A white beam spin echo interferometer for neutron orbital angular momentum generation

The broadband resonant spin echo interferometer, Coherent Averaging Neutron Instrument for Spin-echo Interferometry and fUndamental Science (CANISIUS), is presented. CANISIUS is located at the 250 kW Training, Research, Isotopes, General Atomics research facility of the Atominstitut, TU Wien, Austria. It is built in a versatile way, such that it can be operated in both a continuous broadband beam and a pulsed time of flight beam. This versatility also extends to the modes available to the instrument, such as neutron resonant spin echo, spin echo (modulated) small angle neutron scattering, and coherent averaging to produce structured wavefunctions for scattering. The instrument may also be used as an interferometer, to probe fundamental questions in quantum mechanics. In this paper, we detail both the continuous and time of flight options of the instrument. In addition, we demonstrate the applicability of our interferometer to ultra small angle scattering in a white beam. Finally, we demonstrate a new spin echo interferometry tool, which uses incomplete recombination of the two path states to generate composite wavefunctions with special structure. In particular, we show that this method produces neutron wavefunctions that exist in a superposition of two quantum mechanical orbital angular momentum modes, ℓ = ±1. We illustrate that just as this method can be used to generate certain structured waves, it may also be used to characterize the structure of the input wavefunction.