretical models will be presented, of interest for nuclear structure and astrophysics.
[1] G. Mention et al. , Phys. Rev. D 83 , 073006 (2011)
[2] Double Chooz and Reno Collaborations in Proceedings of the Neutrino 2014 Conference, http://neutrino2014.bu.edu/; Daya Bay Collaboration in Proceedings of the ICHEP 2014 Conference, http://ichep2014.es/.
[3] P. Huber, Phys. Rev. C 84, 024617 (2011).
[4] A. C. Hayes et al., Phys. Rev. Lett. 112, 202501 (2014).
[5] M. Fallot et al., Phys. Rev. Lett. 109 , 202504 (2012).
[6] A A. Sonzogni et al. , Phys. Rev. C 91 , 011301 (R) (2015).
[7] J.C. Hardy et al. , Phys. Lett. B 71 , 307 (1977).
[8] A.-A. Zakari-Issoufou, Phys. Rev. Lett. 115 , 102503 (2015).
[9] V. Guadilla et al., Nuclear Instruments and Methods in Physics Research B 376 (2016) 334.
[10] A. Algora, B. Rubio, J.-L. Tain, M. Fallot, W. Gelletly Review Paper Eur. Phys. J. A 57, 85 (2021).