The design, construction and applications of a novel double-axis helium atom spectrometer

Abstract

<p>A novel helium atoms spectrometer has been developed for the study of elastic and inelastic collisions with surfaces. The spectrometer is a double-axis design, providing the experimentalist with the capability of using an analyzer crystal to provide energy resolution for either elastic or inelastic experiments. The spectrometer is novel in that scattering angle at both axes may be adjusted during the experiment, allowing great flexibility in the design and execution of experiments of solid surfaces;The mechanisms and operating characteristics of the spectrometer are described. The initial tests of the spectrometer, using the well characterized LiF(001) surface, are also presented. These tests demonstrate that the spectrometer may function as a high precision double-axis diffractometer. During these initial tests, spurious scattering events and an insufficient signal to background ratio prevented the observation of single phonon scattering. Subsequent modifications to improve the signal to background are described.</p>