Page 94 - bukuneutron

terial with single crystal monochromator. There is es-
tablished method to measure the wavelength of neu-
tron using Silicon(Si) powder. Usually National British
Standar Si powder can be used. Unit cell of Si crystal
is cubic lattice. Measurement gives values of lattice
constant a,in X direction of unit cell, which is similar
magnitude for b, in Y direction and c, in Z direction.
In the standard, values of d spacing for lattice planes
(111),(220),(311),(400) and (331) are given Table 4.1.

Table 4.1: Lattice spacing for planes

(111),(220),(311),(400) and (331) of Si powder

given in National British Standard for determination

the wavelength of neutron diffraction instrument.

hkl d 2θ 1 tanθ
2dcosθ

1 1 1 3.135555 38.52283 0.1689334 0.3497548

2 2 0 1.920127 65.25756 0.3092322 0.6404907

3 1 1 1.63749 78.44384 0.3942600 0.8168119

4 0 0 1.357735 99.42895 0.5696920 1.1803187

3 3 1 1.245943 112.45742 0.7222156 1.4962769

Where, θ is a scanning angle in neutron diffraction
of Si powder sample. The relationship between θ with
neutron wavelength λ is given in Equation 4.2

tanθ = λ 1θ (4.2)
– tan
2dcosθ 2
cos θ
2

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