Author: Erik B Knudsen (erkn@fysik.dtu.dk), Kristian Sorensen and Philip Smith

Origin: DTU

Date: June 2021

Description

A reflective grating that diffracts incident photons.
The grating is in the XZ-plane. It then reflects the incoming photon using a MC picked angle,
where the angle is picked from a uniform distribution of width d_phi, i.e. U[-d_phi/2,d_phi/2]
The Monte Carlo wight of the ray is then adjusted wrt. to the grating interference pattern, and
the diffraction pattern associated with each grating line. All lines are considered equal.
For more efficient sampling of a particular direction the centre of the d_phi may be shifted
using the parameters order or phi0. In the latter case a set angle is chosen as the centre of the
sampled interval, in the former the centre angle is computed from the specified grating order.
In an upcoming release this grating model will also include a blazed grating.

Input parameters

Parameters in boldface are required;
the others are optional.

Name

Unit

Description

Default

d_phi

deg

Range of diffraction angle that is to be simulated -d_phi/2 ; d_phi/2.

1

R0

Constant reflecticity of the grating [0;1].

1

rho_l

l/mm

Number of lines pr mm of the grating.

800

order

The target order of the grating. If non-zero d_phi will be centered around this scattering line.

0

phi0

deg

Target angle to center d_phi. If this is set to 0 the 0th (or any other chosen by the parameter order) order line will be used.

0

zdepth

m

The length of the grating.

0.015

xwidth

m

The width of the grating.

0.136

verbose

If non-zero, more information will be displayed. Nb. generates much output.

0

Output parameters

Parameters in boldface are required;
the others are optional.

Name

Unit

Description

Default

d

AA

Width of the slits in Angstrom. If zero, default is found using rho_l.

pdir

b

AA

Width of the spacing i Angstrom. If zero, default is found using rho_l/3.