Neutron optics

Abstract

A range of phenomena similar or analogous to those of classical optics is exhibited by slow neutrons. The aim of this review is to discuss this similarity and to display the results obtained in a wide range of experimental work on reflection, refraction, diffraction and interference of neutrons.The motivation of such experiments is discussed in the introductory section. The review is divided into three main sections: geometrical optics, wave optics and crystal optics; with subsections that parallel the typical textbook development of classical optics. Special emphasis is placed on the recent developments in neutron interferometry and on the fundamental tests of quantum-mechanical principles made possible by these novel techniques.

Observation of off-diagonal geometric phases in polarized-neutron-interferometer experiments

“…In particular, neutron interferometry experiments have made an impact for more than two decades [16][17][18][19]. Among them, those with a polarized incident beam served as an ideal tool to investigate properties of a spin-1/2 system [20].…”

Strong pairing approximation in comparison with the exact solutions to the pairing Hamiltonian

“…In the pairing problem we take into consideration 9 levels: from 1 f 5/2 up to 3s 1/2 . The Fermi level corresponds to the subshell 2d 5 17). Several levels (the lowest ones at a fixed quantum numbers of an odd proton) of the theoretical spectrum are shown in Table 1 for the neighbouring nucleus 149 65 Tb 84 .…”

“…[3] follow from commutators of creation and annihilation operators with H BCS . Such a way for deducing diverse formulae is called the equationsof-motion method (EOMM) [5]. Below we show that consistently conducting this method and taking advantage of the foregoing approximations all results of [3] can be obtained, i.e.…”

The photo-neutronrefractive effect

“…Refs. [24,25]. Inserting (8) in (7) leads to a Helmholtz type equation, with k 0 being the vacuum wave vector, if we properly define the refractive index for neutrons n N :…”

“…Moreover, for further experiments it is noteworthy that the AC effect is suppressed by choosing µ E. An interesting aspect of the Foldy-contribution (second term in (24)) is its appearance as a non-local effect. The corresponding neutronrefractive-index modulation is phase-shifted by π/2 with respect to that of the density modulation (25). Thus, measuring the phase shift, e.g.…”