Intense antineutrino source based on a lithium converter. Proposal for a promising experiment for studying oscillations

Abstract

An intense electron-antineutrino source with a hard spectrum ($E_{{{\tilde v}_e}}^{\max }$ = 13 MeV and $\left\langle {{E_{{{\tilde v}_e}}}} \right\rangle$ = 6.5MeV) can be created on the basis of the short-lived isotope ⁸Li (β⁻-decay, T _1/2 = 0.84 s) formed via the (n, γ) activation of ⁷Li. In contrast to a reactor antineutrino spectrum whose uncertainty is large, particularly in the high-energy region ${E_{{{\tilde v}_e}}}$ > 6 MeV, which is experimentally relevant, the lithium ${\tilde v_e}$ spectrum is accurately determined. The proposed accelerator-driven experimental scheme with a neutron-producing target and a lithium converter as an intense ${\tilde v_e}$ source is an alternative to a nuclear reactor. The required amount of high-purity ⁷Li will be reduced in many times by using the suggested heavy-water LiOD solutions. A possible experiment involving the lithium source on search for sterile neutrinos in the mass region Δm ² ≥ 0.2 eV² with a very high sensitivity to mixing-angle values down to sin²(2Θ) ≈ (7–10) × 10^–4 at the 95% C.L. has been considered.