New anomaly observed in 12C supports the existence and the vector character of the hypothetical X17 boson
PERIODICAL PUBLICATIONS
A.J. Krasznahorkay, A. Krasznahorkay, M. Begala, M. Csatlós, L. Csige, J. Gulyás, A. Krakó, J. Timár, I. Rajta, I. Vajda, N.J. Sas:
New anomaly observed in 12C supports the existence and the vector character of the hypothetical X17 boson
Physical Review C 106 (2022) L061601
DOI: https://doi.org/10.1103/PhysRevC.106.L061601
Published: 12 December 2022
Abstract
Employing the 11B(p,γ)12C nuclear reaction, the angular correlation of e+e– pairs was investigated in the angular range of 40∘≤Θ≤175∘ for five different proton energies between Ep=1.50–2.5 MeV. At small angles (Θ≤120∘), the results can be well interpreted by the internal pair creation process of electromagnetic radiations with E1 and M1 multipolarities and by the external pair creation in the target backing. However, at angles greater than 120∘, additional count excesses and anomalies were observed, which could be well accounted for by the existence of the previously suggested hypothetical X17 particle. Our results suggest that the X17 particle was generated mainly in E1radiation. The derived mass of the particle is mxc2=17.03±0.11(stat)±0.20(syst) MeV. According to the mass, and to the derived branching ratio [Bx=3.6(3)×10−6], this is likely the same X17 particle that we recently suggested for describing the anomaly observed in the decay of 8Be and 4He.