Ultracold-neutron infrastructure for the gravitational spectrometer GRANIT

TL;DR

This paper describes the development of a high-density ultracold-neutron source and infrastructure for the GRANIT gravitational spectrometer, enabling precise neutron experiments related to gravity at the Institut Laue Langevin.

Contribution

It introduces a novel ultracold-neutron source using superthermal conversion in superfluid helium with a specialized extraction technique to enhance neutron density for gravitational experiments.

Findings

Neutron density up to 800 1/cm3 achieved

Monochromator using graphite intercalated with potassium

Extraction method limits vertical velocity to improve density

Abstract

The gravitational spectrometer GRANIT will be set up at the Institut Laue Langevin. It will profit from the high ultracold neutron density produced by a dedicated source. A monochromator made of crystals from graphite intercalated with potassium will provide a neutron beam with 0.89 nm incident on the source. The source employs superthermal conversion of cold neutrons in superfluid helium, in a vessel made from BeO ceramics with Be windows. A special extraction technique has been tested which feeds the spectrometer only with neutrons with a vertical velocity component v < 20 cm/s, thus keeping the density in the source high. This new source is expected to provide a density of up to 800 1/cm3 for the spectrometer.