Vectorial velocity filter for ultracold neutrons based on a surface-disordered mirror system

Abstract

We perform classical 3D Monte Carlo simulations of ultracold neutrons scattering through an absorbing-reflecting mirror system in the Earth's gravitational field. We show that the underlying mixed phase space of regular skipping motion and random motion due to disorder scattering can be exploited to realize a vectorial velocity filter for ultracold neutrons. The absorbing reflecting mirror system proposed allows beams of ultracold neutrons with low angular divergence to be formed. The range of velocity components can be controlled by adjusting the geometric parameters of the system. First experimental tests of its performance are presented. One potential future application is the investigation of transport and scattering dynamics in confined systems downstream of the filter.

A Novel Nuclear Emulsion Detector for Measurement of Quantum States of Ultracold Neutrons in the Earth's Gravitational Field

“…) Here, Ai and Bi denote the Airy functions, and are normalization constants. As reported in prior experiments [24], we found that neutrons with high vertical energies interact with the upper rough surface, where they are absorbed or upscattered -and accordingly removed from the measurement. Consequently, only a superposition of the lowest few energy eigenstates is observed in the detector.…”

Rough Mirror as a Quantum State Selector: Analysis and Design

“…Recent first experimental observation of gravitationally quantized ultracold neutrons (UCNs) [2][3][4][5][6] stimulated use of mirrors with random rough surfaces as state selectors instead of simple absorbers in beam and similar experiments with UCNs [7][8][9], as well as for shaping UCN spectra [10][11][12] or exploring the whispering gallery quantum states of cold neutrons [13]. In these experiments a beam of UCNs with large horizontal and small vertical velocities propagates between two horizontal mirrors.…”

Quantized Ultracold Neutrons in Rough Waveguides: GRANIT Experiments and Beyond

“…One of the most interesting recent achievements in neutron physics is a series of GRANIT [1][2][3][4] and GRANIT-inspired [5][6][7] experiments aimed at detection of quantization of neutron motion by the Earth gravitational field. The experiment hinges on sending a beam of ultracold neutrons between rough and flat mirrors.…”