Magnetic scattering neutrons

Unlike these conventional techniques, NSE measures the neutron velocities of the incident and scattered neutrons using the Larmor precession of the neutron spin in an external magnetic field, whereby, the neutron spin vector acts like the hand of an internal clock, which is linked to each neutron and stores the result of the velocity measurement at the neutron itself. The velocity measurement is thus performed individually for each neutron. For this reason, the... 

Skinner, J. L. and Trommsdorf, H. P. Proton transfer in benzoic acid crystals A chemical spin-boson problem. Theoretical analysis of nuclear magnetic resonance, neutron scattering, and optical experiments, J.Chem.Phys., 89 (1988), 897-907... 

Neutron diffraction by crystals has been found valuable for locating hydrogen atoms (especially deuterium atoms, which scatter neutrons strongly), for studying the arrangement of magnetic moments, and for other special purposes. A summary is given by G. E. Bacon, Neutron Diffraction, Clarendon Press, Oxford, 1955. 

An important modern tool for the direct observation of spin configurations is neutron diffraction. Because the neutron is a neutral particle that carries a magnetic moment, it is primarily scattered by only the atomic nucleus and electrons with unpaired spins. Halpern and Johnson (247) have shown that the differential scattering cross section of an atom, including both nuclear and magnetic scattering, is... 

The treatment presented here could be extended to address magnetic materials as well. For the sake of completeness and as an illustration, the magnetic scattering of a neutron beam (unpolarized) can be written equivalently to equation 4 presented earlier as ... 

Extensively used to locate hydrogen atoms. May ve additional information due to spin ) on neutron leading lo magnetic scattering... 

The theory of the magnetic scattering of thermal neutrons has been described in some detail by Marshall and Lovesey (1). Only a brief outline of those relations relevant to the present discussion will be given here. This limits the discussion to elastic scattering by spin-only systems ). Experimental techniques such as time-of-flight diffractometery are not discussed as no applications have yet been made to the subject under discussion. 

The conventional polarized beam experiment is useful only for systems with polarization dependent cross sections. More information can often be gained if the polarization of the scattered neutrons is measured relative to the incident polarization (polarization analysis). This may be done in a triple-axis mode with a polarization sensitive analyzing crystal (Fig. 11). The technique was introduced experimentally by Moon et al. (59). In their apparatus the magnetic field at the sample may be rotated about a horizontal axis. With the sample field vertical the neutron polarization remains vertical, but with the sample field horizontal the neutron polarization at the sample becomes horizontal (a reverse rotation occurs after the sample so that the polarization at the analyzing crystal is again vertical). Thus P can be either parallel or perpendicular to the scattering vector n. 

Fig. 34. One-dimensional antiferromagnetic arrays. The solid and open circles denote magnetic and non-magnetic atoms respectively. The arrows give the spin directions. Cases (a) and (b) will scatter neutrons of opposite polarization differently, Case (c) is intensitive to the polarization of the incident beam [after Ref. (57)]...

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