Millikelvin LEED apparatus: a feasibility study

TL;DR

This paper proposes a design for a low-temperature LEED system operating at around 100 mK to study 2D helium structures, utilizing cryogen-free cooling and optimized detection methods.

Contribution

It introduces a feasible design for a millikelvin LEED apparatus and estimates helium scattering signals using a kinematical model.

Findings

Design feasibility of millikelvin LEED apparatus.

Helium diffraction signals can be detected with delay-line detectors.

Thermal inflow reduction enables ultra-low temperature operation.

Abstract

A low-energy electron diffraction (LEED) apparatus which works at temperatures down to about 100 mK is designed to obtain structural information of 2D helium on graphite. This very low temperature system can be realized by reducing the thermal inflow from the LEED optics to the sample which is cooled by cryogen-free dilution refrigerator. The atomic scattering factor of He is also estimated using a kinematical model, which suggests that the diffraction signal from He atom can well be obtained by using a delay-line detector instead of a fluorescent screen.