Optimizing the ${}^8$Li yield for the IsoDAR Neutrino Experiment

Abstract

The focus of this paper is on optimizing the electron-antineutrino source for the IsoDAR (Isotope Decay at Rest) experimental program. IsoDAR will perform sensitive short-baseline neutrino oscillation and electroweak measurements, among other Beyond Standard Model searches, in combination with KamLAND and/or other suitable detectors. IsoDAR will rely on the high-$Q$ $β^-$ decay of the ${}^8$Li isotope for producing electron-antineutrinos, created mainly via neutron capture in an isotopically enriched ${}^7$Li sleeve surrounding the Be target. In particular, this paper examines the performance, defined in terms of absolute ${}^8$Li (or, equivalently, electron-antineutrino) production rate, of various candidate sleeve materials, including a lithium-fluoride, beryllium-fluoride mixture ("FLiBe") sleeve and a homogeneous mixture of lithium and beryllium ("Li-Be"). These studies show that the ${}^8$Li yield can be increased substantially by employing a Li-Be sleeve and therefore motivate significant changes to the nominal IsoDAR design.

9 pages