First direct measurement of the spectrum emitted by the H3(H2,γ)<…

The spectral 𝛾 ray emission from the reaction 3H⁡(2H,𝛾)⁢5He has been measured for the first time in a magnetic confinement deuterium-tritium plasma experiment at the Joint European Torus. A custom developed gamma ray spectrometer system based on a La⁢Br3 scintillator combined to a LiH neutron attenuator and a zero dead time fast digital data acquisition allowed to measure the weak 𝛾 ray emission under the ≈105 more intense 14MeV neutron field. The 𝑅-matrix analysis of the 5He nucleus has been used to predict the expected gamma ray spectrum which has been compared with the measurement, but cannot predict the relative intensity of the 𝛾 lines. The data analysis has identified the energy and width of the known 16.75 MeV 𝛾 ray emission (𝛾0), from the second excited state to the ground state of the formed 5He nucleus, and confirmed the presence of a second emission (𝛾1) at ≈14⁢MeV due to the transition from the second to the first excited state. The analysis has shown that the 𝛾1 emission is broad and has assessed for the first time in a magnetic confinement experiment the relative yield 𝛾1 to 𝛾0 equal to 1.09±0.25.Received 2 January 2024Accepted 20 March 2024DOI:https://doi.org/10.1103/PhysRevC.110.014625©2024 American Physical SocietyPhysics Subject Headings (PhySH)