Ultracold neutrons

Abstract

Nearly twenty years ago Ya. B. Zeldovich pointed out that free neutrons, if sufficiently slow, could in principle be stored in a closed “bottle”—presumably for periods up to the beta decay lifetime, about 103 seconds. Apparently, according to Bruno Pontecorvo, Enrico Fermi had mentioned this possibility as early as the middle 1930's, but Zeldovich's paper was the first published discussion. The basis for the belief that neutrons could be stored in this way was the behavior of the effective potential for the interaction of neutrons with matter, which for many substances becomes repulsive when the neutrons are sufficiently slow. Thus there is a strong suppression of inelastic processes for these very slow neutrons (energies below about 10−7 eV), and they are totally reflected upon collisions with, for example, container walls.

Quantum motion of a neutron in a waveguide in the gravitational field

“…[41][42][43][44][45] and the references therein, devoted to the theory of the interaction of waves with rough surfaces). Section IV is devoted to the passage of neutrons through the waveguide with a flat neutron absorber, as proposed in [7,8] and Sec. V to their passage with a rough absorber, as proposed in [17].…”

Near-surface quantum states of neutrons in the gravitational and centrifugal potentials

“…% 10 ÏÍÏ [6,7]. £ ÍÂÚÇÔÕÄÇ ÊÇÓÍÂΠAEÎâ µ·¯, ÑÚÇÄËAEÐÑ, ÏÑÉÇÕ ÔÎÖÉËÕß ÑÒÕËÚÇÔÍËÌ ÒÑÕÇÐÙËÂÎ [8] ÒÑÎËÓÑÄÂÐÐÑÌ ÒÑÄÇÓØÐÑÔÕË ÕÄÈÓAEÑÅÑ ÕÇΠËÎË ÒÑÄÇÓØ-ÐÑÔÕË ÉËAEÍÑÔÕË [2], ÄÑÊÐËÍÂáÜËÌ ÄÔÎÇAEÔÕÄËÇ ÐÇÌÕÓÑÐ-âAEÇÓÐÑÅÑ ÄÊÂËÏÑAEÇÌÔÕÄËâ, Ë, ÍÓÑÏÇ ÕÑÅÑ, ÅÓÂAEËÇÐÕ ÏÂÅ-ÐËÕÐÑÅÑ ÒÑÎâ, ÄÊÂËÏÑAEÇÌÔÕÄÖáÜËÌ Ô ÏÂÅÐËÕÐÞÏ ÏÑ-ÏÇÐÕÑÏ ÐÇÌÕÓÑР[9].…”

Application of Diamond Nanoparticles in Low-Energy Neutron Physics

“…UCN are neutrons with very low energy of smaller than a few times 10 -7 eV. They are totally reflected from surface at any incidence angle if their energy is lower than the effective nuclear optical potential of surface material [4,5,6,7]. The characteristic penetration depth is close to its wavelength and equal to a few tens of nanometers.…”