R-matrix description of particle energy spectra produced by low-energyH3+H3

Abstract

An R-matrix model for three-body final states is presented and applied to a recent measurement of the neutron energy spectrum from the T + T → 2n + α reaction. The calculation includes the nα and nn interactions in the final state, angular momentum conservation, antisymmetrization, and the interference between different channels. A good fit to the measured spectrum is obtained, where clear evidence for the 5 He ground state is observed. The model is also used to predict the α-particle spectrum from T + T as well as particle spectra from 3 He + 3 He. The R-matrix approach presented here is very general, and can be adapted to a wide variety of problems with three-body final states.

The effects of ion temperature on the energy spectra of T + T → 2n + α reaction products

“…[2] This data includes contributions from the 5 He (GS), 5 He (ES) and dineutron channels as well as interference between the different reaction channels. The R-matrix calculation was carried out for a reaction energy of 16 keV only and parameter values were chosen so that the spectrum agreed with experimental data.…”

“…The 5 He (GS) channel produces a spectrum peak at 8.7 MeV while the 5 He (ES) channel produces a broad, near-elliptical neutron spectrum. Further details of the different spectral features, for both the n and α particles, may be found in the recent work of Brune et al [2] A major question regarding the TT reaction is the relative strengths of the reaction channels and how the relative strength varies with reaction energy. This has been the focus of much research.…”

“…[5] However, another set of experiments at a mean reaction energy of 16 keV did observe such a peak [6] and this result was supported by theoretical calculations. [2] The lack of clear trends in existing experimental data highlights the need for further investigation of the TT reaction.…”

“…[3] However, the significance of (14) is that, even if the CM frame spectrum contains anisotropic features, the thermal broadening does not depend on angular variations in the CM frame spectrum but only on the angular-averaged spectrum. Therefore, anisotropic emission in the CM frame or effects such as the angular correlation of primary and secondary neutrons emitted by the 5 He (GS) [2] cannot be observed by varying the temperature of a reacting plasma. This may not be the case for reactant distributions other than Maxwellian, even if the distributions are isotropic.…”

T(T,2n)4He and3He(3He,2p)4He: The Reaction Mechanism from Solar Energies to 10 MeV

“…Of less importance is the weaker n-n or p-p final state interaction. A new reaction model has been developed by Carl Brune at Ohio University, Dan Sayre at Lawrence Livermore National Laboratory, and by Gerry Hale at Los Alamos National Laboratory [1]. It is a based on an extended R-matrix which can handle both the three body final states and the presence of identical fermions.…”