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![[Figure 1]](in5031fig1mag.jpg)
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Figure 1
Sketch of a Larmor diffractometer. A polarized neutron beam crosses the uniform field B0 twice. The boundaries of B0 are oriented parallel to the lattice planes dhkl, G = 2π/dhkl. In the resonant spin–echo configuration (NRSE), instead of a uniform field B0 four RF spin flippers C1–C4 define the boundaries of the precession regions, and there is no field along the flight path between the flippers and in the sample region. C1–C4 are double coils, each consisting of two single RF spin-flip coils with opposite field direction (known as the `bootstrap' technique; Gähler & Golub, 1988  ). The Larmor phase shift ΔϕLD and the polarization are obtained from the count rate I versus the position ΔL of the coil C4 (ΔL in the inset is in units of millimetres): I(ΔL) = I0{1 + Pcos[2π(ΔL − ΔL0)/Lper]}, where the period is Lper = 2πvn/ωL, vn is the neutron velocity and ωL the Larmor frequency. With the offset ΔL0, the phase is ΔϕLD = 2πΔL0/Lper. |
![[Figure 1]](in5031fig1.jpg)
 | JOURNAL OF APPLIED CRYSTALLOGRAPHY |
ISSN: 1600-5767
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