Nested Mirror Optics – Towards a New Generation of Neutron Transport Systems?

by Christoph Herb (TUM)

Monday 24 Apr 2023, 14:30 → 15:30 Europe/Berlin

PH HS 3 (Physics Department)

The advent of high-brilliance neutron moderators has raised the question how one efficiently extracts and transports neutrons from compact sources while maximizing the brilliance transfer to an instrument. Nested mirror optics (NMO) are designed to offer a viable and flexible solution for this task by circumventing the under-illumination associated with long neutron guides. A simple assembly of short elliptic mirrors is able to image a well-defined volume of beam phase space from the moderator surface onto a target, e.g., a sample or a virtual source. In contrast to conventional neutron guides, each of the NMO’s individual mirrors reflects neutrons only within a narrow range of angles. Due to its geometrically well-defined reflection kinematics, one can tailor the divergence and spectrum of the transported beam to the needs of an experiment by the design of the NMO. The device thus provides a clean beam without relying on optical elements close to the source or the target, which leads to a number of practical advantages in setting up the sample environment.
Besides an introduction to neutron guides and NMO, we will present the characterization of a polarizing elliptic NMO prototype conducted at MIRA (FRM2). We will further highlight results obtained at the BOA beamline (PSI), which include, among others, the imaging of two-dimensional structures. Supported by McStas simulations, various potential applications of NMO in neutron extraction, transport, and focusing are demonstrated.