The fusion of deuterium (D) with tritium (T) is the most promising of the reactions that could power thermonuclear reactors of the future. It may lead to even more efficient energy generation if obtained in a polarized state, that is with the spin of the reactants aligned. Here, we report first-principles predictions of the polarized DT fusion using nuclear forces from effective field theory.
View Article and Find Full Text PDFThe weakly bound exotic ^{11}Be nucleus, famous for its ground-state parity inversion and distinct n+^{10}Be halo structure, is investigated from first principles using chiral two- and three-nucleon forces. An explicit treatment of continuum effects is found to be indispensable. We study the sensitivity of the ^{11}Be spectrum to the details of the three-nucleon force and demonstrate that only certain chiral interactions are capable of reproducing the parity inversion.
View Article and Find Full Text PDFThe Borromean ^{6}He nucleus is an exotic system characterized by two halo neutrons orbiting around a compact ^{4}He (or α) core, in which the binary subsystems are unbound. The simultaneous reproduction of its small binding energy and extended matter and point-proton radii has been a challenge for ab initio theoretical calculations based on traditional bound-state methods. Using soft nucleon-nucleon interactions based on chiral effective field theory potentials, we show that supplementing the model space with ^{4}He+n+n cluster degrees of freedom largely solves this issue.
View Article and Find Full Text PDFWe provide a unified ab initio description of the ^{6}Li ground state and elastic scattering of deuterium (d) on ^{4}He (α) using two- and three-nucleon forces from chiral effective field theory. We analyze the influence of the three-nucleon force and reveal the role of continuum degrees of freedom in shaping the low-lying spectrum of ^{6}Li. The calculation reproduces the empirical binding energy of ^{6}Li, yielding an asymptotic D- to S-state ratio of the ^{6}Li wave function in the d+α configuration of -0.
View Article and Find Full Text PDFThe low-lying continuum spectrum of the (6)He nucleus is investigated for the first time within an ab initio framework that encompasses the (4)He + n + n three-cluster dynamics characterizing its lowest decay channel. This is achieved through an extension of the no-core shell model combined with the resonating-group method, in which energy-independent nonlocal interactions among three nuclear fragments can be calculated microscopically, starting from realistic nucleon-nucleon interactions and consistent ab initio many-body wave functions of the clusters. The three-cluster Schrödinger equation is solved with three-body scattering boundary conditions by means of the hyperspherical-harmonics method on a Lagrange mesh.
View Article and Find Full Text PDFThe neutron-rich unbound 7He nucleus has been the subject of many experimental investigations. While the ground-state 3/2- resonance is well established, there is a controversy concerning the excited 1/2- resonance reported in some experiments as low lying and narrow (E(R)∼1 MeV, Γ≤1 MeV) while in others as very broad and located at a higher energy. This issue cannot be addressed by ab initio theoretical calculations based on traditional bound-state methods.
View Article and Find Full Text PDFWe apply the ab initio no-core shell model combined with the resonating-group method approach to calculate the cross sections of the (3)H(d,n)(4)He and (3)He(d,p)(4)He fusion reactions. These are important reactions for the big bang nucleosynthesis and the future of energy generation on Earth. Starting from a selected similarity-transformed chiral nucleon-nucleon interaction that accurately describes two-nucleon data, we performed many-body calculations that predict the S factor of both reactions.
View Article and Find Full Text PDFThe chiral low-energy constants c(D) and c(E) are constrained by means of accurate ab initio calculations of the A = 3 binding energies and, for the first time, of the triton beta decay. We demonstrate that these low-energy observables allow a robust determination of the two undetermined constants, a result of the surprising fact that the determination of c(D) depends weakly on the short-range correlations in the wave functions. These two- plus three-nucleon interactions, originating in chiral effective field theory and constrained by properties of the A = 2 system and the present determination of c(D) and c(E), are successful in predicting properties of the A = 3 and 4 systems.
View Article and Find Full Text PDFPhys Rev Lett
August 2008
We develop a new ab initio many-body approach capable of describing simultaneously both bound and scattering states in light nuclei, by combining the resonating-group method with the use of realistic interactions, and a microscopic and consistent description of the nucleon clusters. This approach preserves translational symmetry and Pauli principle. We present phase shifts for neutron scattering on 3H, 4He, and 10Be and proton scattering on 3,4He, using realistic nucleon-nucleon potentials.
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