Definitive Detection of Orbital Angular Momentum States in Neutrons by Spin-polarized ${}^3$He

Abstract

A standard method to detect thermal neutrons is the nuclear interaction ${}^3$He(n,p)${}^3$H. The spin-dependence of this interaction is also the basis of a neutron spin-polarization filter using nuclear polarized ${}^3$He. We consider the corresponding interaction for neutrons placed in an intrinsic orbital angular momentum (OAM) state. We derive the relative polarization-dependent absorption cross-sections for neutrons in an $L=1$ OAM state. The absorption of those neutrons results in compound states $J^{\pi }=0^{-}$, $1^{-}$, and $2^{-}$. Varying the three available polarizations tests that an OAM neutron has been absorbed and probes which decay states are physically possible. We describe the energetically likely excited states of ${}^4$He after absorption, due to the fact that the compound state has odd parity. This provides a definitive method for detecting neutron OAM states and suggests that intrinsic OAM states offer the possibility to observe new physics, including anomalous cross-sections and new channels of radioactive decay.

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Cited by in corpus (3)

• Promises and challenges of high-energy vortex states collisions
• Spin-Textured Neutron Beams with Orbital Angular Momentum
• Theoretical consideration of a twisted atom