Normalisation of the resolution function in TOF technique

Article type: Research Article

Authors: Dorner, Bruno

Affiliations: Institut Laue-Langevin, F38042, Grenoble cedex, France

Note: [] E-mail: [email protected]

Abstract: The normalisation factors of the resolution function are the basic components for the conversion of measured neutron scattering spectra to the scattering function S(Q, ω). The instrumental resolution function and its normalisation factors are derived independently of any sample and its S(Q, ω). As shown earlier for Three-Axis Spectrometer, these factors, also in time of flight (TOF) technique, are symmetric for the incoming beam, with p(kI)k4I, and the scattered beam, with p(kF)k4F, Here kI and kF are the wave vectors of the incoming and scattered neutrons; p(kI) describes the spectrum of the source in phase-space and p(kF) the detector efficiency. In direct TOF the conversion factor is [p(kF)k4F]−1. In inverse TOF it is [p(kF)k4I]−1 The latter depends on the neutron source. For thermal neutrons (gas in thermal equilibrium) the conversion factor is [k4I exp(−k2I/k2T)]−1, where the wave vector kT corresponds to temperature. For epithermal neutrons, in the eV range, the conversion factor is constant.

Keywords: Inelastic scattering, Data analysis

DOI: 10.1080/10238160512331330189

Journal: Journal of Neutron Research, vol. 13, no. 4, pp. 267-274, 2005